Efficacy of Flupyradifurone, Pyriproxyfen and Horticultural Oil, and Dinotefuran Against Gloomy Scale (Melanaspis tenebricosa Comstock)

Abstract

Gloomy scale (GS)(Melanaspis tenebricosa) is a major pest of red maple (Acer rubrum) across much of the eastern USA. Current pesticide recommendations for GS management are efficacious when applications are made at the appropriate time. However, appropriate timing may not always be possible. For instance, the tree owner may not contact pest management professionals in time to make timely applications. We established a field trial to determine the efficacy of the pesticides pyriproxyfen plus horticultural oil and dinotefuran, as well as a relatively new pesticide available in the ornamental woody plant market, flupyradifurone, against GS. There were three primary goals of this study: (1) to quantitatively compare the effectiveness of pyriproxyfen plus horticultural oil and dinotefuran; (2) to compare flupyradifurone with these two generally recommended treatments; and (3) to assess whether flupyradifurone is effective when applications are made later in the summer. We found that pyriproxyfen plus horticultural oil, dinotefuran, and flupyradifurone applications made during the active crawler period were equally efficacious, statistically, and that flupyradifurone treatments applied later in the summer were not statistically differentiable from untreated controls. While these pesticide applications are effective at suppressing GS populations, plant health care tactics aimed at preventing outbreaks should be prioritized and incorporated into the complete pest management strategy.