Foliar fungicide (pyraclostrobin) application on corn and its effects on corn silage composition

The objective of this study was to determine the effects of various applications of foliar fungicide on corn ensiled as corn silage. Treatments were replicated once and assigned to one of eight 0.4-ha plots of corn as follows: control (CON), plants receiving no foliar fungicide application; treatment 1 (V5), where plants received a mixture of pyraclotrobin and fluxapyroxad foliar fungicide (Priaxor, BASF Corp.) at corn vegetative stage 5 (V5); treatment 2 (V5 + R1), where plants received two applications of foliar fungicide, a mixture of pyraclotrobin and fluxapyroxad at V5 and a mixture of pyraclostrobin + metconazole foliar fungicide (Headline AMP; BASF Corp.) at corn reproductive stage 1 (R1); treatment 3 (R1), in which plants received one application of pyraclostrobin + metconazole foliar fungicide at R1. Samples of corn for corn silage were collected at harvest, prepared as 0.9-kg mini-silos and vacuum sealed. These were ensiled for 0, 30, 90, and 150 d postharvest then frozen for later analysis. Applications of fungicide on corn, later ensiled as corn silage resulted in less (P < 0.001) DM content (319, 315, and 317 g/kg for V5, V5 + R1, and R1, respectively) compared with untreated corn silage (CON; 335 g/kg). Corn silage from R1 resulted in a lower (P = 0.03) concentration of lignin (20 g/kg DM) and greater (P = 0.001) concentration of lactic acid (55.0 g/kg DM) when compared with corn silage from other treatments (lignin: 24, 24, and 26 g/kg DM for CON, V5, and V5 + R1, respectively; and lactic acid: 46.5, 50.1, and 50.9 g/kg DM for CON, V5, and V5 + R1, respectively). Treatment R1 had a greater (P = 0.03) concentration of water soluble carbohydrates at 0 and 150 d postharvest (123 and 31.5 g/kg DM for 0 and 150 d, respectively; and an increased lactic acid concentration at 90 d (71.1 g/kg DM for R1 vs. 63.4, 68.4, and 69.2 g/kg DM for CON, V5, and V5 + R1, respectively) when compared to the other treatments. Results suggested that fungicide application on corn at V5 or R1 may enhance the nutritive and fermentative profile when ensiled for feeding ruminants.