Integrating plant essential oils and kaolin for the sustainable management of thrips and tomato spotted wilt on tomato

Integrating plant essential oils and kaolin for the sustainable management of thrips and tomato spotted wilt on tomato

Summary

The purpose of this project is to develop environmentally compatible approaches for management of thrips and tomato spotted wilt of tomatoes. Laboratory studies, complementing the final field trials, were conducted to determine mechanisms by which kaolin and essential oil effects reduce tomato spotted wilt in tomatoes. Kaolin had more pronounced effects on thrips behavior than essential oils. Kaolin reduced thrips feeding by 80%, and thrips were repelled by kaolin. Although no-choice trials showed kaolin and essential oils did not reduce virus transmission, field trials again showed that kaolin and essential oil treatments reduced disease incidence.

Objectives/Performance Targets

1. 1. Compare efficacy of the plant essential oils geraniol, lemongrass oil and tea tree oil, and kaolin to standard insecticides in controlling thrips and tomato spotted wilt in tomatoes.

   2. Optimize use of kaolin and essential oils by determining how they affect thrips and their ability to transmit Tomato spotted wilt virus.

   3. Refine use of plant essential oils and kaolin in the field based on mechanisms determined in laboratory studies of Objective 2.

   4. To determine, through Cost Benefit Analysis of each field trial, the management strategies that yields the greatest financial return to the grower.

   5. Demonstrate and disseminate findings to growers, commodity groups, IPM providers, and the agrochemical industry as a means to generate greater interest in developing plant essential oils as commercial products and provide baseline data on the efficacy of plant essential oils and kaolin to control thrips and tomato spotted wilt.

Accomplishments/Milestones

Objective 2. Optimize use of kaolin and essential oils by determining how they affect thrips and their ability to transmit Tomato spotted wilt virus.
In laboratory assays, we have determined that kaolin, by itself and in combination with lemongrass oil, tea tree oil or geraniol, leads to significant reductions in feeding by western flower thrips. Reductions in feeding ranged from 74 – 87% compared with control plants. Time after application (4 – 24 hours) did not affect this reduction in feeding, showing that there is a significant residual effect of the materials. Reductions in feeding are related to the amount of kaolin coverage on plant surfaces. Further research is being conducted on methods to improve spray coverage. Additional laboratory trials are being conducted to determine if virus transmission is reduced along with the actual amount of thrips feeding.

Objective 5. Demonstrate and disseminate findings to growers, commodity groups, IPM providers, and the agrochemical industry as a means to generate greater interest in developing plant essential oils as commercial products and provide baseline data on the efficacy of plant essential oils and kaolin to control thrips and tomato spotted wilt.
We presented this research at several general public and scientific meetings. Two notable events were the Gadsden County Tomato Forum, where several growers expressed an interest in kaolin and essential oils for tomato spotted wilt management, and the National Allium Research Conference, where several growers also expressed an interest in using kaolin for thrips management in onion after seeing the results of a trial where we demonstrated that kaolin reduced thrips feeding on onion and the incidence of purple blotch disease, which is exacerbated by thrips feeding. Thrips also vector Iris yellow spot virus, which has emerged as a major pest of onions throughout the US.

• Stuart Reitz demonstrating essential oil and kaolin research at North Florida Horticulture Field Day
• Kaolin on the body of a western flower thrips after spray treatment
• Arenas used in lab tests of kaolin and essential oil effects on thrips feeding and virus transmission
• Technician Chase Petrik setting up laboratory experiment testing the effects of kaolin and essential oils on thrips behavior

Impacts and Contributions/Outcomes

Lemon grass oil and tea tree oil applied in combination with kaolin provided as effective control as standard insecticides for managing thrips-vectored tomato spotted wilt virus. By demonstrating the repellent and anti-feedant properties of kaolin and essential oils, the laboratory research provides a mechanistic explanation for the patterns observed in the field. We believe this information will help foster adoption of these practices by growers. These management tactics were used in a demonstration field trial on an organic tomato farm this season. Although the data have not been completely analyzed at this time, one notable additional benefit was less fruit loss to sunburn damage with kaolin treatments.

• Tomato plants after kaolin application

Collaborators: