Studies On Pollution-free Control Technique Of Three Main Pests On Chestnut In Huairou District Of Beijing

Insect pest is one of the key factors that affect yield and quality of chestnut. The research on pests of chestnut and pollution-free pest control to improve revenue of chestnut plantation and fruit quality has a high application value. In this paper, three kinds of pests(Oligonychus ununguis, Dichocrocis punctiferalis, and Dryocosmus kuriphilus Yasumatsu) of chestnut were surveyed and researched in Huairou Chestnut Experimental Station and Qianchawu village in Huairou District of Beijing This study preliminarily analyzed the occurrence of three kinds of pests in Huairou District, the pest resistance of main local cultivated varieties of chestnut (Huaihuang, Huaijiu,Yanhong), and the pollution-free pest control technology in the plantations. This paper got the conclusions as follows:1,Relevant research on Oligonychus ununguisIn Huairou District of Beijing, the average number of Oligonychus ununguis per leaf showed a single peak within the state of growing season, and the initial stage began with mid June, the burst period began with mid July, the end period was in early August. The results of indoor cultivation showed that the average incubation time for Oligonychus ununguis and daily mean temperature showed a significant negative inter-related (R2=0.9861, p<0.01). The result of investigation in plantation showed that the average number of Oligonychus ununguis per leaf had a significant positive inter-related to the injury rate of leaves (R2=0.6492, p<0.01).By measuring photosynthetic physiology of leaves in different levels of injury rate, the results showed that the damage of leaf had no serious impact on their photosynthetic physiology in the injury rate of Level 2 and Level 3, and the normal growth and development of chestnut would not be affected. But in the injury rate of Level 4 and Level 5, total chlorophyll was seriously flawed by 18.8% and 48.8% respectively; the damage of leaf had already serious impact on the growth and development of chestnut. The critical level of control was Level 3. By using 1.8% Avermectin EC 4000 times,20% Fenpropathrin EC 2000 times,43% Propargite EC 2000 times, the effect of spider mites control was significant and the control effect were 96.08%,100% and 100% respectively. In mid-May (period of female inflorescence emergence), and early July (stage of seed coat formation), two pesticide applications could effectively control the average number of spider mites per leaf and reduce the injury of leaves to ensure the plants grow normally.2,Relevant research on Dichocrocis punctiferalisIn Huairou District of Beijing, the result of black light lamp trapping test showed that the starting period of Dichocrocis punctiferalis adults in chestnut plantations began with early August, the burst period began with late August, the end period was in late September. By measuring contents of different varieties of chestnut, and using factor method to analyses the relationship of resistance, the order of resistance in different varieties of chestnut was:Huaijiu>Yanhong>Huaihuang>seedling. By comparing different control measures, the result showed that sunflower trapping zone had the best control effect (68.96%), and sour liquid trapping zone was the worst (28.96%). Chemical control tests of different concentrations of diflubenzuron on Dichocrocis punctiferalis showed that the control effect of 500 times of diflubenzuron was the best (93.33%). Early September was the best time of prevention and treatment on Dichocrocis punctiferalis in Huairou District.3,Relevant research on Dryocosmus kuriphilus YasumatsuIn Huairou district of Beijing, larvae period of Dryocosmus kuriphilus Yasumatsu was from early April to mid-June, the peak appeared in mid-May; the period of white pupal was from mid-May to late June, the peak appeared in early June; the period of black pupal was from mid-May to mid-June, he peak appeared in late June; the period of eclosion was from late June to late July, the peak appeared in mid-July. In the next year of occurrence, the number of gall of chestnut gall wasp was different significantly in the orientation of eastern, western, southern and northern crown of the trees, the southern crown was the most (2.24 per tree) and the northern crown was the least (1.28 per tree). The population density was significantly different in top, middle and low crown layers, and the low crown was the most (4.31 per tree). The weight and volume of cecidiums had significant positive correlation (Rm2=0.6171, Rv2=0.6093; p<0.01) to the zooecium number of Dryocosmus kuriphilus.By investigating the contents of buds and the average number of cecidiums in different varieties of chestnut, method of factor analysis had been used to evaluate their resistance, the result of descend order had been listed as follow:Shifeng, Yanhong, Huaijiu, Huaihuang. Pruning had a significant effect on the number of cecidiums which could be effectively reduced in chestnut plantation, and had a significant effect on preventing the outbreak of Dryocosmus kuriphilus. Spraying 10% imidacloprid WP 0.5g/L in early July could effectively control the amount of cecidiums in the next year (70.44% control effect), and was suitable for production practices and application in chestnut plantations.