Two rates of Fulfill 50 WP, one tested with and without the addition of a wetting agent, Kinetic (0.094%, vol:vol), were evaluated for effectiveness and residual activity and compared with a standard, broad spectrum insecticide, Thiodan 3 EC. Cantaloupe was direct-seeded on 2 Apr at the Central Florida Research and Education Center, Leesburg, FL. Each plot consisted of four 35-ft rows, 6 ft apart with plants spaced 2.5 ft apart. Treatments were replicated four times in an RCB design. On 25 Apr, all plants in all plots were infested with melon aphids that had been reared on squash under row covers to prevent predation and parasitism. All chemicals were applied with a 2-row tractor-mounted boom sprayer with 18 Albuz (lilac) ceramic hollow cone nozzles, spaced 8 inches apart, delivering 133 gpa at 200 psi. Aphids were counted on 20 leaves of similar size per plot each week for 7 wk beginning on 13 May and ending on 24 Jun. Leaves were collected at least 5 DAT. Treatments were applied only when the grand mean of a treatment (the mean of the four replicate means) was equal to or greater than a treatment threshold of 5 aphids per leaf. Thus, all treatments were applied on 7 May, but on 21 May, only the higher rate of Fulfill was applied; on 28 May, only the lower rate without Kinetic; on 4 Jun, only the lower rate with Kinetic; and 18 Jun, only the higher rate. 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.

Infestation of plants with aphids resulted in uniformly high populations. Although the number of aphids on untreated plants declined dramatically by 27 May, there were still significantly higher numbers on these plants than on most of the treated plants until the last sampling date. All treatments, except the high rate of Fulfill, provided good control through 20 May. Residual activity was greatest for Thiodan which controlled melon aphid for the entire season after one application. The higher rate of Fulfill was less effective than the lower rate, and plants had to be treated a total of three times, the last time on 18 Jun when populations were three times higher than on the untreated plants. One possible explanation might be that natural enemies were adversely affected. The other two treatments were applied twice, with the number of aphids kept below the threshold value for one additional week when Kinetic was used.

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