| With the increasing demand on green and non-pollution fruits, traditional chemical control measures for diseases and insect pests, which cause environmental pollution and make the pests and pathogens become resistence to pesticides and fungicide, can not meet the need for contemporary fruit industries. However, green protection and control technology including physical measures have gained a great progress in recent years, with the advantages of non-pollution, stability and a relative low cost. In this experiment, occurrence characteristics of diseases and insect pests and the effect of physical control measures including sticky card traps, multi-frequency vibration-killing lamps and rain shelter cultivation in plastic tunnels were studied. The results were as follows:(1) Difference in the incidence of pear diseases&insect pests between plastic tunnel and open field was investigated in this test. The results showed that diseases especially leaf spot diseases which easily caused early defoliation, such as pear black spot, pear brown spot and pear grey spot were much lighter in the plastic tunnel than in the open filed. However, the occurrence of insect pests particularly Aphididae and Tetranychidae were much heavier in the plastic tunnel.(2) During the earlier growth stages of pear trees, the trapping effects of yellow sticky card traps on insect pests was preliminarily studied in the plastic tunnel. It was found that yellow sticky card traps with advantages of a low cost and stability had a good effect for trapping Grapholitha molesta Busck, Janus piri Okanota et Muramatsu, Homplocampa pyricola Rohwer, Phyllotreta striolata Fabricius and especially alate aphids. For the significant trapping efficiency of sticky card traps to insect pests, trap color, height placement and density were further studied to evaluate the traping effect during the period of fruit development. The result showed that yellow sticky card traps could capture various pear pests such as Grapholitha molesta Busck, Janus piri Okanota et Muramatsu, Psylla chinensis Yang et Li, Phyllotreta striolata Fabricius and Aphidoidea, etc. However, blue sticky traps only had a good trapping effect for Phyllotreta striolata Fabricius. It was suggested that two traps per tree was a good choice for trapping pests based on the consideration of cost and less harm to natural enemies. Trap heights also altered effects on trapping insect pests.(3) Yellow sticky card traps were also used as a tool for estimating absolute densities of aphids in pear orchard. Two-week trapping was conducted in the plastic tunnel and the open field with traps suspended directly up the trees, one trap per tree. Aphids incidence in current shoots and aphids number captured by yellow sticky traps were calculated. It was found that air temperature, maximum and minimum daily humidity were negatively correlated with the number of aphids captured in the plastic tunnel. A significant linear relationship was found between the trapped aphid number and aphid incidence in current shoots. Thus, prediction confidence intervals of aphids on traps combining with the occurrence peak of apterous aphids in fields were suggested to estimate aphid occurence. In addition, the quantities of trapped natural enemies for aphids were correlated with aphid incidence.(4) Multi-frequency vibration-killing lamps could only capture Mythimna separate Walker, Gryllotalpa orientalis,Spilarctia subcarnea and other large insects, but had a poor effect for trapping insect pests to damage pears.(5) Taking open field cultivation (OFC) as control,’Cuiguan’pear was used to study the effect of rain shelter cultivation (RSC) on incidence of pear diseases and insect pests as well as fruit qualities during the period of rain shelter cultivation. The result showed that the incidence of leaf diseases, especially pear black spot were reduced significantly. However, the quantities of aphids increased862.1times higher in RSC than in OFC, inducing serious dark mildew. At the same time, RSC decreased the degree of fruit surface rust, the rust index decreased by50.5%-58.2%. Therefore, under the culture of plastic tunnel, RSC is prefered to reduce the occurence of pear black spot and improve the fruit quality. RSC and OFC should be by turns adopted when aphids and induced dark mildew are serious.To sum up, physical control measures such as sticky card traps, multi-frequency vibration-killing lamps and RSC showed favorable effects on the protection and control of pear diseases&insect pests in plastic tunnel. Sticky card traps could capture multiple small-sized pests in pear garden; multi-frequency vibration-killing lamps could only capture some large-sized insects. And the incidence of leaf spot diseases was reduced significantly in RSC. Thus, the integrated control strategy combining sticky card traps and multi-frequency vibration-killing lamps with pesticides is suggested for pear plastic tunnel culture. For the pear orchards with heavy incidence of aphids, OFC should be practiced for one year after RSC for two or three years. |
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