Investigation of rice root-knot nematode and weeds interactions in rice agro ecosystem.
Interactions between root knot nematode Meloidogyne graminnicola and weeds of rice agro ecosystem in Karnataka were investigated. Studies were conducted to examine the preference and performance of root knot nematode on 15 weeds commonly found in rice agro ecosystem. The extensive surveys were conducted during 2013 in rice growing fields in Shivamogga, Chickmagalore and Davanagere districts indicated that the 15 weeds belongs to different genera and different families both monocotyledons and dicotyledons severely infested which are all annuals. All the weeds had distinct root galling and egg masses, however their numbers and size and pattern may be quite different among the 15 weeds. The weeds of poaceae are classified as good hosts whereas other weeds are poor hosts. These observations suggests that these 15 weeds are alternate host for rice root knot nematode populations and provide a means of survival for the different stages of nematodes and help the nematode to multiply and increase the nematode population in the rice growing areas in the Karnataka or throughout India.