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Funded Project

Funding Program: Regional IPM Competitive Grants - Northeastern

Project Title: Fungi, Predatory Mites, and Habitat Plants for Thrips IPM in Greenhouse Ornamentals

Project Directors (PDs):

Margaret Skinner [1]

Adana Kassa [2]

Lead State: VT

Lead Organization: University of Vermont

Research Funding: $59,077

Start Date: Sep-01-2008

End Date: Aug-31-2011

Pests Involved: western flower thrips

Site/Commodity: greenhouse, ornamentals, nursery, flowers

Area of Emphasis: biocontrol, biological control

Summary: This is a Research project testing a novel approach for IPM of western flower thrips (WFT) in spring bedding plants, combining predatory mites, granular entomopathogenic fungi and indicator plants into one effective "habitat plant system". Adult WFT will be attracted from the crop to flowering marigolds, where they will become established. A portion of the immature WFT will serve as prey for the predatory mite, Neoseiulus cucumeris, sustaining the mite population, and encouraging dispersal throughout the greenhouse. A portion of the WFT escaping predation will drop to the soil to pupate, where they will be targeted with fungi. The granular formulation will enable the fungus to colonize the potting mix, eliminating the need for repeat applications. This concept represents a sustainable, low-cost, ecological approach to combating the most serious pest facing greenhouse growers today. This project addresses all three RIPM program goals. It will contribute to safeguarding human health and the environment by reducing growers' use of chemical insecticides, thereby lessening exposure of applicators, growers, agricultural workers and the public to toxic compounds. This study tests an innovative IPM strategy that could offer economic benefits to growers by reducing WFT damage, increasing plant quality, and minimizing production costs by providing a sustained source of biological control agents within the crop. This could lead to wider adoption of IPM by growers, thousands of whom in the Northeast struggle annually with WFT control. Growers would surely adopt this IPM strategy if they knew it worked better and cost less than chemical control.

Objectives: 1. Assess the impact of soil applications of granular formulations of insect-killing fungi on the population dynamics of western flower thrips.

2. Evaluate the combined effect of a granular fungal formulation and predatory mites within a habitat plant system to prevent the buildup of western flower thrips populations.

Proposal

USDA CRIS data

Interim Report: Oct-01-2009

Outcomes
Results from the three replicated marigold guardian plant caged trials were averaged together to evaluate treatment differences over 6 wks. WFT populations (adults and immature combined) were consistently less throughout the 6 wks after thrips release for the treatment of 8 g fungal granules per pot. At 5 wk average populations were around 10 WFT per plant for the 8 g treatment compared with around 40 WFT per plant for the control and fungal spray treatments. The 8 g treatment provided a control efficacy of 65.5 percent (based on Abbott's formula) while the WFT population of the non-treated control increased to 904.0 percent at 5 wks post-application. WFT populations increased significantly at week 6 in the 8 g treatment, resulting in a decrease in the control efficacy to 10 percent, a level similar to the non-treated control. Though overall differences in WFT populations were not detected between 2 g and 4 g/pot fungal granular treatments, these two treatments were more effective than the foliar spray and drench BotaniGard treatments. WFT populations were less for the drench than the spray treatment. Foliar damage was significantly less on plants of the 8 g/pot than plants from all of the other treatments at 5 and 6 wks post treatment. At week 5 damage in the 8 g treatment was half that of the other treatments (damage rating of 2 [feeding on 10-25 percent of the plant] compared with 3-4 [feeding on 51-75 percent of the plant).

Based on sticky lid counts at the end of the experiment, fewer WFT emerged from the potting mix of 8 g/pot treatment than the other treatments, suggesting either that fewer thrips were in the plants to pupate or that a high proportion of those entering the mix became infected and died without emerging. Thrips emergence was positively correlated with population levels in the plants at 5 wks post-application (Pearson's coefficient = 0.597). Between 40-70 percent of the WFT that emerged were found to be infected with B. bassiana and differences among the fungal treatments made to the potting mix were not significant. Less than 6 percent of the WFT emerging from the potting mix for the foliar spray treatment were infected with B. bassiana, and none were infected in the non-treated control.

Our results clearly demonstrated the potential of granular fungal formulations as a means of reducing WFT populations. This treatment approach, if used at a rate of 8 g per pot applied once, was significantly more effective than the standard recommended foliar fungal spray made weekly. Despite the positive results, thrips populations were not reduced below levels at which little or no damage occurred. The addition of predatory mites to the foliage may address this problem. Together, these two biological control treatments may effectively suppress the thrips population over a longer period. It should be noted however, that the concept of the guardian plant system is that the thrips will be attracted to the marigolds and away from the crop. Therefore it is acceptable if some thrips occur there. However, it appeared that the population was slowly increasing over time even with the 8 g granular treatment. Further refinement of the system is needed before it can be deployed widely in commercial settings.

