The symptoms are also known as cane scaly smut and smut. The most obvious feature of the disease is that the cane tip has a black whip in the downward roll, ranging from several centimeters to dozens of centimeters. The center of the whip is a stem composed of parenchyma or vascular bundles surrounded by a thick layer of chlamydospores. In the early stages of the disease, the diseased whip was covered with a silver-white film, after which a large amount of black powder was broken and finally only the heart was left. Infected species of sugar cane bud early, small stems, leaves slender, light green, increased tiller, after the tiller also grow black whip.
The pathogen Ustilago scitaminea Syd. said the sugarcane whip black powder fungus, belonging to the basidiomycotina subphylum fungi. The chlamydospores are suborbicular, brown or black, and have a single papillae, a size of 5-6 μm, and germinate and grow long and short. The burden of 3 to 4 cells, each cell produces 1 to several spores. The spores are transparent and oval. The bacteria have different physiological races.
Transmission routes and onset conditions Strained soil and perennial root cane are the primary sources of infestation. The chlamydospores are spread by air currents, rainwater, irrigation water, and insects, and then fall on the sugarcane buds and hide in the scales. The germination of water-spraying mycelia can invade the sugarcane buds.
After dormancy, the plant resumed its activity when the cane sprouted with the sugarcane and spread upward along with the growth point. The growth point was stimulated by the bacteria to form a white whip, and the black whip was extracted when the chlamydospores were formed. The resulting chlamydospore then passed through the medium. Spreading on the lateral buds of the cane stalks stimulates sprouting of the sugarcane, allowing the sugarcane to pull out lateral branches or branches and form a whip. The hyphae lurking in the sugarcane buds and the chlamydospores falling into the soil became the primary infestation source for the next season's sugarcane. Chlamydospore germination temperature limit 6 ~ 36 °C, the optimum 25 ~ 30 °C. When the soil is wet, the spores almost all germinate within 48 hours, and germinating spores will soon die when they cannot meet the sugarcane buds. Chlamydospore can live in dry soil for months to 1 year. Drought in winter and spring is good for spore survival. The high temperature and rain in spring favors the occurrence and prevalence of smut. The ratoon sugarcane field is heavier than the newly planted sugarcane field, and the longer the perennial root, the heavier the incidence. Shoot seedlings are more lightly cropped than whole plants. Excessive nitrogen application is heavier.
Control methods (1) Select resistant varieties according to local conditions. Such as South China 56/12, Yuesu 57/423, Yuesu 63/237, Sichuan Cane No. 7, Sichuan No. 11 and so on. (2) Implement rotation. Rotate crops such as rice, corn, sweet potatoes, peanuts or alfalfa. (3) Increase new planting area and plant disease-free seedlings. From no disease area to planting. In the ward, the first shoot of the disease-free plant should be selected for planting. (4) It is best to remove the diseased plant before the black ear is extracted. Pull out the black whip, be careful to cut it in a plastic bag, bring it out of the field and burn it. The sick field does not have any roots, and the diseased plants must be burned. (5) Apply base fertilizer, pay attention to reasonable application of NPK fertilizer. Timely irrigation, timely soil, prevent lodging, reduce the growth of lateral buds. (6) Seedlings disinfection seedlings seedlings soaked with hot water at 52 °C for 18 to 30 minutes, adding 25% triadimefon wettable powder or 80% spray WP wettable powder 500 times better. It can also be soaked in a 1:100 solution of 43% formalin for 5 minutes and then covered with a film for 2 hours. Or 70% mancozeb wettable powder 1:500 times soaking for 5 to 7 minutes. It can also be soaked in 3% lime for 24 hours.
A seedbed or seedling bed is the local soil environment in which seeds are planted. Often it comprises not only the soil but also a specially prepared cold frame, hotbed or raised bed used to grow the seedlings in a controlled environment into larger young plants before transplanting them into a garden or field. A seedling bed is used to increase the number of seeds that germinate.
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