Disease Control in Crops

Plants are affected by fungi, bacteria, viruses and nematodes which cause a range of diseases in plants. Certain abiotic factors such as temperature, nutrition, moisture and toxicity also results in stunted growth, low productivity and death in crops. Globally, about 10-16% crop yield is lost to plant diseases which cost about US$220 billion. Demand for innovative methods of disease management is increasing due to increase in awareness for organic food, non-specificity of chemicals, environmental and health risks of the chemicals, along with the increasing fungicide resistance in pathogens. Management of plant diseases relies on a number of general strategies as fungicide spray, cultivating pathogen resistant varieties, adopting crop rotation and reduction of plant stress. Fungicides are majorly used for the management of plant diseases, which is leading to the increased incidence of fungicide resistance in pathogens. Novel biocontrol methods are being utilized for the control of plant pathogens. Non pathogenic strains of some bacterial species such as F. oxysporum and F. solani collected from a Fusarium wilt-suppressive soil have been demonstrated to be used for crop disesae management. Extracts from natural sources have reportedly been effective in vitro against Erwinia carotovorum subsp. Carotovorum, Ralstonia solanacearum, and Xanthomonas gardneri. Attenuated strain of green mottle mosaic virus (CGMMV) VIROG-43M strain has effectively been used as biocontrol agent for the protection of cucumber plant in greenhouses and laboratory conditions and in commercial greenhouses. Serratia plymuthica HRO-C48 and Gliocladium catenulatum J1446 have been reportedly used effectively as microbial antagonists against Blackleg disease caused by Phoma lingam. False smut (Ustilaginoidea virens) and kernel smut (Neovossia horrida) susceptible rice cultivars showed significantly reduced disease severity when rice was cultivated in 3-year rotation of soyabean and corn. Certain studies have observed that management practices such as management of straw treatments, tilling, and crop rotation of irrigated cropping systems such as wheat (Triticum aestivum) influences the severity of Rhizoctonia solani AG-8, Fusarium pseudograminearum and F. culmorum. In addition, RNAi is a potential molecular strategy for generating pathogen resistant plants by enabling them to combat fungal, bacterial, viral and nematod diseases. The strategy has been demonstrated to be successful in targeting various pathogenic fungi, bacteria and viruses with a possibility of potential for management of plant parasitic nematodes. The use of novel methods of plant disease management and control is expected to reduce the food safety and security concerns along with augumentation in improvement in crop yields.