Growers who attended the Tri-state IPM workshops this year were asked to complete an evaluation of the event, and 94% of the respondents said they learned new techniques they intend to use in the coming year. Many mentioned pH and EC testing as new techniques they learned. Over 82% indicated they made new contacts, listing growers and Extension specialists as their new contacts. Averaged over all of the individual sessions, growers gave the workshop program a ranking of 4.2 out of 5, similar to past year's workshops. In general growers recognized the expertise and knowledge of all of the presenters, and appreciated the efforts we made to transfer IPM information to them. Many growers expressed their desire for more hands-on formats. This is definitely how these growers learn best. Participants were also asked if they used biological control in their operation. Over 58 percent of those who completed the evaluation indicated they used biological control. Of those who used biological control, 64 percent used predators and 32 percent used insect killing fungi. Approximately 40 percent are using some form of plant-mediated IPM system, often marigolds as indicator or trap plants. This suggests that growers in northern New England would likely adopt techniques we are testing using plant-mediated IPM systems in conjunction with predatory mites and insect-killing fungi, once their effectiveness is clearly demonstrated.

Impacts
Results from these experiments demonstrated the potential of granular fungal formulations for management of WFT. It also showed that fungi alone may not sufficiently maintain WFT populations below damaging levels considering that it only targets thrips that pupate in the soil. It is known that some pupate on foliage. Therefore, combining predatory mites with granular applications of fungi to the potting mix may be a better approach to this pest problem. Further research is needed on the guardian plant system before we can encourage adoption by growers. However, thrips remain one of the most persistent pests in greenhouse ornamentals and pesticides continue to be applied frequently in an effort to reduce their damage. Development of this guardian plant system could significantly reduce growers' use of chemical pesticides, and thus their exposure to these toxins, but research is needed to perfect it. Growers continue to complain that the most commonly used chemical pesticide, Conserve, is not working as well as it once did. This suggests that thrips are developing resistance to this compound. Without it, growers will be even more dependent on non-chemical approaches such as the guardian plant system. This has a direct impact on the economics of producing ornamentals. If growers' plants are heavily damaged by thrips, the plants must be discarded, reducing revenues significantly. Therefore it is critical that we make progress towards this goal. Considering the high percentage of growers in northern New England that are using some form on biological control, this group is expected to be very receptive to the guardian plant system if it is shown to be effective.

Report Appendices

PDF

Interim Report: Jan-21-2011

Impacts
Thrips remain the number one pest in greenhouse ornamentals and pesticides continue to be applied frequently in an effort to reduce their damage. Growers continue to complain that the most commonly used chemical pesticide, Conserve, does not work, strongly supporting the assumption that most WFT populations have developed resistance to this compound. Without it, growers are even more dependent on non-chemical approaches such as the habitat plant system. This has a direct impact on the economics of producing ornamentals. If growers' plants are heavily damaged by thrips, the plants must be discarded, reducing revenues significantly. Development of this habitat plant system could significantly reduce growers' use of chemical pesticides, and thus their exposure to these toxins. Our research has already made significant gains towards perfecting it using biological control products currently available commercially. Our results clearly demonstrated the potential of combining either a granular or spray fungal formulation of GHA (Botanigard) and predatory mites to reduce WFT populations and minimize damage. This was more effective than using either the fungus or mites alone. It is promising to find that a fungal spray was almost as effective when used in combination with mites as the granular formulation. Our results could lead to grower implementation of this dual biological control strategy, despite the unavailability of a granular formulation. It should be noted however that the combination of granules and mites are easier to apply to the habitat plant system than the foliar spray. These results show the effectiveness of the fungal/mite combination for suppressing thrips. The next critical step is to determine if the habitat plant system can attract the WFT away from the crop and thus protect the crop plants from damage while at the same time suppressing the pest. Year 3 will begin that evaluation by testing the fungal/mite habitat plant system in several commercial greenhouses. Considering the high percentage of growers in northern New England that are using some form on biological control, this group is expected to be very receptive to the habitat plant system if it is shown to be effective.

Outcomes
Approach and Procedures:

Research is being conducted to test the effectiveness of different rates of granular formulations of a commercially available entomopathogenic fungus within a plant-mediated integrated pest management system (habitat plant) to manage western flower thrips (WFT). In year 1, an experiment was conducted using individual marigold plants (variety Hero Yellow) grown in pots of Metromix potting mix under lights in specially designed clear vented plastic cages, comparing the following six treatments: a) untreated control, b) 2 grams of a granular fungal formulation of B. bassiana GHA (the strain in BotaniGard), c) 4 grams granular GHA, d) 8 grams granular GHA, e) a standard soil drench of BotaniGard, and f) a standard foliar spray of Botanigard at the recommended rate (applied weekly for 4 wk) as per label guidelines. Soil treatments were applied once at the start of the experiment, on the same day that three WFT (24-48 hrs old) were released on each plant. This ensured that the granular applications had time to colonize the potting soil sufficiently and the fungal spore level would be dispersed enough so that pupating thrips were likely to come in contact with spores. Granular formulations were applied and mixed into the upper 2-3 cm of potting soil around the plants.

