In many parts of the state there has been quite a bit of rain in the past few weeks. With rain comes diseases in corn and soybeans. Grey leaf spot in corn and frogeye leaf spot in soybeans are showing up in fields. Fungicide applications have begun as well. And while fungicides are best known for controlling diseases, it’s the multitude of additional benefits they provide that lead to consistent increased yield results year after year.
Most fungicides are preventative in nature and work by slowing respiration in the fungal cells to the point of death. This slowing of respiration also takes place in the plant cells, but rather than causing death, it provides a positive impact. In corn, this results in better utilization of nitrogen, which leads to increased kernel count and increased kernel weight. Slowed respiration also allows for better utilization of water and a reduction in water loss in both corn and soybeans. Because of this, plants will be less stressed during short periods of drought. This won’t save us from another drought like 2012, but it will help during dry periods lasting seven to 10 days.
Another positive side effect of fungicides is the reduction in ethylene production. Ethylene is the plant hormone that promotes senescence, or ripening. By delaying senescence, the plants are able to stay greener longer and add crucial time to the grain fill period. This, paired with disease control, allows plants to naturally dry down, rather than prematurely dying. It adds yield and test weight.
A few other benefits that are directly related to disease control are better standability and improved seed quality. Controlling diseases that affect the stems of soybeans and stalks of corn provides increased integrity and better standability, allowing for faster harvest. Improved seed quality is especially evident in soybeans. Soybeans have better color, shape, and test weight when fungicides are used.
Keep in mind that not all fungicides are created equally. Certain fungicide modes of action are associated with plant health benefits, notably the strobilurin and the SDHI fungicides. Also make sure that applications are occurring at the proper times (VT for corn and R3 for soybeans). For more information or for recommendations on how fungicides can benefit your operation, please consult with your local FS Crop Specialist.