Effects of Foliar Fungicide on Whole Plant BMR and Floury Corn Varieties

Dairy producers rely on whole-plant corn silage (WPCS) as a main forage source for high performance dairy cattle. However, fungal disease can have a negative impact on yield, health, and performance of corn plants for WPCS. The objective of this study was to determine the effect of foliar fungicide application on two corn varieties for WPCS. Brown mid rib (BMR) and floury-leafy (FLY) varieties were planted in 6.76 ha (3.38 ha per variety). Treatments were: BMR without fungicide (BMR/CON), FLY without fungicide (FLY/CON), BMR with fungicide (BMR/FUN), and FLY with fungicide (FLY/FUN). At vegetative tassel (VT) stage, fungicide was applied on both varieties (Headline AMP; BASF Corp.). Statistical analysis was conducted using the MIXED procedure in SAS. Disease evaluations were conducted on 10 random plants in each plot at VT and reproductive stage 5 (R5; kernel dent), and prevalence was measured as a percent of whole plant infected by grey leaf spot (GLS). Number of yellow leaves were counted at R5. Plant weight and height, and cob weight measurements occurred at VT and R5 by measuring 12 random plants from each plot. All treatments were harvested at R5 with dry matter (DM) of 27, 31, 28, and 30% for BMR/FUN, BMR/CON, FLY/FUN, and FLY/CON, respectively. Dry matter was lower (P < 0.001) for corn treated with FUN than CON. Total yield (metric tons/ha) tended to be higher (P = 0.08) for FUN (67.70 ± 1.53) than CON (63.63 ± 1.53). However, DM yield (metric tons/ha) tended to be lower (P = 0.10) for FUN (18.54 ± 0.53) than CON (19.30 ± 0.53). The GLS prevalence was lower (P < 0.001) for plants treated with FUN (5.1 ± 0.2%) than CON (19.5 ± 0.2%). Plants in FUN (737.89 ± 16.39 g) were heavier (P < 0.001) than plants in CON (671.60 ± 16.42 g). Plants in FUN (270.79 ± 1.35 cm) were taller (P < 0.001) than plants in CON (265.56 ± 1.35 cm). There were less yellow leaves (P < 0.001) in FUN (0.09 ± 0.02) than CON (0.26 ± 0.02) plants. Cob weight was higher (P = 0.02) for FUN (150.19 ± 2.38g) than CON (141.01 ± 2.42 g) plants. In conclusion, fungicide treatment increased total yield, health, and performance of corn plants, and thus, could have a positive impact on WPCS to be fed to cattle.