Developing Effective Control Measures

for Thrips

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The Problem:Thrips are one of the most difficult insects for flower growers to control. For wholesale and retail florists, the damage from thrips renders flowers unmarketable.

Background:Research on control of thrips has been ongoing for many years, based primarily on the use of pesticides. Thrips are so small that the untrained eye rarely sees the insect, but the damage is apparent on infested flowers. Proper rotation of insecticides is critical to successful control.

Thrips are known to develop resistance to insecticides very rapidly. Over the last 30+ years, thripscontrol measures have been successful, to some extent, due to the introduction of new classes of insecticides and research showing the proper rotation of pesticides and cultural practices affecting thrips.

The industry is seeing fewer and fewer new insecticide classes introduced to the market, so thrips seem to be developing a greater resistance to existing insecticides.In the past, there have been researchers focusing on pesticide control and others concentrating on biological control measures. In most cases, research has not looked at how best to use insecticides in unison so that specific recommendations could be developed for the industry.Thrips control is very difficult!

Current Research:We have heard from all segments that thrips are the most damaging insect problem faced by the industry. Progress has been made through the following research projects AFE is currently funding:

  1. A Novel Approach to Fungal-based Thrips Management with Marigold Guardian Plants(Lead researcher:Dr. Margaret Skinner, University of Vermont. Other researchers: Bruce L. Parker, Svetlana Gouli)
  2. Objective: Evaluating the persistence of Beauveriabassiana, an insect-killing fungus, that when combined with a solid nutritional substrate (millet) in the potting mix will provide control of western flower thrips for longer periods.
  3. Successful IPM of Western Flower Thrips Starts with Clean Cuttings(Lead researcher: Dr. Rose Buitenhuis, Vineland Research and Innovation Centre. Other researchers: Dr. David Smitley, Michigan State University)
  4. Objective: Investigating the use of cutting dips containing reduced-risk materials (insecticidal soap, mineral oil) and biopesticides (Beauveriabassiana) as a means of reducing thrips infestations on propagative materials to levels where they can be easily managed thereafter using biocontrol.

Future Research:New, innovative approaches to thrips control are needed that combine clean and sanitary conditions at the time of planting, judicious use of insecticides combined with effective biological controls.In addition, cultural practices including nutrition practices and use of selected light quality modifications may be effective approaches for thrips control.

The following projects will be pursued to reduce and control thrips during flower production:

  1. Use of UV resistance to minimize thrips infestation.
  2. Evaluate reflective ground coverings.
  3. Develop an integrated and comprehensive program combining biological and pesticide control practices.
  4. Evaluate the integration of plant-based pest repellents and natural enemy attractants into control practices for thrips.
  5. Investigate whether sterile thrips can be used to reduce the population of thrips in flower production.
  6. Develop a model of migration patterns of thrips from outdoor vegetable farms and natural habitats and relate the migration to weather patterns and flower developmental stages. Determine if this information can be used to provide the industry with preventive programs and thripsalert systems.
  7. Identify practical methods for growers to avoid migrating adult thrips from getting into production areas other than screening (traps, barriers, pheromones, banker plants, etc.).

Industry Education: As new research results demonstrate effective ways to control thrips, AFE will publish trade magazine articles and encourage industry educational programs to include research supported by AFE.

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American Floral Endowment

endowment.org

Email:

1001 N. Fairfax St., Ste. 201, Alexandria, VA 22314 | 703-838-5211 | Fax: 703-838-5212