Austrailians Confirm Roundup-Resistant Brome Grass

Australian weed scientists have confirmed a population of Roundup-resistant great brome grass in the state of South Australia.

"This is the first time that this highly competitive annual grass weed of crops and pastures has evolved resistance to glyphosate and is the third Australian weed species confirmed as resistant to glyphosate in the past 12 months," according to an announcement from the country's Grains Research and Development Corporation. "

The resistant brome grass was found surviving in a pasture where an old fence had been removed and cropped over and a pre-sowing application of glyphosate had been applied. The fence line had previously been sprayed with glyphosate for many years with no other weed control tactics used."

Brome grass test samples in 
Australia after Roundup applications. 
Photo Australian Grain Research 
and Development Corporation.

"This is a huge concern to Australian grain growers because this highly competitive weed has been becoming a major problem in reduced-tillage farming," said Associate Professor Chris Preston, chair of the Australian Glyphosate Sustainability Working Group and leader of the University of Adelaide team which confirmed the result. "Currently, the number of glyphosate-resistant ryegrass populations evolving along fence lines is exploding. That and this new discovery are a real 'wake-up call’ and show that any weed might develop glyphosate resistance and growers need to be vigilant."

Brome grass is a major weed of crop and pasture on lighter textured soils across the southern and western Australian cereal belts. In wheat, there are few effective in-crop herbicide options for this species, and it can reduce yields by 30 to 40%. It also emerges after crop establishment enabling it to compete strongly with the crop and produce large amounts of seed.

Brome grass is also a host to a range of cereal crop diseases including take-all and barley net-blotch, while the mature seeds can injure stock. Populations of brome grass are already resistant to grass selective Group A and Group B herbicides in Victoria and Group B and Group C herbicides in Western Australia.

Preston knows that managing brome grass and other weeds along fence lines requires a diverse approach. Herbicides with different modes-of-action to glyphosate need to be included. On erosion-prone sites ground cover needs to be maintained so control along fences and firebreaks should take place late winter to early spring. The older tactic of sowing crops to the fence line then baling and spraying an area along the edge of the crop for a firebreak is a valuable way of stopping weeds moving into the crop while protecting the soil.

Tankmix Options And Approaches When Dealing With Roundup-Resistant Weeds

Roundup resistance has made tankmix strategies more important than ever for growers who either want to delay its onset or deal with problems that already have developed.

Here's an article from DTN/Progress Farmer that covers resources, like apps and on-line videos, that cover proper tankmix procedures.

Roundup Resistance Management And Weed Control In Cotton And Grains Covered In Video Series

The National Cotton Council has created a series of short educational videos on weed resistance management and control strategies in cases where weed resistance has developed.

The videos cover cotton but also relate closely to the same issues in corn and soybeans. The programs include commentary from a number of Southern weed scientists involved with Roundup-resistant Palmer pigweed, horseweed - marestail and other weed pests that have gained varying degrees of resistance to Roundup and other glyphosate products.

The Weed Resistance Video includes interviews with four cotton producers who have firsthand experience with weed resistance. They discuss why this concern must not be ignored and provide valuable information on how to deal with weed resistance.

Other videos include:

• Biology and Management of Pigweed
• Field Day with the University of Georgia's Stanley Culpepper
• Horseweed: Control this Weed Early
• Field Day with University of Tennessee's Larry Steckel
• Corn Weed Management
• Weed Resistance Management

Roundup-Resistant Pigweed And Johnsongrass Now A Reality In Louisiana

Until just the last year or so, Louisiana has mostly dodged the bullet when it came to Roundup-resistant weeds, especially two severe problems: resistant pigweed and resistant johnsongrass.

But events caught up with the state, and Louisiana State University weed scientists have been confirming more cases of known resistance.

Don't Get Behind With Roundup-Resistant Pigweed, Says Arkansas Farmer

From February's National Conservation Cotton and Rice Conference in Baton Rouge, Louisiana:

Wayne Wiggins, of Arkansas, said herbicide-resistant pigweed appeared on his farm rapidly. “I was just stunned at how fast it came on.” He said it’s important to talk with neighbors about their weed problems and be prepared for resistance issues. 

“You’ve got a narrow window. When you get behind, you are over and done.” Wiggins said he uses atrazine on corn for its residual effects. “I’ll use a residual on all my bean fields this year.” 

He said rice is a good rotation crop to address pigweed, but the weed must be controlled on levees.

Source: Bruce Schultz, LSU Ag Center

Hooded Sprayer From Wilmar Aimed Directly At Roundup-Resistant Weed Control

Hooded sprayers were left to rust and rot in the weeds after Roundup Ready became the dominant weed control measure in cotton and other crops in the South.

Now, though, with the shift toward more Roundup-resistant weeds, hooded sprayers have been reentering fields, and more units are being sold.

Roundup-Resistant Ryegrass: Mississippi Schedules Symposium For March 10

Mississippi farmers are a few years into the fight against glyphosate-resistant weeds, a problem that is the focus of a March 10 field day in Stoneville.

Producers will take a close look at ways to manage herbicide resistance in the Glyphosate-Resistant Ryegrass Field Day at Mississippi State University’s Delta Research and Extension Center in Stoneville. Registration begins at 7:30 a.m. at the Capps Center, and the field day concludes with lunch. The program will move indoors if there is bad weather.

Conventional Cotton Herbicide Control: One Approach

Editor's Note: Rusty Harris, Extension Agent in Worth County, Georgia, developed the following systems approach for his farmers who want to grow cotton that lacks herbicide resistance traits:

This program should provide adequate control of palmer amaranth, ipomea morningglory species, yellow nutsedge, bristly starbur, and tropic croton.

Roundup-Resistant Pigweed Management Plan For 2011 From Georgia

R.J. Byrne, Extension Agent in Thomas County, Georgia, has produced a short video (see below) about Georgia's approach for controlling Roundup-resistant Palmer pigweed in cotton. In the video, Byrne interviews Stanley Culpepper, Georgia Extension Weed Scientist.

Here's a supplemental handout that goes into more detail about herbicides, rates and other factors touched on during the video.

Arkansas Resistant Palmer Pigweed Field Day Video From Arkansas

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.

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

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.

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:

• 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.

- Debra Ferguson

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.

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.

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.

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

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

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

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.

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:

• 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.

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."

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.”