Recently, some fruit growers have reported that last year's pear tree was difficult to cure on pear trees. What are some good solutions? According to the practical experience, the author combined the actual situation of the majority of fruit and agricultural drugs, and talked about superficial views for reference.
In the past year, the occurrence of pear hibiscus should have occurred mildly. It is not too difficult to remove the disease. However, due to the drug habits, drug varieties, and multiple drug use, it has caused certain difficulties in prevention and treatment. Some commonly used pesticides introduced in previous years have been replaced by “avermectin†which has emerged in recent years. Due to large amounts, excessive amounts, and unrestricted continuous use of the drug, the pests have developed drug resistance. In addition, the extensive management, reduction in the number of medications, and the inability to grasp the key medication period for the treatment of the worm, as well as the incompatibility of an appropriate mode of administration and multiples of medication, which do not produce phytotoxicity and ensure certain detoxification effects Therefore, it is not surprising that it is difficult to remove the disease within a certain period of time.
Pyrus communis is one of the main pests that injure pear trees. Its adults and nymphs are clustered on young leaves, fruit stems, and new shoots. They suck juice and affect leaf growth. After the leaves were damaged, there were chlorotic plaques, and when they were severe, they showed yellowishness and early fall. In early spring, the wintering nymphs suck the twigs before they germinate, resulting in injury. The branches are often moist, and those with severe vegetative conditions cause germination delay or even death. The worms occur 4-6 times a year in our land, and adults spend winters in the bark seams, under the deciduous weeds, and in the earth seams. In early spring, when the buds of pear trees expand, the overwintering adults begin to pupate, sucking juice on the shoots and secreting white waxy material, and then copulating and spawning. The flowering period is the first generation egg hatching. After 1-2 days, a colorless transparent waxy waxy substance and a colorless transparent viscous liquid are secreted from the tail, and after the mucus accumulates to a certain amount, it drops from the leaf to the lower leafy fruit and the ground. On the pollution of the fruit surface, reduce the quality. The first generation of adults emerged in early May. Due to the difference in adult oviposition times, subsequent generations overlap. In June, the nymph began to injure the fruit, and the number was highest in 6-8 months, which was the most serious.
To this end, the prevention and control of pear hibiscus should focus on the following aspects.
I. Agricultural control
According to the habit of most adults living in deciduous weeds, the bark should be removed early in the year or early spring to remove litter and weeds in the orchard and burn them in a concentrated manner, or to flood the water in the winter to eliminate most Overwintering adults reduce the population density.
Second, chemical control
1. During the critical period, the overwintering adult worms were harvested during the peak period of the first generation egg hatching (mid-March), spraying 4.5% beta-cypermethrin 1200 times and 50% malathion 1200 times.
From late-May to early-June, adults and young nymphs can be sprayed with avermectin 3.0% 1500-3000 times, 5.0% avermectin 3000 times, and 3000 times liaison additives. If the pear hibiscus occurs seriously and there is more mucus, the best way is to use 5.0% avermectin 1500 times liquid + harm lap auxiliaries 1500 times. The method solves the problem of rapid mucilage speed, good effect, safety and no injury, and the effective period can reach 20-25 days.
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