Fungicides are used to manage diseases in a crop. They limit infection and disease development and thus prevent or minimize yield loss. Disease development is dependent on weather conditions that occur during the growing season. In New York, certain diseases occur every year under the right environmental conditions, for example, northern corn leaf blight and gray leaf spot. A study that compared applications of fungicide made at different growth stages was done in the Finger Lakes Region of Upstate New York in 2018 to evaluate the effect of fungicide on disease and yield.

A plot was established on Lott Farms LLC in Waterloo, New York that was planted to a BMR silage corn and a Pioneer field corn, which each have resistance to diseases prevalent in the area. The plot was set up so that Mycogen F2F379 and Pioneer 9998AMXT each had three replications of hybrids either treated with a fungicide at V5/V6, V12, VT/R1, or with no fungicide application.

Disease assessments on the plot were made throughout the growing season. Assessments for disease was done every two weeks by looking at the canopy of 20-30 plants within each 8 row strip and recording if disease was observed. Disease was not observed within the plot until October 9, 2018. Standability was assessed by observing lodging at harvest. Yield data from each treatment was also collected. Climate Fieldview was used throughout the growing season to monitor the health of the crop through looking at the field health maps to make note of other environmental stresses. These health maps are NDVI (Normalized Difference Vegetation Index) imagery of the field and measure the health of the vegetation. The maps were used weekly to compare the health of the field from one week to the next. Precipitation at the plot location was monitored throughout the growing season using the precipitation element within the Fieldview Climate app.

Disease severity within the plot did not differ among all four of the fungicide treatments. Within the plot Gibberella ear rot was observed in the plot during the 2018 growing season. Gibberella ear rot was first observed at R5 growth stage. No difference in the amount of Gibberella ear rot was observed between the hybrids. More green leaves were seen in P9998 AMXT sprayed with a fungicide at VT/R1 growth stage than the same hybrid in different fungicide treatments, and F2F379. Lodging at harvest was more severe in F2F379 than P9998 AMXT which had no lodging. Less lodging was seen in F2F379 in the V5/V6 and VT/R1 fungicide treatment blocks compared to the no fungicide and V12 fungicide treatments. The yield of P9998 AMXT was greater than that of F2F379.

To better determine if fungicides contribute to improved plant health and greater yields, more testing needs to be done.