Fungicides aren’t typically the first instrument used in a grower’s toolbox for crop protection. Rotation, tillage, hybrid/variety selection, traits, herbicides and insecticides tend to come first; however, fungicides should be a serious consideration in a year with high disease pressure. This year, many growers were forced to plant into cool, wet soils or delay planting because of inclement weather. Planting in these conditions increases the risk for diseases in both corn and soybeans, which is why growers need to consider fungicides this growing season as a preventive solution for foliar diseases.
Seed treatment fungicides are effective against certain soil-borne pathogens in soybeans and corn; however, there are times when foliar fungicides are needed to control advancing diseases such as frogeye leaf spot, white mold and rust in soybeans, and gray leaf spot, northern corn leaf blight, ear molds and stalk rot in corn. If you have fields with a history of these diseases, fungicides should be considered when conditions are favorable for disease development and/or advancement.
Two forms of fungicide applications exist for foliar disease, stalk rots and ear molds — Triazol (curative) and Strobilurin (preventive). Curative fungicides are effective at killing existing fungal bodies on leaf tissue, while preventive type fungicides keep fungal infections from being able to feed on living leaf cellular tissue. Many products now contain both types of active ingredients, giving effective knockdown of existing fungal bodies and preventing disease development. Knowing the chances of further disease development is crucial in deciding the right type of product. Certain diseases will favor cool, wet conditions while other diseases prefer warm, wet environments.
Agronomic best management practices allow for the application of preventive type fungicides as protection against disease development and to allow the crop to transpire (breath) more effectively and efficiently. Curative applications should be made to crops that exhibit disease that will affect the reproductive phase of the crop. On soybeans, if 35 percent or more of the leaf tissue is diseased, a curative fungicide is warranted. On corn, if disease levels reach the ear leaf or above, a curative fungicide is warranted. If disease is present or conditions are such that certain diseases could develop, applications of a preventive type material are warranted. Timing should coincide with initiation of reproduction. For soybeans, this is R1 (beginning to flower) to R3 (1/4” pods), and in corn, this is tassel emergence.
Contact your local Stine representative to learn more about the importance of fungicides and which applications may work best for your fields this year.