Studies On Occurrence Rules And Control Techniques Of Main Pests On Dangshan Pear Plants

The periodically systematical investigation on population of pests on dangshan pear plants by the method of fixed plants and fixed stems was carried out. The results showed that the major pests were Psylla chinensis Yang er Li and Grapholitha molesta (Busck) on pear orchard. The population of pear psylla remained relative stable on early-planted orchard or newly-planted orchard. The number of peak eggs of pear psylla reached350on middle ten days of March, however, which remained lower level on subsequent development period of pear plants. The peak number per thousand stems was99.33individuals on the middle ten days of April. The development peak date of overwintering generation of oriental fruit moth was from April3to April7. The emergence size of first generation adults remained relatively larger from May17to June1, but emergence date of subsequent generations was irregular. There was serious damage in mixed planted of early-maturing pear plants and dangshan pear plants.Three kinds of oriental fruit moth sex pheromones had obvious isotropic effect, which captured amounts were lower than blank control. But the captured amounts ascended gradually after last ten days of August, which indicated that the lasting period of sex pheromones was about three months. The fast acting property emerged on thin and long capillary treatment plot, but which lasting period was ten days shorter than others treatment plots. Unfortunately, the ratios of decayed pear of three treatment plots were still higher than control threshold, due to larger base number and suitable climate.The results of chemical control effect on pear psylla showed that2000multiple diluted solution of1.8per cent abamectin was superior to that of4000multiple and5000multiple diluted solutions of24per cent spirotetramat, which correction control effect reached74.8per cent after spraying24hours. The correction control effects were similar among three chemical treatments. However, the effects of the later were higher than that of the former after spraying14days. Tested insecticides were safe to leafs, fruits and newly tree tops of dangshan pear plants.Different concentration extractive agents with moso bamboo had definite control effects on pear psylla, and correction control effect rise gradually accompany with concentration rise. The control effect of100multiple dilute solution of extractive agents was the best among three concentrations, which value was above43per cent and maximum value reached49.81per cent. The control effect of spraying extractive agents with moso bamboo on pear psylla on early development stages of pear plants was little inferior to that on late development stages of pear plants.