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2020 Herbicide Review

Jun 05, 2020

By the time you read this, most of the crop is planted and in much better position than this time last year, which we are all grateful for.  I wanted to give an update on some observations we’ve been seeing in the field and a couple reminders.

First, the very cold spell we had is having an effect not only on weeds but crop emergence.  We’ve seen up to a 10-degree difference in the same field with soil temperatures due to tillage and residue differences.  The very early and later planted corn fields seem to be emerging well, but fields in the middle per say are struggling.  Poorer stands, erratic emergence and plant height differences are common themes. This is important and makes identifying crop stage to abide by herbicide labels more challenging.  In those fields that are erratic and uneven, I would lean towards the average of the farthest or tallest plants in the field as most herbicide labels allow applications of to V5 12” tall corn. Some herbicides require minimum 4” growth. In this case, I would evaluate to what extent of the field is at this stage and then stay conservative on that end if a minimum plant height is needed to make an application. Be sure to lean on your CFE agronomist if you have concerns or have questions!

Erratic stands and emergence on those troubling fields are going to a be a bit of a concern on crop canopy as well and I would consider adding a layered residual in your post application like Harness ®, Harness® Max, Dual, TripleFLEX®, SureStart®, ect.  By now, most of the pre-emerge herbicides have run out and we are spraying a bit earlier this year, so the second layer of residual herbicide will be important to keep fields clean.

Another observation we’ve seen with the temperatures over 90 degrees and with soil moisture being on the drier side, we want to run additives and keep the crop oils and surfactants at a high enough rate to assist the herbicide gives adequate weed control.  Weeds are tough but can get hardened off in times like these. Their natural defense mechanisms such as a waxy leaf surface, small leaf area or leaf hair make some weeds more difficult to control.  I give a word of caution, depending what is being applied, for example Roundup PowerMAX®, has a surfactant in it or if herbicides are oil based like a residual product, all adds to the surfactant load being sprayed and in extreme heat can cause a crop response.  I encourage you to evaluate the types of chemistry combinations being applied, the type of crop oil and surfactant needed and adjust the rate if needed.  As always, nothing is set in stone and we have to go with the flow depending on environmental conditions.  That’s what keeps it interesting! 

Have a safe spring and stay in contact with your agronomist if you have questions.

Terry Aukes, CFE Agronomy Sales Manager

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