How to diagnose and treat smut of sorghum

Smut often occurs in the growth process of sorghum, the yield reduction is usually 5% to 10%, the more serious disease can be up to 80%. Smut is a key disease control in sorghum production. 1. There are three symptoms of sorghum smut, namely scattered smut, head smut and head smut. The diseased ear of loose smut and its grains and inner and outer glumes all turn into black powder and are covered with a dark gray film. In the later stage, the film is easy to break, and the black powder is scattered after breaking, leaving a long axis. The diseased plant was slightly shorter than the healthy plant, and the heading was earlier than the healthy plant. The diseased ear and grain of hard smut are gray and oblong, full of black powder inside, thin film on the outside, very hard and not easy to break. The whole ear of head smut turns into a gray bag with a white film on the outside. When the disease is mature, the gray bag is easy to break, giving off a large amount of black powder, leaving a black messy silk like hair. two。 Seed transmission is the main infection route of hard smut and loose smut, while head smut is mainly caused by soil. All the three pathogens invaded the seedlings after sowing and invaded the ear during heading to form diseased ear with the growth of the plant. Generally, after sowing, the temperature is low, the emergence of seedlings is slow, and the disease is easy to occur, and the disease is serious in continuous cropping land or the application of bacteria-carrying fertilizer. 3. Control methods (1) rotation, selection of disease-resistant varieties: rotation for more than 3 years, selection of disease-resistant varieties, timely cultivation, diseased plants were found to be uprooted before the black powder was scattered, burned or buried in time. (2) seed dressing. For every 100 kg of seeds, choose: 25% vermicellin wettable powder 0.4 kg or 20% verapamil EC 1.25 liters or 50% carbendazim wettable powder 0.7 kg with proper amount of water and mix the seeds. Mix seeds evenly, generally pile up for 4 hours after mixing, and sow seeds after drying.