摘要
在宁夏 ,玉米叶螨以雌性成螨在土缝、树皮缝、落叶下越冬 ,6月中旬在玉米上始见 ,7月上旬出现害状 ,8月上中旬为螨量和危害的高峰期。玉米叶螨的发生危害程度与当年 7- 8月份的降雨直接有关 ,发生期内雨水频繁 ,日降雨量在 15mm以上 ,可以抑制其发生。玉米产量损失率随单株平均三叶雌螨数、叶螨危害指数和单株平均枯叶数的增加而增大。以 8.5%为玉米叶螨经济允许损失率水平 ,得玉米叶螨防治指标为 :单株平均三叶雌螨数 (R)为 153 .2 2头 ;或叶螨危害指数 (D)为 4 4 .90 ;或单株平均枯叶数为 1.5。
Maize spider mite (Tetranychus urtioae Koch)over winter by female adult in soil crack, bark seam or under fallen leaves. It begins to occur on corn at early June, and damage to corn at the first ten days of July. The time from the second ten days of July to late August is its peak damaging stage and also the critical period of control. The number of population and the damage degree relate directly to the amount of precipitation in July and August. If a rainfall of 15 mm in a day, and frequent rainfall in July or August, the occurrence of the mite will be strained. The loss rate of maize production will increase when the total number of female adult on every three leaves of a plant raises, or the damage index of maize mite raises, or the average number of the yellow leaves per plant raises. When the economic injury level is 8.5%, the economic threshold of controlling to the mite are the total number of female adult on every three leaves of a plant is 153.2 or the damage index is 44.90, or the average number of the yellow leaves per plant is 1.5.
出处
《宁夏农学院学报》
2001年第3期10-12,共3页
Journal of Ningxia Agricultural College
基金
国家自然科学基金项目 (3 916 0 0 49)
宁夏回族自治区科技攻关项目
关键词
玉米叶螨
种群发生
防治指标
宁夏
maize spider mite population occurrence economic threshold of control
