Seed and seedling diseases will reduce germination and/or emergence of crops. Therefore, using a proper seed treatment fungicide product with high-quality seeds is recommended for early soybean and corn plantings in the midsouthern USA.
Environments in which fungicide seed treatments provide benefit are early planting in cool wet soils with anticipated slow seedling emergence and growth, minimum-till or no-till systems, fields with high amounts of surface residue, fields that are planted continuously to the same crop, and fields with a previous history of seedling diseases.
Production inputs for crops generally are applied to either increase yield or prevent yield reductions and/or financial losses. Net return is used to determine the worth of any input, and this is often measured by showing how an input affects yield.
Justifying the use of fungicide seed treatments is often based on the potential increased return from a greater yield. However, seed treatments used on corn and soybean seeds do not always result in increased yields.
Many studies have shown that using a seed treatment results in a greater plant population than is achieved without seed treatment. This, then, can be used to decide what seed treatment expense is justified in the absence of an anticipated yield increase. Two examples illustrate this point.
With corn, a reasonable expectation is that stands will be consistently increased by 2,000 plants per acre when the proper seed treatment is used with the recommended seeding rate. Therefore, planned seeding rate can be reduced by 2,000 seeds per acre to achieve the desired stand. At today’s seed corn prices of about $1.75 per thousand seeds, this translates to a savings of $3.50 per acre. Thus, using a fungicide seed treatment that costs no more than $3.50 per acre can be justified in seed cost savings alone.
With soybeans, stands are often increased by over 10% when the proper seed treatment is used. Therefore, a planned seeding rate of 150,000 seeds per acre can be reduced by at least 15,000 seeds per acre and still achieve the desired stand. For a variety that has 3,000 seeds per pound, this translates to saving 5 pounds of seed or $3.25 per acre when seed cost is $0.65 per pound. Thus, using a seed treatment that costs no more than $3.25 per acre can be justified in seed cost savings alone.
Fungicide seed treatments have a considerable range in price. Therefore, not all fungicide seed treatments will pay for themselves with the level of seed cost savings described above. There must be some other ascribed benefit such as insurance against stand failure followed by replanting, and/or a yield increase resulting from using the seed treatment.
To ensure that a fungicide seed treatment will approach cost-neutrality for corn and soybeans, reduce seeding rate in an amount that the seed treatment is expected to improve stand. By doing this, the input will have at least partially paid for itself up front. Additional benefit will be provided in years and environments which have conditions that will reduce stand below the level for optimum yield potential.