EFFECTS OF 1,3-DICHLOROPROPENE FOR MELOIDOGYNE-INCOGNITA MANAGEMENT ON COTTON PRODUCED UNDER FURROW IRRIGATION

Field trials were conducted during 1990 to evaluate the effects of pre plant soil fumigation with 1,3-dichloropropene (1,3-D) on yield and fi ber quality of furrow-irrigated cotton cultivars subjected to high pop ulation densities of Meloidogyne incognita. We measured the responses of eight upland cotton cultivars with different levels of root-knot ne matode resistance and compared the responses of upland and Pima cotton s. Reductions in lint weight ranged from 10 to 52% among cultivars gro wn in soil without 1,3-D fumigation compared with those grown in treat ed soil. Meloidogyne incognita reduced yields primarily by reducing th e number of bells on each plant, rather than by decreasing boil size. Cotton fiber quality varied among cultivars but was unaffected by M. i ncognita in either study. Upland cotton cultivar Acala 1517-88 and M-3 15/240 sustained less than half the yield reductions observed with M. incognita-susceptible cultivars Deltapine 41 and Paymaster 145. Sixty days after cotton emergence, fewer M. incognita second-stage juveniles were recovered from M-315/240 than all other cultivars.