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Resistant barnyardgrass would be huge problem

A real concern to me is barnyardgrass and what seems to be a general lack of performance of rice herbicides — especially in the later-planted rice. Those who know me or have read my columns for years know I can be pretty direct — the description “plain spoken” has often been thrown around. I actually take pride in that because I simply have never been good at beating around the bush.

Please understand, however, I am never personally critical of farmers as individuals or as a group or of any of the industry that supports our farmers.

This has been the most difficult year I have seen for farmers in terms of input costs and of just trying to make a crop. Some of the same input costs and difficult times the farmers have had in the field have also put a lot of pressure on the support industry as well. With that said, everyone needs to take a good look at what the weeds are telling us.

I mentioned in last week’s article that I heard two prominent university weed scientists — one from Arkansas and one from Tennessee — comment that glyphosate could no longer be considered a pigweed herbicide in those states. That is huge, but if there is a weed that has more potential than others to adversely affect the farm economy in Arkansas it is barnyardgrass.

Like the pigweeds, barnyardgrass has tremendous genetic diversity which gives it the ability to adapt quickly to different environments and different herbicides.

Have you looked around this year in both rice and soybeans? This has been a tough year and weeds love tough years. I believe the tough year is responsible for a lot of the weedy fields, but some of the problems go beyond that.

As recently as four or five years ago it was unusual to see a weed in a Roundup Ready soybean field, which meant it was unusual to see a weed in a soybean field period. It was just plain rare to see a field one would call weedy or grown up.

Over the past three years, I have noted a steady increase in the number of weedy soybean fields, and the primary weed I am seeing is barnyardgrass. I do not know of any cases of documented barnyardgrass resistance to glyphosate.

That does not mean there are none, but the reasons I see for the huge increase in barnyardgrass escapes in Roundup Ready soybeans are from self inflicted wounds. I will expand on the specific reasons next week.

However, when we do not control barnyardgrass in soybeans, there is a tremendous seed bank going into rice. We are having more resistance problems in rice and more cases where barnyardgrass is just overpowering the herbicide programs. I am concerned we are creating a monster.

On another note, I remind growers to not let stink bugs and diseases catch you off guard. Neither is in my area of expertise, but, everyone has a mind-boggling amount of money invested in the rice and soybean crops, and you must maximize yield and quality in both.

The past couple of years have been relatively easy with stink bugs in rice. However, consultants are reporting some high numbers in staging areas. Also, a lot of the crop has more grass in it this year and stink bugs are attracted to barnyardgrass.

With stink bugs and diseases, it is a matter of scouting properly and treating if a pest is present at threshold numbers. Gus Lorenz is the person at the University of Arkansas I go to for specialized help on insects and Rick Cartwright and Scott Monfort are the point men for disease problems. If you need them, your county agent can get you in touch with them or call me and I can get you in touch with them if you do not have their numbers.


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