Arkansas Soybean Verification Coordinator, Chris Grimes, discusses this year's experience with trying to control herbicide resistant pigweed in soybean after rain kept researchers from making a much-needed Valor herbicide application.
Monday, September 6, 2010
Louisiana Confirms First Case Of Roundup-Resistant Palmer Pigweed, Water Hemp Issue Also Suspected
Roundup-resistant Palmer pigweed (aka Palmer amaranth) has been confirmed for the first time in Louisiana, according to a memo from Daniel Stephenson, LSU AgCenter Weed Scientist.
The memo was included Sunday morning, September 5, in AMS AG REPORT, the weekly newsletter published by consultant Roger Carter with Agricultural Management Services, Inc., a firm that covers several parishes in east-central Louisiana.
Carter said that Tim White, a consultant in the firm, "has worked on this farm with Dr. Stephenson for several years trying to manage this weed. This particular farm is near Lake St. John."
Stephenson noted in the memo that Roundup-resistant Palmer pigweed already had been confirmed in Alabama, Arkansas, Georgia, Mississippi, Tennessee and several other other states.
Stephenson reported that he had now "confirmed that Palmer amaranth collected from a cotton field in Concordia Parish is resistant to glyphosate."
According to his analysis, 50% of the Concordia Parish population "is approximately 54 times less sensitive to glyphosate compared to the susceptible standard. In other words, if the labeled use rate of glyphosate is 32 fluid ounces/Acre, a producer will have to apply 118 oz/Acre of glyphosate to control 50% of the Palmer population or 723 oz/A to control 90% of the population.”
In a followup memo Sunday afternoon, Stephenson noted that other cases of hard-to-control pigweed were being investigated.
"Unfortunately, LSU AgCenter weed scientists are following up on many other locations throughout Louisiana where Palmer amaranth or waterhemp, another Amaranthus species, have not been effectively controlled by glyphosate," he noted. "Any producer or consultant in Louisiana should be aware of the potentially devastating effect herbicide-resistant weeds can have on their crop. If you suspect that a weed population is resistant to a herbicide (not just glyphosate, ANY herbicide), please contact your local LSU AgCenter county agent.
"AgCenter personnel need to know of these issues so we can help you avoid or mitigate weeds resistance from spreading throughout Louisiana."
- Owen Taylor
The memo was included Sunday morning, September 5, in AMS AG REPORT, the weekly newsletter published by consultant Roger Carter with Agricultural Management Services, Inc., a firm that covers several parishes in east-central Louisiana.
Carter said that Tim White, a consultant in the firm, "has worked on this farm with Dr. Stephenson for several years trying to manage this weed. This particular farm is near Lake St. John."
Stephenson noted in the memo that Roundup-resistant Palmer pigweed already had been confirmed in Alabama, Arkansas, Georgia, Mississippi, Tennessee and several other other states.
Stephenson reported that he had now "confirmed that Palmer amaranth collected from a cotton field in Concordia Parish is resistant to glyphosate."
According to his analysis, 50% of the Concordia Parish population "is approximately 54 times less sensitive to glyphosate compared to the susceptible standard. In other words, if the labeled use rate of glyphosate is 32 fluid ounces/Acre, a producer will have to apply 118 oz/Acre of glyphosate to control 50% of the Palmer population or 723 oz/A to control 90% of the population.”
In a followup memo Sunday afternoon, Stephenson noted that other cases of hard-to-control pigweed were being investigated.
"Unfortunately, LSU AgCenter weed scientists are following up on many other locations throughout Louisiana where Palmer amaranth or waterhemp, another Amaranthus species, have not been effectively controlled by glyphosate," he noted. "Any producer or consultant in Louisiana should be aware of the potentially devastating effect herbicide-resistant weeds can have on their crop. If you suspect that a weed population is resistant to a herbicide (not just glyphosate, ANY herbicide), please contact your local LSU AgCenter county agent.
"AgCenter personnel need to know of these issues so we can help you avoid or mitigate weeds resistance from spreading throughout Louisiana."
- Owen Taylor
Friday, May 21, 2010
Roundup-Resistant Pigweed Getting Away From Tennesse Farmers. Control Options Aren't Promising.
The following is from Larry Steckel, Tennessee Extension Weed Specialist, who this week addressed the fact that wet weather in the upper Delta has caused a huge - read that, expensive - problem with Roundup-resistant Palmer pigweed. He offers options, none of which seem all that promising, considering the way this weed operates in its Roundup-resistant form - Owen Taylor
Roundup-resistant Palmer pigweed is geting away from us fast.
Due to all this wet weather, the pre applied herbicides are giving out quickly. Moreover, it has often been too wet to spray post emergence as timely as we need to.
This is shaping up into a perfect storm.
I received the first calls of the year on Palmer pigweed issues in soybeans and cotton. One consultant called and said that Prefix applied last week had not controlled 4-inch-tall Palmer.
This is not surprising. A 4-inch-tall gramoxone-resistant (GR) Palmer pigweed (amaranth) is getting too large for any PPO herbicide to control. Ignite at higher rates (32 to 40 oz/A) can control Palmer up to about 6 inches, though this can be inconsistent at times.
The unfortunate truth is that if Roundup/glyphosate is unable to control tall Palmer amaranth due to resistance there is no herbicide that will.This coupled with the fact that a 2-inch Palmer amaranth can quickly become an 8-inch Palmer amaranth even with 44 ozs/A of Roundup PowerMax on it (as seen in last year’s picture at right) leaves us very few days to get these post herbicides applied.
Other reports have come in on RR Flex Cotton where the management plan was to use overlapping residual herbicides. The problem being that it was too wet to get the second overlapping residual on and now there is a heavy flush of Palmer pigweed in a good cotton stand.
There are not any real good options for fields in this shape with resistant Palmer pigweed. It is still early enough to replant soybeans and if we can get in next week cotton, as well. Depending upon the density of the GR Palmer this would probably be the best option.
The number one question of the week is from folks wanting to spray Ignite on cotyledon WideStrike cotton. The first Palmer pigweed flush is right with cotton emergence in a number of fields. In other cotton fields we are seeing some late regrowth of horseweed.
The main question is how safe is it to spray cotyledon WideStrike cotton with Ignite to control these weeds?
The answer from research we have conducted here as well as some from Georgia is that cotyledon WideStrike cotton tolerates Ignite a little better than 5-leaf cotton. My observations from this work have been that the waxy cotyledons do not seem to show effects from Ignite like a true cotton leaf will. In general we will see about 10% injury on cotyledon WideStrike cotton and typically 15 to 20% injury on more mature cotton.
What about tank-mixing Dual Magnum with my Ignite on WideStrike cotton?
My answer is in areas where GR Palmer amaranth is already established the benefits outweigh the risk. We have conducted several trials with this tankmix (I would like to run several more) and seen anywhere from 0 to 5% more injury compared to Ignite alone. If the Dual Magnum gets activated this may save one or even two over the top Ignite applications to the cotton.
What about tank-mixing Prowl H2O with Ignite on WideStrike cotton?
I have not looked at this tankmix on WideStrike cotton. I have seen it on one trial several years back in Liberty Link cotton. I did not like the results. We saw antagonism on the Palmer amaranth control compared to Ignite alone or Ignite tankmixed with Dual Magnum.
Moreover, the injury to the LL cotton from the Ignite tankmixed with Prowl H2O appeared to be more than I saw with the Dual Magnum tankmix. This is only one trial, but it suggested to me that we need more research on it before we recommend Ignite tank mixtures with Prowl H2O on LL cotton as well as WideStrike cotton.
Monday, April 19, 2010
Roundup Resistant Weeds: A Battle Plan For 2010
Dr. Ken Smith, extension weed scientist for the University of Arkansas Division of Agriculture, is dead serious about the subject of herbicide resistant weeds, especially the obnoxious pigweed. He wants to see the seed dead before it even has a chance to germinate.
In Pigweed: Kill the Seed, Beat the Weed Smith makes these points:
In Pigweed: Kill the Seed, Beat the Weed Smith makes these points:
- Pigweed seed has a fairly short life in the soil.
- Deep tillage is a promising tactic that exploits pigweed’s weakness.
- Burndown does NOT destroy pigweed seed, and it may actually stimulate germination by creating light.
- "Zero tolerance" combines hand hoeing and supplemental herbicide application, a method that may ensure pigweed doesn’t reach maturity and produce seed.
Friday, April 16, 2010
Purging Valor from herbicide spraying tanks and systems
Valor has emerged as an important herbicide tool where farmers are either trying to prevent Roundup resistant weed development or are coping with this serious problem.
The downside to Valor is that even faint traces of it carried over in later sprays can harm other crops.
Valent, the herbicide's manufacturer, has issued an updated list of recommendations for farmers or applicators who need to purge Valor residue from spray equipment.
Here's the link.
The downside to Valor is that even faint traces of it carried over in later sprays can harm other crops.
Valent, the herbicide's manufacturer, has issued an updated list of recommendations for farmers or applicators who need to purge Valor residue from spray equipment.
Here's the link.
Palmer Amaranth (Pigweed) Herbicide Program Suggestions (In Roundup Ready Cotton Only)
The following was sent to us by Scott Brown, Colquitt County, Georgia, Extension Agent
It is not a question of if you will have glyphosate resistant Palmer amaranth in your fields but when. It is going to happen to you sooner or later, so be prepared. Also remember that we have many fields with ALS inhibitor resistant Palmer amaranth in them so precautions should be taken. Use the best yellow and at-plant residual program for your situation.
First Law of Cotton Weed Control: Use a yellow herbicide (Prowl, Treflan or generic equivalent) on every acre.
It is not a question of if you will have glyphosate resistant Palmer amaranth in your fields but when. It is going to happen to you sooner or later, so be prepared. Also remember that we have many fields with ALS inhibitor resistant Palmer amaranth in them so precautions should be taken. Use the best yellow and at-plant residual program for your situation.
First Law of Cotton Weed Control: Use a yellow herbicide (Prowl, Treflan or generic equivalent) on every acre.
Second Law of Cotton Weed Control: When in doubt about using a yellow herbicide in cotton refer to First Law of Cotton Weed Control.
RESIDUAL AT-PLANT HERBICIDES: Due to the resistance issue a preemergence at-plant herbicide such as Valor, Reflex, fluometuron (Cotoran), diuron (Direx), or Staple (in some fields) is strongly recommended. Where possible you should irrigate to activate pre-emergence herbicides, if no rain within 5-7 days after planting. Unless you plan to cultivate all residual at-plant herbicides should be broadcast.
