THE INFLUENCE OF LEACHATES FROM ROOTS OF MORNINGGLORY (IPOMOEA LACUNOSA), HEMP SESBANIA (SESBANIA EXALTATA), AND JOHNSONGRASS (SORGHUM HALEPENSE) ON REPRODUCTION OF ROTYLENCHULUS RENIFORMIS WITH EMPHASIS ON THE ECLOSION AND HATCHING OF EGGS
Pontif, M. J. and E. C. McGawley. 2008. The influence of leachates from roots of Morningglory (Ipomoea lacunosa), Hemp Sesbania (Sesbania exaltata) and Johnsongrass (Sorghum halepense) on eclosion and hatching of eggs of Rotylenchulus reniformis. Nematropica 38: 23-35. In greenhouse experiments, leachates from roots of morningglory and johnsongrass, but not hemp sesbania, caused significant reductions in reproduction of Rotylenchulus reniformis on soybean. Laboratory experiments evaluated the influence of nonfiltered and 0.45 and 0.80-μm cellulose membrane filtrates of leachates from the roots of the three weeds on the development and hatch of eggs of R. reniformis. Embryonic development and hatch events were divided into four categories: 1-un-differentiated, granular eggs; 2-eggs at the 4 to 8 cell stage; 3-vermiform juveniles within the egg, and 4-hatched juveniles. One ml suspensions of eggs in leachates from each weed, along with appropriate controls, were placed into sterile 3-ml capacity wells. Eggs were enumerated and assigned to the appropriate developmental category over 10 days. Reductions in the development and hatch of eggs occurred with nonfiltered portions of leachates from all three weeds. Over four experiments, 91% of eggs in distilled water hatched by day 10. Significantly reduced hatch occurred with eggs incubated in leachates; averaging 59% for morningglory, 57% for hemp sesbania and 53% for johnson-grass. There were no differences in egg development and hatch in control and leachate samples that passed through a 0.45-um filter. Control and leachate samples that passed through a 0.80-μ m filter retained inhibitory activity similar to that observed for the nonfiltered portion.
