In this article we will discuss about:- 1. Occurrence of Plasmodiophora Brassicae 2. Symptoms of the Disease 3. Economic Importance 4. Control Measures
- Occurrence of Plasmodiophora Brassicae
- Symptoms of the Disease
- Economic Importance of Plasmodiophora Brassicae
- Control Measures for Plasmodiophora Brassicae
1. Occurrence of Plasmodiophora Brassicae:
The fungus is an obligate endoparasite. It was first discovered, as causal organism of club root OT finger and toe disease of all crucifers including many wild and economically important species of Brassica by Woronin in 1878. The disease is one of the most widespread and the causal agent (P. brassicae) is one of the most intensely studied pathogen.
2. Symptoms of the Disease:
The infected roots bear malformations which take on a variety of shapes. In cabbage and its close relatives, the malformations are spindle-shaped in the case of single point infection. Multiple infections in close proximity induce modifications of spindle type. If an infection takes place at an early stage, the clubs or malformations are formed on the main root and the disease is named club root disease.
The development of lateral roots is suppressed. The late infections produce galls on the lateral branches suggesting an alternative name of ‘Finger and Toe’ disease. The above ground symptoms of the disease are noticeable when it has progressed to a considerable extent. The drooping of leaves at noon or bright days is the first sign. Subsequently it leads to permanent wilting or retarded growth.
3. Economic Importance of Plasmodiophora Brassicae:
Two species are of great economic importance. They are Plasmodiophora brassicae and Spongospora subterranea. The former is the causal agent of club root disease of cabbage and other crucifers. Spongospora subterranea causes a powdery- scab disease of potatoes. Both are destructive diseases.
A variety of Spongospora subterranea (S. subterranea f. nasturtii) is a pathogen of water cress. These diseases cause a twofold loss. Firstly, there is damage to the crop. Secondly, the contaminated soil becomes unproductive for many years for replanting the same crop plants.
4. Control Measures for Plasmodiophora Brassicae:
Due to effective control measures, the disease is no longer the scourge that it originally was. The use of resistant varieties and long rotation are effective control measures Fungicidal transplanting liquids are also employed with varying success.
The use of pentachloronitrobenzene and mercuric or mercurous chloride in the transplantic liquid is effective to check infection. The other chemicals which are equally effective are aldrinvapam, sodium dithiocarbamate and tetrachloronitrobenzene. Use of soil free from the pathogen in the transplantation of seedlings is useful preventive measure.