What are the common pests and diseases of corn? How should they be prevented and controlled?
Corn is a food that is both delicious and rich in nutritional value. It originated in Central and South America, and is now grown all over the world. What are the common pests and diseases of corn and their prevention and control methods?
1. Corn rust
Corn rust in our country can be divided into two types, namely common corn rust and southern corn rust, which mainly occur in the regions of South China and Southwest China.
The early stage of corn rust mainly appears as small light yellow elongated and oval brown pustules on both sides of the leaves. Then, after the pustules rupture, rust-colored powdery material appears, which is the summer spores of the pathogen. In the later stage of development, black oval or elongated raised spots appear on the leaf surface of the corn. After they split open, dark brown winter spores are exposed.
Prevention and control methods
Choose to plant varieties with resistance to corn rust; strengthen field management, clear weeds in the field, and reduce the invasion of pathogens; manage scientifically, apply fertilizer and water in appropriate amounts, and improve the resistance of corn to the disease source; in severely affected areas, spraying can begin at the early stage of the disease, generally 2 to 3 sprays at intervals of about 8 days.
2. Northern corn leaf blight
Northern corn leaf blight develops from small leaf spots. In the early stage, northern corn leaf blight is water-soaked, then turns grayish green. In severe cases, the large elongated spindle-shaped spots can reach about 20 cm in length, and finally develop into brown necrotic spots. If rain occurs, black mold-like material grows on the diseased spots.
Prevention and control methods
Select excellent, high-yield, disease-resistant corn varieties to eliminate the disease source at the root; where conditions permit, plant the fields with mixed varieties as much as possible; carry out deep plowing and winter irrigation of the land to eliminate field disease sources; pay attention to chemical fertilizers and the rational combination of nitrogen and phosphorus to enhance the resistance of the corn itself; remove weeds in the field and at the edges as early as possible to avoid infection by fungal sources.
3. Southern corn leaf blight
Southern corn leaf blight can occur from the seedling stage of corn all the way to the mature stage. The diseased spots are very small, and the long ones do not exceed 1 cm; but they are numerous, similar to oval in shape, brown, darker in the center and lighter around the edges; the width is limited to between two leaf veins.
Prevention and control methods
Choose a suitable period and sow early, so as to avoid the peak period of disease occurrence; keep the base fertilizer sufficient and increase phosphate fertilizer and potassium fertilizer; appropriately remove several leaves from the bottom of the corn to reduce the relative humidity in the field and make the plants grow more robust; after high-temperature fermentation, use the corn stalks in the field as compost.
There are many common pests and diseases of corn, and they are also very common. When encountering these problems, do not worry too much. We can consult relevant materials and use scientific methods for prevention and control.