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United States Department of Agriculture

Agricultural Research Service

Title: Thrips management program for plants for planting)

item Bethke, Jim
item Chamberlin, Joe
item Dobbs, Jeff
item Faver, Narka
item Heinz, Kevin
item Lindquist, Richard
item Ludwig, Scott
item Mckenzie, Cindy
item Murphy, Graeme
item Oettig, Ron
item Osborne, Lance
item Palmer, Cristi
item Parrella, Mike
item Rechcigl, Nancy
item Yates, Rick

Submitted to: Electronic Publication
Publication Type: Other
Publication Acceptance Date: 3/8/2010
Publication Date: 3/8/2010
Citation: Bethke, J., Chamberlin, J., Dobbs, J., Faver, N., Heinz, K., Lindquist, R., Ludwig, S., McKenzie, C.L., Murphy, G., Oettig, R., Osborne, L., Palmer, C., Parrella, M., Rechcigl, N., Yates, R. 2010. Thrips management program for plants for planting. 2p. Available:

Interpretive Summary: This document presents a program to manage thrips including but not limited to Western Flower Thrips (Frankliniella occidentalis) and Chilli Thrips (Scirtothrips dorsalis) on plants. This program does not require a pesticide application when the first thrips is detected. However, it does outline steps to manage and maintain thrips populations throughout the initial propagation and active growth stages at levels to enable complete control on final plant material being shipped. Growers should apply pesticides when scouting reports identify population densities at levels where experience and/or extension personnel dictate action be taken. These densities would depend on many factors including the crop, source(s) of infestation, history of viral infection, and environmental conditions.

Technical Abstract: Thrips Management includes sanitation, exclusion, chemical control and biological control. Sanitation. Remove weeds, old plant debris, and growing medium from within and around the greenhouse. Eliminate old stock plants as these are a source of thrips and viruses. Removing old flowers may reduce the number of WFT adults and eggs. Place flowers into a sealed bag or container and dispose. Exclusion. Screen greenhouse openings such as vents and sidewalls with the appropriate screen size (<0.88 mm) to exclude adult thrips from entering the greenhouse. Airflow may be obstructed with the use of screening containing small pore sizes and as a result the screened surface area must be increased to compensate for this. Check with your extension specialist about proper screen sizing. Chemical Control. No insecticide will provide complete control of thrips. It is important to detect and start management strategies before thrips populations have a chance to increase to moderate or high levels. Re-application intervals are determined in accordance with label requirements. Use the shortest labeled interval when pest pressure is high and temperatures are warm. Insecticides should be rotated by changing modes of action with each treatment or at most with each generation of thrips unless the label indicates otherwise. Modes of action are included on the table found on pg.2. Biological Control. Several biological control agents (BCA) are available for managing thrips, including predators (i.e. Neoseiulus or Amblyseius spp., Orius spp. and Hypoaspis mites), nematodes (Steinernema feltiae) and entomopathogenic fungi (i.e. Beauveria bassiana). The key to using biological control against WFT is to release natural enemies early. Releases must be initiated before thrips enter terminal or flower buds. Biological control agents will not control a large existing thrips population.

Last Modified: 05/27/2017
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