Causes and Control methods of fungal Maize Leaf spot

Corn leaf spot, leaf spot and gray leaf spot are the main diseases in maize production, which often occur in combination, and the occurrence degree is moderate. At present, a large area of corn in some areas has entered a period of vigorous growth, and there are too many Rain Water this year, and it is expected that a large area of epidemic will be harmful and have a serious trend in August. therefore, we should actively do a good job in the prevention and control of maize leaf spot to ensure a bumper harvest.

Cause of occurrence

1. Cold and wet conditions are easy to develop.

two。 The number of bacteria source is large, different maize varieties have different resistance, and the planting of susceptible varieties is common.

3. The management level of farmers in most mountainous areas is low, coupled with the overcast and rainy weather from July to August, the suitable climatic factors are very easy to cause the circulation infection of maize leaf spot.

4.August is the heading period of most maize, and it is also the peak period of the occurrence of maize leaf diseases. many of the above factors are conducive to the occurrence of maize diseases.

Prevention and cure method

1. Agricultural control: timely removal of diseased leaves in the lower part of diseased plants, strengthening the middle and late management of corn fields, ploughing and weeding, paying attention to drainage in low-lying land, improving the microclimate environment of corn fields and enhancing plant disease resistance.

2. Timely fertilization: 20 kg of chemical fertilizer can be applied properly from jointing to heading stage to improve the resistance of varieties, so as to control and reduce the harm of maize leaf spot and small leaf spot.

3. Chemical control: the prevention and control of maize leaf spot should be carried out as soon as possible, and emphasis should be placed on the prevention of susceptible varieties and diseased fields over the years. In general, when sporadic diseased plants are found in corn planting fields, chemical control should be carried out to control the disease center and reduce the spread of epidemic. The main prevention and control agents are as follows: the following agents can be used in rotation: 100g / mu with 25% triadimefon, 500g / mu with 50% carbendazim wettable powder, 500g / 100g / mu with 75% chlorothalonil wettable powder, 400g / 500x solution with 65% Dysen zinc wettable powder, and methyl thiophanate (methyl thiophanate), propiconazole, oxaprozole (Shigao), etc. Spray once every 7-10 days, control 2-3 times continuously, choose sunny day to apply medicine, after application, it is effective to ensure that it does not rain for more than 5 hours.

4. Increase the application of phosphorus and potassium fertilizer: for corn plots with phosphorus deficiency symptoms, potassium dihydrogen phosphate can be sprayed to supplement trace elements to improve corn resistance; for seriously affected fields, after the disease is controlled, potassium dihydrogen phosphate or other foliar fertilizer can also be sprayed to restore corn growth as soon as possible and ensure a bumper harvest.

5. Collect sick and disabled bodies and burn them in time.