玉米丝黑穗病(Sphacelothca reil—iana var zeae)在七十年代以前极少发生或没有发生,但自从推广玉米杂交种以来,此病才逐年扩大和严重,现己成为仅次于玉米大、小斑病的玉米第三大病害。此病主要分布于南宁、百色、柳州,河池四地区中的昼夜温差较大的山区县,发病率一般在10%以下,多的20—30%,个别种植感病杂交种或自交系的地块高达50—60%。由于玉米发病后整个果穗常被破坏,发病率一般几乎等于损失率,故对生产造成的损失是很大的。靖西县1977年因此痫损失粮食达919.5万斤。天等县1982年估计损失粮食60万斤。基 Sphacelothca reil-iana var zeae seldom occurred or did not occur before the seventies, but it has been expanding and serious year by year since the popularization of corn hybrids. Now it has become the second only to corn, The third major disease of small spotted corn. The disease is mainly distributed in mountainous counties with large temperature difference between day and night in Nanning, Baise, Liuzhou and Hechi areas. The incidence rate is generally below 10% and more than 20-30% respectively. In some individualized susceptible hybrids or inbreds Lot up to 50-60%. Since the entire ear of corn is often destroyed after the onset of the disease, the incidence is generally equal to the loss rate, so the loss caused by the production is great. Jingxi County, so loss of food in 1977 amounted to 919.5 kg. Tianxian County in 1982 estimated the loss of food 600000 kg. base