The Prairie Giants Crop Report

Field observations at your fingertips

April 28, 2023

Taylor Kurtenbach

Pre-Seed Burndown

Spring has finally sprung! The birds are chirping, the sun is shining, and the weeds are growing 😉. In general, we have found that the field’s that had a pre-harvest application the previous fall have less weed pressure than those that did not, especially perennials. A pre-seed burndown reduces competition from these weeds for moisture, nutrients and light early in the growing season to get your crop off to the best start. It is also a good way to help combat herbicide resistance.

There are so many products registered for pre-seed, that it can sometimes be overwhelming. How do you choose the right product?
Target Weeds – each product label lists which weeds are controlled, suppressed, and have extended control when applicable. There are products with large labels that control many weeds, and some products geared towards specific weed problems. For instance, if you’re looking to control foxtail barley before cereals, you could apply Olympus, Fierce or Focus

Residual vs. Non-residual – we almost always recommend applying a residual product when possible. In some crops, like canola, there are very few residual products registered. These include Avadex, Fortress and Edge. In cereals, where there are both available, a non-residual product tends to be only recommended when the spray window of residual products is missed. Many residual products need to either be applied pre-seed or 3 days post-seeding, whereas non-residual products can usually be applied up to ground crack. The exception to this is Heat LQ and Voraxor brand products which are residual and can be applied up to ground crack. 

Moisture Activation – many residual products need moisture to activate. For this reason, some products are geared more towards a fall application but can still be applied in spring. When applied in spring, they often need ¼" to ½" rain after application.

Herbicide Group – it is important to think about herbicide layering and rotating herbicide groups for resistance management. Herbicide layering is the practice of using multiple herbicides throughout different stages of the growing season with the goal of controlling tough to control weeds and preventing herbicide resistance[1]. For example…
  • Applying Avadex followed by a group 1 or 2 in-season to control wild oats in wheat
  • Spraying Certitude or Prospect in spring followed by your in-crop herbicide and Facet L to control cleavers in canola
Overwintered cleaver

Overwintered cleaver.

Utilizing multi mode of action products is also something to consider, not only is it a resistance management tool but often offers better weed control. Using a product, like Paradigm Pre, which has two groups (2 & 4) has better activity on overwintered species like dandelions and cleavers due to the group 4 Arylex active.

New products alertInsight is a group 14 (tiafenacil), non-selective, non-residual pre-seed herbicide from Gowan for use in front of wheat. It needs to be tank mixed with glyphosate (minimum 180 grams) and an MSO surfactant (Merge, Journey). It can also be tank mixed with Liquid Avadex. Since it is non-selective it will burn down anything green and growing – including established foxtail barley and one-leaf wild oats. We have limited quantities available this spring, so talk to us if you’re interested.

Voraxor Complete is a group 14 (saflufenacil, trifludimoxazin) and 15 (pyroxasulfone) registered in front of pulses. It offers the same residual broadleaf control as Voraxor, with the added residual suppression of grassy weeds including green foxtail, barnyard grass, and wild oats. It also needs to be tank mixed with glyphosate.

As always, reach out to us with any questions and we can help you decide on the best product for your farm. We are excited for the new growing season and can’t wait to see what this year brings!

Sources
[1] Kanters, J. 2017. Managing weeds with herbicide layering. Top Crop Manager. [Online] Available: https://www.topcropmanager.com/herbicide-layering-to-manage-weeds-19229/

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