Disease characteristics and control methods of corn borer and spider mites in maize pest map

Corn borers are also called corn beetles and greasy insects. It is an important pest of grasses.

(1) Hazard characteristics:

1 The host has a wide range, which is harmful and spreads diseases. In addition to harming corn, sorghum, barley, millet, rice and other crops, aphids can still be harmed on weeds such as foxtail, crabgrass, gar, reed. The corn aphids use the sap and the sap to absorb the plant juice, and the seedlings are concentrated in the heart.

Secretion of "nectar" at the same time can form a layer of black mold on the leaf surface, affecting the photosynthesis of the crop, leading to reduced yield; in addition, it can spread the disease of corn dwarf mosaic virus, which is even more harmful.

2 breeding algebras, adapt to a wide temperature. Corn borers can be propagated for about 20 generations a year. When the temperature rises to around 7 °C in March, it starts to move in the heart of the wintering host, and most of them breed harm in the heart of the wheat seedling. As the plant grows and moves upwards, it concentrates on the newly formed heart leaf hazard. After heading, most of it migrates to the unearthed plant or the inactive mites, and rarely in the ear.

From late April to early May, a large number of winged crickets were successively moved to the heart of the corn, sorghum and millet. After the tassels of spring corn are extracted, they are concentrated on the tassels, especially before and after flowering, the temperature is high (23-25 ​​°C), the nutrition is rich, and the amount of sputum is proliferating. After the milk is cooked, it migrates to the summer corn. In summer, the temperature can be multiplied at 27-28 °C. In October, a large number of winged crickets were moved to the wintering host.

3 corn borer has many natural enemies, which can inhibit it. Such as spiders, there are small black spiders in the grass, long back micro spiders. As long as there is a small black spider in the corn heart, it can inhibit the occurrence of corn borer. It can prey on 12-25 corn borers per day. Ladybugs are waxy ladybugs, heterosexual ladybugs, etc. In addition, cockroaches, grasshoppers, cockroaches, walking insects, and cockroaches are natural enemies of corn mash.

(2) Prevention and treatment methods:

1 Remove the weeds beside the Tianbiangou, eliminate the breeding base and reduce the amount of insects.

2 chemical control. Can spray 40% dimethoate or 80% dichlorvos 1500 ~ 2000 times liquid, or 50% malathion EC 1000 times. In addition, it can be combined with the prevention and treatment of granules for corn mash. The stem can also be coated on the ears of corn with 40% omethoate emulsifiable concentrate or 40% monocrotophos emulsifiable concentrate.

Corn borer is widely distributed in corn producing areas and can be used to damage corn, wheat, sorghum, rice and various grass weeds. In the seedling stage, the mites and nymphs are clustered in the heart leaves. After heading, they are harmful to the ear, absorb juice, hinder growth, and spread a variety of grassy cereal viruses. Is a homoptera, aphididae. Common name is wheat stubble, greasy insects, ant worms. Distributed throughout the country.

[Characteristics]

Cheng, Ruoqi sucks plant tissue juice, causing the leaves to turn yellow or red, affecting growth and development, and when the plant is dead, it will die. The corn borer clusters in the heart leaves, secreting honeydew when the leaves are damaged, and produces black mold.

Don't be sorghum. On compact corn, it mainly harms male flowers and upper 1-5 leaves. The lower leaves are lightly damaged, sucking the sap of corn, causing the leaves to turn yellow and die, often causing the leaves to become black and mild, affecting photosynthesis and reducing grain weight. Transmission of viral diseases has resulted in reduced production. Host corn, sorghum, wheat, foxtail, etc.

[Feature Description]

The winged fetus has a body length of 1.5 to 2.5 mm, a black chest and a grayish abdomen, and dark side spots in the anterior segment of the abdominal tube. The antennae are 6 knots, and the antennae, ankles, feet, abdominal joints, abdominal tubes and tails are black. The wingless parthenogenetic corpus callosum is long-ovate, the living insects are dark green, covered with white powder, the appendages are black, and the compound eyes are reddish-brown. The head and chest are black and shiny, and the abdomen is yellowish red to dark green. The tentacles are 6 knots shorter than the body. Other features are similar to the wingless type. The egg is oval.

