玉米丝黑穗病是白城地区的重要病害,一般发病率为3—5%,重者高达30%以上,是生产上急待解决的问题。其症状以正常型为主,有时出现矮化型、矮化丛生型和多分蘖型等特异症状。病株以雌穗为黑穗、雄穗为健穗及雌雄穗皆为黑穗者居多。病穗上自然脱落的厚垣孢子萌发率高,病穗内的萌发率明显降低。此病为系统侵染病害,种子及土壤均可带菌传病,以土壤带菌为主,属土传病害。厚垣孢子在土壤里能存活三年,土壤带菌量越多,菌土覆盖种子越厚,发病率越高。丝黑穗病菌侵染玉米幼苗时间较长,从种子萌芽到四叶期最易侵染,五叶期后,侵染明显下降,八叶期后不再侵染。在幼苗叶片上接菌不能侵染致病。玉米丝黑穗病菌不能侵染高梁。高梁丝黑穗病菌能侵染玉米,但侵染率甚低。侵染玉米后的病菌,不再侵染高梁,只侵染玉米,且致病力明显增强。两菌是同一菌种的不同生理型。用来自九个省、市的丝黑穗病菌接种于不同抗性的自交系鉴定寄主,其致病力不同,陕西和新疆的致病力弱,辽宁和吉林的致病力强。在田间人工接种条件下,鉴定了二百余份自交系和杂交种的抗病性,品种间有明显差异,高抗的近于免疫,高感的发病率在90%以上。抗病性遗传规律表现为双亲高抗的,其后代亦抗,以母本的抗病性起主导作用。选百余种农药处理种子,筛选结果:个别药剂防效有高达70%以上者,但年度间效果不稳定,多数药效稳定在50%左右。 Maize head smut is an important disease in Baicheng area, the general incidence of 3-5%, as heavy as 30% or more, is the production of urgent problems to be solved. The symptoms of normal type, sometimes dwarf, dwarf tufted and tiller-type and other specific symptoms. The diseased plants were mostly black spikes, male spikes and male spikes. Disease spikes naturally fall off chlamydospore germination rate is high, the disease spike germination rate significantly reduced. The disease is a systematic infection disease, seed and soil can carry the disease, to soil-borne diseases, is a soil-borne disease. Chlamydospore can survive in the soil for three years, the more soil bacteria, bacteria and soil cover the thicker the seed, the higher the incidence. Head smut infection of corn seedlings longer, from the seed germination to the four-leaf stage the most vulnerable to infection, five-leaf stage, the infection decreased significantly after eight-leaf period no longer infected. Inoculation of seedling leaves on the pathogen can not be infected. Corn smut can not infect sorghum. Sorghum stalks can infect corn, but the infection rate is very low. Infected corn germs, no longer infected with sorghum, only infected with corn, and significantly increased pathogenicity. Two bacteria are different physiological types of the same species. Pathogenicity was identified by inoculation of Head smut from nine provinces and municipalities on inbred lines with different resistances. The pathogenicity was weak in Shaanxi and Xinjiang, and the pathogenicity in Liaoning and Jilin was strong. Under artificial inoculation conditions in the field, the resistance of more than 200 inbred lines and hybrids was identified. There was a significant difference among varieties. High anti-immunity and high susceptibility were more than 90%. The genetic law of resistance showed that the parents were highly resistant, and their offspring also had resistance, which played a leading role in the resistance of the female parent. Selected more than 100 kinds of pesticides to deal with the seeds, screening results: individual agents have as high as 70% control effect, but the effect of instability between the year, most of the efficacy of stable at about 50%.