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棉花枯萎病在陕西关中,近几年由局部地区发展到点面发生,蔓延速度和面积已超过黄萎病。一般发病和死苗在30—50%,严重的棉田在90%以上。一些黄萎病区逐渐转为枯、黄萎混合发生区,枯黄萎同株型极为普遍。此病在棉花苗期即表现症状,潛育期为10—20天。1—2片真叶发病率达10—15%;5—6片真叶(蕾期)即会引起大量枯死和萎蔫。土壤致病温度平均在20°—25℃,维持10天以上,发病最烈;28℃以上病势减轻。土壤含水量在60—75%之间,枯萎病发病率最高。每年枯萎病发生消长与5、6月份的温、湿度及降雨量有一定关系。以4—6片真叶期,枯死植株发展较快,开花后期枯死率显著下降,到吐絮期尚有高峯出现。各品种间的枯死规律基本相同;仅有枯死程度上的差异。防治棉花枯萎病主要途径以抗病品种为主。由1956—1961年已鉴定出抗病品种(系)有52-128、鸭棚、147-Φ、57-50、南通二号、F96,F80等。其中确定能在病区生产应用的有52-128,鸭棚,平均降低发病率在30—70%,增产15—40%左右。并发现抗病免疫类型有中棉“嘉定硬子”。远缘杂交材料(353×G 1472)×芙蓉葵353 F_2可作杂交原始亲本材料。在病区增施氮、磷无机肥料,有降低苗期枯萎病的作用。轮作防病在关中采取二年小(?)、玉米轮作倒茬,发病率由原来的85%降低到38%,死苗率由50%下降到20%,有一定防病增产效果。
Fusarium wilt of cotton in Shaanxi Guanzhong, in recent years from the development of local areas to the point of occurrence, the spread rate and area has exceeded Verticillium wilt. The incidence and dead seedlings in general 30-50%, serious cotton fields in more than 90%. Some verticillium wilt gradually turned into dry, yellow wilt mixed area, withered yellow wilt the same type is extremely common. The disease symptoms in the cotton seedling performance, the incubation period of 10-20 days. 1-2 true leaf incidence of 10-15%; 5-6 true leaves (bud stage) that will cause a large number of dead and wilting. Pathogenicity of soil temperature in the average of 20 ° -25 ℃, maintained for 10 days or more, the incidence of the most severe; 28 ° C above the disease reduced. Soil moisture content of 60-75%, the highest incidence of wilt disease. The annual occurrence of Fusarium wilt and May, June temperature, humidity and rainfall have a certain relationship. To 4-6 true leaf stage, withered plants developed rapidly, the late flowering mortality rate dropped significantly to the boll opening period there are peaks. The law of withered death among the varieties is basically the same; only the degree of withered difference. The main ways to prevent and control cotton wilt disease-resistant varieties based. From 1956 to 1961 has identified disease-resistant varieties (lines) 52-128, duck shed, 147-Φ, 57-50, Nantong II, F96, F80 and so on. Which identified in the ward production and application of 52-128, duck shed, the average reduction in the incidence of 30-70%, an increase of 15-40%. And found that the type of disease-resistant cotton in the “Jiading hard child.” The distant hybridization material (353 × G 1472) × Hibiscus mairei 353 F_2 could be used as the hybrid parent material. In the ward increased nitrogen and phosphorus inorganic fertilizers, to reduce the effect of seedling wilt disease. Rotation for disease prevention in Guanzhong to take two years (?), Corn crop rotation, the incidence rate from the original 85% to 38%, the rate of dead seedlings from 50% to 20%, there is a certain anti-disease effect of increasing production.