EVALUATION OF TWO SYSTEMIC INSECTICIDES FOR CONTROL OF MELON APHID AND SILVERLEAF WHITEFLY ON SQUASH, 1998

Abstract

EVALUATION OF TWO SYSTEMIC INSECTICIDES FOR CONTROL OF MELON APHID AND SILVERLEAF WHITEFLY ON SQUASH, 1998: Two rates of CGA-293343 and one rate of CGA-293343 in combination with weekly applications of CGA-245704 (a fungicide) were evaluated for efficacy against melon aphid and silverleaf whitefly and compared with a standard, Admire. Yellow crookneck squash, 'Dixie,' was direct-seeded on 16 Apr at the Central Florida Research and Education Center, Leesburg, FL. Soil type was Alachua fine sand. Each plot consisted of four 35-ft rows, 6 ft apart, with plants spaced 2.5 ft apart within the row. Treatments were replicated four times in an RCB design. Admire and CGA-293343 were applied as drenches (1 pt diluted formulation per hill) at planting. CGA-245704 was applied weekly as a foliar spray, beginning on 20 May and ending on 10 Jun, with a 2-row tractormounted boom sprayer with 14 Albuz (lilac) ceramic hollow cone nozzles delivering 110 gpa at 200 psi. Five nozzles were spaced 8 inches apart over each row, and 2 drop nozzles were positioned to spray the sides of each row. Rates are given in the tables. On 12 May, all plants in all plots were infested with melon aphids from a laboratory colony. Adult whiteflies from a laboratory colony were released in the plots at 2to 3-d intervals from 12 to 28 May. Adult whiteflies were counted by turning over the fourth leaf down from the terminal shoot of 20 plants per plot on 19 May and 2 Jun. Aphids and whitefly eggs and nymphs were counted on 20 leaves of similar size per plot on 19 and 26 May and on 2 and 9 Jun. Aphids were counted on whole leaves. Whitefly eggs and nymphs were counted on 3 leaf disks from half of each leaf (total area of 3 disks = 1.0 in2). A square root transformation was used to stabilize the variance of counts for analysis. A two-way ANOVA and a mean separation test (Waller-Duncan k-ratio test) were used to determine significant differences among treatments.