Figure 1 Penn State SEAREC- 2014 Corn Response to Fungicide Applications- D.G. Voight and A. Collins.
During times of continuing wet, humid weather many growers asking about foliar applications of a fungicide on tasseling corn. Research performed in 2014 at the Southeast Agricultural Research and Extension Center (figure 1) tested 4 different fungicides on corn, with products applied at the V5 and R2 (blister) stages. In 6 out of the 10 treatments, there was a significant response to the application of a fungicide exceeding 11 bu/acre. However, the decision is not as much which product to use but whether the hybrid will respond to an application, and in the case of this study the hybrid used was susceptible to leaf diseases. When considering products and their effects on specific diseases, Purdue Extension's Fungicide Efficacy for Control of Corn Diseases is an excellent starting point.
When asking whether a fungicide application is necessary consider the following criteria:
If one or more of these criteria apply to your situation, than a fungicide application may provide an economic return and it may be time to discuss options with your agronomist or seed supplier. Both growers and agronomists should consider conditions field by field and take action from there.
Most labels dictate that applications be made between the VT and R1 stages. In addition, the labels I reviewed also require that adjuvants are NOT to be used after corn has reached the V8 stage and some recent research has shown that beer can ears can result from the application of adjuvants near VT. In addition, growers may be tempted to add additional products to the tank while going over the field. Most labels allow for the inclusion of insecticides but caution that growers only apply approved tank mixes and observe the most restrictive labeling. Finally on some products there is a 30 day harvest restriction for forage and grain so bear in mind that an early forage harvest might need to be delayed should an application be made.