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.