Control of spider mites in eggplants and thrips in field sweet peppers using guardian plants and predators

Control of spider mites in eggplants and thrips in field sweet peppers using guardian plants and predators

Summary

IPM Laboratories, Inc. collaborated with one New York farmer, one Niagara County Cooperative Extension agent, and one Environmental consulting firm to evaluate marigolds as a Guardian Plant for thrips in sweet pepper fields and snapbeans as Guardian plants for eggplant fields. The 2012 season data has been collected and is now being analyzed. During the 2012 season, a twilight meeting on the Zittel farm was organized by Robert Hadad of the Cornell Cooperative Extension for grower Mark Zittel and Entomologist, Carol Glenister to explain the project to area growers. The project cooperators also shared the 2011results at a Western NY Vegetable Growers Meeting in Lockport in late February 2012 and the Mid-Atlantic Fruit and Vegetable Conference in Hershey in February.

Objectives/Performance Targets

In 2010, the Zittel farm in Eden, New York, experienced extremely high numbers of thrips and significant damage on pepper plants that had been transplanted from the greenhouse to the field despite 5 insecticide treatments. Beneficial insects are extremely successful at controlling thrips in greenhouse peppers because pepper flowers support continuous reproduction of the thrips predator, Orius insidiosus. In 2011, we tested marigold Guardian Plants for pulling thrips from pepper fields and supporting Orius reproduction until the peppers begin to flower and support Orius reproduction on their own. We repeated this experiment in 2012.

In 2012, Mark Zittel seeded marigolds in the greenhouse so that they would be flowering at the time the peppers were to be transplanted to the field during the last week of May (North Boston Road and Bley Road). In 2011, two spacings for the marigolds were used: singles and blocks. However, since single marigolds did not provide any benefits over blocks, in 2011 and the single marigolds were harder to plant and water, approximately 6 blocks of 24 marigolds were used in each of these two fields. A third field with peppers only was designated as the Control field. One thousand Orius were applied to the marigolds in the Bley field on June 21st.

Weekly scouting of the three fields of was conducted from May 24 until July 5. Thirty marigold beat samples in the two experimental fields were taken during each visit. Fifty pepper samples were taken at each of five distances from the marigold blocks (adjacent, 30 feet, 60 feet, 90 feet, and 120 feet) in the experimental fields plus fifty pepper samples were taken randomly in the control field. Since the Orius did not always fall out of the pepper flowers when they were beaten, we visually inspected the flowers. The number of adults and the number of nymphs for both Orius and thrips were recorded as well as the general height of the plants, the number of flowers on the plant, and the number of flowers in the beat sample. At the end of the season, the data was compiled and is currently being analyzed to discover if Orius established in the field (judged by the presence of nymphs) and to see how far into the field the predator would spread from the marigold blocks.

In another area of the Zittel farm, imidicloprid pesticide used in June to control Colorado potato beetle on eggplants devastates the spider mite predator population, resulting in spider mite outbreaks that bronze the fields and require 2 summer sprays. In 2010, snapbeans were planted in the pesticide-free tractor lanes as trap plants for spider mites and reproduction sites for predatory mites. The predator mites spread at least four rows into the eggplants and suppressed the spider mites to a level similar to miticides in the rest of the field. In 2011, we repeated this planting scheme for a second year, under more controlled conditions. A portion of this experiment was repeated again in 2012 to gain more data.

In 2012, the eggplant field was divided into 3 groups of three treatments with one buffer row between each set of three treatments. For each group, a drive row was planted with snapbean guardian plants and then eight rows of eggplants were planted. The three treatments were: no predators added controls, predators added to the snapbeans, and predators added to the eggplants.

Weekly scouting of the fields of was conducted from July 12 through August 23. Two thousand Neoseiulus fallacis were released on the treated rows on July 26 when spider mites began to appear on the beans and again on August 10. Observation of the three treatments began after the application of the predator (August 2 through August 23). During each visit the level of spider mites was estimated on 30 leaves showing damage using a scale of 0 to 3, the number of predators was counted, the type of plant (bean or eggplant) was recorded along with the row number and the treatment type. In 2012, spider mites and predators were found to be scarce on the snapbeans, therefore only distance data was collected for eggplants 4 rows removed from the untreated eggplant control row (i.e., no predators applied), 1 row removed from the treated eggplant row, and 3 rows removed from the treated eggplant row. A final exit survey was conducted on September 20.

At the end of the season, the data was compiled and is currently being analyzed to discover if Neoseiulus established in the field, if the beans were required for successful establishment or if releasing predators directly onto the eggplants was sufficient, and to see how far into the field the predator would spread from the treated eggplant rows.

Accomplishments/Milestones

A No-Cost Extension for this project was requested and granted in March of 2012 so that left-over funds could be used to collect a second year of data. Growers Mark Zittel and Paul Zittel were interested and willing to participate. The activities and timetable in 2012 were similar to that in 2011.

