The abundant light resources and irrigation conditions in Gansu Hexi Corridor are important domestic seed production bases. In recent years, seedlings of corn seedlings have been severely developed and have a tendency of development. The incidence of serious disease fields is as high as 30% or more. Some fields are severely deficient in seedlings and turned into ploughs, which has affected the high yield of corn for planting and increased farmers' income. Important issues. The preliminary results of the investigation and research are reported below. I. Symptoms and Pathogens Maize seedling blight occurs mainly in mid-May and late May. Maize grows in the 4-7 leaf stage. Symptoms are characterized by the appearance of yellow-brown withered stripe spots on the edge of leaves, and wilting in individual leaves or plants. 3 - After 5 days the leaves turned grayish or brownish and dead. In the early stage of the diseased root hairs, yellowish-yellow-brown infestation spots appeared, and after 1-2 days, it became yellow-brown water-stained necrosis. In severe cases, the cortex rotted and the root hairs fell off. Pulled up the diseased plant, sometimes appear white, gray or pink moldy material in the diseased part of the root, namely pathogenic conidiophore and conidia. After isolation, cultivation and determination of pathogenicity, the pathogen causing seedling blight is mainly Fusarium moniliforme. On potato agar medium, small conidia are produced in multiple clusters, there are also spherical globose, oval, oval, and spindle. Colorless, unit cell, a few with a compartment, size 3.5-5.8um2.2-5.2um; large conidia crescent, foot cell, with 3-5 diaphragm, also 6-7 Diaphragm, but a few colorless, size 5.5-60.0um2.5-4.7um. Second, the epidemic of maize seedling blight of the initial infection of many sources, the cause of the disease is more complex, mainly: 1. Diseases and soil bacteria. Continuous cropping is the main cause of sickness and soil contamination. According to the survey, the incidence of seedling blight disease was 7.1%, 11.6%, and 15.9%, respectively, for successive crops from 1 to 3 years old. The major cause of serious diseases in continuous cropping plots was mainly due to the large population of Fusarium residue soil and diseased plant residues. And accumulation, so that the base number of soil pathogens rise year by year. The second reason is that due to the selectivity of nutrient elements in the same crop, the nutrients in the soil are physiologically unbalanced. According to the determination, with the increase of continuous cropping years, the total amount of N, P, and K in the soil does not change much, but zinc is available quickly. The content of boron decreased exponentially, and the contents of hydrolyzable nitrogen and available potassium decreased significantly, with an average reduction of 15-17 ppm. Therefore, the disease resistance of the plants was significantly reduced. 2. Seed carrier. This is the main reason why seedling blight occurs early and can form a central disease strain. The seed surface was separated and monitored after being sterilized with 0.2% Hg, and the seed carrier rate averaged 0.5% to 3.5%. 3. Fertilizer carrier. In recent years, farmers have reduced the amount of organic fertilizer applied to the land, and some have also produced fertilizer on the land. In the corn producing areas, pigs and forage materials are mainly crushed with corn stalks and seeds as the main raw material. After the experiment, the seedling blight strains were collected and fed with cattle feed for 2 days. After collecting feces, the corn seedlings with the dryness rate of 6.4%-13.5% were not fermented and decocted. Therefore, the carrier of fertilizer was also the main cause of seedling blight. one. 4. The land is uneven. The low incidence of soil in the low-lying water and around the field is mainly due to the heavy soil, low temperature and high soil moisture, which is not conducive to the root development of the seedlings and the decline of plant disease resistance. 5. Relationship between disease and climate. According to the survey, the climate was warm in April-May, the soil was warmed up and the seedlings were light. From April to May 2001, no cold incursion occurred. The temperature was 1-1.5°C higher than that of the same period, with rapid emergence and vigorous growth. The incidence rate did not exceed 10%, and some fields only sporadically occurred. From late April to early May of 2002, there were more rainy days and low soil temperatures. The incidence rate was 5%-21%, and the seriousness was as high as more than 30%. Third, the prevention and treatment methods Maize seedling blight disease more than the first time, early onset, plant death rate, prevention and control difficult. Therefore, comprehensive prevention and control should be based on methods based on agricultural measures and seed disinfection. 1. The rotation is down. We should try our best to arrange the cornices and rotate crops with non-corn pod crops. In particular, we should scientifically arrange the former buckwheat wheat strips to be used for small dumps. 2. Deeply exterminate and level land. After harvest, corn should be promptly deep-smashed, promote the decomposition of diseased bodies, inhibit the proliferation of pathogens, and reduce the amount of soil bacteria. Precise sowing must be done to prevent water accumulation, promote root development, and enhance plant resistance to disease. 3. Increase the maturity of organic fertilizers. It is forbidden to use raw manure on the ground to block the route of fertilization by the fertilizer and reduce the incidence. 4. Seed disinfection. One week prior to sowing, inoculate with 50% Carbendazim WP 800 times or 40% Kethomycin 600 times for 40 minutes, and dry after sowing. Or immersing the seed for 12 hours with a solution of 1 part of water and 20 parts of water, so as to prevent disease and increase seed production. 5. Seedlings transplant seedlings. The economic benefits of seed production for corn production are relatively high. It is feasible to solve the problem of seedling ridge deficiencies caused by seedling blight when appropriate seedlings are transplanted to make up for seedlings. When the corn is sown, choose a leeward sunny place to finish the seedbed or prepare a nutrition bowl. To reduce the production cost, the nutrient bowl can be made of old plastic or kraft paper. The specifications are 7-8cm in diameter and 8-9cm in height. The seedbed soil and substrate are mixed with slag and river sand in a ratio of 3:1, and a suitable amount of organic fertilizer is added into the bed and the carcasses, and watered. After 2-3 days, seeds are disinfected. Transplanting must be done with soil (or substrate) transplanting, watering in a timely manner, can not hurt the root, resulting in slow seedlings, otherwise the plant can not be normal development, affecting the pollination time and production.