Root disease management in organic agriculture

Abstract

Conventional farming practices with time have led to decline in soil structure, fertility and microbial diversity and simultaneously given rise to many soil and root borne diseases. Root diseases are more damaging when soil conditions are poor as a result of inadequate drainage, poor soil structure, low organic matter and low soil fertility. In organic farming systems, famers practice many cultural measures like cultivar choice, promotion of soil health by organic amendments, low tillage and natural habitat diversification. Pathogen suppression under organic farming depend upon quality of residues, stage of their decomposition, microbial activity, microbial population dynamics, nutrient concentrations and other associated chemical and physical factors. Organic amendments coupled with no pesticide use enhance both microbial diversity and biochemical activities in soil which decrease disease inoculam through competition and antibiosis mechanisms and increases defense mechanism by antioxidant production. In organic systems plant roots get better colonized by mycorrhizal fungi which protect them from root invading pathogens. Organic farmers also use biological control agents and natural toxic compounds of plant extracts; however, these are methods of last resort.