First, Damage:
The pear bollworm is a destructive pest that affects various fruit trees and is also considered an international quarantine organism. It has over 150 host species, including kiwifruit, apples, pears, peaches, plums, grapes, and cherries. In recent years, it has caused significant damage in areas such as Zhouzhi, Laoshan, and Meixian. The infestation leads to withered trunks, cracked bark, corky lesions, and degeneration of vascular tissues, which hinders the normal growth of branches and leaves. In severe cases, entire plants may die. On the fruits, there are numerous blemishes and purple spots, significantly reducing fruit quality and market value.
Second, Life Cycle:
In Shaanxi, the pear bollworm completes three generations per year. The second instar nymphs overwinter on branches and become active when spring sap flow begins. By April, both males and females can be observed. Males emerge in mid-April, and mating starts in early May, after which they die shortly afterward. The first generation of females lays eggs from late July to early September, while the second generation reproduces from September to early November. This means that the fruit trees are under threat throughout the growing season, making it essential to implement control measures in September and October.
Additionally, pear bollworms can reproduce sexually, and unfertilized females can still produce offspring. A single female can lay between 54 to 108 eggs at a time, and up to 362 in some cases. The second generation tends to have more offspring, leading to rapid population growth. When the nymphs hatch, they climb onto shoots, fruits, and leaves, where they begin feeding using their piercing-sucking mouthparts. In the fall, they tend to gather on the veins of leaves, especially during the late harvest period in Qin Mei, causing heavy damage.
Third, Prevention and Control Measures:
1. Garden Cleanliness: Thoroughly clearing the orchard is essential to eliminate overwintering second instar nymphs, particularly on branches. This helps reduce the population at the source. A mixture of 25% Jin Lux diluted 6000 times, 40% Dazhong diluted 800-1000 times, and soft water diluted 4000 times can effectively kill overwintering pests.
2. During the Growing Season: It's crucial to control the population when males emerge and females begin laying eggs. Using 40% Anminle diluted 1200-1500 times with soft water at 4000 times is effective. Alternatively, combining 40% Anminle with 70% Nanaixin at 1500 times and soft water at 4000 times can also be used. If tree growth is weak, adding a fruit-friendly amino acid solution and 6000 times diluted trace element liquid can help improve plant health.
3. Protecting Natural Enemies: There are dozens of natural predators of the pear bollworm, mainly including red-spotted ladybugs and kidney-spotted ladybirds. These beneficial insects can consume up to 700 nymphs and larvae in a month. Therefore, it's important to avoid using banned pesticides and instead opt for eco-friendly alternatives to protect these natural enemies. Preserving them is key to long-term control of the pear bollworm.
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