玉米粗缩病发病规律及综合防治研究

玉米粗缩病(MRDV)是七十年代以来河北省部份玉米产区的主要病害之一,严重病田因病绝收毁种.经研究明确了此病害是由灰飞虱传播的病毒病害,病原是具双层衣壳的球形病毒.田间冬小麦上的“绿矮型”病株,包括与丛矮病毒(WRSV)混生的矮缩病株是玉米粗缩病的初侵染来源.在玉米上传毒并造成危害的主要是灰飞虱的第一代成虫.此病在玉米不同主育期的感病程度差别较大,芽鞘期至七叶一心期的病情指数为55.0—67.9%,八叶一心期为35.0%,而十至十二叶期极轻,仅2.8%.为此提出了以调整播期为主的农业措施结合药剂的综合防治.包括:治麦保秋;选用抗病品种,调整播期,即春玉米提前在四月份播种,套种玉米推迟到麦收前几天播种,扩大麦收后毁茬播种的面积;结合定苗拔除病株;加强管理及药剂防治.经一万一千余亩大面积防治示范,病株率由防治前的58.3%压低到15.0%,病情指数由防治前的29.6%压低到4.4—5.3%.与不防治田相比,病株率降低78.1%,病情指数降低77.9%.

STUDIES ON THE OCCURRENEC OF MAIZE ROUGH DWARF VIRUS DISEASE AND INTEGRATED PROGRAM CONTROL

Studies indicate that the disease is caused by a virus pathogen .The virions arc spherical shaped and enwrapped with double-layer capsule. The winter wheat plants with "dark-green dwarf" symptom and those stunted plants double-infected with Wheat Rosette Stunt Virus (WRSV) and MRDV are the initial source of inoculum. The planthopper (Laodelphax Striatallus Fallen) is the vector of this virus and the adult of its first generation is the main agent for distribution of this virus causing damage to corn. The disease index caused by this virus varies greatly with the time of infection in respect to the growth stages of corn. The disease index is 55.0-67.9% for seven leaves and a whorl, whorl stage and 35% for eight leaves and a whorl, and still dropped to 2.8% for eleven or twelve leaves. The integrated program control is pased mainly on the rearrangement of planting dale and measures, such as WRSV disease prevention for dcmir.ishing the source of inoculum,planting tolerant cultivars, eradication of diseased seedlings, favorable cultural practices and chemical control. The large demonstration area of 7.33ha has proved this integrated program to be effective. The contrast is sharp. The percentage of diseased plant is depressed from 53.3% to 15.0% and the disease index from 29.6% to 4.4-5.3% comparing to the previous culture nontreated. The comparison to the neighbouring fields in the same year non-treated shows that the percentage of diseased plant and the disease index are depressed by 78.1% and 77.9% respectively.