Alternaria-Brassica Associations: Research progress and prospects

Alternaria is a ubiquitous fungal genus that comprises saprobic, endophytic, and pathogenic species. the Alternaria blight or black spot disease(however, the disease is known by more than 40 names on the basis of symptoms formed on different parts of cruciferous crops) is the main bottleneck in the global production of cultivated oilseed brassica crops. Four Alternaria species including A. alternata, A.brassicae, A. brassicicola and A. raphani have been recorded pathogenic to cruciferous crops. An abrupt epidemic breakout of plant disease can cause huge economic losses. to manage such circumstances, understanding plant disease triangle and disease epidemic forecasting is very important. Although, the genus Alternaria is known as an imperfect fungus, it shows genetic variability within a species and this variability might be due to the existence of mutation, somatic hybridization, hetero-karyoses, uniform host selection, extensive dispersal or of a cryptic sexual stage. some useful information is available on chemical control of various Alternaria diseases, however, much more is needed in order to develop a viable disease control strategy under field conditions. Efforts should also continue to search for low cost effective chemicals, which can provide economically significant disease control. Active ingredient of plant extracts should also be identified. Control of Alternaria diseases in rapeseed-mustard by microbial antagonists should also be explored. seed treatment with Trichoderma spp., Gliocladium spp., Penicillium spp., and Mycostop-like preparations of Streptomyces spp. should be further investigated to determine their level of control and economic feasibility under field conditions. Similarly, control by foliar applications of Streptomyces rochei, S. higroscopicus, S. arabicus and Nectria inventa should also be evaluated under field conditions. No single methods or approach can be effective and economical. therefore, all means of plant disease control including chemical, biological, cultural, host resistance and biotechnology tools for early detection of disease should be integrated to manage the disease at early stage of plant growth. Considering the role of insects like aphids (virus transmission) and flea beetles (transmission of A. brassicicola to cabbage) insecticides should be one of the components in integrated disease management package and practices. disease forecasting system should be strengthened using modern information technology to warn farmers in advance for timely action by adopting proper control strategy.