In recent years, due to the gradual expansion of the planting area of pear trees, the insect pests that have appeared have also become more, and some that were not very serious in the past have also become "cancerous tumors" in the production of pear trees after years of vicious development. In order to better produce high-quality pears and provide more consumers with excellent quality pears, it is necessary for us to remove these "cancers".
Chinese pear lice, belonging to the family Homoptera, has been mistakenly called pear lice in the past, but in fact there are certain differences between the two, including harmful characteristics, living habits and so on. Chinese pear lice was originally not a very serious pest, but due to the initial lack of attention, it has become a key control object among pear tree pests in recent years.
Winter-type Chinese pear lice
In recent years, Chinese pear lice has been distributed in various pear-producing areas in China, especially in the northeast, north China, northwest and other northern pear-producing areas, mainly harmful to various pear trees, in various places and harm has been aggravated trend, so we must pay enough attention.
The harmful symptom of the Chinese pear lice is that adults and nymphs sting the sap of the host tender green part. In the spring, the adult and larvae are mostly concentrated in the new shoots and petioles, and in the summer and autumn, they are mostly sucked on the leaf surface.
Chinese pear lice are harmful to the symptoms of pear tree leaves
The veins of the affected leaves are twisted, the leaf surface is crumpled, and the dry spots are produced, and gradually become black and fall off early. And nymphs secrete a large amount of mucus, often making the leaves stick together or stick to the fruit, inducing coal disease, polluting the leaves and fruit surfaces, fruit development is stunted, the growth of the affected branches is stopped, not full, and vulnerable to frost damage.
Coal diseased leaves infected with pear lice
Morphological characteristics of Chinese pear lice Adult insects are divided into two types: winter and summer. The winter type is 2.8 to 3.2 mm long, grayish brown, with obvious brown spots in the rump area of the posterior margin of the forewings, and the summer type is small, 2.3 to 2.9 mm long, yellow-green, and has no markings on the wings.
Adults have 4 reddish-yellow or yellow longitudinal stripes on the dorsal thorax and are stacked on the body in a ridge-like manner when stationary. The ovoid is round, initially pale yellowish white, posteriorly yellowish, bluntly rounded at one end, with a thorn-like protrusion underneath, fixed to the plant tissue. The other end is thin and elongated into 1 filament. Nymphs hatch in the nymphs are oblate oval, pale yellow, flattened and round after 3 instars, greenish brown, and the wing buds are oblong, protruding on both sides of the body.
Summer-type pear lice
The annual occurrence of pear lice in China varies from region to region: 3 to 4 generations in Liaoning, 4 to 6 generations in Hebei and Shandong, with overlapping generations. Winter-type adult insects overwinter in bark crevices, deciduous leaves, weeds and soil crevices everywhere.
In the area of 4 to 5 generations in 1 year, the adult wintering generation begins to move in early March when the buds of pear trees germinate. In mid-March, the whitening of the scales of the pear blossom buds is the peak period of stinging, and the final stage of stinging is in late March. After the adult worm emerges from the sting, it feeds on the branches of the year and lays eggs.
The first generation of eggs begins in mid-March, peaks in mid-April, and ends in early May. The peak period of overwintering adult insects is the early stage of the emergence of the first generation of eggs, which is a favorable time for drug control.
Chinese pear wood lice nymph
After the first generation of nymphs appeared in large numbers, the generations overlapped, the habitats were different, the leaves were dense, and the nymphs were mainly pests, and the nymphs were often submerged in the mucus they secreted, or sneaked into the curly leaves of the aphids as pests, and the medicinal liquid was not easy to contact the insect body, which caused difficulties in control.
The occurrence period of each generation of adults is roughly as follows: the first generation of adults appears in early May, the second generation occurs in early June, the third generation occurs in early July, and the fourth generation occurs in mid-August. The fourth generation of adults is the overwintering type, but eggs can still be laid earlier, and the fifth generation appears in mid-September.
The overwintering generation lays eggs in the 1-year branches, fruit tables, short fruit branches and leaf marks and bud axils, with more short fruit branches and leaf marks, arranged in intermittent yellow lines. Later generations mostly lay eggs in grooves along the leaf veins of the leaf surface, and also in the serrations of the leaf margin or on the back of the leaf, scattered or 2 to 3 grains are produced together. The average female lays more than 290 eggs. Adults are lively and jumpy, and nymphs are gregarious, prefer to be shady, and mostly inhabit crevices in curly or overlapping leaves. Generally dry early or seasonal occurrences are heavier.
<h1>Prevention and control methods</h1>
1. Artificial control and control Of early spring, scrape the bark, clean the orchard, and burn the scraped bark and dead branches, leaves, weeds and other things in a concentrated way to eliminate the overwintering adult insects and reduce the density of the insect population.
Scrape the bark to remove overwintering adults
2. Pharmaceutical control The key period of prevention and control is the peak period of adult overwintering generation, that is, the early stage of the emergence of the first generation of eggs, and most of the adult insects are eliminated before laying eggs. The mastery of the key period is the phenological period, that is, the whitening period of the scales of the pear blossom buds; the second is to check the eggs and find the yellow egg line at the short fruit branches and leaves, and immediately spray the control.
Commonly used agents are: 20% imidacloprid concentrated solvent 6000 ~ 8000 times liquid, 0.9% avermectin 2500 times liquid, 25% thiamethoxine water dispersible granules 4000 times liquid, 2.5% cypermethrin 3000 times liquid, 20% permethrin emulsion 3000 times liquid, 4.59% high efficiency cypermethrin emulsion diluted into a concentration of 20.8 ~ 31.25 mg / kg (active ingredient) of the liquid, 522.5g / L aerocyanide • chlorpyrifosium emulsion diluted to water concentration of 261 ~ 348mg/kg (active ingredient) of the liquid, 200g / L imidacloprid solution diluted into a concentration of 40 ~ 80 mg / kg (active ingredient) of the liquid, etc., in the wintering adult sting and spawning peak spray twice, you can basically control the harm.
Preventive agents
Technical knowledge: If the Chinese pear lice has developed serious resistance to avermectin and other agents, it should be selected in the 1st and 2nd generation nymph incubation periods, 24% spirant ethyl ester suspension 4000 ~ 5000 times liquid spray, can effectively control its harm, the effective period of up to 30 days.
The above is the details of the Chinese pear lice shared today and the prevention and control methods, medication and other technical points, I hope to be able to provide practical help to the growers who plant pear trees, if you have better technical knowledge, you are very welcome to leave a message in the comment area to discuss. Regarding more fruit tree management technology, Sichuan Zongfu Fruit Industry will update from time to time, welcome everyone to pay attention to and review.