Clubroot

Cabbage Clubroot
Scientific classification
(unranked):	SAR
(unranked):	Rhizaria
Phylum:	Cercozoa
Class:	Phytomyxea
Order:	Plasmodiophorales
Family:	Plasmodiophoraceae
Genus:	Plasmodiophora
Species:	P. brassicae
Binomial name
Plasmodiophora brassicae Woronin, 1877

Clubroot is a common disease of cabbages, broccoli, cauliflower, Brussels sprouts, radishes, turnips, stocks, wallflowers and other plants belonging to the family Brassicaceae (Cruciferae). It is caused by Plasmodiophora brassicae, which was once considered a slime mold but is now put in the group Phytomyxea. It is the first Phytomyxea for which the genome has been sequenced. It has as many as thirteen races. Gall formation or distortion takes place on latent roots and gives the shape of a club or spindle. In the cabbage such attacks on the roots cause undeveloped heads or a failure to head at all, followed often by decline in vigor or by death. It is an important disease, affecting an estimated 10% of the total cultured area worldwide.

Historical reports of clubroot date back to the 13th century in Europe. In the late 19th century, a severe epidemic of clubroot destroyed large proportions of the cabbage crop in St. Petersburg. The Russian scientist Mikhail Woronin eventually identified the cause of clubroot as a "plasmodiophorous organism" in 1875, and gave it the name Plasmodiophora brassicae.

In 18th, 19th and early 20th century Britain clubroot was sometimes called finger and toe, fingers and toes, anbury, or ambury, these last two also meaning a soft tumor on a horse.

The potential of cultural practices to reduce crop losses due to clubroot is limited, and chemical treatments to control the fungus are either banned due to environmental regulations or are not cost effective. Breeding of resistant cultivars therefore is a promising alternative.

Cabbage Clubroot is a disease of Brassicaceae (mustard family or cabbage family) caused by the soil-borne Plasmodiophora brassicae. The disease first appears scattered in fields, but in successive seasons it will infect the entire field, reducing the yield significantly and sometimes resulting in no yield at all. Symptoms appear as yellowing, wilting, stunting, and galls on the roots. It is transmitted by contaminated transplants, animals, surface water runoff, contaminated equipment, and irrigation water. The pathogen can survive in a field for years as resting spores without a host present and will infect the next crop planted if it is a susceptible host. This pathogen prefers a wet climate and a pH around 5.7, so proper irrigation and the addition of compounds that raise the pH can be used to control this disease. Other control methods include sanitation to prevent transmission, chemical control, and resistant varieties.

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