Department of Plant Pathology, Punjab Agricultural University, Ludhiana-141004
National Symposium on “Plant Pathology in the Changing Global Scenario” held at National Bureau of Plant Genetic Resources, New Delhi on February 27–28, 2009
Root knot nematode is an important pathogen of vegetable crops like tomato, brinjal and cucurbits causing yield losses. Limitation of availability of nematicides enforces us to look for other management options for sustaining yields. Various cultural practices are being used/tested of which green manuring is one practice which not only adds nutrient contents to soil but roots of certain plants when incorporated into soil and their decomposition helps in reduction of root knot nematode. Therefore, studies were conducted on the effect of green manuring with nonconventional crops like sorghum and guara in sick field for their effect on root knot nematode. Two varieties of sorghum viz., SGL-87 and SL-44 and one variety of guara ((Guara 80) were sown in 7x4 sq m plots for two years. One plot was kept as fallow which was later taken as control. Each treatment was replicated thrice in field. Guara and Sorghum varieties were incorporated into soil fifty days after sowing. Field was ploughed twice for proper incorporation of sorghum and guara and left as such for fifteen days. After fifteen days brinjal (susceptible to root knot nematode) was transplanted. Observations on root galling index were taken at mid –crop and at harvest. Tomato was the second successive susceptible crop to be transplanted after brinjal. Root galling index in tomato crop was also taken at mid –crop and at harvest. Observations reveal that green manuring in the sorghum and guara varieties reduced root knot infestation in brinjal. Maximum decrease in root galling index in brinjal at harvest was observed in plots green manured with sorghum variety SGL-87 (RGI=2.4 in first year and 2.2 in second year) as compared to control (RGI =3.9 and 4.0, respectively) thus resulting in 37% decrease in root knot infestation in first year and 45% decrease in second year. RGI in successive crop tomato was also decreased at harvest in SGL-87 green manured plots (RGI=2.8) as compared to control (RGI= 4.2) indicating the persistent effect of green manuring on second succeeding crop tomato also though the decrease in RGI of tomato was comparatively less than in brinjal.
