EFFECT OF PLANTING DATE ON POPULATION-DENSITIES OF HOPLOLAIMUS-COLUMBUS AND YIELD OF SOYBEAN

During the 1991 and 1992 soybean growing seasons, field plots were est ablished in South Carolina to study the effect of planting date on at- planting nematode densities and subsequent yield losses caused by Hopl olamius columbus. The susceptible and intolerant soybean cv. Braxton w as planted on five dates from 10 May to 28 June in 1991 and from 12 Ma y to 28 June in 1992. Nematodes were recovered from soil samples colle cted before nematicide treatment with 1,3-D (Pi), at 6 weeks after pla nting (Pm), and at harvest (Pf). Initial nematode population densities did not differ among the five dates of planting in either year. The i ncrease in numbers of nematodes from planting to 6 weeks after plantin g (Pm/Pi) and fr om planting to harvest (Pf/Pi) were not different amo ng the five planting dates in either year. Root samples also were e co llected at 6 weeks after planting and at harvest, but planting date di d nor affect the number of nematodes extracted from roots on any sampl e date in either year. Altering planting dates between early May and l ate June was not effective in preventing yield suppression due to H. c olumbus.