Effects of Soil Edaphic Components on Incidence of Tomato Collar Rot Disease Caused by Sclerotium rolfsii (Sacc.)

The collar rot caused by Sclerotium rolfsii is most destructive soil borne disease of tomato. The soil edaphic components i.e., available soil Nitrogen (N), Phosphorous (P), Potassium (K), soil organic carbon, soil pH, soil moisture, soil texture and resting structures of plant pathogens etc. were reported to influence the disease incidence. Hence to know the relation between these components to disease development, experiments were carried out at Department of Plant Protection, Palli-Siksha Bhavana, Visva-Bharati during 2014-15. Soil samples were collected from tomato growing areas of red and lateritic zone of West Bengal and thereafter different soil edaphic components viz. available soil Nitrogen, Phosphorus, Potassium, organic carbon, soil pH, number of sclerotia of S. rolfsii was determined following the standard techniques. The disease incidence was also recorded during soil sample collection. Appropriate statistical tool was employed for correlation and regression analysis. Also to know the effect of soil texture, soil pH and soil moisture on the development of disease pot experiments were conducted during 2014-15. The soil analysis revealed that the available quantity of different soil edaphic components i.e., Nitrogen (N), Phosphorous (P), Potassium (K), Organic carbon (OC), soil pH and No. of Sclerotia / gm of soil were ranged from 185.0 -488.0 kg/ha, 17.0-63 kg/ ha,122.0-446.0 kg/ ha, 0.33-0.98%, 5.1-6.6 and 0.2-1.2 respectively and disease incidence was ranged from 7.36% to 21.06% in red and lateritic zone of West Bengal. Disease incidence showed significantly positive correlation with available soil Nitrogen, Organic carbon, Soil pH and Sclerotia population of soil but negatively correlated with available soil Potassium (K) and Phosphorous (P). Sandy clay loam soil, 6.5-7.0 pH level, and 15% moisture level of soil found highly favorable for collar rot disease.