Category: Rice

Biological Control of Hemp Sesbania in Rice

Hemp sesbania growing in organic rice in Texas

It doesn’t take you long to figure out the hemp sesbania (Sesbania exaltata) is one of the toughest weed problems we have in organic rice. It is an annual plant, but it acts like a tree as you can see in the picture. It has a few other names, but the most common other name I have ever heard is “coffee weed.”

In a recent meeting with organic rice producers this particular weed became a huge topic of discussion (mostly cussing). This conversation got me to thinking about the possibility of some “bioherbicide” or even some beneficial insect or nematode that might be able to control this noxious weed.

In the process of doing many searches, trying all kinds of names or phrases, I did find this article written in 2014, “Biological Control of the Weed Hemp Sesbania in Rice by the Fungus Myrothecium verrucaria.” (Just click to read)

The authors are at the USDA Stoneville, MS research station and do crops research but some of that research is on biological control of pests in crops. In this research they were looking at applying different rates of the fungus and at different weed plant heights. They looked at 3 concentrations of the fungus sprayed on weed plant heights of 4-8 inches, 8-16 inches, and 16-24 inches.

They did find that the best results were achieved when they used Silwet L-77, an OMRI approved surfactant, with the fungus mix. Overall, the fungus did best at the higher rate and on the youngest plants and control at that timing was 100%! That is phenomenal, but even the bigger plants had control levels around 90%.

Why don’t we have this fungus available to use? That is an excellent question and one I hope to find out soon. I am sure this research was put on the shelf because of changing rice herbicide strategies like Clearfield and the relatively small organic rice industry without much voice. But I think there is a growing interest in organic rice and as a result a growing interest in organic weed control in rice. More details are to follow!

Texas Organic Rice Production Guide

Texas organic rice acreage has steadily increased over the past decade, driven by increased market demand. Since 1995, organic rice acreage has increased in the U.S. by almost six-fold, with a majority of acreage being grown in the Southern U.S. The acreage in Texas alone reached more than 19,000 in 2022.

Texas has over 70 certified organic rice producers scattered from Beaumont to Victoria all along the Texas coast with a few just south of Houston – still! These producers sell to nearly a dozen different organic rice buyers and this rice makes its way into several Texas grocery chains.

What are the major issues facing organic rice producers? Fertility is a concern with almost every crop and rice is no exception. Using organic cover crops though can be a real benefit to rice producers supplying 60 to as much as 108 lbs of N to the subsequent rice crop. In rice these cover crops have to be incorporated early, as much as 4 weeks early, to prevent a strange condition known as straighthead. This extra time allows the cover crop to break down with little to no effect on the crop.

Another major issue is having good organic rice varieties. Fortunately we not only have great Texas A&M AgriLife rice breeders we also have an outstanding Rice Foundation Seed Program begun way back in the spring of 1941. As researchers develop new varieties, Foundation Seed makes those varieties available to rice farmers including organic rice farmers.

If you want to learn more about rice and the rice programs of Texas A&M Agrilife go to https://beaumont.tamu.edu. If you want to read the Texas Organic Rice Production Guidelines publication go to https://tinyurl.com/cdbz3fjd. And remember to eat Texas organic rice every chance you get!