What are the control methods for corn smut?
In recent years, corn smut has become fairly common, and when the ear is affected it loses its value for food and feed, so control work should be done early.
Throughout the entire growth period of corn, all young aboveground parts can be affected by corn smut. The diseased part is tumor-like, and the size of the tumor varies depending on the affected part; tumors on leaves are smaller, while tumors on the ear or stem nodes can often reach the size of a fist. When the tumor is immature, it is a mass of white tender tissue covered by a thin membrane; after it matures, the entire interior of the tumor turns into black powder (the pathogen's chlamydospores), and after the membrane dries and cracks, the black powder disperses. The pathogen overwinters as chlamydospores in soil, diseased residues, compost, and manure, and is mainly transmitted through soil; seeds can also carry the pathogen. Chlamydospores are spread by wind onto plants, and after producing the pathogen they can cause repeated infection. High temperature and high humidity, tender growth, drought, long-term continuous cropping, excessive application of nitrogen fertilizer, insect pests, and wounds caused by storms and rain are all factors that easily lead to disease occurrence. Non-flint-type varieties and varieties with thick, long, tightly wrapped ear husks have poorer disease resistance.
To control corn smut, the following measures should be taken: select disease-resistant varieties; dress each kilogram of seed with 40 milliliters of 20% triadimefon emulsifiable concentrate; carry out timely deep plowing to reduce the source of primary infection; increase potassium fertilizer application, and ensure organic fertilizer is fully decomposed to prevent carrying the pathogen; promptly control pests such as the Asian corn borer to reduce wounds; during periods of high temperature and high humidity or frequent drought, spray a 1:1:120 Bordeaux mixture for prevention; before the membrane of the diseased tumor ruptures, cut it off early and carry it out of the field for deep burial or burning, and smear the wound with thin mud slurry; keep the field clean, reduce diseased residual plants and fallen leaves, and implement a rotation of more than 3 years in heavily diseased fields.