[occurrence law]

From the north to the south, there are 10 to 20 generations a year. Generally, the females with no wings are overwintering in the heart of wheat and grass weeds. At the end of April and early May, it moved to spring corn and sorghum. Before the corn is plucked, it has been clustered in the heart leaves to breed. After the males are squirmed, they spread to the tassels and the ears are breeding. The flowering period is the most favorable period for the breeding of the corn blasts. Therefore, the control period should be before the corn plucking.

The temperature is moderately high and humid, that is, the average temperature is about 23 °C, and the relative humidity is more than 85%. When the corn is in the period of vigorous flowering, it is most suitable for the proliferation of corn borer, and the storm has a greater control effect on corn borer. In the field where weeds are heavier, corn borer is also more serious.

[Control method]

1. Clear the weeds in the field in time to eliminate the breeding base of corn borers.

2, in the corn heart leaf stage, the rate of sorghum is up to 50%, when the number of sputum is more than 2,000, 50% anti-蚜威 3000 times solution, or 40% omethoate 1500 times solution, or 50% dichlorvos 1000 Double liquid, or 2.5% enemy kill 3000 times liquid evenly sprayed, can also use the above liquid medicine to fill the heart, can also use 40% omethoate 50 ~ 100 times liquid to coat the stem.

China's corn production is widely distributed, and it is planted in many provinces, municipalities and autonomous regions across the country. In recent years, farmers have generally promoted new cultivation techniques such as no-tillage and straw returning. With the increase of corn area and the replacement of corn varieties, new changes have occurred in corn pests and diseases. At present, the main pests of corn in China include eight species of pests such as Noctuidae, corn thrips, corn borers, corn leafhoppers, armyworms, corn borers, peach aphids and cotton bollworms.

Today, Wang Zhenying, a researcher at the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences, will give you a detailed introduction to the prevention and control of corn borers.

Two kinds of corn pests - the commonalities of aphids and spider mites

Expert: Aphids and leafhoppers are sucking pests. Corn locusts are commonly known as worms, Homoptera, Polygonaceae, and host crops include corn, sorghum, wheat, and foxtail. The morphological features are: oval oval. It is divided into winged parthenogenetic and wingless parthenogenetic type 2. The body length is about 1.6-2mm. The antennae are 4-6 knots, and the skin is smooth and striated. The winged ankle antenna is usually 6 knots, the front wing midrib is divided into 2-3, and the hind wing often has 2 elbow veins.

It is mainly distributed in Northeast China, North China, East China, Central China and Southwest China. It directly affects photosynthesis and pollination of corn, and can transmit viruses, causing corn dwarf mosaic disease, which can reduce corn yield by 15~30%. In China, corn glutinous rice, cereal glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice glutinous rice bran

Corn that is damaged by corn mites can cause large losses in yield

Experts: Cheng, Ruoyi clustered on the back of the leaves, heart leaves, filaments and tassels to feed, can secrete "nectar" and often form black mildew in the affected part, affecting photosynthesis, yellowing of leaves; occurring in tassel It will affect pollination and lead to reduced yields; the plants with severely damaged plants are thinner, the seeds are not full, and the bald tips are longer. In addition, aphids can also spread corn dwarf mosaic virus and red leaf virus, resulting in greater yield loss from viral diseases.

How to prevent corn mites

Expert: Agricultural control. Remove weeds in the field and reduce early insect sources.

Chemical control. Seed coating or seed dressing. It is coated with 70% thiamethoxam (Ruisheng) seed coating agent or seeded with 10% imidacloprid wettable powder, which has better control effect on seedling stage aphids.

Use granules. In the heart leaf stage of corn, before the locusts are spurted, 1.5 to 2 kg of 3% phoxim granules per acre are sprinkled in the heart leaves, or 15% chlorpyrifos granules are 300-500 g/mu, according to 1:30-40. The proportion of fine sand mixed evenly in the heart leaves, and treat corn borer.

Spray control. Seedling stage and early stage of tasseling are the key period for controlling corn mites. If more mites are found, use 10% imidacloprid WP 1000 times solution, 10% beta-cypermethrin EC 2000 times solution, 2.5% cyhalothrin 2500 times solution or 50%. It is sprayed with 2000 times solution of Kangwei Wettable Powder and 6000 times of 25% Thiamethoxam Water Dispersant.

The website of this paper: The characteristics of corn worms and the disease characteristics of corn borer and leaf mites

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