Get TOUGH on Weeds that Can REDUCE Corn Yield
TIMING OF WEED INFESTATIONS
As we strive to control weeds with pre and post emergent herbicide programs for season long control, this may not always be possible. As weeds grow in a corn field, they compete for sunlight, water and of course the nutrients applied. The longer that weeds persist and compete with the corn (Photo 1), the greater the loss you can expect.
While there are strategies that can be employed in a weed management program to minimize the negative impact of the weeds, according to University of Nebraska1, the level of crop yield loss will depend on:
- environmental variables,
- weed species composition within a given field,
- weed density, and
- time of weed emergence relative to the crop growth stage.
During the critical period of weed control (CPWC), management is imperative to minimize impact of weeds on yield (and profits). It is important to determine the CPWC, create an integrated weed management program including herbicides with different modes/sites of action, and implement the program during this critical time period.
Recently, Belchim USA sponsored a forum executed by Beck Ag. Dr. Bill Johnson, Professor of Weed Science, Purdue University spoke about the impact of weed infestations on corn yields. “We’ve seen everything from light infestations causing just a couple of bushels per acre to heavy infestations, causing up to almost 80% to 90% yield loss. It always seems like corn has the ability to produce an ear, but I know in certain situations, especially where we’ve had Palmer Amaranth in drought conditions, that we have not been able to harvest areas of fields due to Palmer Amaranth. It was going to be too much wear and tear on a combine and too much seed going into a combine to harvest some patches of that weed and create some other issues by spreading that seed over the clean areas. So again, the yield loss can be as high as 80% and particularly in years where the weeds come up early and you get into a drought situation where you don’t have a good canopy formation.”
A TOOL TO IMPROVE CONTROL
In 2017, Belchim began coordinating with key universities across the US corn belt to evaluate TOUGH® 5EC, with the active ingredient pyridate, in numerous research trials. Pyridate works by blocking a weed’s photosystem II process, triggering the release of toxic forms of oxygen and causing rapid cell wall degradation. Pyridate is a highly effective mode of action in corn and shows increased levels of weed control in tank-mix combinations. Trials and 2021 commercial field use revealed significant increase in weed control when TOUGH 5EC was included in the tank mix.
For over a decade, weed resistance (palmer amaranth and common waterhemp) to HPPD inhibitors (Group 27) has been on the rise. TOUGH 5EC is an ideal tank mix partner, as a resistance management tool, with HPPD inhibitors. TOUGH 5EC herbicide puts a synergistic charge in your post emergence weed control program with rapid and complete control of your broadleaf weeds including resistant common waterhemp, palmer amaranth, and giant ragweed. Adding TOUGH 5EC to the tank mix, improves performance; resulting in faster weed death and overcoming HPPD resistance.
Additionally, TOUGH 5EC is an ideal product to combine with other PSII’s, such as atrazine, because it interacts with the weed differently. Pyridate has fast foliar absorption to get to the target site but also degrades rapidly in the soil to prevent carry over concerns. Atrazine has slow leaf absorption and primarily works through root absorption which requires moisture. Atrazine has residual effects for weed control but can result in carry over; maximize the PSII class with this combination.
Dr. Johnson, who has conducted research trials with TOUGH 5EC since 2017, has seen the results first hand, and commented; “What ends up happening when you put on Tough and a herbicide like Callisto together is you have these free radicals produced by Tough. And then with Callisto you inhibit the plant’s ability to produce these pigments and so the photosynthetic operation starts really reeling out of control. And the end result is a plant that turns brown and dies much more quickly than it would have with either herbicide alone. So again, one of the unique things about Tough is its ability to make Atrazine and Callisto work better. And so I think that’s relatively unique when we think about all the different things that we can do. When we tank-mix herbicides we always hope that the effect is additive. And in a situation like this, it’s almost a multiplicative effect in how much better it makes it work.”
Orville Fulk, Chemical Division Manager at Sur-Gro Plant Food in Weston, Missouri saw TOUGH 5EC in action in 2021. In the fall of 2020, the spray technician came to Orville as he noticed resistance traits showing up on a farm that had been treated with the same weed management program for 10 years (glyphosate and topramezone). Orville heard about TOUGH 5EC and was able to get enough product to treat about 320 acres of this farm for the 2021 season. They mixed TOUGH 5EC, along with mesotrione and glyphosate, and applied when the waterhemp was about 4-6 inches tall. The remaining acres were treated with the glyphosate and topramezone mix.
Orville walked the field himself about 5-7 days after application and noticed the acres treated with TOUGH 5EC looked great. “TOUGH 5EC had a quick take down; the waterhemp was on the ground and non competitive. Fields stayed clean and regrowth in the TOUGH 5EC treated area held off until early September.” Orville went on to say, “The real testament to the control that TOUGH 5EC provided was when the farmer came up to the spray technician and said to make sure that whatever was used on those 320 acres, was used on the whole farm next year. He could tell to the row where the TOUGH 5EC treatment had stopped.” The photos show how the fields looked in September 2021 and the difference between the areas that included TOUGH 5EC in the mix, and did not is clear.
1 https://cropwatch.unl.edu/critical-period-weed-control-corn