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Herbicide application timing crucial

Herbicide application timing crucial

Some say time the application to 2- to 3-inch pigweeds. Others say you can wait until 3 to 4 inches. That is a moot point when they grow 2 to 3 inches per day. With any of those timings, if you miss it by two to three days, you are in trouble.

Farmers this year should make absolutely sure they either have the spray equipment or they have made proper arrangements to spray their first postemergence applications timely. By timely I mean being prepared to hit a two- to three-day window if necessary.

Like it or not, our cotton and soybean weed control programs have reverted to where application timing is everything again. You may not like it, but the weeds do not care.

I heard a lot of excuses why applications were not made timely last year. Most commonly it was “the weather.” A ton of growers seemed to have been rained out of the field during a time we were going four and five weeks without rain to activate preemergence herbicides!

I am not being critical. I have done a lot of spraying in my career, and I missed a lot of application timings. Far more of the misses were due to self-inflicted reasons than they were to factors beyond my control. I can be sympathetic, but the weeds do not care.

We are depending upon the PPO inhibiting herbicides like Flexstar, Cobra and Ultra Blazer for postemergence pigweed control in Roundup Ready soybeans. The application window is very narrow. Everyone has an opinion on timing, but mine is to spray when the pigweeds are still in the “red stage in the early morning sun” — seven to 10 days after emergence.

I hear some say time the application to 2- to 3-inch pigweeds and others say, “No, you can wait until 3 to 4 inches.” That is a moot point when they grow 2 to 3 inches per day. With any of those timings, if you miss it by two to three days, you are in trouble.

Sure, some people tell me they were impressed with how big the pigweeds were when they killed them with Flexstar. The problem is what you can do sometimes, you can not do consistently, and “sometimes” is not good enough.

It would appear this year that LibertyLink acres are going to significantly increase like I actually thought they would two years ago. A herbicide name change was recently announced and the Ignite name will be phased out and changed back to Liberty. I will still call it Ignite for a few articles because that is what the labels in the pipeline say right now.

For the sake of argument, perhaps the application window for Ignite is a little wider than for Flexstar. The timing window may be more like seven to 14 days after emergence instead of seven to 10 or a 3- to 4-inch pigweed with Ignite as opposed to 2- to 3-inch for Flexstar. From a practical standpoint it does not really matter — the real difference is a day or two.

I have people tell me, “Doc, you won’t believe how big a pigweed I killed with my Ignite.” Don’t get sucked into that because consistency is what matters. You also have a lot more firepower in a LibertyLink program with a second application of Ignite. However, the first one needs to be timely.

We have gone through 10 years or so when we had a lot of flexibility in application timing, but that day is over. You do not have years to make the transition back to timely applications. In many cases you have to do it this year.

I am concerned that we do not have the ground application equipment available to get over all of the necessary acres timely. We obviously have enough to spray when we get around to it, but that day is over. The farmer with pigweeds that sprays when he gets around to it will likely be out of business in short order.

I encourage every grower to make arrangements now for getting the weeds sprayed as you plant. I have heard agronomists say for years, “Don’t plant more in a day than you can harvest in a day.” Most did not pay a lot of attention to that and sometimes regretted it later. I am saying do not plant more in a day than you have arrangements to get sprayed timely in a day.

You are probably thinking, “Doc, you are nuts to say we have to operate in a two- to three-day timing window.” You do not have a choice — the weeds don’t care!

TAGS: Cotton
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