Plant disease management: Prospects of pesticides of plant origin

Abstract

The indiscriminate use of chemical fungicides led to pesticide residues in food products, risk of development of new pathotypes and pollution of soil and water ecosystem. This resulted in several ill effects on human beings, flora and fauna. To overcome the ill effects of chemical pesticides, attention had been paid to explore into products of higher plants for developing novel biopesticides in plant disease management. Our ancestors had been using these botanicals for the management of plant diseases, before the era of conventional fungicides. But the popularity of pesticides of plant origin has again been increasing due to its potential fungicidal action against several plant pathogens without any deleterious effect to the crop plants as well as environment. Several plants have been identified for antimicrobial properties which can suppress the growth and multiplication of plant pathogens, reduction in storage decay and spoilage of food products. The potential plant origin pesticides, viz. neem (Azadirachta indica), garlic bulb (Allium sativum), eucalyptus (Eucalyptus globulus), turmeric (Curcuma longa), tobacco (Nicotiana tabacum), ginger (Zingiber officinale), etc., have been successfully used for the management of several plant diseases. Moreover, seed treatment∈+∈foliar spray of freshly prepared garlic bulb extract has resulted into the reduction of Alternaria blight (35.6 %), white rust (50.4 %), powdery mildew (67.7 %) and Sclerotinia rot (80.3 %) in mustard with 27.3 % increase in yield over untreated control. These pesticides can suitably fit in any integrated pest management framework as well as in organic farming system which is a necessity in the current situation. Keeping in view the ever-increasing demand for safe food, pesticides of plant origin have a pivotal role to play in the management of plant diseases in comparison to the conventional chemical pesticides. These pesticides are not only useful to the developing countries due to their easy availability, being relatively cheap, easy sustenance in any crop protection programme and having direct relevance to the developed countries for healthy and quality produce of foodstuffs.