I. Maize head smut
Symptoms: Mainly female and male ears. Some inbred lines or hybrids can also show obvious symptoms at seedling stage. There are mainly the following types:
1. Bamboo shoot type: the upper and middle leaves are dense, the stem flat base is thick and short, such as bamboo shoot.
2. Shrinkage cluster type: after 9-leaf stage, it was dwarfed obviously, only 1/2-1/3 higher than healthy plants, with dark green leaves and more tillers.
3. Yellow stripe type: the upper 2-3 leaves have 1-2 longitudinal stripes along the veins.
4. Abnormal leaf type: dark green, narrow, thick, hard, brittle, small leaf opening, upright in a "V" shape.
5. Top leaf roll-twist type: the heart leaf is dark, tightly twisted like oxtail, so that the tassel can not be pulled out, dwarfing, only 1/2 of the healthy plant height. 6. Abnormal stem twist type: early manifestation of stem deformity and distortion.
Control method: spray 25% times 500 times spray powder or 50% times carbendazim or seed dressing 800 times liquid spray.
2. Corn Rough Shrinkage Virus
Symptoms: The plant is obviously dwarfed, the leaf color is deep, the vein is waxy white and small protuberances have a rough feeling, the tiller increases, sometimes the heart leaf twists into bow-shaped flexion, and does not bear a panicle in serious cases.
Prevention and treatment: use A500 times of virus, spray 800 times liquid spray, or use other antiviral agents to control.
Three. Corn borer
Corn borer, also known as Corn borer, damages the stem of larvae, damages the stem tissue of cereals, affects nutrient transport, and is vulnerable to wind breaks, ear dysplasia and unsatisfactory grain filling. In the ear stage of maize, it often eats the ear axis, the filament and the grain, and leads to the mildew of the grain. Maize yield was reduced by 20-30% in serious areas.
Control methods: According to the life history of corn borer, the larvae can be hatched in early July and adults emerge in early August. 1. Kill 800 times of mixed cyanogen EC with spray. 2. Drop irrigation with 50% dichlorvos diluted 500 times liquid into a small bottle between filaments and axillaries of leaves to kill larvae.
4. Corn Red Spider
Corn red spider overwinters in weed root or soil crevice with female cockroaches. After cockroaches in the early spring of the next year, it feeds and breeds on weeds first, and then turns to crop hazards after crop emerges.
Control methods: 1. Spraying acaricide on weeds in the ridge of field edge at 4-5 leaf stage of maize can effectively kill mites. 2, combined with the prevention and control of the mixture of acaroid mites, namely acaric and acarite.
