Gangrene

Phoma foveata, Phoma exigua

Symptoms: Phoma foveata

• Only becomes visible during storage
• Black and violet fungal growth inside tubers
• Sunken skin with parallel wrinkles

Symptoms: Phoma exigua

• Sunken skin looks like a thumbprint
• Slow development
• Tissues discolour to brown/grey

Infection and spread

• Survives on tubers and in the soil
• Moderate, wet summers and late harvesting increases the chance of Phoma infection. Do not harvest below 10°C
• Infection via eyes, lenticels and harvesting damage
• Develops at a low temperature (< 8°C)

Infection and spread

• Dry rot (Fusarium spp.)
• Phoma eupyrena