Diseases that adversely affect soybean seed and seedlings are prevalent in Midsouth production environs and can often lead to poor emergence and/or failed stands. Injury from species within the Pythium and Phytophthora pathogen complexes are potentially the most detrimental to establishment of adequate stands in Midsouth soybeans.
Fortunately, there are numerous fungicide seed treatments that are very effective against these diseases. However, it is hard to prove their worth in the absence of a measurable effect on seed yield, which is often the case (see below).
There are now insecticide and nematicide seed treatments to go along with the fungicide seed treatments that have been available over the last two decades.
A thorough, up-to-date discussion of seed treatment components and their use for soybeans is available in a White Paper on this website.
Pertinent statements from the White Paper follow.
- Using an appropriate fungicide seed treatment on soybean planting seeds will increase the probability of achieving a satisfactory stand. Also, soybean stands are often increased by over 10% when the proper seed treatment is used. Thus seeding rate can be reduced to cut costs while still achieving the desired stand.
- Environments in which fungicide seed treatments provide benefit are early planting into cool wet soils and minimum and no-till fields that have a high amount of surface residue.
- Using a broad-spectrum seed treatment is cheap insurance to avoid replanting a failed stand, especially since replanting will result in a later planting date.
- Results from previous studies indicate that using insecticidal seed treatments that are effective against insects such as bean leaf beetle, thrips, and three-cornered alfalfa hopper will result in small but significant yield increases.
- All indications are that using a seed treatment product that contains both a fungicide and an insecticide will increase the benefits above those from using a fungicide seed treatment alone. Research that was conducted in Mississippi found that using a seed treatment with both components resulted in yield increases of 1.8, 4.3, and 2.1 bu/acre at Starkville, Verona, and Stoneville, respectively. The increased returns from these yield increases were positive. Click here for the report with these results.
- Adding a nematicide to the seed treatment complex will not replace the use of resistant varieties and variety/crop rotation as primary nematode control practices.
- It is difficult to place a value on the additional benefits gained from using a soybean seed treatment in years and environments that have a history of unforeseen conditions after planting that will reduce stand below the level for optimum yield potential.
In the realm of agricultural research, affirmation of prior results and statements is a valuable tool in the quest to provide accurate information about pertinent subjects to producers. Such is the case with a recent article that was published in the September 2014 issue of Agronomy Journal and authored by Gaspar, Marburger, Mourtzinis, and Conley.
“Soybean Seed Yield Response to Multiple Seed Treatment Components across Diverse Environments” presents results from a 3-year study that was conducted at 10 locations (30 total environments) in Wisconsin. Major findings from this research follow.
- Seed treatments that contained both a fungicide and insecticide component increased plant stands by at least 10% across the study.
- Using a seed treatment that contained only a fungicide component did not result in increased seed yield.
- Using a seed treatment that contained fungicide and insecticide components sometimes but not always resulted in increased yields. The largest yield increases were about 2.5 bu/acre.
- Though a fungicide + insecticide seed treatment consistently increased plant stand, yield increases were variable and contingent on unpredictable factors.
The results from this study support the statements on the use of seed treatments presented in the above White Paper and in other articles on this website.
The take-home message from all of this is: “Using seed treatments should not be done with an expectation of a consistent and/or large yield increase, but rather as a hedge against a poor or failed stand, and the enhancement of early-season vigor of established seedlings. That alone is often worth the expense, especially when an early planting date cannot be recovered with replanting a failed stand, seed of the preferred variety may not be available for the replanting, and early-season plant vigor is needed.”