Reflex (applied at planting) and Valor (applied preplant) are used interchangeably depending on crop rotation. It is our opinion that only one of these products should be used on the same acreage per crop year. The label does not prohibit the use of both sequentially on the same cropping system but is a UGA recommendation to help prevent PPO resistance development.
Reflex should not be used where sensitive vegetables or other crops will be rotated behind treated cotton (especially brassicas such as: cabbage, collards, turnips, etc). Valor has a short rotational restriction for most crops. Valor can only be used prior to planting: conventionally planted cotton (beds already knocked off) 30 days and a 1 inch rain event; no-till planted cotton 21 days and a 1 inch rain event; strip-till cotton 14 days regardless of rain event). Valent recommends that Valor should always be followed by a preemregence herbicide (Prowl, diuron, cotoran, Staple) at planting. Please check the label. WHEN USING VALOR PLEASE FOLLOW THE VALENT VALOR TANK CLEANOUT PROCEDURE.
Note about STAPLE use: It is our opinion that Staple post plant treatments should not be made if a Staple at plant treatment was applied (Situation 3 below). The label does not prohibit the use of sequential treatments in the same cropping system; this is a UGA suggestion to help prevent ALS inhibitor resistance development.
SITUATION 1.) Fields with major glyphosate resistant Palmer amaranth problems but no ALS inhibitor resistance (if Valor (2 oz/A) is substituted for Reflex then it must be applied at least 14-30 days prior to planting, dependent on cropping system, as outlined above):
Step 1.) Yellow herbicide (use full label rate) PPI or at planting.Step 2.) Reflex (12-16 oz/A) + diuron (Direx) 4L (16 oz/A) at-plant. Note: Staple at 1.7-2.1 oz/A can be substituted for diuron (Direx) at planting but this eliminates the over-the-top glyphosate + Staple option in Step 3.Step 3.) Glyphosate (label rate) + Dual Magnum (16-21 oz/A) at 4 leaf stage if no Palmer is emerged. If Palmer is emerged then glyphosate (label rate) + Staple (2.6-3.8 oz/A).Step 4.) MSMA (32-42 oz/A) + diuron 4L (32 oz/A) + crop oil concentrate. Note: Layby Pro or Suprend may be substituted for diuron. Check label for rates.
NOTE: If Palmer escapes occur earlier than 4 leaf then apply Staple over-the-top beginning at the 2 leaf stage of the crop but before pigweeds are 2 inches tall. This would be between Steps 1 and 2. Do not mix Staple with Dual (or any metolachlor product) or apply within 3+ days either way of a Dual application. Valor is labeled to be used at layby but it is our suggestion to not do so if Reflex was used at planting.
SITUATION 2.) Fields with major glyphosate and ALS inhibitor resistant Palmer amaranth problems:
Same as Situation 1.) but Staple is not an option in Step 2 or Step 3.
SITUATION 3.) Fields with heavy Palmer Amaranth populations but sensitive to glyphosate and ALS inhibitors (if Valor (2 oz/A) is substituted for Reflex then it must be applied at least 14-30 days prior to planting, dependent on cropping system, as outlined above):
Step 1.) Yellow herbicide (use full label rate) PPI or at planting.Step 2.) Reflex (12-16 oz/A) or diuron (Direx) 4L (16-32 oz/A*) or Cotoran (2-3 pts/A) or Staple at 1.7-2.1 oz/A. If Staple is used at plant then it should not be used in Step 3 or for early escapes.Step 3.) Glyphosate (label rate) + Dual Magnum (16-21 oz/A) at 4 leaf stage if no Palmer is emerged. If Palmer is emerged then glyphosate (label rate) + Staple (2.6-3.8 oz/A).Step 4.) MSMA (32-42 oz/A) + diuron 4L (24-32 oz/A*) + crop oil concentrate. Note: Layby Pro or Suprend may be substituted for diuron. Check label for rates.
NOTE: If Palmer escapes occur earlier than 4 leaf then apply Staple over-the-top begining at the 2 leaf stage of the crop but before pigweeds are 2 inches tall. This would be between Steps 1 and 2. Do no mix Staple with Dual (or any metolachlor product) or apply within 3+ days either way of a Dual application.
*To avoid potential rotational issues do not exceed 3 total pints of diuron (Direx) as a pre and post treatment per year. Further, diuron is potentially more injurious to cotton seedlings at higher rates than Cotoran. On lighter soils lower use rates of diuron should be considered. Diuron should not be used on very sandy soils due to potential injury.
SITUATION 4.) Fields with low-moderate glyphosate and ALS inhibitor sensitive Palmer amaranth problems:
Step 1.) Yellow herbicide (use full label rate) PPI or at planting.Step 2.) Diuron (Direx) 4L (16-32 oz/A*) or Cotoran (2-3 pts/A) or Staple at 1.7-2.1 oz/A. If Staple is used at plant then it should not be used in Step 3 or for early escapes.Step 3.) Glyphosate as needed.Step 4.) MSMA (32-42 oz/A) + diuron 4L (24-32 oz/A*) + crop oil concentrate. Note: Layby Pro or Suprend may be substituted for diuron. Check label for rates. Can layby with Valor, since no Reflex was used.
NOTE: If Palmer escapes occur early then apply Staple over the top beginning at 2 leaf stage of crop but before pigweeds are 2 inches tall. This would be between Steps 1 and 2. Do no mix Staple with Dual (or any metolachlor product) or apply within 3+ days either way of a Dual application.
*To avoid potential rotational issues do not exceed 3 total pints of diuron (Direx) as a pre and post treatment per year. Further, diuron is potentially more injurious to cotton seedlings at higher rates than Cotoran. On lighter soils lower use rates of diuron should be considered. Diuron should not be used on very sandy soils due to potential injury.
Thursday, April 8, 2010
How Fast Can Roundup-Resistant Palmer Pigweed Build? Read This.
Leaving just 5 Roundup-resistant female Palmer pigweed plants per acre - even with 99.9% control the next year - leads to 400 per acre the next year. With similar control, by the third year you’ll have 32,000 female plants producing resistant offspring. See last week's Seminole Co., Ga., E-letter for more info on seed bank concept.
- Owen Taylor
- Owen Taylor
Burndown Herbicide Options For Cotton And Soybeans In 2010
From Donnie Miller, Daniel Stephenson, and Bill Williams, Louisiana State University Weed Scientists
An extremely positive attribute to the herbicides glyphosate and glufosinate, used in a Roundup Ready or Liberty Link weed control system, respectively, is that both can exhibit excellent activity on weed species larger in size than what is recommended for optimum activity on individual labels.
Unfortunately, this can also be an extremely negative attribute to each herbicide.
Delaying herbicide application for the sake of having a greater population present to get more “bang for the buck” with a single application can allow weeds to compete with emerging crops. Early season weed competition in both soybean and cotton can result in reduced yield with little impact often observable prior to harvest. In addition, application to larger weeds can result in reduced control of less-sensitive species with glufosinate (pigweed, goosegrass, and broadleaf signalgrass) and glyphosate (morningglory species, hemp sesbania, and prickly sida).
This in turn can lead to increased weed seed-bank populations in the soil due to continued seed production and negate long term weed management efforts.
Although weed resistance to glyphosate has not been scientifically documented in Louisiana to date, the fact is that various weed populations have proven difficult to control with the herbicide in some cases (amaranths, ragweed, and Johnsongrass).
This “practical” resistance is becoming a larger issue and although attributable to spraying weeds that are too large in some instances, a “red flag” should go up whenever control failures exist. Resistance issues in other states have led to increases in herbicide management costs of 40 to 50$/A with additional herbicides needed or complete field abandonment. The economic impact of weed resistance is also realized in decreased value of the transgenic technology, as weeds previously controlled in the system become less and less susceptible, and potential decreased land rent value.
Use of residual herbicides in today’s transgenic world of soybean and cotton production can result in positive benefits including reduced early-season weed competition through prevention of weed germination in early crop development stages and weed resistance management through introduction of alternative modes of action to glyphosate or glufosinate.
To achieve maximum activity from residual herbicides, proper activation of the material must occur. Activation is placement of the herbicide in the soil region that maximizes opportunity for herbicide uptake by the emerging weed seedling. Herbicide activation is accomplished through rainfall/irrigation or mechanical incorporation. Most labels will call for a rainfall or irrigation amount of 0.5 inches or greater, preferably in one event. Mechanical uniform incorporation of the herbicide in the top 2 to 3 inches will adequately activate most herbicides. The majority of herbicides soil applied at planting will require mechanical uniform incorporation preferably within 7 to 10 days after application if rainfall is not received.
Below is a brief discussion of some of the relatively newer compounds available for preplant use in soybean in 2010, a number of which have been evaluated by LSU AgCenter Weed Scientists. Please refer to individual herbicide labels for plant-back intervals, precautions/restrictions, soil type and rates, and special requirements/uses (ie reduced rate application in planned PRE/POST programs, incorporation instructions, activation requirements, notes for maximum control of selective species etc.). Herbicide labels can be accessed at the following website: http://www.cdms.net/LabelsMsds/LMDefault.aspx?srchPdt%20=%20&t. A table summarizing replant intervals to field corn, cotton, grain sorghum, soybean, and wheat following application of most pre-plant herbicides also follows.
Newer Herbicides for 2010
Authority First (soybean): Authority First combines the active ingredient sulfentrazone (Spartan herbicide) and cloransulam-methyl (FirstRate herbicide). This product is labeled for control of pigweed (Amaranths), morningglory (suppression on pitted), prickly sida (teaweed), groundcherry, hophornbeam copperleaf, smellmellon, yellow and purple nutsedge, and annual sedge. It provides suppression of most annual grasses. The use rates range from 6.45 oz/A (soils 3% organic matter or less) to 8 oz/A (soils greater than 3% organic matter). Do not apply to soils classified as sands with organic matter less than 1%.
Authority MTZ (soybean): Authority MTZ combines the active ingredient sulfentrazone (Spartan herbicide) and metribuzin (Sencor or Lexone herbicide). This product expressed good activity on pigweed (Amaranths), morningglory, prickly sida (teaweed), groundcherry, hophornbeam copperleaf, smellmellon, yellow and purple nutsedge, and annual sedge. It provides suppression of most annual grasses. The use rates range from 12 to 20 oz/A depending on soil type (see label). On soils with Ph greater than 7.5, use rate should not exceed 12 oz/A. Research has shown excellent activity at the rate of 14 ounces product per acre, which provides an equivalent rate of 5 oz/A metribuzin. The herbicide label should be consulted for listing of metribuzin-sensitive soybean varieties.
