|
What is it?
Clubroot is caused by a soil-inhabitating fungus called plasmodiophora brassicae. It is dangerous to all plants in the cabbage family; they include broccoli, brussels sprouts, cauliflower, chinese cabbage, collards, kale, kohlrabi and of course the common cabbage. Clubroot can also attack weeds such as mustard and pennycress.
What does it look like?
Cabbage family plants affected with clubroot with have swollen, or misshapen roots with large misshapen swellings just below the surface of the soil. Old, outer leaves on cabbage family plants may begin to wilt, turn yellow or drop off. Sometimes the first sign of the fungal infection is the wilting leaves on plants.
How does it manifest?
Plasmodiophora brassicae fungus can exist in the soil for many years, even in treated soil. The presence of the fungus along with optimal conditions such as acidic soil and hot, moist weather lead the spread of the fungus. Typically the fungus enters from the soil into the roots of the cabbage family plant, which causes the characteristic swellings of clubroot. As the fungi cause rapid multiplication and growth of cells within the plant, the root tissue swells and the rest of the plant becomes weakened, which causes the wilting of outer leaves. As the plant lives out its life with the fungus, the roots will decompose and spread more of the fungus into the soil. Additionally, water spreads the fungus and it can be transported to other areas of the garden on the soles of shoes.
What can you do about it?
An infected plant cannot be cured, or salvaged. It will eventually weaken to the point that it dies. However, you can treat the soil by using a PCNB containing fungicide, mixing 3 tablespoons per gallon of water. When planting in infected soil, you will want to pour a cup of this solution directly on the soil around the roots of the transplant to help stave off infection. Additionally, changing your soil to a more alkaline base will help stop spread of the fungus. However, your best bet once you find that your cabbage family plants and soil have been infected is to avoid growing plants susceptible to plasmodiophora brassicae in that area for at least five to seven years because the fungus can be present in the soil for at least that long.
|
| |
