The tomato bollworm is also called borer, belonging to the order Lepidoptera, Noctuidae. It occurs all over China. Helicoverpa armigera is one of the main pests of tomato in the open field and tomato in autumn. Today, Kobayashi will tell you about the pathogenesis and control methods of the cotton bollworm.
First, the characteristics of tomato bollworm
The larvae feed on flowers and fruits, and can also harm the young stems, leaves and buds. After the flower bud is damaged, the potato chips open and turn yellow. The fruit is harmed, the young fruit is eaten empty or caused to rot, and after the fruit is hollowed out, the rainwater and the bacteria easily enter into the rot and fall off, which seriously affects the yield.
Second, the incidence of cotton bollworm
The mature larvae overwinter in the 3~9 cm topsoil. Adults lay eggs at night and lay eggs. The eggs are scattered on the shoots, young leaves, fruit stalks and stem bases of the top to the fourth compound leaf of tomato plants. Each female produces 100 to 200 eggs. The newly hatched larvae feed on the tip of the leaf and the bud of the flower bud. The fruit is eaten at the 3rd age, and the fruit is eaten at 4~5 years old, generally affecting 4~5 bells, up to 10 bells.
The larvae transfer damage time is mostly at night and early morning, which is conducive to prevention and treatment. The larvae are self-mutilating, especially for larvae older than 3 years old. Most of the larvae are 6 years old, a few 5 years old, and they are thrown into the soil after being cooked, and the net is used as a soil chamber.
Helicoverpa armigera is a thermophilic and hi-wet pest. Adults lay eggs suitable for temperatures above 23 degrees Celsius, and rarely spawn at temperatures below 20 degrees Celsius. Larval development is most suitable for 25 to 28 degrees Celsius and air relative humidity of 75% to 90%. In the north of China, the effect of humidity on cotton bollworm is the most obvious. The monthly precipitation is above 100 mm, and the relative humidity is more than 70%. If the rain is too large, causing soil compaction, it is not conducive to larvae into the soil, and the mortality of cockroaches increases, and heavy rain can wash away some eggs.
Adults are mostly feathered at night, and they inhabit the flora during the day, hiding in the back of the leaves and so on. Adults have strong phototaxis to wilting willows and black light. Adults mate at night, and lay eggs 2 to 3 days after mating. Most of them lay eggs at dusk and rainy days. The spawning period is 7 to 13 days, and the maximum number of eggs can be produced. Autumn tillage, spring tillage or winter tillage can be used to kill wintering, and it is turned into a shovel below 10 cm. It is difficult to unearth after emergence. Adults tend to eat nectar, close to the fields of honey-sourced plants, and suffer heavily.
The natural enemies of Helicoverpa armigera include more than 10 species such as ladybug, grass ridge, Trichogramma, Iguana, scorpion, and spider, which can also inhibit the occurrence of cotton bollworm.
Third, tomato cotton bollworm prevention and treatment methods
1. Using cotton bollworm adults to produce 95% of the eggs from the top of the tomato to the fourth layer of compound leaves, timely pruning and playing the right, can effectively reduce the amount of eggs laid, but also pay attention to the removal of the capsules, and reduce the insect population. When planting tomato early, middle and late varieties, early-maturing varieties should be transplanted as early as possible to avoid the harm of second-generation cotton bollworm.
2. Continuous spraying of bacterial insecticides (Bt emulsion, HD-1 Bacillus thuringiensis preparation) or Helicoverpa armigera nuclear polyhedrosis virus 4 to 8 days after the peak of the second generation cotton bollworm eggs can effectively control cotton bolls Insect larvae. Artificial breeding and release of natural enemies may also effectively control the occurrence and damage of cotton bollworm.
3, cotton bollworm adults have strong phototaxis, can be trapped by black light.
4. When the chemical control is carried out, the key is to grasp the larval stage from the incubation period to the 3rd instar larva, and the larvae should not be applied when applying the fruit. The available medicinal agents are cockroach cockroach (21% synergistic cyanide/horse emulsifiable concentrate) 5000 times solution, or 2.5% kungfu emulsifiable concentrate 5000 times solution, or 2.5% Uranus emulsifiable concentrate 3000 times solution, or 2.5% enemy killing emulsifiable concentrate 2000 times solution. , or 10% chrysanthemum emulsifiable oil 1500 times solution, or 20% sterilized emulsifiable concentrate 2000~2500 times liquid, etc., have good control effect.
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