Axiom DF (soybean): Axiom DF combines the active ingredient flufenacet and metribuzin (Sencor or Lexone herbicide). The herbicide controls barnyardgrass, crabgrass, foxtail species, goosegrass, and fall panicum. Will provide suppression of seedling johnsongrass, broadleaf signalgrass, pigweed species, prickly sida, Pennsylvania smartweed, and waterhemp. Use rate range is 7 to 13 oz/A. The herbicide label should be consulted for listing of metribuzin-sensitive soybean varieties.
Envive (soybean): Envive combines the active ingredients of chlorimuron ethyl (Classic herbicide), thifensulfuron methyl (Harmony GT herbicide), and flumioxazin (Valor herbicide) in one pre-mix product. Envive offers the advantage of two independent modes of action, which can aid in weed resistance management. This product expresses strong efficacy on pigweed, morningglory, sicklepod, prickly sida (teaweed), smartweed, and hophornbeam copperleaf while suppressing annual grasses. Use rates range from 2.5 to 5.3 oz/A. It can be applied up to three days after planting. In non-STS or RR/STS soybean, do not apply within 14 days before or after application of an organophosphate insecticide. Higher rates of Envive may “carry over” when applied to soils with a pH of 7.5 or greater and injure crops planted the following year due to the Classic portion of the herbicide. If a producer wishes to apply Envive on a high pH soil, then Enlite at 2.8 oz/A may be an option. Enlite combines the same active ingredients as Envive except the Classic portion is less. Enlite provides similar performance against the weed spectrum previously listed for Envive.
Gangster (soybean): Gangster is a multi-pack combination of the active ingredients flumioxazin (Valor SX) and cloransulam methyl (FirstRate). Labeled for control of morningglory species, pigweed species, Palmer amaranth, prickly sida, smartweed, copperleaf, and wild poinsettia. Suppression of barnyardgrass, large crabgrass, giant foxtail, goosegrass, panicum, and broadleaf signalgrass can be expected. Use rates range from 3 to 3.6 oz/A. The 3 oz/A rate is equivalent to applying 2.5 oz/A Valor SX and 0.5 oz/A FirstRate.
Prefix (soybean): Prefix combines the active ingredient s-metolachlor (Dual Magnum) and Reflex (fomesafen). Provides control of barnyardgrass, crabgrass, foxtail species, goosegrass, seedling johnsongrass, pigweed species, wild poinsettia, and smartweed species. It provides partial control of morningglory species, yellow nutsedge, and prickly sida (teaweed). Use rates range from 2 to 3 pt/A depending on soil type.
Sharpen (soybean): Sharpen contains the active ingredient saflufenacil. This product shows good activity on pigweed species, morningglory species, Palmer amaranth, waterhemp, and prickly sida (teaweed). Use rate is 1 oz/A.
Valor XLT (soybean): Valor XLT combines the active ingredients flumioxazin (Valor SX) and chlorimuron ethyl (Classic). Weeds controlled with this herbicide include copperleaf, prickly sida, pigweed species, morninglory species, palmer amaranth, smartweed, and wild poinsettia. Suppression of barnyardgrass, large crabgrass, broadleaf signalgrass, goosegrass, and panicums can be expected. Use rate ranges from 3 to 5 oz/A.
Plantback intervals for at-planting soil applied herbicides in soybean and cotton
118 month replant interval if 6.45 to 8 oz/A was applied to soils with organic matter 1.5% or less and pH > 7.
2 Field corn can be planted 4 months after application at 14 oz/A or less. Grain sorghum can be planted 12 months after application at 20 oz/A or less.
318 month replant interval for rate greater than 3.5 oz/A and pH > 7. Field corn can be replanted in 9 months given Canopy rate does not exceed 6 oz/A.
4Refer to label for Requirements for Planting Time section.
5Longer replant intervals must be observed for soil pH 7 or greater.
6 Fomesafen is the active ingredient in herbicides such as Dawn, Reflex, and Rhythm.
7Metolachlor or s-metolachlor (see specific label for active ingredient contained) is the active ingredient in herbicides such as Dual Magnum, Cinch, Me-too-lachlor, Stalwart, Parrlay, Parallel, and similar commercially available herbicides.
8Pendimethalin is the active ingredient in herbicides such as Prowl 3.3 EC, Prowl H2O, Pendimax 3.3 and similar commercially available herbicides.
918 month replant interval for rates above 8 oz/A.
10If applied on a band (not exceeding 50% row width) and thorough soil mixing occurs, a 9 month replant interval must be observed. If rate does not exceed 3.8 oz/A total broadcast, a 10 month interval should be observed without additional soil mixing beyond normal in your particular production system.
11See label for additional replant notes.
12Trifluralin is the active ingredient in herbicides such as Treflan HFP and Trifluralin 4 EC and similar commercially available herbicides.
13One inch rainfall must be received in addition to replant interval. Intervals are for rates of 2 oz/A or less.
Unfortunately, this can also be an extremely negative attribute to each herbicide.
Delaying herbicide application for the sake of having a greater population present to get more “bang for the buck” with a single application can allow weeds to compete with emerging crops. Early season weed competition in both soybean and cotton can result in reduced yield with little impact often observable prior to harvest. In addition, application to larger weeds can result in reduced control of less-sensitive species with glufosinate (pigweed, goosegrass, and broadleaf signalgrass) and glyphosate (morningglory species, hemp sesbania, and prickly sida).
This in turn can lead to increased weed seed-bank populations in the soil due to continued seed production and negate long term weed management efforts.
Although weed resistance to glyphosate has not been scientifically documented in Louisiana to date, the fact is that various weed populations have proven difficult to control with the herbicide in some cases (amaranths, ragweed, and Johnsongrass).
This “practical” resistance is becoming a larger issue and although attributable to spraying weeds that are too large in some instances, a “red flag” should go up whenever control failures exist. Resistance issues in other states have led to increases in herbicide management costs of 40 to 50$/A with additional herbicides needed or complete field abandonment. The economic impact of weed resistance is also realized in decreased value of the transgenic technology, as weeds previously controlled in the system become less and less susceptible, and potential decreased land rent value.
Use of residual herbicides in today’s transgenic world of soybean and cotton production can result in positive benefits including reduced early-season weed competition through prevention of weed germination in early crop development stages and weed resistance management through introduction of alternative modes of action to glyphosate or glufosinate.
To achieve maximum activity from residual herbicides, proper activation of the material must occur. Activation is placement of the herbicide in the soil region that maximizes opportunity for herbicide uptake by the emerging weed seedling. Herbicide activation is accomplished through rainfall/irrigation or mechanical incorporation. Most labels will call for a rainfall or irrigation amount of 0.5 inches or greater, preferably in one event. Mechanical uniform incorporation of the herbicide in the top 2 to 3 inches will adequately activate most herbicides. The majority of herbicides soil applied at planting will require mechanical uniform incorporation preferably within 7 to 10 days after application if rainfall is not received.
Below is a brief discussion of some of the relatively newer compounds available for preplant use in soybean in 2010, a number of which have been evaluated by LSU AgCenter Weed Scientists. Please refer to individual herbicide labels for plant-back intervals, precautions/restrictions, soil type and rates, and special requirements/uses (ie reduced rate application in planned PRE/POST programs, incorporation instructions, activation requirements, notes for maximum control of selective species etc.). Herbicide labels can be accessed at the following website: http://www.cdms.net/LabelsMsds/LMDefault.aspx?srchPdt%20=%20&t. A table summarizing replant intervals to field corn, cotton, grain sorghum, soybean, and wheat following application of most pre-plant herbicides also follows.
Newer Herbicides for 2010
Authority First (soybean): Authority First combines the active ingredient sulfentrazone (Spartan herbicide) and cloransulam-methyl (FirstRate herbicide). This product is labeled for control of pigweed (Amaranths), morningglory (suppression on pitted), prickly sida (teaweed), groundcherry, hophornbeam copperleaf, smellmellon, yellow and purple nutsedge, and annual sedge. It provides suppression of most annual grasses. The use rates range from 6.45 oz/A (soils 3% organic matter or less) to 8 oz/A (soils greater than 3% organic matter). Do not apply to soils classified as sands with organic matter less than 1%.
Authority MTZ (soybean): Authority MTZ combines the active ingredient sulfentrazone (Spartan herbicide) and metribuzin (Sencor or Lexone herbicide). This product expressed good activity on pigweed (Amaranths), morningglory, prickly sida (teaweed), groundcherry, hophornbeam copperleaf, smellmellon, yellow and purple nutsedge, and annual sedge. It provides suppression of most annual grasses. The use rates range from 12 to 20 oz/A depending on soil type (see label). On soils with Ph greater than 7.5, use rate should not exceed 12 oz/A. Research has shown excellent activity at the rate of 14 ounces product per acre, which provides an equivalent rate of 5 oz/A metribuzin. The herbicide label should be consulted for listing of metribuzin-sensitive soybean varieties.
Axiom DF (soybean): Axiom DF combines the active ingredient flufenacet and metribuzin (Sencor or Lexone herbicide). The herbicide controls barnyardgrass, crabgrass, foxtail species, goosegrass, and fall panicum. Will provide suppression of seedling johnsongrass, broadleaf signalgrass, pigweed species, prickly sida, Pennsylvania smartweed, and waterhemp. Use rate range is 7 to 13 oz/A. The herbicide label should be consulted for listing of metribuzin-sensitive soybean varieties.
Envive (soybean): Envive combines the active ingredients of chlorimuron ethyl (Classic herbicide), thifensulfuron methyl (Harmony GT herbicide), and flumioxazin (Valor herbicide) in one pre-mix product. Envive offers the advantage of two independent modes of action, which can aid in weed resistance management. This product expresses strong efficacy on pigweed, morningglory, sicklepod, prickly sida (teaweed), smartweed, and hophornbeam copperleaf while suppressing annual grasses. Use rates range from 2.5 to 5.3 oz/A. It can be applied up to three days after planting. In non-STS or RR/STS soybean, do not apply within 14 days before or after application of an organophosphate insecticide. Higher rates of Envive may “carry over” when applied to soils with a pH of 7.5 or greater and injure crops planted the following year due to the Classic portion of the herbicide. If a producer wishes to apply Envive on a high pH soil, then Enlite at 2.8 oz/A may be an option. Enlite combines the same active ingredients as Envive except the Classic portion is less. Enlite provides similar performance against the weed spectrum previously listed for Envive.
Gangster (soybean): Gangster is a multi-pack combination of the active ingredients flumioxazin (Valor SX) and cloransulam methyl (FirstRate). Labeled for control of morningglory species, pigweed species, Palmer amaranth, prickly sida, smartweed, copperleaf, and wild poinsettia. Suppression of barnyardgrass, large crabgrass, giant foxtail, goosegrass, panicum, and broadleaf signalgrass can be expected. Use rates range from 3 to 3.6 oz/A. The 3 oz/A rate is equivalent to applying 2.5 oz/A Valor SX and 0.5 oz/A FirstRate.
