By Scout Nelson
Black rot is a bacterial disease that poses a serious threat to brassica crops, including cabbage, cauliflower, kale, and broccoli. The disease is caused by Xanthomonas campestris pv. campestris (Xcc) and spreads rapidly during hot and wet weather, leading to severe crop loss.
The disease can appear at any stage of plant growth but is more common in spring and late summer. Bacteria enter plants through leaf pores, insect wounds, or water splashes. Once inside, they move through the veins, causing yellow, V-shaped lesions on leaf edges.
As the infection worsens, veins turn black, leaves die, and the disease can move into stems, eventually killing the entire plant.
Spread and Risk Factors:
Black rot spreads through infected plant residue, contaminated water, and even seeds. It can survive in soil and on decaying plants for up to three years.
Farmers are advised to avoid overhead irrigation and instead use drip or soaker hoses to reduce splashing water that can spread the bacteria.
Management Practices:
Effective management focuses on prevention. Farmers should buy certified clean seeds or heat-treat seeds before planting. Using resistant crop varieties, removing infected plants, and disinfecting tools are also essential.
Crop rotation is recommended, avoiding brassica crops in infected fields for at least two to three years. Copper-based sprays can offer limited protection if applied before high-risk weather conditions.
Diagnosis:
Black rot can be identified by triangular yellow patches with black veins. It can be confused with soft rot or fusarium wilt, so accurate diagnosis is important.
Farmers are encouraged to seek help from plant diagnostic clinics for confirmation and advice on managing outbreaks effectively.
Photo Credit: pexels-orlovamaria
Categories: South Dakota, Crops, Fruits and Vegetables, Sustainable Agriculture