Apple, Evaluation of Bacillus Thuringiensis Products for Tabm, 1995

Abstract

Abstract Two rates of two Bacillus thuringiensis products were compared to the organophosphate Lorsban for control of TABM. The treatments were applied to single tree plots in a randomized complete block design consisting of 3 replicates of ‘Golden Delicious’ and 3 replicates of ‘Rome Beauty’. Treated plots were separated by others not sprayed with insecticides. The trees were 17 yr old and planted at a spacing of 24 X 35 ft. Sprays were applied with a handgun at 400 psi from a truck-mounted sprayer equipped with a Kohler 23 gpm pump. Approximately 5.5 gal of spray were applied per replicate tree (ca 300 gpa). The dates of application for the treatments were 9 and 23 Jun (1st brood control, 20-30% and 80-90% egg hatch [585-640 degree days (DD) and 910-965 DD, respectively, from first phenomena trap capture of TABM) and 11, 21 and 31 Aug (2nd brood control, 20-30%, 50-60% and 80-90% egg hatch [2355-2435 DD, 2585-2665 DD and 2815-2890 DD, respectively, from first trap capture of TABM). All plots received a regular fungicide maintenance schedule of Benlate 50DF, Dithane 75DF, Nova 40WP and Ziram 76WP. Also, an alternate row middle application of Swat 8EC was made for aphid control on 29 Jun and an alternate row middle application of Kelthane 50WP plus Carzol 92SP was made for mite suppression on 28 Jul. Effect of the test chemicals on the ERM/TSSM complex was evaluated by counting the mites several times during the season on samples of 25 random leaves/tree, 150 leaves/ treatment. Shelters of the various leafrollers were counted in a 5 min examination of each replicate on 18 Jul. All larvae were collected and returned to the laboratory for identification. On 20 Sep, ≈ 150 apples (75 top and 75 bottom) were randomly sampled for fruit injury from each ‘Golden Delicious’ tree. On 2 Oct the same number of apples and sampling scheme was used for each ‘Rome Beauty’ tree. Up to 25 dropped fruit per tree were also evaluated for fruit injury.