Prefix (soybean): Prefix combines the active ingredient s-metolachlor (Dual Magnum) and Reflex (fomesafen). Provides control of barnyardgrass, crabgrass, foxtail species, goosegrass, seedling johnsongrass, pigweed species, wild poinsettia, and smartweed species. It provides partial control of morningglory species, yellow nutsedge, and prickly sida (teaweed). Use rates range from 2 to 3 pt/A depending on soil type.
Sharpen (soybean): Sharpen contains the active ingredient saflufenacil. This product shows good activity on pigweed species, morningglory species, Palmer amaranth, waterhemp, and prickly sida (teaweed). Use rate is 1 oz/A.
Valor XLT (soybean): Valor XLT combines the active ingredients flumioxazin (Valor SX) and chlorimuron ethyl (Classic). Weeds controlled with this herbicide include copperleaf, prickly sida, pigweed species, morninglory species, palmer amaranth, smartweed, and wild poinsettia. Suppression of barnyardgrass, large crabgrass, broadleaf signalgrass, goosegrass, and panicums can be expected. Use rate ranges from 3 to 5 oz/A.
Plantback intervals for at-planting soil applied herbicides in soybean and cotton
| Herbicide | Corn | Cotton | Grain Sorghum | Soybean | Wheat |
| Authority First | 10 mo1 | 18 mo | 12 mo | 0 | 4 mo |
| Authority MTZ DF | 10 mo, 4 mo2 | 12 mo | 18 mo, 12 mo2 | 0 | 4 mo |
| Axiom DF | 0 | 8 mo | 12 mo | 0 | 4 mo |
| Boundary 6.5 EC | 8 mo | 8 mo | 12 mo | 0 | 4.5 mo |
| Canopy3 | 9/10 mo, 18 mo | 10 mo,18 mo | 10 mo, 18 mo | 0 | 4 mo |
| Command 3 ME | 9 mo | 04, 9 mo | 9 mo | 0 | 12 mo |
| Cotoran 4L/Fluometuron | 8 mo | 0 | 9 mo | 9 mo | 3 mo |
| Enlite | 9 mo | 9 mo | 9 mo | 0 | 4 mo |
| Envive5 | 10 mo, 18 mo | 10 mo, 30 mo | 10 mo, 18 mo | 0 | 4 mo |
| FirstRate | 9 mo | 9 mo | 9 mo | 0 | 3 mo |
| Fomesafen6 | See label | 0 | 10 mo | 0 | 4 mo |
| Gangster | 9 mo | 9 mo | 9 mo | 0 | 3 mo |
| Lorox DF/Lorox L | 0 | 4 mo | 0 | 0 | 4 mo |
| Microtech | 0 | 0 | 0 (treated seed) | 0 | See label |
| metolachlor/s-metolachlor7 | 0 | 0 | 0 | 0 | 4.5 mo |
| Outlook | 0 | Next spring | 0 | 0 | 4 mo |
| Pendimethalin8 | 0 | 0 | Next year | 0 | 4 mo |
| Prefix | 10 mo | 1 mo | 10 mo | 0 | 4.5 mo |
| Pursuit/Pursuit Plus | 8.5 mo | 18 mo | 18 mo | 0 | 4 mo |
| Scepter | 9.5 mo | 18 mo | 11 mo | 0 | 3 mo |
| Sharpen | 0 | See label | See label | See label | See label |
| Spartan 4F | 10 mo | 12 mo | 10 mo9 | 0 | 4 mo |
| Staple LX/Pyrimax 3.2 L | 9 mo, 10 mo10 | 0 | Not next season | 10 | 4 mo |
| Synchrony XP11 | 7 mo | 8 mo | 9 mo | 0 | 3 mo |
| Trifluralin12 | 12 mo | 0 | 12 mo | 0 | 4 mo |
| Valor13 | 1 mo | 1 mo | 1 mo | 0 | 1 mo |
| Valor XLT5 | 10 mo, 18 mo | 10 mo, 30 mo | 10 mo, 18 mo | 0 | 4 mo |
2 Field corn can be planted 4 months after application at 14 oz/A or less. Grain sorghum can be planted 12 months after application at 20 oz/A or less.
318 month replant interval for rate greater than 3.5 oz/A and pH > 7. Field corn can be replanted in 9 months given Canopy rate does not exceed 6 oz/A.
4Refer to label for Requirements for Planting Time section.
5Longer replant intervals must be observed for soil pH 7 or greater.
6 Fomesafen is the active ingredient in herbicides such as Dawn, Reflex, and Rhythm.
7Metolachlor or s-metolachlor (see specific label for active ingredient contained) is the active ingredient in herbicides such as Dual Magnum, Cinch, Me-too-lachlor, Stalwart, Parrlay, Parallel, and similar commercially available herbicides.
8Pendimethalin is the active ingredient in herbicides such as Prowl 3.3 EC, Prowl H2O, Pendimax 3.3 and similar commercially available herbicides.
918 month replant interval for rates above 8 oz/A.
10If applied on a band (not exceeding 50% row width) and thorough soil mixing occurs, a 9 month replant interval must be observed. If rate does not exceed 3.8 oz/A total broadcast, a 10 month interval should be observed without additional soil mixing beyond normal in your particular production system.
11See label for additional replant notes.
12Trifluralin is the active ingredient in herbicides such as Treflan HFP and Trifluralin 4 EC and similar commercially available herbicides.
13One inch rainfall must be received in addition to replant interval. Intervals are for rates of 2 oz/A or less.
Wednesday, March 31, 2010
Canada Confirms Firsf Cases Of Roundup Resistant Weed
From a press release
WINNIPEG, MANITOBA - University of Guelph weed scientists have completed evaluations of a giant ragweed (Ambrosia trifida) population in Ontario and can now confirm the first case of a glyphosate-resistant weed in Canada.
"We have been able to demonstrate that plants from this population of giant ragweed meet all five requirements necessary to confirm resistance, including surviving increased rates of glyphosate and the ability to pass resistance along to the next generation," said Dr. François Tardif of the department of plant agriculture at the University of Guelph.
The population in question underwent both greenhouse and field testing by university researchers, working in conjunction with Monsanto Canada, in order to confirm resistance. While over 30 other species of weeds in Canada have developed resistance to herbicides, this is the first confirmation of a glyphosate-resistant weed in Canada. In other countries around the world, 17 weed species – including giant ragweed – have been confirmed as resistant to glyphosate. Ten of those species are in the United States. All of these glyphosate-resistant weed biotypes have been managed with other herbicides and cultural practices.
"Growers frequently use glyphosate as an important weed control tool so the appearance of a glyphosate-resistant population is an important reminder for growers to consider diversity in their weed management strategies and crop management practices," added Dr. Sikkema, a plant agriculture professor at the University of Guelph's Ridgetown Campus. "Fortunately, we have already been able to identify some options for this producer that will provide effective control in corn and wheat."
This finding is the result of research that began late in 2008 when the population was first brought to the attention of the University of Guelph researchers and Monsanto. The glyphosate-resistant population is limited to giant ragweed from a single field site. Dr. Sikkema is working directly with the affected grower on alternative strategies to manage this giant ragweed population.
As part of an ongoing collaborative research effort between the University of Guelph and Monsanto, other giant ragweed populations in southwestern Ontario are also being tested for their susceptibility to glyphosate. Results from these tests will help determine the scope of the issue and any need to adjust weed management strategies and recommendations. Dr. Sikkema advises growers to include diversity in their cropping systems. This includes a diverse crop rotation with multiple herbicide modes of action over time. Growers are advised to use appropriate rates and other herbicides in their program where possible, including existing residual herbicides, to reduce the likelihood of glyphosate resistance developing in their fields.
"There are definitely crop management practices that can increase the risk of resistant weeds developing. That is why we strongly recommend farmers scout their fields, follow sound crop rotation practices and use additional modes of action that complement the Roundup Ready system to control problem weeds and reduce the likelihood of developing resistance," said Dr. Mark Lawton, Monsanto's technology development lead for Eastern Canada.
Monsanto's current best management practices include:
WINNIPEG, MANITOBA - University of Guelph weed scientists have completed evaluations of a giant ragweed (Ambrosia trifida) population in Ontario and can now confirm the first case of a glyphosate-resistant weed in Canada.
"We have been able to demonstrate that plants from this population of giant ragweed meet all five requirements necessary to confirm resistance, including surviving increased rates of glyphosate and the ability to pass resistance along to the next generation," said Dr. François Tardif of the department of plant agriculture at the University of Guelph.
The population in question underwent both greenhouse and field testing by university researchers, working in conjunction with Monsanto Canada, in order to confirm resistance. While over 30 other species of weeds in Canada have developed resistance to herbicides, this is the first confirmation of a glyphosate-resistant weed in Canada. In other countries around the world, 17 weed species – including giant ragweed – have been confirmed as resistant to glyphosate. Ten of those species are in the United States. All of these glyphosate-resistant weed biotypes have been managed with other herbicides and cultural practices.
"Growers frequently use glyphosate as an important weed control tool so the appearance of a glyphosate-resistant population is an important reminder for growers to consider diversity in their weed management strategies and crop management practices," added Dr. Sikkema, a plant agriculture professor at the University of Guelph's Ridgetown Campus. "Fortunately, we have already been able to identify some options for this producer that will provide effective control in corn and wheat."
This finding is the result of research that began late in 2008 when the population was first brought to the attention of the University of Guelph researchers and Monsanto. The glyphosate-resistant population is limited to giant ragweed from a single field site. Dr. Sikkema is working directly with the affected grower on alternative strategies to manage this giant ragweed population.
As part of an ongoing collaborative research effort between the University of Guelph and Monsanto, other giant ragweed populations in southwestern Ontario are also being tested for their susceptibility to glyphosate. Results from these tests will help determine the scope of the issue and any need to adjust weed management strategies and recommendations. Dr. Sikkema advises growers to include diversity in their cropping systems. This includes a diverse crop rotation with multiple herbicide modes of action over time. Growers are advised to use appropriate rates and other herbicides in their program where possible, including existing residual herbicides, to reduce the likelihood of glyphosate resistance developing in their fields.
"There are definitely crop management practices that can increase the risk of resistant weeds developing. That is why we strongly recommend farmers scout their fields, follow sound crop rotation practices and use additional modes of action that complement the Roundup Ready system to control problem weeds and reduce the likelihood of developing resistance," said Dr. Mark Lawton, Monsanto's technology development lead for Eastern Canada.
Monsanto's current best management practices include:
- Start with a clean field by either utilizing a burn down herbicide or tillage to control weeds early.
