Biology, Yield Loss and Integrated Management of Root-Knot Nematode, Meloidogyne hapla infecting Carrot in Nilgiris

Carrot is a major vegetable crop cultivated in Nilgiris. It is highly susceptible to the attack by the root-knot nematode (Meloidogyne hapla), and severe yield reductions occur each year as a result of nematode infection. In view of the increasing importance of root-knot nematodes in carrot-based cropping systems in the changing agricultural scenario, investigations were carried out to study the biology and yield loss in carrot due to M. hapla and develop an integrated management technology with biocontrol agents viz, Pseudomonas fluorescens and Paecilomyces lilacinus in combination with a lower dose of chemical nematicide, carbofuran 3G. The life cycle of the M. hapla from egg to egg stage was 26 days under glass house conditions at a temperature ranging between a maximum of 22±1⁰C and a minimum of 15±1⁰C. Symptoms of root-knot nematode damage were severe galling, large proliferation of secondary roots, tap root malformation, forked and stubby carrots resulting in poor quality. The avoidable yield loss in carrot due to M. hapla was 35.95 per cent. Combined application of P. fluorescens @ 1 kg/ha along with P. lilacinus @ 2.5 kg/ha and carbofuran 3G @ 0.25 kg a.i./ha at the time of sowing enhanced the yield of carrot to the tune of 43.58 per cent compared to untreated control and reduced the soil nematode population by 66.19 per cent.