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.