- Use Roundup Ready technology as the foundation of a total weed management program.
- Add other herbicides or cultural practices where appropriate as part of the Roundup Ready cropping system.
- Use the right herbicide rate at the right time.
- Control weeds throughout the season and reduce the weed seed bank.
- Rotation to other Roundup Ready crops will add opportunities for introduction of other modes of action.
Thursday, March 4, 2010
Understanding The Difference Between Glufosinate And Glyphosate
University of Illlinois Extension Weed Specialist Aaron Hager cautions farmers to know the differences between glufosinate and glyphosate.
When glyphosate-resistant soybean came on the market a few years ago, many believed it was unlikely that another herbicide or herbicide-resistant crop would be needed again, Hager said. However, over time, farmers saw more and more glyphosate-resistant weed species popping up but no new herbicide active ingredients coming into the marketplace to control them.
"Resistance evolves in weeds through repeated applications of the same type of herbicide," Hager said. "The once-perceived invincibility of glyphosate has been tempered by the realities imposed by the diversity of our Illinois cropping systems. New weed management practices are needed to manage the consequences of long-term weed control."
One new herbicide-resistant variety, glufosinate-resistant soybean, became commercially available in 2009. Glufosinate, another non-selective herbicide, is sold under the trade name Ignite.
And while glyphosate and glufosinate may sound alike and share certain similarities as they provide broad-spectrum weed control, lack soil-residual activity, and require herbicide-resistant crops for in-crop applications, they should not be used interchangeably.
"Significant differences exist between these two popular herbicides that require deeper understanding of how each one works," Hager said. "For example, in 2010 you would not want to spray glyphosate on glufosinate-resistant soybean, or glufosinate on glyphosate-resistant soybean."
Glufosinate inhibits a plant enzyme involved in the early steps of nitrogen assimilation. Its target site is completely different than glyphosate's. Because of this, glufosinate can control glyphosate-resistant weed populations such as waterhemp and marestail.
While their spectrum of control is comparable for several weed species, glufosinate tends to be more effective on annual broadleaf weeds than annual grasses, while glyphosate is more effective on grasses.
Glufosinate is a "contact" herbicide, in contrast to glyphosate being extensively translocated within the plant. Hager encourages farmers to utilize application parameters that provide for the best coverage of target weeds and consider environmental conditions that optimize glufosinate's performance.
For example, glufosinate performs better in bright sunshine and warm air temperatures. Due to its limited translocation, glufosinate should be applied when annual weeds are 6 inches tall or less.
"We can control large weeds with glyphosate," Hager said. "But we have to manage weeds with glufosinate. We need to think differently about how we apply it. Farmers may want to include soil-residual herbicides or spray glufosinate twice — early when the weeds are smaller because it needs contact with the whole plant and a second time due to waterhemp's late emergence."
When glyphosate-resistant soybean came on the market a few years ago, many believed it was unlikely that another herbicide or herbicide-resistant crop would be needed again, Hager said. However, over time, farmers saw more and more glyphosate-resistant weed species popping up but no new herbicide active ingredients coming into the marketplace to control them.
"Resistance evolves in weeds through repeated applications of the same type of herbicide," Hager said. "The once-perceived invincibility of glyphosate has been tempered by the realities imposed by the diversity of our Illinois cropping systems. New weed management practices are needed to manage the consequences of long-term weed control."
One new herbicide-resistant variety, glufosinate-resistant soybean, became commercially available in 2009. Glufosinate, another non-selective herbicide, is sold under the trade name Ignite.
And while glyphosate and glufosinate may sound alike and share certain similarities as they provide broad-spectrum weed control, lack soil-residual activity, and require herbicide-resistant crops for in-crop applications, they should not be used interchangeably.
"Significant differences exist between these two popular herbicides that require deeper understanding of how each one works," Hager said. "For example, in 2010 you would not want to spray glyphosate on glufosinate-resistant soybean, or glufosinate on glyphosate-resistant soybean."
Glufosinate inhibits a plant enzyme involved in the early steps of nitrogen assimilation. Its target site is completely different than glyphosate's. Because of this, glufosinate can control glyphosate-resistant weed populations such as waterhemp and marestail.
While their spectrum of control is comparable for several weed species, glufosinate tends to be more effective on annual broadleaf weeds than annual grasses, while glyphosate is more effective on grasses.
Glufosinate is a "contact" herbicide, in contrast to glyphosate being extensively translocated within the plant. Hager encourages farmers to utilize application parameters that provide for the best coverage of target weeds and consider environmental conditions that optimize glufosinate's performance.
For example, glufosinate performs better in bright sunshine and warm air temperatures. Due to its limited translocation, glufosinate should be applied when annual weeds are 6 inches tall or less.
"We can control large weeds with glyphosate," Hager said. "But we have to manage weeds with glufosinate. We need to think differently about how we apply it. Farmers may want to include soil-residual herbicides or spray glufosinate twice — early when the weeds are smaller because it needs contact with the whole plant and a second time due to waterhemp's late emergence."
Bayer Announces Ignite Herbicide Price Cuts - More LibertyLink Acreage For 2010?
In a move that could well encourage more growers to plant LibertyLink crops, Bayer today announced that it is cutting the price of Ignite, the broad spectrum herbicide applied on those varieties. Here's part of a press release from Bayer:
Bayer CropScience announced today a price cut on Ignite herbicide in time for the 2010 season. The company is reducing its price for the herbicide in the range of 20 percent — effective immediately.
“The use of Ignite herbicide and the LibertyLink trait is fundamental in preserving the utility of glyphosate and glyphosate-tolerant crops as a viable crop production tool,” said Andy Hurst, Bayer CropScience product manager for Ignite herbicide and LibertyLink.
“Growers want to avoid weed resistance yet maintain simple and efficient weed management,” Hurst explained. “The launch of LibertyLink in soybeans and new FiberMax® cotton varieties with the LibertyLink trait enable effective weed management combined with high yields.”
In corn, growers can take advantage of their Herculex®, SmartStax, and Agrisure hybrids with corn borer protection by choosing the cost-effective option of Ignite on those acres this year.
Additionally, Ignite is an effective burndown tool prior to emergence of glyphosate-tolerant crops. Ignite can be applied as a burndown treatment prior to planting or emergence of cotton, soybean, canola, corn or sugarbeet.
Bayer CropScience is fully committed to supplying Ignite herbicide to meet the demand as crop acres with the LibertyLink trait ramp up, said Hurst.
“The company has invested more than $150 million in expansion of Ignite manufacturing capacity to accommodate expected demand,” Hurst said. “In addition to seed and crop protection portfolios, Bayer CropScience will lead in the development and commercialization of next-generation herbicide-tolerant traits and other traits of value in soybeans, cotton, corn, canola and other crops.”
Bayer CropScience announced today a price cut on Ignite herbicide in time for the 2010 season. The company is reducing its price for the herbicide in the range of 20 percent — effective immediately.
“The use of Ignite herbicide and the LibertyLink trait is fundamental in preserving the utility of glyphosate and glyphosate-tolerant crops as a viable crop production tool,” said Andy Hurst, Bayer CropScience product manager for Ignite herbicide and LibertyLink.
“Growers want to avoid weed resistance yet maintain simple and efficient weed management,” Hurst explained. “The launch of LibertyLink in soybeans and new FiberMax® cotton varieties with the LibertyLink trait enable effective weed management combined with high yields.”
In corn, growers can take advantage of their Herculex®, SmartStax, and Agrisure hybrids with corn borer protection by choosing the cost-effective option of Ignite on those acres this year.
Additionally, Ignite is an effective burndown tool prior to emergence of glyphosate-tolerant crops. Ignite can be applied as a burndown treatment prior to planting or emergence of cotton, soybean, canola, corn or sugarbeet.
Bayer CropScience is fully committed to supplying Ignite herbicide to meet the demand as crop acres with the LibertyLink trait ramp up, said Hurst.
“The company has invested more than $150 million in expansion of Ignite manufacturing capacity to accommodate expected demand,” Hurst said. “In addition to seed and crop protection portfolios, Bayer CropScience will lead in the development and commercialization of next-generation herbicide-tolerant traits and other traits of value in soybeans, cotton, corn, canola and other crops.”
Sunday, February 28, 2010
Louisiana Consultants, Farmers Meet With Monsanto Over Herbicide Fees To Supplement Roundup And Bollworm Slippage In Bollgard II Cotton
Roger Carter, who operates the consulting firm Agricultural Management Services in east-central Louisiana, reported in his newsletter today about a meeting earlier in the week with Monsanto representatives that was attended by a number of key consultants and several farmers.
Topics included fee structures that Monsanto is extending for herbicides needed to bolster Roundup applications in an area now dealing with widespread cases of Roundup-resistant weeds.
The meeting also touched on tech fees and bollworm slippage in Bollgard II cotton.
Here is Mr. Carter's report:
Monsanto was prepared with tough hides since “they” are common fodder for many producers woes. Most farmers in attendance have been to one or more of these types of meetings before where Monsanto is searching for ways to help the end users of its technology manage risk. It was noted that Monsanto has helped somewhat in weed resistance management by rebating a small amount ($2.50/ac or so) for each of several herbicides if they are applied. However, it would require that a producer use all five herbicides on the list in order to get a total of $12.50/ac in return.
And there is no consideration for rates. Cotoran and diuron, for instance, must be used at the highest labeled rates for most of our soil types where cotton is grown in our area, yet the same amount of $ is allocated per acre regardless. The $2.50/ac rebate for Cotoran would be less than 20% of the cost of a efficacious rate of that herbicide for many of our acres. We appreciate the thought, but we need more bucks if Monsanto truly wants to help with resistance management in our area.
And there is no help for insect resistance management for bollworms that are “slipping” through Bollgard II cotton and must be treated with pyrethroids that are becoming less effective with each application. We were supposed to have enough control of bollworms with BGII to not have to treat for bollworms.
Jesse Young (a farmer and independent crop consultant) pointed out that the cap had been removed from the top end of what farmers would pay per acre for technology and that if farmers planted the recommended amount of seed (4 seed/row ft on 38” rows) tech and seed costs would be $133/acre. The reason the cap was removed is that few farmers were hitting the cap. The reason they didn’t “cap out” was that the cap was too high and should have been lowered to a total of $75/acre for seed and technology. Laugh if you want, Big M, but this is reality.
Monsanto explained that in order to continue research such as the drought resistant cotton on which they are currently working, it took X number of research dollars and that they could not lower the fees and still conduct the necessary research. Most in the audience agreed that drought tolerant cotton would not help, but actually hurt, the Mid-South and Southeast since it would be of more benefit to drier areas and encourage production there. In other words, it would help our area farmers’ competitors. Monsanto should not try to woo us with talk that “they” are only making these research investments for the American farmer…..it is for Monsanto’s shareholders and no one else.
