Alfalfa Sprout Rot
Cause.
Erwinia chrysanthemi survives for up to 2 weeks on inoculated dried seeds. Air, the water supply, or greenhouse workers may introduce bacteria into a sprouting house. Spread within a tray is by seed to seed contact. Rot is most severe at high moisture and temperatures of 28°C and above. Little disease occurs below 21°C.
Symptoms.
Radicles are a translucent yellow as they emerge from the seed. In 24 to 48 hours, seeds stop growing and turn into a yellowish, odiferous mass that contains numerous bacteria. Disease initially occurs in a few trays, but it may spread throughout all trays in a few days.
Management
1. Control temperature in the sprouting house.
2. Practice sanitation. Bacteria likely survive in water remaining in tanks used for soaking seeds.
3. Soak seeds for 2 hours in 0.5% sodium hypochlorite or calcium hypochlorite. However, hypochlorite is not currently registered for alfalfa seed treatment in the United States.
