板栗树针叶小爪螨发生规律及其防治研究

Seasonal Occurrence and Control of Spruce Spider Mite, Oligonychus ununguis (Jacobi) on Chestnut Trees

1984—1986年,作者等在北京市密云县着重研究了针叶小爪螨在板栗树上的发生规律及其防治技术.小爪螨越冬卵的孵化期与板栗树展叶抽梢期相符合.田间虫口数量,年与年之间相差很大,主要受自然天敌的影响.总结出乐果涂干的时期,药液浓度、施药次数、操作注意事项等技术措施要点.一次涂干的控制效果可达一个月以上,涂干树的栗实在收获期已检测不出乐果,在针叶小爪螨中度发生年和严重发生年,乐果涂干可增产板栗10%以上,净收益与成本相比约为9:1.

Studies on the seasonal occurrence and control of the spruce spider mite, Oligonychus ununguis (Jacobi) , on chestnut trees were carried out during 1984-1986. The winter eggs hatched in the middle May. The mite population occurred from late May to middle August, sometimes to middle September. Generally from early June the population increased. When the number of mites exceeded 50 per leaf most leaves turned brown. Natural enemies including the chrysopids, Chrysopa spp. coccinellids, Stethorus punctilium Weise, and thrips, Scolothrips takahashi priesner have been shown to be effective in controlling the injuries by mites, but the results were different.Excellent control effects by a single application of dimethoate dilution to the basal trunk of the chestnut tree without causing significant injury to the plant were achieved. The best period of treatment was found to be the hatching stage of the winter eggs. For trees treated with this insecticide,the fruit yields increased about 13% in comparing with the untreated trees. No residues of dimethoate were detected in the Chestnut fruit.