The good thing: Monsanto took notes. And some of us were encouraged that perhaps they will begin to help us by sharing more of the risk, reducing some tech fees, and encouraging better stewardship of the technology by not selling “canned” packages of technology in areas where certain technology is not needed or wanted, such as areas where resistant pigweed have caused the value of Flex to become nil. Yet the Bt traits may still be wanted and affordable.
Although the meeting was two hours long there was no “name calling” - at least none that we could hear. And we wondered what the four lost souls that were “sacrificed” and sent to make this trek had done wrong to deserve such punishment. Dave Rhylander is a veteran of such gatherings and has become used to wearing body armor. Phil Miller exhibited traits of being a Southern gentleman and appears sincere in his remarks. Regardless, the crowd left them unscathed, but hopefully more educated about what can be done to help us keep cotton in the United States.
We believe that Monsanto is listening. We thank “them” or “it” for aiding us with a contributions towards weed resistance management. We hope that neither they nor us wasted our time. The fish was good, but it wasn’t enough to feed our families for a year nor enough to offset tech fees. And we don’t necessarily feel that a “tech rebate” check is in the mail yet, but we’re getting there.
Topics included fee structures that Monsanto is extending for herbicides needed to bolster Roundup applications in an area now dealing with widespread cases of Roundup-resistant weeds.
The meeting also touched on tech fees and bollworm slippage in Bollgard II cotton.
Here is Mr. Carter's report:
Monsanto was prepared with tough hides since “they” are common fodder for many producers woes. Most farmers in attendance have been to one or more of these types of meetings before where Monsanto is searching for ways to help the end users of its technology manage risk. It was noted that Monsanto has helped somewhat in weed resistance management by rebating a small amount ($2.50/ac or so) for each of several herbicides if they are applied. However, it would require that a producer use all five herbicides on the list in order to get a total of $12.50/ac in return.
And there is no consideration for rates. Cotoran and diuron, for instance, must be used at the highest labeled rates for most of our soil types where cotton is grown in our area, yet the same amount of $ is allocated per acre regardless. The $2.50/ac rebate for Cotoran would be less than 20% of the cost of a efficacious rate of that herbicide for many of our acres. We appreciate the thought, but we need more bucks if Monsanto truly wants to help with resistance management in our area.
And there is no help for insect resistance management for bollworms that are “slipping” through Bollgard II cotton and must be treated with pyrethroids that are becoming less effective with each application. We were supposed to have enough control of bollworms with BGII to not have to treat for bollworms.
Jesse Young (a farmer and independent crop consultant) pointed out that the cap had been removed from the top end of what farmers would pay per acre for technology and that if farmers planted the recommended amount of seed (4 seed/row ft on 38” rows) tech and seed costs would be $133/acre. The reason the cap was removed is that few farmers were hitting the cap. The reason they didn’t “cap out” was that the cap was too high and should have been lowered to a total of $75/acre for seed and technology. Laugh if you want, Big M, but this is reality.
Monsanto explained that in order to continue research such as the drought resistant cotton on which they are currently working, it took X number of research dollars and that they could not lower the fees and still conduct the necessary research. Most in the audience agreed that drought tolerant cotton would not help, but actually hurt, the Mid-South and Southeast since it would be of more benefit to drier areas and encourage production there. In other words, it would help our area farmers’ competitors. Monsanto should not try to woo us with talk that “they” are only making these research investments for the American farmer…..it is for Monsanto’s shareholders and no one else.
The good thing: Monsanto took notes. And some of us were encouraged that perhaps they will begin to help us by sharing more of the risk, reducing some tech fees, and encouraging better stewardship of the technology by not selling “canned” packages of technology in areas where certain technology is not needed or wanted, such as areas where resistant pigweed have caused the value of Flex to become nil. Yet the Bt traits may still be wanted and affordable.
Although the meeting was two hours long there was no “name calling” - at least none that we could hear. And we wondered what the four lost souls that were “sacrificed” and sent to make this trek had done wrong to deserve such punishment. Dave Rhylander is a veteran of such gatherings and has become used to wearing body armor. Phil Miller exhibited traits of being a Southern gentleman and appears sincere in his remarks. Regardless, the crowd left them unscathed, but hopefully more educated about what can be done to help us keep cotton in the United States.
We believe that Monsanto is listening. We thank “them” or “it” for aiding us with a contributions towards weed resistance management. We hope that neither they nor us wasted our time. The fish was good, but it wasn’t enough to feed our families for a year nor enough to offset tech fees. And we don’t necessarily feel that a “tech rebate” check is in the mail yet, but we’re getting there.
Friday, February 26, 2010
Glyphosate-Resistance at the Farm and Gin Show
Are you surprised to know that everyone is getting to know the term, glyphosate-resistance weeds? Yeah, you thought it was just big news down on the farm, but even consumer media outlets are giving a nod to the issue. Every farm magazine talks weed resistance, and today's Memphis Commercial Appeal used the item to talk about this weekend's 58th Annual Farm and Gin Show in Memphis, Tennessee.
Based on my limited Gin Show experience, the estimated crowd of 20,000 includes plenty of folks in the agricultural business, but the non-farm attendance is far greater. Everyone from kids going through to pick up the free rulers and candy to farmers eyeing the latest combines or cotton pickers will probably get a whiff of the increasing panic over glyphosate-resistant Palmer pigweed, more commonly known as mare's tail.
For those who are looking for more than free rulers, four weed experts from Arkansas, Louisiana, Mississippi and Tennessee will be giving a seminar, and I'm sure answering many questions throughout the day.
Based on my limited Gin Show experience, the estimated crowd of 20,000 includes plenty of folks in the agricultural business, but the non-farm attendance is far greater. Everyone from kids going through to pick up the free rulers and candy to farmers eyeing the latest combines or cotton pickers will probably get a whiff of the increasing panic over glyphosate-resistant Palmer pigweed, more commonly known as mare's tail.
For those who are looking for more than free rulers, four weed experts from Arkansas, Louisiana, Mississippi and Tennessee will be giving a seminar, and I'm sure answering many questions throughout the day.
Friday, February 12, 2010
Roundup and Roundup Resistance Turns Out To Be Too Much Of A Good Thing, Says Texas Economist
Too much of a good thing might be a bad thing when it comes to controlling weeds, a Texas AgriLife Extension Service specialist said.
Prior to herbicide-resistant crops, producers used a variety of methods to control weeds, including herbicides, cultivation and hoeing crews, said Dr. Peter Dotray, an agronomist with AgriLife Extension and Texas AgriLife Research in Lubbock.
Dotray, speaking at the Texas High Plains Grain Elevator Workshop in Amarillo recently, told the crowd, “As we’ve changed the things we plant, we’ve changed the way we try to control weeds.”
Across the U.S., he said, agriculture as a whole is controlling weeds differently using some of this “very good technology.” For example, 90 percent of the cotton planted last year had resistance to glyphosate (Roundup) in it.
That has resulted in some areas of resistant weeds, especially in the states where the technology was adopted the quickest, Dotray said.
There are many benefits to Roundup Ready systems, including broad-spectrum control, convenience and simplification of weed control, he said.
Dotray said another study looked at conventional tillage, no-till and strip-till systems, along with 16 different pre-plant treatments and a variety of different application timings of residual herbicides. It showed that while tillage is a very effective tool to control weeds in conjunction with herbicides, the Roundup-only system had effective control without the use of residual herbicides.
“And the Roundup system was as profitable as any,” he said.
In another study, he worked with three growers who planted 60 acres of dryland cotton each and controlled the weeds with a Roundup Ready system. A side-by-side comparison was made on each farm which had conventional fields on which cultivation and hand-hoeing crews were used to control weeds.
“Roundup Ready was every bit as good, if not better, and the inputs were the same or less, so it was more profitable,” Dotray said. “That’s why the technology is being adopted.”
But this intense focus on one herbicide means less plowing, less cultivation, bigger application equipment and less use of herbicides with different modes of action, he said.
“We are relying more on one herbicide and we are starting to see resistant weeds developing and population shifts,” Dotray said. “Weeds that prefer less tillage are becoming more problematic. It doesn’t mean they’ve developed resistance, but it tells me we are doing something different in controlling weeds.”
Resistance in weeds is not a new concern, but it is a big concern because many thought this herbicide was the answer – a silver bullet of sorts, Dotray said.
He said there are more than 340 different resistant biotypes of weeds found in more than 300,000 fields on a worldwide basis, so this is a problem worldwide. The resistance to Roundup began developing in 1998, first in rigid ryegrass and then in 2000 in marestail and later ragweeds and Palmer amaranth.
“The problem was most apparent in states that had put the cultivator away and had early adoption of Roundup,” Dotray said.
“So what’s next?” he asked. “We have to try to make sure producers are aware so that they know the problem is real.”
To determine if weed resistance is becoming a problem, Dotray advised producers to look at the weed patch of concern and see if there is a whole spectrum of weeds that was not controlled, or just one type of weed.
“I like to collect seed and do my own tests,” he said. “We want to make sure we have thorough coverage on that area and that it wasn’t a result of poor coverage or some other operator error.”
Dotray said some strategies producers with resistant weeds are already using are more cover crops, deep tillage, herbicides at planting and other technologies like Liberty Link cotton.
While Texas was not one of the first states to adopt widespread use of Roundup Ready crops and was not one of the early states to see the resistant weeds, it is beginning to see reduced tillage and less use of dinitroaniline herbicides such as Treflan and Prowl, he said.
Dotray said herbicide resistance can be somewhat predictable. The weeds are generally annuals that produce a lot of seeds and have several germination flushes a year. Also, if there are a lot of different biotypes of that particular weed, it is more likely for one to develop a resistance.
He said it is possible to delay – not prevent – the development of herbicide-resistant weeds by not relying on glyphosate-only systems and incorporating tillage into the system, as well as other modes of action.
“As the trend toward herbicide resistance begins to occur here, I would like to see other means of weed control in our weed-management programs and not just relying on one herbicide during the course of the year or for several years in a row,” Dotray said.
Prior to herbicide-resistant crops, producers used a variety of methods to control weeds, including herbicides, cultivation and hoeing crews, said Dr. Peter Dotray, an agronomist with AgriLife Extension and Texas AgriLife Research in Lubbock.
Dotray, speaking at the Texas High Plains Grain Elevator Workshop in Amarillo recently, told the crowd, “As we’ve changed the things we plant, we’ve changed the way we try to control weeds.”
