White rust is considered as a significant extensively prevalent disease of cruciferous crops which cause huge economic losses due reducing yield worldwide. Albugo candidais the causal agent of this disease. It is reported that, this disease has caused major losses in many countries. For instance, in Canada, the % yield losses range from 1-60% in Turnip rape1, 23-89.8% in Indian mustard2 and 5-10% in Australia3 as well. Moreover, considerable yield losses are also reported in radish4.
This pathogen produces white or creamy pustules on cotyledons, true leaves as well as pods which ultimately decrease the photosynthetic activity leading towards low output and retard growth and development of plant. Moreover, it also deteriorates the quality of leaves making them inappropriate human consumption. Additionally, market value of the vegetable also gets reduced in this way.
Moreover, lesion produced on foliage causes wide distortion, hypertrophy, hyperplasia as well as sterility of inflorescences, this condition is usually known as “systemic infection”, which enhances fruit shattering and lessens the yield of mustard. Depending on the host area, many disease estimation keys have been developed for several diseases5. But, no sufficient literature is available in this regard.
Considering this situation, Khajan Singh6 and companion scientists conducted a research to generate a photographic disease assessment keys for White rust of Rapeseed-Mustard. To date, only diagrammatic or numerical assessment keys have been reported to screen Rapeseed-Mustard germplasm against White rust disease but none of them is available on the basis of their real photographs.
Khajan singh6 and team took the photographs of plant regarding disease severity on transparent graph paper. Afterwards, images of disease free cotyledons and leaf, less than 5, 5-10, 11-25, 26-50% and above 50% area covered by white rust pustules were examined for assessment key.
Scientists found that disease severity scoring keys are probably beneficial to estimate White rust and some other diseases of Rapeseed-Mustard including Alternaria blight caused by Alternaria brassicae and white leaf spot caused by Pseudocercosporella capsellae. Conclusively, this investigation can help to assess the level of disease and can assist farmers to control this by employing managing practices on time.
Key words: white rust, Albugo candida, pustules, hypertrophy, hyperplasia, systemic infection, fruit shattering, rapeseed-mustard germplasm
- Berkenkamp, B. and K. Degenhardt, 1972. Diseases of rapeseed in central and Northern Alberta in 1971. Can. Plant Dis. Surv., 52: 62-63.
- Bains, S.S. and J.S. Jhooty, 1979. Mixed infections by Albugo candida and Peronospora parasitica on Brassica juncea inflorescence and their control. Indian Phytopathol., 32: 268-271.
- Barbetti, M.J., 1981. Effects of sowing date and oospore seed contamination upon subsequent crop incidence of white rust (Albugo candida) in rapeseed. Aust. Plant Pathol., 10: 44-46.
- Kadow, K.J. and H.W. Anderson, 1940. A study of horseradish diseases and their control. Univ. Illinois Agric. Expt. Stn. Bull., 469: 531-543.
- James, W.C., 1971. An illustrated series of assessment keys for plant diseases, their preparation and usage. Can. Plant Dis. Surv., 51: 39-65.