Control of common corn diseases and insect pests, how to do corn pest control measures?

Control Strategy of Diseases and insect pests in Organic cultivation of Maize

The diseases easy to occur in the process of maize cultivation are leaf spot, coal sheath, rust and mosaic disease, and the pests are corn borer and aphids. The occurrence of diseases and insect pests is closely related to climatic conditions, so the timing of control should be determined according to climatic factors and the occurrence of diseases and insect pests in the field. This paper describes the symptoms and symptoms of major diseases and insect pests in corn, and uses clove oil, neem essence, egg parasitoids and microbial preparations for pest control.

1. Corn leaf spot (flax leaf blight):

The main damage to the leaves, the initial needle-like spots, and then turned into light brown spots, limited by the veins of the leaves and become long or spindle-shaped, the center of light brown, the edge of dark brown. Maize occurs in all growing periods throughout the year, and it is most likely to occur when the temperature is 20-32 ℃, and the middle and lower leaf spot is more common. When it occurs, it is sprayed with 400 times of clove oil, and the estimated control rate can reach 70-75%.

Second, corn coal sheath disease:

The main damage to the leaves, the initial needle-like spots, and then gradually expanded into a water-immersed spinning shape, 2-15 cm long gray-green disease spots, the surface of high humidity produced gray-black mildew. In the middle period of spring cropping, that is, from late March to mid-May, the temperature is 18-27 ℃, which is most likely to occur in high humidity, but not suitable in winter and summer, so it rarely occurs. The control method is the same as that of leaf spot disease. It is estimated that the prevention and treatment rate can reach 70-75%.

Third, corn rust:

Divided into common type and southern type of rust, disease spots are more common in leaves, but leaf sheaths and bracts can also be infected. The summer spores of common rust accumulate under the leaf epidermis and produce brown powdery summer spores after rupture. The summer spores of southern type rust are buried under the leaf epidermis, which are small round and golden yellow. The disease is easy to be infected in the seedling stage, but it mostly occurs in the middle and later stage of growth in the field. The control method is the same as that of leaf spot disease. It is estimated that the rate of prevention and treatment can reach 70%.

4. Corn mosaic disease:

Maize dwarf mosaic virus type B system is the main pathogen, which infects healthy plants by mechanical transmission or aphid vector. At the initial stage of the disease, after the dense macula appeared at the base of the leaf, it spread to the whole leaf and became yellow and green. In severe cases, the leaves turn green and yellowing, even on the stem, leaf sheath, ear leaves and male flowers. If infected at the seedling stage, the growth is slow and the plant is dwarfed. According to the control method, when the corn was infected in the 6th and 7th leaves, one additional nitrogen fertilizer could be applied to promote the growth of the diseased plants. if the infection occurred after the 8th leaf, the effect on the yield was very small and could be ignored without control. In addition, attention should be paid to the control of vector insects, corn aphids.

5. Corn borer:

It is the most important pest of maize, and the corn sown from March to September was seriously damaged. In the middle of the night, the adults lay their eggs on the back of the maize leaves with a plant height of more than 20 centimeters. The hatched larvae harm all parts of the corn and finally pupate in the damage part. According to the control method, Trichogramma egg parasitoids can be released at a plant height of 20 cm, with 200 pieces of bee slices per hectare to inhibit the hatching of corn borer eggs. In addition, 16000iu/mg granules were applied to the heart leaves in the early and middle stages of maize whorls, 4-5 days before male flowers and 3-4 days after silking of female flowers. Use 5 kilograms per hectare. The rate of prevention and treatment can reach 70-80%.

6. Corn aphids:

It is the main pest in the late growth stage of maize, especially in dry climate. Aphids clustered heart leaves or bracts, male flowers and female pedicels to absorb juice, resulting in poor plant growth, which was prevented by spraying 4.5% neem oil 2500 times when it occurred. It is estimated that the prevention and treatment rate can reach 70-80%.