Corn big spot disease, commonly seen in the process of corn cultivation, occurs to varying degrees every year, making it difficult for many farmers to control effectively. Consequently, the prevention and treatment methods are crucial to prevent significant yield losses in corn. Let's delve into how to prevent and treat corn big spot disease.
Symptoms of Corn Big Spot Disease
The main symptoms of corn big spot disease begin with the lower part of the plant, showing water-soaked brown spots initially, which later develop into oval, rectangular, or fusiform lesions with reddish-brown edges and yellow-brown centers. In severe cases, the lesions merge, causing leaf withering, yellowing, and death, leading to a substantial decrease in chlorophyll content, photosynthesis, and yield, with severe cases affecting over half of the yield.
Prevention and Treatment Methods
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Selection of Resistant Varieties: Opt for disease-resistant varieties such as Dongdan 1331, Longchuang 310, Denghai 710, etc. Planting varieties with multiple resistances and implementing proper layout and rotation can prevent cross-infection of diseases.
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Seed Treatment: Treat seeds by coating them with seed dressing agents for better prevention. Chemical seed dressing agents such as carboxin, thiophanate-methyl, and carbendazim, combined with chemical insecticides such as thiodicarb, can be used for seed mixing or soaking treatment.
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Enhanced Management:
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Timely Sowing: Arrange sowing time reasonably, with early sowing recommended for spring corn to advance the growth period, avoiding late high-temperature and rainy seasons. Early sowing of summer corn can reduce disease incidence, contributing to disease prevention and increased yield.
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Interplanting: Advocate for intercropping with crops such as cotton, soybeans, peanuts, and sweet potatoes.
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Water and Fertilizer Management: Timely drainage, reduce field humidity, strengthen intertillage, balance fertilization, promote robust plant growth, and enhance disease resistance.
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Leaf Removal: Remove diseased leaves promptly, take them out of the field, and burn or compost them at high temperatures.
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Chemical Control: Spray chemicals around corn tasseling when the disease incidence rate in the field reaches above 70% and the rate of diseased leaves is around 20%. Suitable chemical agents include 50% carbendazim wettable powder, 50% mancozeb wettable powder, or 90% thiram manganese zinc. Apply the chemicals at a concentration of 500 times the volume with water, spraying 50-75 kg of the solution per acre, and repeat spraying every 7-10 days.
In summary, corn big spot disease is an epidemic disease that usually occurs under high-temperature and high-humidity conditions. Therefore, attention should be paid to climate changes, strengthened planting management, and timely chemical spraying to effectively prevent significant yield losses caused by big spot disease.
