Alternaria blight is one of the most destructive fungal diseases in mustard crops, significantly impacting yield and seed quality. This disease is caused by Alternaria brassicae and Alternaria brassicicola, thriving in humid conditions and moderate temperatures. Effective management is crucial for healthy mustard production.
Symptoms of Alternaria Blight in Mustard
- Small, dark brown circular spots with concentric rings on leaves.
- Lesions merge, leading to yellowing and premature leaf fall.
- The spots may have a yellow halo around them.
- Blackish-brown spots on stems and pods, affecting seed formation.
- As the disease progresses, the spots can turn into dark brown or black lesions that can crack.
- Severe infections can cause leaves to fall off the plant.
- Small brown spots may appear on the head of the plant, which can deteriorate quickly.
- Severe infection results in shriveled seeds with poor germination capacity.
Causes and Favorable Conditions
- High humidity (above 80%) and moderate temperatures (20-30°C).
- Continuous mustard cultivation without crop rotation.
- Use of infected seeds or plant residues.
- Overcrowded sowing and excessive nitrogen application.
Best Practices for Alternaria Blight Management in Mustard
1. Cultural Control Methods
- Rotate mustard crops with non-host crops like wheat or pulses.
- Use disease-free, certified mustard seeds for sowing.
- Avoid dense sowing to promote better air circulation.
- Remove and destroy infected plant debris after harvest.
- Proper weed management to eliminate alternative hosts.
- Use of Resistant Varieties.
2. Biological Control
-
Katyayani Tyson Trichoderma Viride 1% WP Bio Fungicide Powder [Dosage- 1 - 2 kg/ Acre.]
3. Chemical Control Measures
Seed Treatment: Use Captan or Thiram @ 2-3 g/kg seed before sowing.
Foliar Sprays: Apply fungicides like:
- KATYAYANI KZEB M-45 MANCOZEB 75% WP - Dose - 350- 400 GM / acre
- Katyayani Boost Propiconazole 25% EC - Dose - 200 ml per acre
- Katyayani Hexa 5 Plus Hexaconazole 5 SC - Dose - 200-250 ml per acre
- Katyayani Meta - Manco Metalaxyl 8 % + Mancozeb 64 % wp, Dose - 350- 400 GM / acre
FAQs :
Q. What is the best time to apply fungicides for Alternaria blight in mustard?
A. Fungicides should be applied at the first sign of infection and repeated at 10-15 day intervals for effective control.
Q. Can crop rotation help in managing Alternaria blight?
A. Yes, rotating mustard with non-host crops like wheat or pulses reduces pathogen build-up in the soil.
Q. How can I prevent Alternaria blight in mustard naturally?
A. Using disease-free seeds, maintaining proper spacing, and removing infected plant debris can help prevent the disease naturally.
Q. Does excessive nitrogen application increase disease severity?
A. Yes, excessive nitrogen promotes lush growth, making the plants more susceptible to Alternaria blight.
Written by :- Dheeraj Rajendra Mahajan, Agristudent