Across the U.S., he said, agriculture as a whole is controlling weeds differently using some of this “very good technology.” For example, 90 percent of the cotton planted last year had resistance to glyphosate (Roundup) in it.
That has resulted in some areas of resistant weeds, especially in the states where the technology was adopted the quickest, Dotray said.
There are many benefits to Roundup Ready systems, including broad-spectrum control, convenience and simplification of weed control, he said.
Dotray said another study looked at conventional tillage, no-till and strip-till systems, along with 16 different pre-plant treatments and a variety of different application timings of residual herbicides. It showed that while tillage is a very effective tool to control weeds in conjunction with herbicides, the Roundup-only system had effective control without the use of residual herbicides.
“And the Roundup system was as profitable as any,” he said.
In another study, he worked with three growers who planted 60 acres of dryland cotton each and controlled the weeds with a Roundup Ready system. A side-by-side comparison was made on each farm which had conventional fields on which cultivation and hand-hoeing crews were used to control weeds.
“Roundup Ready was every bit as good, if not better, and the inputs were the same or less, so it was more profitable,” Dotray said. “That’s why the technology is being adopted.”
But this intense focus on one herbicide means less plowing, less cultivation, bigger application equipment and less use of herbicides with different modes of action, he said.
“We are relying more on one herbicide and we are starting to see resistant weeds developing and population shifts,” Dotray said. “Weeds that prefer less tillage are becoming more problematic. It doesn’t mean they’ve developed resistance, but it tells me we are doing something different in controlling weeds.”
Resistance in weeds is not a new concern, but it is a big concern because many thought this herbicide was the answer – a silver bullet of sorts, Dotray said.
He said there are more than 340 different resistant biotypes of weeds found in more than 300,000 fields on a worldwide basis, so this is a problem worldwide. The resistance to Roundup began developing in 1998, first in rigid ryegrass and then in 2000 in marestail and later ragweeds and Palmer amaranth.
“The problem was most apparent in states that had put the cultivator away and had early adoption of Roundup,” Dotray said.
“So what’s next?” he asked. “We have to try to make sure producers are aware so that they know the problem is real.”
To determine if weed resistance is becoming a problem, Dotray advised producers to look at the weed patch of concern and see if there is a whole spectrum of weeds that was not controlled, or just one type of weed.
“I like to collect seed and do my own tests,” he said. “We want to make sure we have thorough coverage on that area and that it wasn’t a result of poor coverage or some other operator error.”
Dotray said some strategies producers with resistant weeds are already using are more cover crops, deep tillage, herbicides at planting and other technologies like Liberty Link cotton.
While Texas was not one of the first states to adopt widespread use of Roundup Ready crops and was not one of the early states to see the resistant weeds, it is beginning to see reduced tillage and less use of dinitroaniline herbicides such as Treflan and Prowl, he said.
Dotray said herbicide resistance can be somewhat predictable. The weeds are generally annuals that produce a lot of seeds and have several germination flushes a year. Also, if there are a lot of different biotypes of that particular weed, it is more likely for one to develop a resistance.
He said it is possible to delay – not prevent – the development of herbicide-resistant weeds by not relying on glyphosate-only systems and incorporating tillage into the system, as well as other modes of action.
“As the trend toward herbicide resistance begins to occur here, I would like to see other means of weed control in our weed-management programs and not just relying on one herbicide during the course of the year or for several years in a row,” Dotray said.
Tuesday, February 2, 2010
Palmer pigweed rescue options in beans, cotton
The following article appeared on our main web site last July:
Glyphosate-Resistant Palmer Amaranth Rescue Treatments in Soybean.
The calls have been coming in on what to do with Palmer amaranth that has survived high rates of glyphosate or glyphosate plus a PPO herbicide (Flexstar, Cadet, etc). This Palmer amaranth is typically 8 to 12 inches tall.
 16 oz/A Flexstar + 2 oz/A 2,4DB |
 16 oz/A Flexstar |
 Gramoxone + Valor Hooded Application |
Unfortunately, I do not have any silver bullets! I have tried several rescue treatments which include 16 oz/A Flexstar, 8 oz/A Flexstar, 0.6 oz/A Cadet, or 2 oz/A 2,4-DB. None of these treatments alone provided a satisfactory level of control of escaped Palmer amaranth. However, when I tankmixed 16 oz/A Flexstar with either 0.6 oz/A Cadet or 2 oz/A 2,4-DB it appeared 5 days after application that we were able to improve control from 50% to 70% of escaped larger Palmer. We will continue to monitor regrowth of these treatments next week.
I know that having 30% surviving GR Palmer amaranth is way too many in most cases but when GR Palmer amaranth gets some size, we are in a rescue mode.
The goal is having some soybeans to harvest this fall. It is way too late to stop yield loss from competition.
Glyphosate-Resistant Palmer Amaranth Rescue Treatments in Cotton.
Questions on good hooded or post direct treatments for Palmer amaranth have been common this week. When glyphosate will no longer provide Palmer control the only option is to use some of the very hot hooded applications that were common 10 years ago. The best GR Palmer amaranth hooded application I know of is 32 oz/A of Gramoxone Inteon + 1 oz of Valor + 0.25% crop oil (Picture Right). This is obviously a very hot mixture. Some other options that have worked well on GR Palmer amaranth are listed below:
Direx 32 oz/A + Valor 1.5 to 2 oz/A + MSMA 2.67 pt/A or Glyphosate 0.75 lbs ae/A:
Cotton should have 4” of bark to reduce chances of cotton stem injury.
- Advantages: Good burndown and residual pigweed control. Direx + Valor tankmix can burndown large GR Palmer as well.
- Considerations: MSMA should be the tank-mix of choice with Valor in fields where GR Palmer is present. Sloppy post-direct of Valor will burn cotton leaves.
Layby Pro 1 qt/A – Equivalent to 16 oz/A of Direx + 16 oz/A of Linex.
Add one percent crop oil for better control.
- Advantages: Good control of many grasses and broadleaves including pigweeds and morningglories. This premix will provide some residual pigweed control.
- Considerations: This premix can be weak on grasses. The addition of MSMA 2.67 pt/A of 6L formulation or glyphosate at 0.75 lb ae/A will control grasses. Sloppy post-direct of Linex will burn cotton leaves.
Ignite 280 29 oz/A
Cotton must be at least 6” tall.
- Advantages: Will cause little crop injury if cotton is a WideStrike variety. Ignite can control tall horseweed and giant ragweed. It provides good control of many broadleaf weeds including morninglories and GR Palmer up to 8” tall.
- Considerations: Some regrowth of large Palmer pigweeds can happen. Aim may be tankmixed with Ignite to improve burndown of large pigweeds. Ignite will offer no residual control. Caparol may be tankmixed with Ignite to provide residual pigweed control.
Caparol 32 oz/A + MSMA 2.67 pt/A or Glyphosate 0.75 lbs ae/A
Cotton must be at least 6” tall.
- Advantages: Causes less injury than some other tankmixes and is also economical. The Caparol + MSMA mixture has taken out some GR Palmer in past years if they were smaller than 6”. Caparol will provide good residual control of pigweed and horseweed.
- Considerations: Caparol and MSMA or glyphosate tankmixtures need good agitation to stay in suspension.
Wednesday, January 27, 2010
Cotton Herbicide Programs: What Some Farmers Are Looking At For 2010
I found a thread this morning on the independent forum, New Ag Talk, that discusses cotton herbicide plans that these farmers intend to use in 2010's crop.
Significantly, I doubt if this discussion would have taken place 5 years ago, back when Roundup resistance wasn't a known factor and the main question was, "When do you spray Roundup?" Comments cover Alabama, Arkansas, Mississippi, Missouri and Texas.
If you grow cotton and want a quick basis of comparison, here's the thread:
http://talk.newagtalk.com/forums/thread-view.asp?tid=146482&posts=10&start=1
- Owen Taylor
Significantly, I doubt if this discussion would have taken place 5 years ago, back when Roundup resistance wasn't a known factor and the main question was, "When do you spray Roundup?" Comments cover Alabama, Arkansas, Mississippi, Missouri and Texas.
If you grow cotton and want a quick basis of comparison, here's the thread:
http://talk.newagtalk.com/forums/thread-view.asp?tid=146482&posts=10&start=1
- Owen Taylor
Tuesday, January 26, 2010
Will Roundup Face A Bleak Future Due To Resistant Weeds?
That's the scenario painted by Steve Powels, an Australian plant biologist, who spoke at the recent Pan-American Weed Resistance Conference in Miami.
“Glyphosate (active ingredient in Roundup) will be driven to redundancy in the cotton, corn and soybean belt,” said Powles in a report by Forest Laws in Delta Farm Press. “Outside of these areas of the U.S., then glyphosate should continue to be effective because it is not massively used.
“Within the cotton, corn and soybean belt the massive reliance on glyphosate means that it will be driven to redundancy because many of the big driver weeds such as Palmer pigweeds, waterhemp, ragweed and Johnsongrass will be resistant. There may be many weed species still controlled by glyphosate, but glyphosate will fail on the driver weeds and that means overall failure.”
Friday, January 22, 2010
California: dealing with herbicide resistance in almond orchards
In the row-crop business, we tend to think of herbicide resistance as being just a problem in cotton, grains, peanuts and similar crops. But resistance also has become a factor in orchard crops. Here's an overview of the problem in California's Central Valley and recommendations for dealing with it. It comes from David Doll, University of California Cooperative Extension Farm Advisor in Merced County.
As David writes in a late-December posting on his blog, The Almond Doctor, "Since herbicide resistant weeds are becoming more prevalent in the San Joaquin Valley (think Hairy Fleabane, Horseweed/marestail), it is becoming more important for growers to utilize practices that reduce the chance of herbicide resistance."
He also notes: "Glyphosate is one of the most widely used herbicides for this practice, and, until recently, has provided good control."
As David writes in a late-December posting on his blog, The Almond Doctor, "Since herbicide resistant weeds are becoming more prevalent in the San Joaquin Valley (think Hairy Fleabane, Horseweed/marestail), it is becoming more important for growers to utilize practices that reduce the chance of herbicide resistance."
He also notes: "Glyphosate is one of the most widely used herbicides for this practice, and, until recently, has provided good control."
Putting Roundup-resistant Palmer pigweed in perspective
Carl Hobbs, an agronomist with Helena Chemical Co. (based in Ashburn, Georgia) wrote this morning: "I heard an Alabama farmer friend say yesterday, 'If you have glyphosate resistant Palmer (pigweed), you don't have any other problems.'"
The image above, included in a PowerPoint presentation made by Univerisity of Georgia weed scientist Stanley Culpepper, illustrates that point.
