What Is It? | Facts in Depth | For the Professional Diagnostician
Brassica Diseases | Black Rot
Black Rot
Identification
Seedlings
- Young seedlings are very susceptible to black rot infection
- Leaves are chlorotic
- Premature leaf drop occurs
- Seedlings eventually die
Mature Plants
- Leaf edges are chlorotic or necrotic
- Lesions form in a distinct “v-shape,” with the base of the “V” directed along the vein
- Veins are brown to black in color
- Lesions eventually expand downward toward the base of the leaf
- Infection spreads down the petioles and up and down the stems
- Vascular tissues are discolored and exhibit a yellowish bacterial slime
- Diseased plants wilt and eventually die
Favorable Environmental Conditions
- Warm, humid environmental conditions with occasional periods of rain
- Rain or damp days promote the spread of the disease
- Temperatures from 75°F to 95°F are most favorable for disease development
Often Confused With
- Nutrient deficiencies
- Fusarium yellows
Scouting Notes
- Scout following periods of rainfall after humid and warm conditions
- Young seedlings are the most susceptible to black rot infection
- Very distinct chlorotic V-shaped lesions form on the leaves of mature plants
- Leaf veins become brown or black in color
