Contents tagged with herbicide resistance

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Some older herbicides might help fight resistance, but may be less convenient than common spray application methods.

Applying Edge in the fall with a Valmar on a harrow drawbar, harrowing once in fall and once in spring before seeding is enough incorporation for effective weed control.

Treflan, Edge and Avadex® are all still on the market. They’re becoming more popular again and provide extra herbicide groups to fight weed resistance issues.  Adding one of these products provides another tool in the resistance management fight. 

To use Edge, growers are spreading the granular product with a Valmar applicator mounted on a harrow bar. A lot of our customers harrow cereal stubble anyways, to manage some of that extra trash, especially if it was a high-yielding crop.. 

Harrowing Edge once in the fall will provide a decent level of incorporation, but running over it again with harrows in the spring before you seed is a best practice because it re-disturbs the product in the soil again in the spring, and uses increasing spring temperatures to enhance activation time.  If applied in the spring, harrowing the field once will be sufficient as the soil is typically warmer than fall and will still allow good activation.

In the spring, everyone wants to get seeding as soon as they can. If it’s a dry spring, they might not want to dry out the soil more with harrows. But that often can make a difference in final weed control. 

Last year, the guys that harrowed their fall applied Edge again in the spring, with the dry conditions, really benefited in the long run. Once we started getting some moisture and weed germination, that’s when the residual control really started to show. 


Treflan and Edge are trademarks of Dow AgroSciences. Avadex® is a registered trademark of Gowan Company


With the price of pulse crops this year, it’s tough to talk cereals right now. But with Group 2 resistant weeds like kochia and wild mustard, including a cereal crop in your rotation provides opportunities to use products with different modes of action, to help manage the spread of resistant weeds.

Add a tank mix partner with your pre-seed glyphosate burnoff and space out your rotations.

With pulse prices the way they are, it’s tough to talk cereals right now. But farmers need to space out their rotations, with a pulse crop every third year, rather than every second year or back-to-back. With Group 2 resistant weeds like kochia and wild mustard, mixing up the crop rotation by throwing in a cereal definitely helps. 

Preventing glyphosate resistance from spreading into our area is another concern. We’re recommending that farmers tank mix when doing their burnoffs to make sure there’s a double mode of action against some of those key weeds.

Most of the lentils grown in our area are Clearfield®, which rely on Group 2 technology. The weed resistance challenges are mostly Group 2 resistant weeds like kochia, stinkweed and wild mustard. We want to keep Group 9 resistant kochia out if possible, as well.

We’re recommending a tank mix of glyphosate and Heat® for pre-seed burnoff. For in-crop control of Group 2 resistant wild mustard, we’re recommending Sencor®. 

Most of the lentils grown in our area are Clearfield® varieties, which rely on Group 2 weed control technology. But we do have Group 2 resistant weeds in the area, including kochia, stinkweed and wild mustard. Another challenge is that Group 9 resistant kochia may soon be an issue that we have to deal with.

We recommend a tank mix of glyphosate and Heat® for our pre-seed burnoff. Where we don’t have Group 9 resistance that gives us two modes of action against the kochia and should help delay resistance from developing. It also provides two modes of action against the Group 2 resistant weeds. 

For Group 2 resistant wild mustard in-crop, we recommend Sencor®. While it’s tough on the lentils, it’s the only product we can use. 

Clearfield® is a registered trademark of BASF. Heat® is a registered trademark of BASF. Sencor® is a registered trademark of Bayer CropScience.

With a clubroot scare in the last year, farmers in the area need to lengthen their rotations. It’s hard to switch to different crops, but doing so will break cycles of weeds and disease.

Canola:snow:canola can increase the risk for resistant weeds developing, as well as diseases like clubroot. We need to lengthen crop rotations and add more crop diversity to battle both issues.

I’m encouraging growers to add more crops to their rotations. We’ve had canola:snow:canola on a lot of fields, but with a clubroot scare in the last year, farmers in the area are now trying to lengthen their rotations. 

This year will be our biggest year in recent memory for peas, with stronger prices and the need for a better rotation. It’s hard to switch into different crops, but if you’re facing weed resistance and clubroot, I encourage you to try adding faba beans or soybeans to your rotation. 

A more diverse crop rotation allows you to get away from using the same groups of chemicals, which helps when dealing with herbicide resistance. More crops in the rotation also helps reduce the risk of diseases like clubroot. 

It’s a work in progress – we’ve got to be vigilant, or there will be big problems ahead.

Straight glyphosate burnoff increases selection pressure for resistant weeds.

Add a tank mix partner with glyphosate so at least two modes of action are working on target weeds. Even if it’s something as simple as 2,4-D or MCPA, at least you’re incorporating another mode of action. 

It can be tempting to think about just increasing the rate of glyphosate, and calling that good enough for the preseed burnoff. However this will continue to select for glyphosate resistant weeds. Think about how many times in a year we are spraying glyphosate alone out of necessity – in canola, soybean and as a preharvest, and postharvest. There are a lot of options in the preburn, take advantage of them.

For 2016, farmers in my area will be planting a lot of lentils, which rely on Group 2 herbicides for weed control. Pushing their rotations may help Group 2 resistant weed populations get more established. We want to use crop rotations to help reduce the risk of resistant weeds, including glyphosate-resistant kochia, from developing.

In the cereal year of your crop rotation, include products with dicamba to control any Group 2 and 9 resistant kochia.

A common crop rotation in the area is lentils:durum:canola, which is decent for weed resistance management and provides a good mix of herbicide options. But this year, if two-thirds of the farm is going into lentils, that will increase the resistance risk. 

We’re recommending products with dicamba get used in the preseed burnoff of the cereal year of the rotations. A product like Korrex™, which includes dicamba, provides a third mode of action in the cereal burnoff that should help prevent the development and spread of group 9 kochia.

A common practice is a pre-seed burnoff tank mix of glyphosate and PrePass™ or Express® SG and these products work well. If you are looking to get away from the Group 2 to help manage resistant kochia adding Group 4 or 14 products incorporate more groups into the rotation.

PrePass™ and Korrex™ are registered trademarks of the Dow Chemical Company. Express® SG is a registered trademark of DuPont.