EXPERT TIP: Fungicide timing

EXPERT TIP: Fungicide timing

By: Jeff Caldwell 02/11/2011 @ 2:42pm

Looking ahead to this year's corn crop and wondering how you'll handle fungicide applications? The easiest way to do it may not be the most effective, according to recent research.

The easiest way to apply fungicide in most situations, says University of Kentucky Extension plant pathologist Paul Vincelli, is to tank-mix with herbicide between V4 and V8 growth stages. That does eliminate the need for an additional pass in the field, but the numbers show it's out of the strike zone for maximium efficacy.

"if you must use a fungicide, an early application is not as good a time to apply as VT/R1.  Fungicide application in the V4-V8 window often results in a loss of disease control, compared to fungicide application at VT/R1.  This makes sense, because diseases like gray leaf spot accelerate during grain fill, and a V6 application can "run out of gas" by the disease really gets going," Vincelli says. "If you are considering using a fungicide, direct it to fields with greatest risk of gray leaf spot and other leaf diseases and apply it between tasseling and the time when silks begin to turn brown."