Disease Management in Crops During the Rainy Season

MAJOR DISEASE AFFECTING CROPS DURING MONSOON

Root Rot Disease

• This is a fungal disease. The likelihood of this disease increases with waterlogging in the field. Affected plants start showing signs of root rot. The stems near the soil surface also begin to decay and turn brown. The plant leaves gradually turn yellow. Eventually, the plant starts to dry out.

Powdery Mildew Disease

• This disease is also known as Powdery Mildew. In the initial stages of this disease, white spots begin to appear on the upper surface of the plant leaves. Gradually, these spots increase in size and cover the entire leaf with a white, powdery substance. As the disease progresses, white spots may also appear on the plant branches and fruits. This disease interferes with the process of photosynthesis, causing the affected leaves to gradually turn yellow. The affected leaves eventually dry out and fall off, hindering plant growth. This disease can lead to a significant reduction in crop yield and quality.

Wilt Disease

• The main cause of Wilt Disease is the fungus Fusarium oxysporum. This disease can reduce crop yield by 10 to 12 percent. If the disease severity increases, the yield can decrease by 50 to 78 percent. Wilt Disease affects various crops including pigeon peas, chickpeas, pea, sugarcane, rice, lentil, tomato, eggplant, bottle gourd, mango, guava, and others. The fungus causing this disease can survive for up to 6 years without any nutrition or control. In the early stages of the disease, the lower leaves of the plant start to wilt and dry out. As the infection progresses, the entire plant wilts and dries up. If fruits have already developed on the plants, symptoms of the disease may also appear on the fruits, which may show brown-black spots.

Common Crop Fungal Diseases During the Rainy Season

Different crops are affected by different pathogens, but several fungal diseases become especially common during wet and humid weather.

• Leaf spot: Produces brown, black, or yellow-edged lesions on foliage.
• Blight: Causes rapid browning and death of leaves, stems, or shoots.
• Anthracnose: Creates dark, sunken lesions on leaves, stems, and fruits.
• Downy mildew: Produces yellow patches on upper leaf surfaces and fungal growth underneath.
• Powdery mildew: Appears as white or grey powdery growth on leaves and shoots.
• Rust: Causes yellow, orange, or brown pustules on foliage.
• Fruit rot: Leads to soft, discoloured, or sunken areas on developing and harvested fruits.
• Root rot: Damages roots under waterlogged or poorly drained conditions.

Crops Most Vulnerable During the Rainy Season

Fungal diseases can affect nearly every crop, but vegetables, fruits, pulses, oilseeds, cereals, and plantation crops may face particularly high disease pressure during prolonged wet weather.

Vulnerable crops often include:

• Tomato
• Chilli
• Potato
• Brinjal
• Onion
• Grapes
• Banana
• Groundnut
• Soybean

Rainy-Season Crop Protection Practices

An integrated approach provides better results than depending on a single treatment. Effective rainy-season crop protection should combine field sanitation, drainage, resistant varieties, balanced nutrition, weather monitoring, and timely disease control.

1. Check fields immediately after heavy rain.
2. Remove standing water and clear blocked drainage channels.
3. Inspect lower and inner leaves for early symptoms.
4. Remove infected plant parts where practical.
5. Review the weather forecast before spraying.
6. Apply treatments only under suitable weather conditions.
7. Maintain accurate records of disease symptoms and applications.

Common Mistakes to Avoid

• Waiting until the disease is severe before taking action
• Ignoring standing water and poor drainage
• Using excessive nitrogen during humid weather
• Planting crops too closely
• Spraying immediately before heavy rainfall
• Repeating the same fungicide mode of action continuously
• Leaving infected crop residue in the field
• Applying unregistered products or incorrect dosages