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Serving: Central

Drift damage, lack of rainfall boosting weeds

I have begun fielding questions about and looking at drift complaints. The season has started out difficult in many areas of the state — primarily due to the lack of rainfall. A lot of the residual herbicides applied in all crops have not been activated properly, which puts more pressure on the postemergence herbicide timing.

As with most spring seasons, we have had a lot of windy days. When folks get behind spraying and the wind blows every day, drift frequency increases. Most of the early calls were on Gramoxone spotting on seedling rice. While it is never good to have herbicide drift on a crop, Gramoxone spotting is usually cosmetic in nature until it is severe enough to kill plants or burn them to the ground. Often, however, a photosystem 2 herbicide such as Cotoran, atrazine or metribuzin (depending on the crop) is added to the Gramoxone to slow it down and make it translocate better. Unfortunately, this also makes the effect of any drift more severe.

Calls about glyphosate drift on young rice are also coming in and I have looked at several fields. Glyphosate translocates readily and has a longer-lasting effect on seedling rice. If it is not so severe that excessive stand loss occurs, the rice often makes a remarkable recovery. Again, this does not mean it is good that it got on there. By the time I get to the field, the primary decision involves whether or not to keep the crop. If there is enough rice there to call a stand — regardless of how thin it may look — I almost always recommend keeping the stand.

One thing I rarely if ever recommend is re-seeding into the stand that is left. Reseeding usually just results in two stands of rice and you have to decide which stand to manage and which you let become a weed. If it is bad enough to need sweetening up with more seed I usually recommend starting all over.

If we do not get into a better rainfall pattern to get residual herbicides activated we are going to have a lot of crops in the ditch. A lot of consultants are already struggling with rice weed control. In most situations where Command and other residuals were not activated, the grass is also drought-stressed. This usually brings about the dreaded question of “do I flush and spray or spray and flush?” I usually recommend doing both.

If we cannot get a lot of these situations turned around right now, we will be fighting grass all season. Nobody likes the dreaded “F” word but a lot of fields should have been flushed to activate herbicides. At the time it sounds good to say, “I am not going to flush and will just use postemergence herbicides.” These decisions are biting a lot of folks right now.

In soybeans, we are headed for a train wreck if we cannot get some residuals activated. I am getting calls in a lot of situations where I am thinking, “Your life would be much easier right now if you had planted LibertyLink soybeans!” They can struggle under adverse conditions as well, but you have more firepower. It sounds simple to say, “I am just going to use a pre-emergence herbicide (or multiple residuals) until they do not work.”

Remember that Palmer pigweed is essentially a desert plant and dry conditions do not phase it in the least. Under heavy pigweed pressure, if you fail to get the residuals activated and miss the first postemergence timing a few days, it often results in either a replant situation or a grown-up mess.

Get the Flexstar applied in Roundup Ready soybeans as soon as you see anything out there but soybeans. In a LibertyLink program spray the first Liberty or Ignite application on 1- to 2-inch pigweeds if possible. Sure you can often kill them bigger than that, but they grow 2 inches per day and you cannot spray them all the same day.

We have a lot of crops out there where the weed control season will be over by Mid May — at least in the first planting — unless the right decisions are made early.

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