San Jose scale (SJS), Comstockaspisperniciosus(Comstock), is a phytophagous insect pest that damages peachtrees by directly feeding on plant tissues, causing leaf chlorosis, twig or limb die-back, and tree death if populations are large.Currently, management relies on two dormant applications of horticultural oils. These oils kill primarily through suffocation, and are onlyeffective if trees are thoroughly covered.As the technology of horticultural oils has improved, oils have become more refined, but it is still recommended for use at low concentrations when the tree is dormant to limit phytotoxic impacts on leaves and fruit.Unfortunately, we still experience severe SJS outbreaks and faceconsiderable losses in tree health and productivity. To improve SJS management in Southeastern peach production, we investigated within-seasonapplications of low concentrations of horticultural oil on the impact of San Jose scale and tree phytotoxicity. During 2019, we tested the application of low concentration rates of Omni Supreme oil at 0.5% and TriTekoil at 1.0% with water and applied bi-weekly between 28 May and 8 August 2019. The abundance of SJS immatures and leaf phytotoxicity were recorded and compared between the two treatments and an untreated control. The oil treatments significantly reduced the number of SJS collected compared to the untreated trees without causing concerning levels of phytotoxicity to the leaves. These results support the tentative recommendation applying a low concentration of horticultural oil throughout the season with standard cover sprays, may enhance management of SJS without supplementary insecticides.
