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Fungicide treatment guards rice seed

“Should I use a seed treatment?” “What is the best seed treatment?” Now that it is too late to help, I figured to take a stab at this topic. Typical, right?

Fungicides are just one type of seed treatment for rice, others being zinc, gibberellic acid and the insecticide Icon.

I have tested beaucoup (French for many) rice seed treatments over the years and developed a general “feel” for what helps, at least in dry-seeded rice. Water-seeded fields have their own set of problems.

First, good seed is, well, good. The best way to get good seed is to buy it — rice seed grown and handled as seed and certified for high germ. Whether you do it or someone else does it, rice should be grown and managed differently for seed than for grain.

Second, most stand problems occur with early planting and/or true no-till planting. It appears that pythium fungi in the soil are the culprits. So, in our April tests, the pythium fungicides Apron XL and Allegiance tend to give the best results.

In a few tests, mostly early no-till plots, combination treatments containing Allegiance and Vitavax (various forms), Apron XL and Maxim, Stiletto and others have been a little better. Even with a stand increase, yields in these small-plot tests are often the same because rice can compensate for a thin stand.

So, if you are planting early or in no-till seedbeds, use a fungicide seed treatment containing Apron XL or Allegiance for insurance. If you plant too early or too nasty or too deep, then nothing will help. These are not miraculous products.

Later in the spring, when temperatures are warm and rice will come up in seven days or so, you likely don't need any fungicide seed treatments. However, if you are planting high-value rice seed like Clearfield or using a very low seeding rate, you should probably consider using fungicide seed treatments. Hybrid rice seed is already treated.

Some folks like to aggravate me by asking, “What about treating seed to control kernel smut?” Nope, doesn't help because the kernel smut fungus is already in every rice field in the South, and the little dab of smut spores on your seed is not going to influence the disease later in the season.

Okay, what about treating seed to control false smut? For what it's worth, I still suggest trying to clean as many smut balls out of the seed as you can and treating the seed with one of the combination seed treatments. Does it really help? I don't know but if you reap what you sow, and you are sowing smut balls, what do you think?

What about treating seed to control blast on susceptible varieties? Tricky subject since we know the blast fungus can be seed-borne but it also can survive in the straw, and spores can be moved by wind. Fleet Lee, Dave TeBeest and Jim Correll with the University of Arkansas are working on this idea.

My question is: “If you planted seed completely free of the blast fungus, would it help later in the season?” These researchers are trying to figure that out for Arkansas conditions.

Anything new? We have been testing azoxystrobin (the active ingredient in Quadris fungicide) as a seed treatment for rice for several years now. It has given good results on protecting stand in my tests and may be labeled in the future for use as a rice seed treatment. It will likely be a different formulation and name besides Quadris, though.

Good luck with your crop.

Rick Cartwright is an Extension plant pathologist with the University of Arkansas Division of Agriculture.

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