Symptoms and Management of Rhizopus Soft Rot of Sweet Potato
Causal Organism: Rhizopus stolonifer Or Rhizopus nigricans.
Symptoms of Rhizopus Soft Rot of Sweet Potato
♦ Watery soaked rot with a characteristics odor of fermentation on burst of the skin.
♦ Later a ring rot appears of about 2 inches in diameter and 0.5 inches depth.
♦ In 4 to 5 days, the entire inner tissues of the root rot become soft, slimy and watery as they liquefy.
♦ If rotted area ruptured; the mycelium, sporangiospores and sporangia become visible.
♦ The root becomes murnmify.
Favorable condition of Rhizopus Soft Rot of Sweet Potato
♣ Elevated temperatures of 25-29°C favor disease progression.
♣ Higher humidities.
Disease transmission
Considering this is primarily a post-harvest disease, it is often transmitted due to unsanitary harvest equipment, wash lines, packing equipment and transportation containers.
Control measures/Management of Rhizopus Soft Rot of Sweet Potato
1. Avoid root injury.
2. Curing of sweet potato before storage.
3. Sterilization of storehouse with 2 % formalin.
4. Store sweet potatoes at 85% humidity and 13°C with proper ventilation.
5. Before storage, treated 1% Bordeaux mixture.
6. Rodents should be controlled.
7. Cultivation of resistant varieties. e.g. Julian, Southern queen.
8. Transport roots in sanitary containers.
