Should Mississippi Soybean Farmers use an Insecticide Seed Treatment?
A relatively new management option for Mississippi soybean farmers is the treatment of planting seed with an insecticide in addition to the already proven effective treatment with fungicides. Available products contain systemic insecticides that provide effective control of early generations of bean leaf beetle, thrips, and three-cornered alfalfa, among others. They generally have a short period of efficacy (30 to 45 days), and are not a replacement for late-season insect control that may be necessary in some fields.
Results from numerous recently conducted studies indicate that using these insecticidal seed treatments results in small but significant yield increases that apparently result from lessening the damage caused by insect pests early in the season. One of the studies conducted at Starkville, Verona, and Stoneville over a 3-year period was supported by the Mississippi Soybean Promotion Board. Those results are available on this website.
All-in-one products that contain both fungicides and an insecticide are now available. Two such products are Trilex 6000, which contains the fungicides found in Trilex 2000 and the insecticide found in Gaucho, andCruiserMaxx, which contains the fungicides found in ApronMaxx and the insecticide found in Cruiser. CruiserMaxx Plus (available in 2011) is a new product that contains a nearly 2X rate of mefenoxam fungicide for increased protection against Pythium and Phytophthora fungal pathogens, which are problematic in Delta clay soils. Some seed suppliers routinely add extra mefenoxam to accomplish this purpose as well.
All indications are that the addition of CruiserMaxx or CruiserMaxx Plus to seed by the supplier will cost about $11 to $14 per 50 pounds of seed, respectively. Since the fungicide alone applied to seed costs about $3 per 50 pounds of seed, the insecticide component adds about $8 to $11 to the cost. Thus, average yield increases of around 3 bu/acre measured in a majority of the above studies are economically significant, especially with the current price for soybeans.
In an earlier article, I touted the benefits from using a fungicide seed treatment. All indications are that those benefits are increased by using one of the seed treatment products that combines fungicides and an insecticide. This should be true as long as bean prices remain above about $5 per bushel.
Resistance management is always paramount when using pesticides; therefore, these products should be used only if you the producer are confident that you have had or will have potential crop damage from early-season insects. This has certainly been the case with three-corned alfalfa hopper in many Mississippi fields over the years, and there is evidence that increasing pressure from thrips is worth taking note of.
I thank Normie Buehring, Angus Catchot, Gus Lorenz, Jeff Gore, Zack Stewart, Andy Moore, and Jason Mize for information used in this article.
larryheatherly@bellsouth.net