Apple, Phytotoxicity Test of Thuricide hpc and Hpsc, 1977

Early and late season applications of Thuricide HPC and HPSC were applied to four year old Golden Delicious apple trees in plots of 12 trees each for the evaluation of fruit russet injury. Materials were applied as 6X concentrates (467.69 litre/ha) with a Swanson truck mounted airblast sprayer operating at 7.04 kg/cm2. Thuricide HPC and HPSC were each applied at 39.54 and 14.83 BlU/ha (HPC 9.35 and 3.51 litre/ha; HPSC 2.49 and 0.93 kg/ha) on May 13 and 20. Thuricide HPC and HPSC were also applied at 39.54 BlU/ha September 2. A water control was applied on May 13 and 20. Dikar 80W (6.73 kg/ha) was included in all treatments. The following cover sprays were applied: Dikar 80W (6.73 kg/ha) June 7 and 27; Dikar 80W (2.52 kg/ha), Guthion 50W (0.84 kg/ha), and Plictran 50W (0.32 kg/ha) July 8; Dikar 80W (2.52 kg/ha) and Guthion 50W (0.84 kg/ha) August 1; and Dikar 80W (2.52 kg/ha) August 18. All but the June application of Dikar 80W were 6X concentrate sprays (233.84 litre/ha) applied with the same equipment as the Thuricide treatments, but to one side of the trees only. The June applications of Dikar 80W were dilute sprays applied to run-off to one side of the trees with a handgun and the Swanson airblast sprayer equipped with a high-pressure pump operating at 17.59 kg/cm2. Minimum temperatures of 0.6, -3.3, -2.2, and 0°C occurred May 9, 10, 11 and 12, respectively. No further freezing occurred after these dates.