Take Advantage of Opportunity to Prevent and Control Walnuts

Recently, it was the period of multiple occurrences of walnut limb moth. Many readers called the newspaper to inquire about the pest prevention and control method. The reporter interviewed Ma Zhifeng, professor of Yangling Vocational and Technical College, on how to scientifically control the moth extermination for the purpose of guiding the majority of growers. .

Walnut excavation moth commonly known as walnut black, in North China, Northwest, Southwest, South China and other walnut production areas have occurred in the soil, wet, overgrown barren ravine is particularly serious. The main harm to the fruit, the fruit damage rate of 70% to 80%, up to 100%, is the main pest to reduce walnut yield and quality.

Harmful symptoms

The larvae eat many insects in the meat of the peel, and they are filled with insect excrement. The victim's skin becomes dark and damages the early crops. The dried kernels shrink and fall early; Larvae can be stripped from the fruit within 30 days of being killed, and sometimes there are more than a dozen larvae in one fruit.

Morphological characteristics

Adults are small black moths with wingspan 13-15 mm. The wings are long and narrow, the wing hairs are longer than the wing widths, oval white spots are found at the 1/3 of the fore wings, and crescent-shaped or nearly triangular white spots are found at 2/3. After the foot is full, lift up when resting. There are black and white scales in each section of the abdomen and back. Eggs are round, about 0.4 mm long, milky white at the time of first birth, and reddish-brown before hatching. The larvae are 7-9 mm long, brownish, and pale yellow, with white bristles per section. The worm is a spindle, 4-7 mm long, yellow-brown, brown pods outside the pods, often adhered to grass and fine soil particles.

Habits

Walnut moths occur in one generation in Shandong, Hebei and Shanxi in one year; Henan and Shaanxi have one to two generations in one year. Let the mature larvae live in the soil 1-2 cm deep under the canopy. From mid-May to mid-June, the adult larvae emerged from early June to mid-July, and the larvae generally started to harm in mid-June. July was the most serious. Adults spawn at the gap between two adjacent fruits, spawning 3-4 eggs and hatching 4-5 days. The larvae have effluent after the pods, showing water droplets. There are 5 to 7 larvae in one fruit, up to more than 30 heads. Larvae in the fruit within 30-45 days of damage, mature from the fruit after the prolapse, fall into the soil to cover the winter.

Control methods

1. Eliminate the dead branches, fallen leaves and weeds in the lower part of the canopy before the insect source is frozen, scrape off the old skin of the base of the trunk, and burn it in a concentrated manner. Plowing the soil under the trees can eliminate most of the overwintering larvae. Before the young fruit is shed, cut it in time and remove it to bring it out of the orchard to prevent it from harming once again.

2. Plough the soil and collect fruit until the soil is frozen or plowed in the early spring next year. The depth is about 15 cm, and the range is slightly larger than the projected area of ​​the canopy. Combining with tillage, 5% phoxim should be applied on the ground under the canopy. Powder, 2 kilograms per acre. After application, turn the earthworms to mix the earth and mortar, and extirpate moths before excavation.

3. Chemical control If the orchard harmed by extremities has hit the contact agent, the main use of pyrethroid pesticides, cypermethrin, deltamethrin, etc. can be, now is the spawning period of the moth, because the entire spawning The period is longer, so growers should fight the orchard once every 10 to 15 days and play three times. Because larvae crawl into fruit after crawling for one to three hours, the pesticide can kill it. After the larvae have drilled into the fruit, black pods appear on the fruit surface. After the larvae develop to a certain degree, some walnuts will fall off naturally, and some worms will remove the fruit and drill into the ground and continue to harm them in the next year.

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