The main objective was to explore the associations of corn plant foliar fungicide application on harvested whole-plant corn silage digestibility. Treatments were control (CON), corn received no foliar fungicide application; treatment 1 (1×), corn received one application of pyraclostrobin foliar fungicide (PYR; Headline; BASF Corp. Florham Park, New Jersey) at corn stage V5; treatment 2 (2×), corn received 2 applications of foliar fungicides, PYR at corn stage V5, and a mixture of pyraclostrobin and metconazole (PYR+MET; Headline AMP; BASF Corp. Florham Park, New Jersey) at corn stage R1; and treatment 3 (3×), corn received 3 applications of foliar fungicides, PYR at corn stage V5, PYR+MET at corn stage R1, and PYR+MET at corn stage R3. Corn was harvested at the same time and ensiled for 7 mo. Three cannulated lactating multiparous Holstein cows (376 ± 28 DIM) were used to measure corn silage in situ digestibility. Dried unground corn silage was put into 288 (3 time points/treatment/cow) 10 × 20 cm bags and incubated for 0, 2, 4, 8, 12, 48, 72 or 96 h. A sample of unground undried corn silage was also placed into a 20 × 40 cm bag and incubated for 48 h. The degradable portion of DM was greater (P = 0.01) for corn silages treated with fungicide when compared with CON (0.36, 0.42, 0.40 and 0.47 for CON, 1×, 2×, and 3×, respectively). There was a linear (P < 0.001) effect of treatment frequency on the proportion of DM digestibility. The 2 different sizes of bags used (10 × 20 vs. 20 × 40 cm) for the in situ digestibility technique were different (P < 0.02) for DM, NDF, ADF, CP, and starch for 48h digestibility. Larger bags had greater (P < 0.03) digestibility for DM (33, 35%), and lower digestibility for NDF (42, 35%), and ADF (47, 39%), than smaller bags. In conclusion, corn silage with fungicide application had higher DM digestibility and a trend for a lower rate of digestion as well as linear effects for decreasing DM solubility, increasing DM degradability, and decreasing rate of DM digestion.