Plant Nutrition in the Management of Plant Diseases with Particular Reference to Wheat

Abstract

Plant diseases are major limiting factors in agricultural production. The control of plant diseases using pesticides although quite easy and effective is being objected due to the rising concerns for food safety, environmental quality, and development of pesticide resistance in pathogens, pressing for alternative pest management practises. The plant nutrients may be important factors in changing the levels of disease tolerance or resistance in plants. However, the effect of nutrients on plant diseases and the many factors that influence this response is not properly studied. This chapter summarizes the information related to the effect of nutrients, N, K, P, S, Mn, Mg, B, Zn, Cl, Fe, Cu, and Si, on host resistance and management of plant diseases with particular reference to wheat diseases. In most of the cases of obligate plant pathogens, high N level increases the severity of the infection. In the case of facultative pathogens, higher rates of N application decreases the incidence of diseases. Potash (K) in most cases is helpful in enhancing plant resistance to pathogens. The effect of P in plant resistance to diseases, however, appears to be inconsistent. Among the micronutrients, Mn application is helpful in disease management since it plays an important role in lignin and phenol biosynthesis to limit the spread of pathogens and also in the photosynthesis of plants. Boron reduces the severity of many diseases and plays a role in cell wall structure, plant membranes, and plant metabolism. Chlorine also enhances the resistance level in host plants to diseases. Silicon helps in the control of diseases in rice. Zinc may have negative, positive, or no effect in the management of diseases. The nutrients may have synergetic effect but in some cases may affect the effect of one nutrient in reducing the severity of diseases. The incidence of diseases of wheat like leaf blotch, powdery mildew root rot, tan spots, bunt, take-all, smuts, and stem, leaf, and stripe rusts is decreased by the application of K. Nutrients may, therefore, become an important part of integrated disease management in wheat and other crop plants.