The technology of preventing and controlling walnut limb moth

The technology of preventing and controlling walnut limb moth

1 morphological characteristics and occurrence regularity of walnut limb moth

Walnut upright moth belongs to Lepidoptera, Lepidoptera. Scientific name: Atrijuglanshetaohei Yang, also known as walnut black. Distributed in Henan, Hebei, Beijing, Shandong, Shanxi, Shaanxi, Sichuan, Guizhou and other walnut producing areas, endangering the fruit of walnut.

1.1 Hazard characteristics

The larvae eat walnut fruits and kernels, and the damaged fruits turn black (figure 1), and most of them fall off early.

Fig. 1 harm of walnut limb moth

1.2 morphological characteristics

Adult: the body length is about 6 mm, the wingspan is about 13 mm, dark brown, ventral silvery white, narrow lanceolate wings, long marginal hairs, half moon-shaped white spot at the tip of the forewing, and an oblong white spot at the base of the trailing edge (figure 2). The hind foot is long, and it is raised to the upper side when perched, hence the name of the moth (figure 2). Eggs: oval, milky white at first birth, yellowish white gradually, reddish brown before hatching. Larvae: about 8 mm long, colostrum white, head yellowish brown to dark brown, reddish back, forechest shield and chest feet yellowish brown (figure 3). Pupa: about 5 mm long, yellowish brown to brown. Cocoon: about 9 mm long, long oval.

1.3 Life history and habits

Fig. 2 Adult of Plutella xylostella

Fig. 3 Walnut lift-limb moth larva

The walnut lifting moth has two generations a year in Zhangqiu City, overwintering with mature larvae in the soil, rocks or weeds at a depth of about 3 cm under the tree, and a few in the bark seams at the base of the trunk. The overwintering generation larvae pupate from early May to late May, the pupal period is about 7 days, the overwintering generation adults occur from the middle of May to the end of May, and the overwintering adults lay eggs from late May to early June. the egg period is about 5 days, the first generation larval stage is from late May to the end of June, and the larval stage is about 40 days. The pupa stage of the first generation is from the end of June to the middle and late July, the adult stage of the first generation from the first ten days of July to the end of July, the egg stage of the second generation from the middle of July to the first ten days of August, the larval stage of the second generation from late July to early September, and the second fruit drop stage from the first ten days of August to the end of August. Adults sleep during the day and come out at night, generally producing 1-4 grains per fruit, but more in the later stage, and 7-8 grains can be produced on one fruit. A female can lay 35-40 eggs. After hatching, the larvae crawled on the fruit surface for 2-3 hours and began to drill into the fruit green peel and feed vertically and horizontally (figure 4). The pericarp was full of insect dung, and the affected fruit finally turned black and most of them fell off (figure 5), so it was called "walnut black". The occurrence degree of walnut limb moth is closely related to soil moisture and climate, such as high soil moisture, heavy occurrence of weeds, severe occurrence in wind, shade and damp places and deep mountain areas, light occurrence in dry places and shallow mountain areas, and serious occurrence in barren sloping land than in cultivated land. The occurrence of dry weather is lighter in years with dry weather, and more serious in years with more Rain Water.

Fig. 4 Walnut limb moth larva harms the shape of young fruit

Fig. 5 fruit drop after damage by walnut limb moth

2 comprehensive pollution-free prevention and control measures

2.1 Agricultural control

Turn the tree plate deeply in late autumn or early spring, or scrape the old bark with a hard brush to eliminate the overwintering larvae in the soil or in the bark cracks, or cover the ground with plastic film before the larvae are unearthed at the end of April to prevent the larvae from being unearthed and reduce the base number of overwintering larvae; pick up the fruit in time in the growing season and pick up the fallen fruit every 3-5 days, centralized treatment, reduce the base number of the first generation larvae. The stacking place of walnut with green skin should be cleaned in time, and the remaining green skin of walnut should also be treated in time to eliminate the larvae. The above methods are the simplest and most convenient and pollution-free control methods that everyone can do. [Jishan Huayao]

2.2 Biological control

Where there are conditions, chickens and geese can be raised in the orchard and peck at the cocoon larvae in the fallen fruit or in the soil.

2.3 Drug Prevention and treatment

Before the adult Eclosion was unearthed at the beginning of May, 50% phoxim granule 5 kg and 50 kg fine sand were evenly sprinkled under the tree crown, or 50% phoxim EC 800 times solution plus Beauveria bassiana wettable powder was used to spray the soil under the crown, and then shallow ploughing the soil, 5 cm to 10 cm deep, so that the soil medicine was fully mixed and the control effect was improved. At present, these two kinds of pesticides are the longest residual period of soil treatment to control this insect, and the effect is good. Drugs such as pyrethroids or imidacloprid can also be used. In the middle of May, the end of May, the first ten days of July and the end of July, in the early and late stages of the emergence period of overwintering or first generation adults, 2000 pyrethroid pesticides or 1500 times 25% thiazuron 3 suspension agent plus Beauveria bassiana wettable powder could be used for timely control. If it rains after spraying, you should make up the spray in time. Smoke agent can be used to kill adults in valleys or closed orchards. The best time for chemical control is to concentrate on a large area, which can improve the control effect.