Farm Progress

Permit Plus and STS soybeans for nutsedge. Sprangletop could be a problem this year.

Ford Baldwin

May 17, 2013

3 Min Read

Several consultants have commented about this being a nutsedge year, and I have had several calls about controlling nutsedge in soybeans. The best program for nutsedge control in soybeans — before planting or in-crop — is to plant STS soybeans and use Permit Plus.

It seems the STS tolerance is not often advertised or is overlooked in the Roundup Ready varieties. You could be planting a STS variety and not realize it, or it may take a simple variety switch to utilize this technology. Be sure they are STS because Permit Plus as a soil residual from a burn-down application or as a topical application will kill them if they are not.


From weed control to weed management


I remember a call early one morning years ago. The unidentified caller asked what would happen if he put Permit on his (non-STS) soybeans? I responded that it would kill them graveyard dead. After a short silence he said, “Well, I guess I know what is wrong with mine then. But it sure did a good job on my nutgrass!”

Over the past several years I have also received an increasing number of calls about dayflower control in soybeans. This is another situation where Permit Plus in STS soybeans can make a nice treatment. Storm is another good treatment for dayflower.

If we have a lot of nutsedge up in fallow land and in soybeans, I am sure we do in rice as well. I do not get a lot of calls on nutsedge in rice because most rice farmers know to get some Permit, Permit Plus or Halomax into their programs.

While I have not had a lot of sprangletop calls yet, I would be surprised if this is not a sprangletop year because it is a wet-soil germinator. Most growers are using Command upfront and it is an excellent sprangletop herbicide. However, I see more situations every year where it needs some help on tighthead sprangletop. That help can come from more Command in a split application. However, what I really like is following a Command pre-emergence treatment with Bolero delayed pre-emergence or with RiceBeaux very early postemergence. Those combinations also help a lot on resistant barnyardgrass control.

We are into the time of the season now where postemergence herbicide timing is everything. Whether it is barnyardgrass in rice or pigweed control in soybeans, missing the timing by a few days can be the difference between a clean crop and a failure. The pigweeds germinated much later this year than last year, but they have done so with vengeance. For the sake of time, some growers have skipped the residual herbicide.

While it has been a wet spring, the rains are getting further apart and we will have residual herbicides that were applied but not activated. With the Prefix, Flexstar (and generics of these), and Ultra Blazer, the best timing is the “red stage” — seven to 10 days after emergence. It is usually critical that you follow with another treatment in seven to 10 days to kill the next flush or finish the “cripples” from the first application.


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If you have any plans to rotate to rice, corn or grain sorghum, you are limited to one application of fomesafen (Prefix, Flexstar, Reflex or generics of these) per season. That means to get two applications of a PPO inhibitor, a lot of Ultra Blazer will have to be used. If you use a fomesafen product pre-emergence, then you can use a split application of Ultra Blazer. If you use a fomesafen product postemergence as the first application, you can follow with Ultra Blazer for the second application.

There are a lot of combinations of fomesafen and Ultra Blazer that can be used. The keys are timing of the first application and then following with the second whether you think you need it or not.


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About the Author(s)

Ford Baldwin

Practical Weed Consultants

Ford Baldwin served as a weed scientist with the University of Arkansas Cooperative Extension Service from 1974 to 2001. During that time he conducted extensive applied research trials in rice, soybeans, cotton and wheat, and developed weed management recommendations and educational programs for farmers. Since January 2002, Baldwin has been a partner in Practical Weed Consultants with his wife, Tomilea.

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