Clubroot of cabbage

CLUB ROOT OF CABBAGE AND ITS MANAGEMENT

1. COLLEGE OF AGRICULTURAL TECHNOLOGY (Affiliated to Tamil Nadu Agricultural University, Coimbatore-3) Kullapuram (Po), ViaVaigai Dam, Theni-625 562 CLUBROOT OF CABBAGE Submitted by Course teacher D.Priyadharshini . Dr.S.Parthasarathy 2015021100 Assistant Professor (Plant Pathology)

2. CLUBROOT OF CABBAGE INTRODUCTION DISTRIBUTION PATHOGEN SYMPTOMS SYSTEMIC POSITION DISEASE CYCLE MANAGEMENT

3. INTRODUCTION Cabbage is a leafy green, red, white biennial plant. Cabbage is a member of the genus Brassica and the mustard family, Cruciferaceae . The sulforaphane found in cabbage may help protect cancer.

4. DISTRIBUTION India, Nepal, China, West Bengal, Canada, Bulgaria, Denmark and Hongkong .

5. HISTORY Historical reports of clubroot date back to the 13 th century in Europe. In 19 th century, a severe epidemic of clubroot destroyed large proportions of the cabbage crop in St. Petersburg.

6. The Russian scientist Mikhail Woronin eventually identified the cause of clubroot as a “ Plasmodiophorous organism” in 1875, and gave it the name Plasmodiophora brassicae .

7. ECONOMIC SIGNIFICANCE Clubroot can be a reccurring problem, for years because it is easily spread from plant to plant. P. brassicae is able to infect 300 species of cruciferous plants.

8. SYMPTOMS Developing plants may not show any symptoms but as the plants get older they will start to show symptoms of chlorosis or yellowing. Wilting during hot days and stunted growth. The roots experience cell proliferation due to increased auxin or growth hormone production.

9. Gall formation occurs and restrict the xylem tissue inhibiting efficient water uptake by the plant. Galls appear like clubs or spindles on the roots. The roots will rot and the plant will die.

10. CLUBROOT OF CABBAGE ©www.alamy.com ©blog-yard-garden.com

11. SYSTEMIC POSITION Domain : Eukarya Kingdom : Protozoa Phylum : Cercozoa Class : Phytomyxea Order : Plasmodiophorales Family : Plasmodiophoraceae Genus : Plasmodiophora Species : P. brassicae

12. DISEASE CYCLE OF P lasmodiophora brassicae In the spring, resting spores in the soil germinate and produce zoospores and then these spores swim and enter host plants through wounds or root hairs. The plasmodium eventually divides and forms secondary zoospores that are once again released into the soil.

13. The secondary infection by the zoospores can infect the first host or surrounding hosts. The secondary zoospores form a secondary plasmodium that affects plant hormones to cause swelling in root cells. These cells turn into galls or “ club “.

14. The secondary plasmodium forms the overwintering resting spores which get released into the soil as the “ club “ rot and disintegrate. These resting spores can live in soil for upto 20 years while they wait for a root tip to come in close proximity for them to infect.

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16. PATHOGEN Obligate parasite. Plasmodium shaped body. Can survive in soil as resting spores for many years. Produce primary and secondary zoospores. Zoospores are biflagellate.

17. ZOOSPORES ©www.apsnet.org

18. MODE OF SPREAD Primary : Resting spores Secondary : Zoospores

19. FAVOURABLE CONDITION It prefers warmer temperature and moist conditions. Soil temperature between 20 - 24°C. p H less than 6.5.

20. INTEGRATED DISEASE MANAGEMENT Seedlings can carry the pathogen so the use of disease free seedlings is therefore very important. Remove the affected roots to reduce the pathogen population in the soil. Practice long term crop rotation with potato, tomato, bean and leeks.

21. Incorporate lime into the field at the rate of 2.5t/ha two weeks before transplanting . Seed treatment with Captan or Thiram 4g/Kg, followed by T. viride 4g/Kg. Soil drenching with Copper oxychloride 0.25%.

22. REFERENCES R.S.Singh , Diseases of Vegetable Crops, Published by Scientific International Pvt. Ltd. www.aspnet.org