In Arkansas and Louisiana cotton, in-furrow fungicides treatments typically require combinations of several products. The reason? Cotton seedling diseases usually show up as a complex.
“Typically, we use an Allegiance or Apron-type product that takes care of Pythium.” Says Cliff Coker, Arkansas Extension plant pathologist. “Then, farmers normally use a seed treatment. To deal with Rhizoctonia and Fusarium, cottonseed comes treated with Allegiance or Vitavax, Thiram or Baytan.”
Seed treatments on commercial seed normally have a combination coating. But if you're going with an in-furrow, you have a lot of options, says Coker.
“Until the weather arrives, we really don't know what kind of problems we'll be facing. That normally means growers need to prepare with a combination of products. Ridomil Gold (for Pythium) plus Quadris (for Rhizoctonia) is a popular product as is Ridomil Gold PC (to control Rhizoctonia). We also use Terraclor Super X — that's PCNB (for Rhizoctonia) plus Terrazole (for Pythium). There's also Rovral (for Rhizoctonia) plus Ridomil Gold.”
Patrick Collier, an LSU AgCenter plant pathologist stationed at the Red River Research Station near Bossier City, tells growers to get seed that's been treated.
“You definitely need such a variety and going without one is a recipe for a lot of problems. Usually, whatever the seed company supplies has two or three active ingredients to deal with a spectrum of seedling pathogens.”
Collier says the bigger question comes later when considering if an in-furrow treatment is needed.
“Generally, what I tell growers is that environment is the most important thing to consider. Soil temperatures and soil moisture are the most critical factors in determining whether to use an in-furrow. Cool soils tend to mean a seed that germinates more slowly. So the window of seedling infection opportunity is greater. Another consideration is that some of the fungi are more active in cooler soils.”
That's why paying close attention to the environment is critical, says Collier. Pay attention to the soil temperature, look at the moisture often, and check what the weather will do for the next four or five days.
“If there's a period of warm soils and you aren't facing a cold snap soon, you can usually get away with applying lower rates of fungicides or switching to a hopper-box material. Or, if you're late enough in the growing season (in Louisiana, April 20-25 is prime planting time) the soil is usually warm and seedlings emerge after four to six days. Later in the season, the need for a fungicide drops — you may not even need one.”
On Louisiana cotton, Terraclor Super X is the Cadillac, says Collier. “It's been around a while, we know it works and it's a product that doesn't leave much doubt. There has been a move away from it to some degree, though, because of its cost.
“Ridomil PC — a Syngenta product — has also been around and does a good job. Like Terraclor, Ridomil contains formulations to deal with both Rhizoctonia and Pythium.
“Quadris has only been around a short while in comparison. According to our data, it looks pretty good although it's a bit weak on Pythium. If a grower is in a Pythium problem area, I'd encourage that Ridomil be put in with the Quadris.”
Collier isn't as high on Rovral as he is on other products. “It doesn't seem to hold up as long under pressure — it seems to break down quicker.”
Coker says on soybean seed treatments, Arkansas growers normally use, “something like Apron Maxx or Stilleto (both combo products). As with cotton, in soybeans both Rhizoctonia and Pythium are problems. A combination product is often needed — maybe Vitavax (for Rhizoctonia) and Allegiance (for Pythium).”
With soybeans, you get what you pay for — whether in-furrow fungicides or seed treatments.
“In cotton, I think the seed treatments that come on the seed are plenty — particularly if you have good germination conditions, a nice bed to plant into and planting is likely to go smooth,” says Coker. “But if you're planting early because you have a bunch of acres to get in, the environment isn't exactly what's needed for germination and emergence, it's best to put in an in-furrow fungicide along with the seed treatment.”
As a rule, Louisiana growers don't use in-furrow fungicides on soybeans, says Collier.
“There have been a lot of questions lately, though. Typically, soybeans were planted when soils were warm and there were fewer problems. Now, with all the Group 4s going in, there's some earlier plantings going on. Even with that, though, I doubt many farmers use an in-furrow on beans.”
Because of all the trouble with seed crops last year, growers need to check their cotton and soybean seed's vigor test.
“Go ahead and check the germination test, but make sure the vigor is solid. Make sure a cold tolerance test has been done. Theoretically, you could have 85 percent germ and 10 percent vigor,” says Coker.
“I've always told cotton farmers to find out what the cool germ is on their seed. That cool germ tells a lot. Most of the time, seed companies have good cool germs. But every once in a while, there's a year when high-quality seed isn't as available. What you want to try and do is narrow the window of opportunity for infection. One way to do that is to get seed that is vigorous. Such seed germinates quicker and emerges faster.”