By Angie Peltier
According to the 2015 Illinois Crop Budgets prepared by University of Illinois Economist Dr. Gary Schnitkey, an estimated average of $78 per acre will be spent on soybean seed - the single largest direct cost of producing soybean. According to the USDA- Economic Research Service, prices for both conventional and bio-tech soybean seed have more than more than doubled in the past 10 years (Figure). It is no wonder, then, that soybean producers are looking for ways to protect this important investment.
Unlike corn seed, the majority of which comes pretreated with both an insecticide and one or more fungicide, producers have more choice when purchasing soybean seed. There are many classes of seed treatments, including fungicides, insecticides, nematicides, plant growth regulators and inoculants. To help to make sense of the many seed treatments that are available to field crop producers, the University of Wisconsin's Nutrient and Pest Management Program has produced an online guide titled, What's on Your Seed?. As more than 125 seed treatment trade names are listed as labeled for use on soybean and crop producers may not have the license, equipment, or patience needed to apply seed treatments while gearing up for planting time, an informal survey of the seed treatments available from five seed retailers in the Western Illinois region was conducted.
Although the assortment of seed treatments is large, the seed treatments offered at regional retailers may not be (Figure). In this informal survey, one retailer did not offer a choice, all seed came treated. While another retailer (Retailer 1) offered an insecticide + fungicide treatment and customers could opt to either treat or not treat their seed. Another retailer (Retailer 2), offered two standard options, fungicide + insecticide with or without a nematicide. An inoculant could be added to one of the standard treatments as an additional option. Retailer 3 offered several more choices, with packages ranging from $8 to $28 dollars. Retailer 4 was the only one to offer a fungicide-only option and was also willing to add any other active ingredient upon request.
Inputs and lower commodity prices: breaking even. During this period of low commodity prices, it becomes even more important for producers to at least break even with an input. To break even with an input, the input must increase yield enough to at least pay for itself (yield response ≥ application and active ingredient costs). As commodity prices decrease and input prices increase, the break-even yield response increases. By testing an input against untreated controls in replicated trials, over a period of years and in many environments, scientists are able to identify those environmental conditions under which an input is more likely to result in a break-even yield response.
Insecticidal seed treatments. In the Bulletin in October 2014, University of Illinois Entomologist Dr. Michael Gray summarized a report that was released late last year by the US Environmental Protection Agency regarding the use of neonicotinoid insecticidal seed treatments in soybean. The authors of this EPA report analyzed data from numerous research trials conducted throughout the corn-belt and concluded that "U.S. soybean growers derive limited to no benefit from neonicotinoid seed treatments in most instances. Published data indicate that most usage of neonicotinoid seed treatments does not protect soybean yield any better than doing no pest control." These insecticidal seed treatments were registered for use on soybean beginning in 2004. For those that have an interest, it may be worthwhile to investigate the results of some of the last 11 years of replicated insect management research trials in Illinois in regards to both grain yield and insect-management (on Target) and Dr. Gray's analysis of this report.
Fungicidal seed treatments. Producers can likely quickly name in which fields, in which years and under which environmental conditions they have had issues with poor soybean stand establishment. Seed and seedling disease in Illinois can be caused by one or more fungi or oomycete pathogens. Seed treatment fungicides may provide up to approximately 3 weeks of protection against one or more of these pathogens, however the active ingredients that are effective against oomycetes may not be effective against true fungi, and vice-verse (Figure). Several years ago, University of Illinois Plant Pathologist Dr. Carl Bradley conducted a series of soybean fungicidal seed treatment trials in multiple years (2005-2010) and at multiple locations (Urbana, DeKalb, Monmouth, Ridgway, Belleville, Auburn, Perry) throughout the state for a total of 23 location-years. He summarized the results of these trials in the Bulletin. Briefly, fungicidal seed treatments resulted in an average yield response of 0.3 bu/A, and the yield response tended to be larger in those trials planted into cooler, wetter soils.