Rhizoctonia solani

Rhizoctonia solani is a plant pathogenic fungus with a wide host range and worldwide distribution. It is one cause of the condition known as damping off, which is a cause of death of seedlings in agriculture. It is also responsible for black scurf and stem and stolon canker in potatoes and wire stem, a disease of cabbage, cauliflower and related plants that is similar to damping off but attacks older seedlings and produces a constricted, wiry stem. Also crown rot in carrots.

Symptoms
Causes brown, irregular cankers to develop on the lower stems, lesions can enlarge and girdle the stem. Injury is more common during warm weather.

Treatment
Plants that are not severely damaged by rhizoctonia solani may recover in the field.

Chemical
Fumigation of plant beds will eradicate seedling pathogens, such as rhizoctonia solani; however, fumigated soil can become reinfested if pathogen-infested field soil is moved to fumigated areas. For cabbage and broccoli, quintozene fungicide can be used in the transplant water at a rate of 6-8 T/gal (3/4 pint/plant). This fungicide is not registered for use in turnips or kale.

Prevention
Choose a fertile, well-drained site for the plant bed. Poor drainage favors seedling disease. Avoid excessive amounts of nitrogen fertilizer. Succulent plants are more susceptible to infection. Seed brassicas when the soil temperature reaches 21°C (69°F) and seed as shallowly as possible so that germination and emergence are rapid. Discard transplant seedlings that show symptoms of wire stem. Avoid banking or throwing soil up around plants during field cultivation. Harvest cabbage heads early. Cabbage leaves become more susceptible the longer they stand in the field.