Planting Date and Seeding Rate Impact Ear Rots, Mycotoxins, and Quality in Corn SilageDOWNLOAD FILE
Changing weather patterns and increasing lepidopteran ear-feeding insect flight, especially, western bean cutworm (WBC), is augmenting ear and stalk infections and mycotoxins in corn (Zea mays L.) silage in Great Lakes region. Planting date and seeding rate affects crop canopy microclimate and hence can influence insect and fungal infections and are an important components of integrated management strategies for growing good quality silage. Field trials in split-plot design were conducted during 2019-21 in Lansing, MI to evaluate impacts of planting date (whole-plot factor) and seeding rate (split-plot factor) on WBC, ear rots, yield, and quality. Corn was planted from early-May to early-June (thrice with 15-20 days interval) at four seeding rates (69,160; 83,980; 98,800 and 113,620 seeds ha-1). Additionally, multilocation seed rate trials were performed in randomized complete block design to understand changes in optimum seed rate in different environments. Planting date did not impact ear damage in 2019 and 2021. However, late-May planted crop (mid) had highest insect and disease damage in 2020, probably due to high humidity (>75%) and leaf wetness (50%) in the week following silking. At Huron county, highest seed rate showed highest WBC severity in 2020 and 2021. Yield did not vary across planting date in 2019, but in 2020, mid-crop (15 Mg ha-1) yielded 15% less than the early crop (17.5 Mg ha-1). Yield increased with seed rate at Ingham 2019, Allegan 2020, and Huron 2020. Feed digestibility and milk yield in early crop was higher than mid and late crop which indicated superior quality. However, seed rate did not influence forage feed quality. Overall, results indicated that seed rate response was location specific and planting corn early helped escape insect and disease pressure, providing better yield and quality as most susceptible growth stages do not coincide with periods of high humidity and wetness.