Mark Zittel and the Zittel farm staff cared for the pepper plants and eggplants as part of their normal production in spring 2012. In addition, they grew and transplanted the marigolds into the experimental fields and planted the snapbeans in June in the middle of the tractor lanes in the eggplant field. Mark released the Orius at the Bley Road pepper field on June 21. Mark released Neoseiulus fallacis into the eggplant field on July 26 and August 10. He shared his experiences with other growers at 2 meetings organized by Robert Hadad of Cornell Cooperative Extension.

The scout visited the site weekly from May 24 through July 5 for the marigold/ pepper project and July 12 through August 23 for the snapbean/ eggplant project for data collection and data entry. The scout made an additional visit on September 20 for a final exit survey of the snapbean/ eggplant field.

Robert Hadad of Cornell Cooperative Extension organized a field meeting on August 27 for local growers to see the predators in action in the marigold/ pepper fields. He will be available to speak at vegetable grower meetings as opportunities arise.

Carol Glenister and her staff were responsible for data analysis, reporting, business management, and outreach. Carol made 7 visits to Zittel’s farm to manage the projects, perform the surveys when necessary and participate in the twilight meeting. Additionally, she and Mark Zittel gave a joint powerpoint presentation of the work at the Western NY Vegetable Growers Meeting in Lockport, NY on Feb 27, 2012.

Dr. Sally Newman of Flora and Fauna compiled the data and is currently analyzing it. She also prepared the 2012 Annual Report. Data analysis commenced in mid-September at the completion of the data collection. The final report will be completed and submitted within 60 days of the project end date April 15, 2013.

Impacts and Contributions/Outcomes

One important impact from this project is that local growers near the Zittel farm have become more aware of the presence of natural enemies. Mark Zittel has shared the discovery of abundant Orius in pepper and eggplant fields with all growers willing to listen, and they have found them almost everywhere that they have looked.

We propose that success in the marigold/ pepper Guardian Plant System is demonstrated by the following:

•The presence of Orius nymphs in the marigold beat samples is evidence of Orius establishment and reproduction.

•The marigolds draw thrips away from the pepper plants, resulting in few thrips on the peppers and obvious thrips on the marigolds.

•The Orius keep the thrips numbers from exploding on the marigolds.

•As the peppers begin to flower, the Orius transfer over to the pepper plants and reproduce on them as well.

•Thrips numbers subside with the expanding natural enemy population.

Preliminary 2012 results for marigold/ pepper Guardian Plant System found:

•Orius establishment and reproduction did occur as indicated by the presence of Orius nymphs in both the marigold and the pepper beat samples. Also, Orius populations did increase over the season. However, there was such a large population of naturally occurring Orius, the control field, which had no marigolds and no application of Orius, had just as high an Orius population at the end of the season as the Bley Road field which had both marigolds and 1000 Orius added.

•In the Bley Road field, thrips were more easily detected on the marigold than on the peppers. However, in the North Boston Road field, the number of thrips on the marigolds and on the peppers were similar.

•The Orius did keep the thrips number from exploding. No sprays were required in 2012.

•In the two fields that were planted with marigold blocks, Orius transferred to the pepper plants 1 week earlier than in the control field.

•Up until June 28, thrips populations did decrease with increasing Orius populations. After June 28, while thrips populations began to increase in all three fields, they remained at low levels and required no pesticide treatments for thrips all season.

Our conclusion currently is that although the marigolds did aid in the establishment of Orius 1 week sooner than in the control field, there is so much naturally occurring Orius in the vicinity of the Zittel farm the addition of 1000 extra Orius is unnecessary.

Success in the eggplant/snapbean Guardian Plant System was proposed to be demonstrated if the following questions can be answered by the weekly scouting data:

•Will the predators establish on the bean release rows as evidenced by increasing numbers over the season? And, if so, how far will the predators spread from the bean release row?

•If there are no beans, will the predators establish on the eggplant rows onto which they were released? And, if so, how far do they spread from the release rows?

•What are the spider mite and predator levels on the bean rows,the eggplants in the release row, eggplants one row away from the eggplant release site and eggplants 3 rows away from the eggplant release site?

•What are the spider mite and predator levels on the eggplants that had predators released onto them directly and control eggplants that received no predators?

Preliminary 2012 results for snapbean/ eggplant Guardian Plant System found:

•Predators were detectable on the bean release rows 2 weeks after their first release and increased on the release rows 6-fold over the first detection over the following 6 weeks.

•In the eggplant rows where predators were applied directly to the eggplants, predators were detectable on the eggplant release rows 1 week after their first release and increased on the release rows 5-fold over the next 2 weeks but then declined to twice the first detection thereafter. During the exit survey, predators were detected on eggplants 3 rows away at low levels similar to the release row.

•At the end of the season the difference between the spider mite levels on the control and treated eggplant rows was small, and overall spider mite levels were 1/3 of what they had been in August overall.

Collaborators: