Efficacy of insecticides for season-long control of thrips (Thysanoptera: Thripidae) in winter strawberries in Florida.

Authors: RENKEMA, JUSTIN - Agriculture And Agri-Food Canada; Krey, Karol; DEVKOTA, SHASHAN - University Of Florida; LIBURD, OSCAR - University Of Florida; FUNDERBURK, JOE - University Of Florida

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary: Flower thrips can be significant pests of strawberry, and recently in Florida, chilli thrips has become an established, early-season, foliar pest. Insecticides that were used for flower thrips management are now also used for chilli thrips, resulting in the need to evaluate newer insecticides. A researcher at USDA-ARS Wapato in Washington, in collaboration with scientists from University of Florida, have determined that most rotations reduced thrips populations and the number of strawberries injured by thrips feeding. They found that the need to evaluate newer insecticides in order to diversify rotations and mitigate overuse of insecticides with the same mode-of-action is important in spray decisions. This adds information on the importance of continued research for fine-tuning insecticide rotations, with a focus on testing against high chilli thrips populations in early-planted strawberries and on developing effective sampling methods to optimize timing in order to reduce the number of applications.

Technical Abstract: Florida, Scirtothrips dorsalis Hood has become an established, early-season, foliar pest. Insecticides that were used for flower thrips management are now also used for S. dorsalis, resulting in the need to evaluate newer insecticides in order to diversify rotations and mitigate overuse of insecticides with the same mode-of-action. We evaluated 10 and 12 season-long rotations in field plots in central Florida during the 2016-2017 and 2017-2018 winter strawberry seasons, respectively. We found that most rotations reduced thrips populations and the number of strawberries injured by thrips feeding. An early season application of chlorantraniliprole + thiamethoxam, used for other strawberry pests, reduced S. dorsalis populations and strawberry injury, although S. dorsalis populations were relatively low in both years. Cyantraniliprole was nearly as effective as spinetoram against Frankliniella spp., while tolfenpyrad and sulfoxaflor did not perform as well. Flupyradifurone was as effective as acetamiprid when used as a follow-up application to spinetoram or cyantraniliprole. Rotations including or entirely composed of OMRI-listed insecticides for organic production were not as effective as conventional insecticide rotations, with only spinosad, and to a lesser extent, Burkholderia spp., providing acceptable thrips control. In conclusion, spinetoram, acetamiprid and spinosad were confirmed to be effective against thrips and can be used as the backbone of rotation programs in conventional and organic strawberry production systems. Diamide insecticides were effective alone and in rotation, while flupyradifurone and flonicamid may be used when follow-up applications are needed. Continued research is critical for fine-tuning insecticide rotations, with a focus on testing against high S. dorsalis populations in early-planted strawberries and on developing effective sampling methods to optimize timing in order to reduce the number of applications.