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Issue link: https://read.dmtmag.com/i/105677
Before You Spray "I would caution arborists to check the label of any pesticide they decide to use very carefully for federal and state application restrictions. Since this pest has a long period of activity and the authors recommend treatments every two to four weeks, the label restrictions I would be concerned about would be: the number of applications allowed per season, the amount of active ingredient that can be used per season, and retreatment intervals. Gloomy scale also attacks younger wood and can contribute to dieback in some instances. This requirement for complete coverage may not be feasible for a large tree. What about a soil drench, trunk-only spray, or granules of systemic insecticides for large trees? Results from our field studies suggest that systemic insecticides applied with an indirect method provide unsatisfactory control. Our field studies also show that horticultural oil or a combination of horticultural oil with an insect growth regulator (buprofezin or pyriproxyfen) suppresses the gloomy scale population. It is important to remember that there are two types of horticultural oil—dormant oil and horticultural or summer oil. Dormant oil is a heavy, less refined petroleum oil that should be applied in early spring before the buds begin to swell. On the other hand, horticultural or summer oil is a highly refined petroleum, paraffinic, or plant-derived oil that could be used when leaves are present, as long as the temperao o ture does not exceed 95 F (35 C) or below freezing at the time of application. Red maples are especially sensitive to horticultural oil; therefore, follow all labeled precautions. Horticultural oil has the added benefit of being "soft" on natural enemies due to its very short residual efficacy (typically 3 days). Other insecticides may have more days or even weeks of residue. So, any natural enemies residing on the red maples after the application of horticultural oil will not be killed by the insecticidal residue 34 Of course the target pest, host plant, and treatment site must also be listed on the label for the product to be used legally. Personal protective equipment (PPE) requirements for the applicator and reentry intervals for unprotected persons must also be followed. It is also important to remind arborists that the pesticide label is a legal document ("the label is the law") and all directions for use that are applicable to their particular situation must be followed exactly. This ensures that pest control is achieved effectively, that impact to the environment is reduced, and that any hazards to the applicator and the public are minimized." —Patrick Parker, Plant Health Care Program Director, SavATree and can get down to the business of munching on those pesky gloomy scales. Bob Polomski, Ph.D., School of Agricultural, Forestry, and Environmental Science, Clemson University Juang-Horng "JC" Chong, Ph.D., Clemson University Pee Dee Research and Education Center, Florence, SC George M. Dickert, Agriculture/Natural Resources Agent Clemson University Cooperative Extension Service Spartanburg County Sources Frank, S. D., W. E. Klingeman, N. A. Ward, S. A. White, and A. F. Fulcher. 2012. IPM for Select Deciduous Trees in Southeastern US Nursery Production. Chapter 10: Maples – Acer spp. (see www.clemson.edu/extension/ horticulture/nursery/ipm/book_files/chapter_10) Raupp, M. J., A. B. Cumming, and E. C. Raupp. 2006. "Street tree diversity in eastern North America and its potential for tree loss to exotic borers." Arboriculture and Urban Forestry 32: 297-304. City Trees