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Foliar Insecticides for Control of Insect Pests on Apples A.B. Smith, N.B. Shamiyeh, and J. Cranmer Interpretive Summary Trees treated with Danitol had similar numbers of aphids as trees treated with Guthion. No phytotoxic effects were present in any of the treatments. Introduction Apples have been an important crop for a number of years. With the introduction of more and better dwarf and semi-dwarf varieties the popularity of apples in both small and large production continues to grow. Several insect species can be harmful to both the apple tree and the fruit. Many of the traditional chemical treatments have been lost in recent years. For this reason an experiment was conducted at the Plateau Experiment Station at Crossville in 2003 to test the efficacy of some insecticide treatments. Materials and Methods A plot was measured out in an established orchard of semi-dwarf ‘Golden Delicious’ trees. Row spacing is 20 ft with 20 ft between trees. Plots were a single tree, with trees of similar size being used for all treatments. Disease control was Dithate at 4.8 lb ai/A during bloom, with Captan at 2.93 lb ai/A and benomyl methyl (Benlate) at 0.19 lb ai/A on a ten day interval beginning after petal fall. Test materials were applied using a Solo motorized backpack sprayer calibrated to spray 40 gal/A. Test treatments were sprayed on July 21, Aug 1, and Aug 13. Evaluations were made once a week for insect infestations. Experimental design was randomized complete block with four replications. All data were analyzed by analysis of variance method, and means were separated by Duncan’s multiple range at the 0.05 level of probability. Results and Discussion Aphids were the only insect to appear in significant numbers on apple trees during the 2003 season. No significant mite populations were detected in the orchards including the control trees. Trees treated with Danitol at 0.300 lb ai/A were among those with fewer colonies of aphids, and had significantly fewer colonies than the untreated trees on the July 29 and August 2 evaluations (Tables 1 and 2). No significant differences were found between the number of colonies found on August 14 (Table 3). The reason for this is unknown, but could be a hard rain that took place a few days earlier. No phytotoxic effects were apparent for any of the treatments. Table 1. Treatments used, number of aphid colonies present, and phytotoxic effects of treatments evaluated on apple trees July 29, 2003 at the Plateau Experiment Station.
Table 2. Treatments used, number of aphid colonies present, and phytotoxic effects of treatments evaluated on apple trees Aug 2, 2003 at the Plateau Experiment Station.
Table 3. Treatments used, number of aphid colonies present, and phytotoxic effects of treatments evaluated on apple trees Aug 14, 2003 at the Plateau Experiment Station.
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