Foliar fungicide application effects on whole plant BMR and floury corn varieties, and whole plant corn silage composition

The objective of this study was to determine the effects of foliar fungicide (FUN; Headline AMP; BASF Corp., applied at vegetative tassel growth stage) and ensiling time (0, 30, 90, 150 d) on fiber composition of 2 corn varieties (brown midrib; BMR and floury; FLY). Treatments were assigned to 16 3.38-ha plots in a completely randomized split-plot block design. Treatments were: BMR without FUN, FLY without FUN, BMR with FUN, and FLY with FUN. Samples of whole corn plants were collected and separated into leaves, stalks, flag leaf (FL), and cobs. Fresh-cut, whole-plant corn silage (WPCS) samples were collected at harvest and sealed inside mini silos for the duration of their respective ensiling times. Statistical analysis was performed using the MIXED procedure in SAS (v9.4). Brown midrib corn plants had a greater number of green leaves than FLY with 11.81 and 11.34 ± 0.09 leaves, respectively (P = 0.001). Corn plants in control (BMR without FUN and FLY without FUN; CON) had a greater number of yellow leaves than FUN corn plants with 0.28 and 0.08 ± 0.02, respectively (P < 0.0001). Corn treated with FUN tended to yield more WPSC than CON with 63,634 and 60,488 ± 1,533 kg/ha, respectively (P = 0.08). Whole plant corn silage acid detergent lignin (ADL) content decreased as days ensiled increased with 31.61, 28.48, 25.48, and 22.38 ± 0.77 g/kg of DM for 0, 30, 90, and 150 d, respectively (P < 0.0001). Floury WPSC had a greater ADL content than BMR WPSC with 31.25 and 22.72 ± 0.61 g/kg of DM, respectively (P < 0.0001). Brown mid-rib WPSC had a greater neutral detergent fiber digestibility at 30 h (NDFD30) than FLY WPSC with 572.6 and 492.3 ± 6.9 g/kg of DM, respectively (P < 0.0001). Floury WPSC had greater undigested NDF (uNDF) than BMR WPSC with 125.3 and 96.1 ± 2.1 g/kg of DM, respectively (P < 0.0001). Brown mid-rib corn kernels had a greater kernel vitreousness than FLY corn kernels with scores of 3.11 and 2.65 ± 0.13, respectively (P = 0.05). A variety × treatment interaction was observed for kernel vitreousness score with scores of 3.23, 2.99, 2.49, and 2.80 ± 0.14 for BMR/CON, BMR/FUN, FLY/CON, and FLY/FUN, respectively (P < 0.0001). In conclusion, BMR treated with FUN and ensiled for 90 to 150 d yielded the best WPCS for feeding to dairy cows.