Hybrid Selection and Fungicide Application for Managing Ear Rots and Mycotoxins in Silage Corn
Ear rot caused by Fusarium, Aspergillus sps. can lead to mycotoxin accumulation in silage corn (Zea mays L.) and negatively impact animal health. Infections have intensified in Midwestern US due to favorable environment and increased flight of ear damaging insects (mainly western bean cutworm, WBC). A grower survey conducted across Michigan showed presence of >15 mycotoxins in most silage samples. Therefore, the objective of this research was to evaluate the impact of management strategies such as hybrid selection and fungicide application on ear rots, mycotoxin accumulation, and overall silage quality. Field trials were conducted over two years in randomized complete block design with five replications at four locations (two used for final analysis). Three hybrid insect protection trait classes were used: Conventional, Agrisure (Cry1F) and Agrisure Viptera (Cry1F+Vip3A). Prothioconazole at 416.5 ml ha-1 was sprayed at silking stage. In 2019, dry spell following silking caused lower ear rot incidence except Ingham location where artificial inoculation was used. Insect flight was low at both locations in 2019. Agrisure and Viptera hybrids showed lower insect feeding (<10%) than conventional hybrids (incidence >25%, severity ≥15%). Ear rot severity was lowest (<1%) in Viptera hybrids across all site years. Viptera hybrids also had lowest mycotoxin levels than the other two hybrid classes. Co-occurrence of multiple mycotoxins were also observed in most samples. Fungicide neither reduced disease and mycotoxin accumulation nor improved yield at any location. Silage quality was not impacted by treatments except neutral detergent fiber digestibility (NDFD) and crude protein, both were influenced by hybrid class with NDFD highest for Viptera hybrids. Results showed that hybrid selection plays an important role in managing ear rots and mycotoxins in locations with high insect pressure, however fungicide application had limited benefits. Overall, an integrated management approach must be used to minimize mycotoxins in silage corn.