HATCH AND EMERGENCE OF HETERODERA-GLYCINES IN ROOT LEACHATE FROM RESISTANT AND SUSCEPTIBLE SOYBEAN CULTIVARS

Egg hatch and emergence of second-stage juveniles (J2) of Heterodera, a glycines races 3 and 4 from cysts exposed to soybean root leachate o f cv. Fayette (resistant to H. glycines) and H. glycines-susceptible c ultivars A2575, A3127, and Williams 82 were determined in three sets o f experiments. In the first experiment, cysts of both race 3 and race 4 were exposed to leachate of 8-week-old plants for a 2-week period. I n the second experiment, cysts from populations of races 3 and 4 were raised on cultivars A2575, A3127, and Williams 82. Cysts then were exp osed to leachate from 8-week-old plants for a 2-week period in all pos sible race-per-cultivar combinations. In the third experiment, cysts o f races 3 and 4 were exposed at 4-day intervals to leachate from plant s as the plants developed eloped 7 to 59 days after planting. In exper iments 1 and 2, leachate from 8-week-old Williams 82 and A3127 stimula ted more hatch and emergence of H. glycines than leachate from A2575, Fayette, or the control. In the first experiment, cumulative hatch and emergence were greater for race 3 than for race 4. In experiment 2, n o apparent relationship developed between leachate from a cultivar and the population developed on that cultivar in terms of stimulation of hatch and emergence. In the third experiment, A2575 stimulated more ha tch and emergence of both race 3 and race 4 than A3127, Fayette, and W illiams 82. Leachate fi om Fayette stimulated less hatch and emergence of both race 3 and race 4. Hatch and emergence were greatest during t he initial 12 days of the experiment.