- Owen Taylor
Thursday, January 21, 2010
Georgia study: why glyphosate stewardship fails to gain ground
ShareEditor's Note: The following is from a press release received today from Weed Science, a publication of the Weed Science Society of America. The journal publishes articles on the biology, ecology, physiology, or management and control of weeds. It also focuses on herbicides, growth regulators, and related topics. To learn more about the society, please visit: http://www.wssa.net/
In the southeastern United States , weeds that can tolerate or resist the popular herbicide glyphosate are threatening cotton crops. In the article “Loss of Glyphosate Efficacy: A Changing Weed Spectrum in Georgia Cotton,” (Weed Science Volume 58, Issue 1, 73-79)
Theodore M. Webster and Lynn M. Sosnoskie examine how the use of glyphosate-tolerant cotton (GTC)—created through genetic modification—has affected weed control issues since its introduction in 1997.
The article is featured in the January–February 2010 issue of Weed Science, published by the Weed Science Society of America. As farmers plant more acres of GTC, they are seeing a change in the most prevalent weeds, which now include varieties that tolerate or resist glyphosate.
The two most troublesome weeds in Georgia cotton are:
These weeds typically develop in systems without diverse weed control practices. “The management practices necessary for minimizing the development of herbicide resistance have not been widely implemented,” Webster and Sosnoskie write. They see a need for farmers to work toward greater stewardship, which is the sum of the management decisions and practices used to preserve the utility of a crop trait, and try new or varied weed management strategies that often may be more expensive.
“Agricultural practices aimed at delaying or preventing the development of herbicide resistance are not viewed as being economical in the short term and are not readily used by all growers,” they write. “Because herbicide resistance can spread quickly, indiscriminate use of glyphosate may result in a loss of weed susceptibility for all growers, a tragedy of the commons.” Webster and Sosnoskie identify two reasons why growers are not adopting methods that promote glyphosate stewardship:
The authors outline several possible incentives for cotton farmers, including industry initiatives to promote better glyphosate stewardship and voluntary government farm programs.
However, they say it likely will take a combination of incentives and a move toward new methods to improve weed control.
“Principles of ecological weed management used in conjunction with herbicide-based weed control systems will likely be an important component of future weed management systems,” Webster and Sosnoskie write.
They also identify several areas for future research: how to limit the development of herbicide-resistant and herbicide-tolerant weeds; whether there is a need to limit the use of glyphosate; factors that may improve control and stewardship of herbicide options; how herbicide resistance traits move across the landscape; what factors could be used to determine a species’ risk of developing resistance; and incentives to help improve herbicide stewardship. The full-text article is available at http://www2.allenpress.com/pdf/WEES_58.1_73-79.pdf.
Farmers who use herbicide-tolerant crops face a growing challenge from herbicide-tolerant and herbicide-resistant weeds, which are evolving and spreading across cropland.
In the southeastern United States , weeds that can tolerate or resist the popular herbicide glyphosate are threatening cotton crops. In the article “Loss of Glyphosate Efficacy: A Changing Weed Spectrum in Georgia Cotton,” (Weed Science Volume 58, Issue 1, 73-79)
Theodore M. Webster and Lynn M. Sosnoskie examine how the use of glyphosate-tolerant cotton (GTC)—created through genetic modification—has affected weed control issues since its introduction in 1997.
The article is featured in the January–February 2010 issue of Weed Science, published by the Weed Science Society of America. As farmers plant more acres of GTC, they are seeing a change in the most prevalent weeds, which now include varieties that tolerate or resist glyphosate.
The two most troublesome weeds in Georgia cotton are:
- Benghal dayflower, which is tolerant to glyphosate and many of the herbicides used in agronomic crops.
- Palmer amaranth, which has developed resistance to many classes of herbicides including glyphosate.
These weeds typically develop in systems without diverse weed control practices. “The management practices necessary for minimizing the development of herbicide resistance have not been widely implemented,” Webster and Sosnoskie write. They see a need for farmers to work toward greater stewardship, which is the sum of the management decisions and practices used to preserve the utility of a crop trait, and try new or varied weed management strategies that often may be more expensive.
“Agricultural practices aimed at delaying or preventing the development of herbicide resistance are not viewed as being economical in the short term and are not readily used by all growers,” they write. “Because herbicide resistance can spread quickly, indiscriminate use of glyphosate may result in a loss of weed susceptibility for all growers, a tragedy of the commons.” Webster and Sosnoskie identify two reasons why growers are not adopting methods that promote glyphosate stewardship:
- The belief that a new technology will be developed to solve the resistance and tolerance problems, although no new herbicides have been introduced commercially since 1998
- The belief that resistance management strategies will be futile because most farmers think herbicide resistance traits are mobile through pollen-mediated transfer and their fields are affected by other nearby farms
The authors outline several possible incentives for cotton farmers, including industry initiatives to promote better glyphosate stewardship and voluntary government farm programs.
However, they say it likely will take a combination of incentives and a move toward new methods to improve weed control.
“Principles of ecological weed management used in conjunction with herbicide-based weed control systems will likely be an important component of future weed management systems,” Webster and Sosnoskie write.
They also identify several areas for future research: how to limit the development of herbicide-resistant and herbicide-tolerant weeds; whether there is a need to limit the use of glyphosate; factors that may improve control and stewardship of herbicide options; how herbicide resistance traits move across the landscape; what factors could be used to determine a species’ risk of developing resistance; and incentives to help improve herbicide stewardship. The full-text article is available at http://www2.allenpress.com/pdf/WEES_58.1_73-79.pdf.
Tuesday, January 19, 2010
Managing Herbicide Resistant Palmer Amaranth (Pigweed) in Field Corn, Peanut, and Soybean - 2010
Eric P. Prostko, Georgia Extension Weed Specialist, has released a white paper on dealing with glyphosate-, atrazine- and ALS-resistant weeds in that state. He includes a variety of weed control options. including approaches where Roundup/glyphosate and ALS resistance are found in the same field.
Here's a link to the paper.
Here's a link to the paper.
Top 10 Questions And Answers About Liberty-Link Soybeans And The Fit With Roundup Resistance
Two Georgia Extension workers released a white paper this month on where, generally speaking, Liberty-Link (LL) soybeans will fit in that state, especially from the standpoint of dealing with Roundup-resistant pigweed, which probably rates now as that state's number one agronomic problem in field crops.
Nobody is saying that LL beans are a silver bullet, and the report delves into some limitations with the system. But the paper does examine the parameters of the technology. It was written by Jared R. Whitaker (Extension Agronomist – Soybean and Cotton) and Eric P. Prostko (Extension Agronomist – Weed Science).
Here's a link to their report.
Nobody is saying that LL beans are a silver bullet, and the report delves into some limitations with the system. But the paper does examine the parameters of the technology. It was written by Jared R. Whitaker (Extension Agronomist – Soybean and Cotton) and Eric P. Prostko (Extension Agronomist – Weed Science).
Here's a link to their report.
Roundup Flex: Treat it like regular Roundup Ready cotton now?
The Beltwide Cotton Conference, as you might expect, included plenty of data and comments about Roundup Ready cotton, especially the new Flex varieties that allow Roundup applications past the fifth node, the cutoff point for first-generation Roundup Ready varieties.
More than once, I heard Extension workers and even some crop consultants say that it will be far safer to treat Flex cotton the same as the first-gen varieties. Reasons include the need to hit weeds far earlier than cotton's fifth node to gain better control and reduce potential for more Roundup-resistant weed development. With many of the weed sessions focusing on Palmer pigweed -- and secondarily on marestail (horseweed) and things like Italian ryegrass -- resistance management or prevention was on everyone's mind, whether or not they now have the problem.
One estimate given was that Roundup Ready cotton, in general, had lost $19 per acre of its value for growers due to continued reissntance problems. That number was given by a university weed scientist during the consultants conference, which preceeded the Beltwide.
Roger Carter, a veteran crop consultant from east-central Louisiana, wrote in his Beltwide report on January 10:
"One focus was on the economic value of the cost of transgenics. Surveys of farmers and consultants indicated that the current charges for biotechnology, particularly the Flex charges, are much too high in exchange for the good we are getting. Because of resistance management more residual herbicides are needed than ever before. And more direct contact herbicides are necessary to battle resistant pigweeds and other species. Therefore, the use of glyphosate over the top after the 5th true leaf on cotton is a mute point in areas where we are using resistance management programs. And that should be most of the Cotton Belt. Are you listening, folks?"
More than once, I heard Extension workers and even some crop consultants say that it will be far safer to treat Flex cotton the same as the first-gen varieties. Reasons include the need to hit weeds far earlier than cotton's fifth node to gain better control and reduce potential for more Roundup-resistant weed development. With many of the weed sessions focusing on Palmer pigweed -- and secondarily on marestail (horseweed) and things like Italian ryegrass -- resistance management or prevention was on everyone's mind, whether or not they now have the problem.
One estimate given was that Roundup Ready cotton, in general, had lost $19 per acre of its value for growers due to continued reissntance problems. That number was given by a university weed scientist during the consultants conference, which preceeded the Beltwide.
Roger Carter, a veteran crop consultant from east-central Louisiana, wrote in his Beltwide report on January 10:
"One focus was on the economic value of the cost of transgenics. Surveys of farmers and consultants indicated that the current charges for biotechnology, particularly the Flex charges, are much too high in exchange for the good we are getting. Because of resistance management more residual herbicides are needed than ever before. And more direct contact herbicides are necessary to battle resistant pigweeds and other species. Therefore, the use of glyphosate over the top after the 5th true leaf on cotton is a mute point in areas where we are using resistance management programs. And that should be most of the Cotton Belt. Are you listening, folks?"
Organic group contends industry study "echoes" its findings on overuse of glyphosate
The Organic Center (TOC) contends in a press release today that a recent study - that included participation by two Monsanto scientists - "echoes" conclusions that the center's staff already has drawn about the effect that overuse of Roundup is having on the future of transgenic crops.
From the press release:
"Published in Proceedings of National Academy of Sciences (PNAS) in December 2009, the Monsanto-funded research states that 'evolution of resistance to the widely used, nonselective herbicide glyphosate in weedy species endangers the continued success of transgenic glyphosate-resistant crops and the sustainability of glyphosate as the world's most important herbicide.'"
It always seems a bit suspect when organic groups fret over the future of conventional and biotech ag.
From the press release:
"Published in Proceedings of National Academy of Sciences (PNAS) in December 2009, the Monsanto-funded research states that 'evolution of resistance to the widely used, nonselective herbicide glyphosate in weedy species endangers the continued success of transgenic glyphosate-resistant crops and the sustainability of glyphosate as the world's most important herbicide.'"
It always seems a bit suspect when organic groups fret over the future of conventional and biotech ag.
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