Start Clean, Stay Clean

Fall Weed Control Management Strategies

As combines are starting to roll through soybean and edible bean fields across the province, it is a great opportunity to start planning your weed management program for your 2020 wheat crop if you have not already done so. The Wheat Team has always encouraged producers to manage weeds in the fall rather than waiting until spring. More often than not, timing spring herbicide applications can be a challenge. Its either to windy, to cold, to wet, the weeds are to big then we are too late as the wheat is to far advanced in its growth stages and we risk injuring the plants, causing yield loss. The greatest efficacy for control of perennials, biennials and winter annual weeds is in the fall. Furthermore, perennials, biennials and winter annuals will cause more yield loss than summer annuals.

What are the options for fall application timings?

Pre Harvest:

The products used and timing will depend on the crop being grown. With the current glyphosate restrictions on certain crop classes, glyphosate may not be allowed to go in the tank. This has created some challenges controlling perennials with pre harvest applications. Talk with your Agronomist to determine which products you can use for your crop. Pre harvest applications can work really good as it helps the crop dry down, gaining two to three days of wheat planting. It also allows for a clean start prior to planting.

Pre Plant:

Applying herbicides pre plant can be a great way to tank mix products with multiple modes of action for effective control of perennials, biennials and winter annuals. The only issue with pre plant applications is getting it sprayed following harvest but prior to the drill going across the field. If the drill is following the combine immediately, this application timing can be tricky. 

Pre Emergence:

I like the pre emergence option because the wheat gets in the ground as quick as possible, dealing with the herbicide after. However, if you are looking at a pre emerge timing, DO NOT WAIT more than one day after planting to spray. If for some reason it is too windy or it rains after planting, you could be out of the field for multiple days. The more you wait the more chance there is to injure the wheat. Depending on planting depth, soil moisture and temperature, wheat can emerge in five days or less!

Post Emergence (Fall):

The wheat is in the ground, it’s well established but the weeds are growing as well. Spraying winter wheat in the fall with post emerge products has proven to be an excellent option to mix up herbicide modes of action while still providing effective control of perennials, biennials and winter annuals. The post emerge herbicides on the market today have excellent crop safety when used according to the label. The only issue with post emerge herbicide applications are getting it done before the weather turns too cold or wet. The longer applications are delayed into the fall, tougher it is to get done. Just remember, if you are going to attempt a post emerge application and ground conditions are marginal, the tire tracks from the sprayer will more than likely still be there in the spring.

If a fall post emerge application is something you are interested in doing please review the below chart from Dr. Peter Sikkema, University of Guelph Ridgetown Campus. It outlines various products used post emergence in the fall and the corresponding yield from each treatment. 

Over the last couple of years there have been new products/formulations brought to the marketplace that have great crop safety and efficacy on the target weeds in a fall post emergence herbicide program. Some of them include Infinity, Infinity FX, Pixxaro, Enforcer M, Barricade M and Simplicity.   

There are many products on the market that do a great job for all of these application timings. Talk with your Agronomist to determine the right product(s) for your operation. The main goal of fall herbicide applications is to start clean and stay clean to set your 2020 wheat crop up for success. 

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