Responses of Meloidogyne arenaria and M. incognita to Green Manures and Supplemental Urea in Glasshouse Culture.

The recent loss of many effective nematicides has led to renewed interest in alternative methods of nematode management. Greenhouse experiments were conducted to determine the effects of rapeseed and velvetbean green manures, and supplemental urea, on the root-knot nematodes Meloidogyne arenaria and M. incognita. Green manures were incorporated with M. arenaria-infested soil using rates totaling 200,300, and 400 mg N/kg soil. Squash plants grown in this soil were evaluated using a gall index and plant dry weight. A second experiment tested ratios of rapeseed green manure to urea resulting in rates of 50, 100, and 150 mg N/kg soil on viability ofM. incognita eggs and degree of galling on squash test plants. A third experiment examined combinations of velvetbean green manure and urea resulting in rates of 100, 200, and 300 mg N/kg soil on viability of M. incognita eggs. When applied at rates of 200, 300, and 400 mg N/kg soil, rapeseed green manure was more effective than velvetbean green manure at reducing galling of squash roots caused by M. arenaria. Decreased viability of M. incognita eggs was observed from treatments that received rates >/= 1200 mg N/kg soil with higher percentages of N from urea.