Joanna visits with Kiersten Wise, University of Kentucky Extension Plant Pathologist to talk about timing fungicide applications in corn.
Corn growth stage varies across KY, but is rapidly approaching time for fungicide applications. Fungicides most profitable when used in disease risk conditions. Be sure to check hybrid resistance ratings for diseases like gray leaf spot. Corn on corn. And scout prior to application. UK research shows that tasseling/early silking (VT/R1) is the best timing. It is best for disease control and profitability. Many questions about late vegetative stage applications (V12-V14). Pros: can be applied with ground equipment, easy to control application timing. UK research indicates in LOW DISEASE PRESSURE years, these applications control disease and yield similarly to VT applications. Cons: In a year with high southern rust pressure, another application may be needed later in the season. It is important to remember, with late V-stage application – no non-ionic surfactant (NIS) can go with these applications. These can result in arrested ear syndrome. Trend towards waiting until “brown silk” to spray fields. UK research shows that applications at “brown silk” or later may not achieve full benefits of fungicide. Brown silk is difficult to determine and may be too late-blister is latest to spray and see full benefits and silks will not appear brown at this time. The bottom line is: aim for VT/R1, V12/V14 is ok but leave surfactants out of the tank, and be precise about timing to get best yields from fungicide applications.
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Warren County Cooperative Extension Service
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