The granular formulation was produced on millet grain, which supports good fungal growth during production and provides granules that are easy to apply to the soil. The granular formulation contained 1 x 108 conidia per gram. The BotaniGard spray was a commercial wettable powder formulation (WP) (Laverlam International Co., USA) (2.0×1010 conidia/g) which was applied according to label recommendations (10.4 ml of 400-fold dilution/plant). The BotaniGard drench was applied at 10.0 ml of a 500-fold dilution/pot. Each treatment was replicated three times. Thrips numbers on each plant were monitored weekly by lightly tapping the plants 10 times over a sheet of laminated white paper. Foliage damage from WFT was also rated visually for each plant throughout the experiment based on a 0-5 scale. At 6 wks post-application, the plants were cut off at ground level and the pot was covered with a sticky lid to assess final WFT emergence from the potting mix. Thrips mycosis was also evaluated by removing thrips from the lids and plating them on a B. bassiana selective medium. In Year 2, using the same experimental system, one granular fungal formulation and the spray formulation were tested in combination with predatory mites released on the foliage. In Year 3, the system will be pilot tested in commercial greenhouses. Results from the research will be reported annually to greenhouse growers, researchers, Extension specialists and State Department of Agriculture personnel at the Tri-state greenhouse IPM workshops held annually in Maine, New Hampshire and Vermont, and other appropriate venues.

Progress:

A laboratory trial was conducted using the test system developed last year in which individual marigold plants were caged, treated and infested with laboratory-reared WFT. The following six treatments were tested for management of WFT: a) untreated control (notreat); b) a marigold plant with a predatory mite sachet (mite); c) a plant-mediated system using a granular (GR) fungal formulation within potting soil of a marigold plant (GR); d) a plant-mediated system combining a granular (GR) fungal formulation and predatory mites on marigolds (GR+mites); e) a standard foliar spray of BotanigardÒ (spray) ; and f) a standard foliar spray of BotanigardÒ with predatory mites (spray+mite). For the plant-mediated system, a rate of 8 g of a granular formulation of B. bassiana GHA (the fungus in BotanigardÒ) per habitat plant pot was selected based on last year's results. One slow release sachet per plant containing around 30 ml of a bran carrier with the predatory mite Neoseiulus cucumeris and bran mites as a food source (produced by Applied Bionomics, Canada [Fig. 4]) was hung on each habitat plant. The sachets acted as sustained miniature breeding units. The standard fungal foliar spray (BotaniGard WP, 400×) was applied weekly for 4 wk. The fungal treatments (GR and first foliar spray) and the predatory mites were applied to the plant at the same time, after which three 1-2 day old adult female WFT were released. Each treatment was replicated three times and three replications of the entire experiment were completed. Potting soil was sterilized by autoclaving at 121°C for 30 min to control plant disease. Plants were evaluated for thrips and mite population levels and foliar damage for 6 wk and thrips numbers emerging from the soil were determined at the end of the experiment.

One-day IPM grower workshops were held in Maine, New Hampshire and Vermont in January 2010, reaching 147 participants. This was a collaborative effort with assistance from Extension specialists, Department of Ag personnel and University researchers from the three states. Results from this research and other related IPM subjects were discussed with greenhouse growers in Northern New England. Alison Kutz-Troutman, Sound Horticulture, Bellingham, WA, spoke about compost tea. Brian Krug, Univ. of New Hampshire and Bruce Watt, Univ. of Maine, covered disease and nutrient deficiency diagnosis, Margaret Skinner, Univ. of Vermont, presented data on using fungi and predatory mites within a plant-mediated system and Steve Wraight, USDA Agric. Research Service, discussed his research on insect-killing fungi. In VT Thomas Gilbert, Highfields Center for Composting, talked about making and using compost. Handouts describing plant-mediated IPM systems were prepared and distributed to growers. Individual growers were recruited to cooperate with the future greenhouse trial.

Outcomes:

Based on the number of WFT adults on plants at 6 wk post treatment, the habitat plant treatments combining predatory mites with either the granular fungal formulation or the BotaniGard spray were the most effective in terms of suppressing WFT populations, resulting in an average of 3.0 - 3.8 WFT per plant (larvae and adults), compared with 36.0 per plant in the untreated controls. Plants with mite sachets only provided moderate suppression with an average of 9.2 WFT per plant. The fungal treatments alone, either as a granular or spray resulted in WFT populations similar to the untreated controls (over 36 WFT per plant). A significant increase in WFT populations was first observed in the untreated controls and two fungal treatments (spray and granular) 2 weeks after infestation, and continued to rise throughout the test period, with no clear evidence of a fungal treatment effect. In all treatments involving mites (mites alone, mites with granular fungus and mites with fungal spray), an average of 3-6 predatory mites per plant were observed (based on tapping the flowers) with no significant difference in mite numbers among the three treatments over 6 wks. This strongly suggests that the fungal treatments have no adverse effect on mite populations, and that the mites are sustained either from the sachets or on marigold pollen and thrips for at least 6 weeks, without requiring replacement of the sachet. The number of WFT adults emerging from the pots at the end of the experiment followed the same pattern as the thrips numbers on plants. The number of thrips emerging for the two fungal/mite treatments was around 1.2 compared to 3 for the mite only treatment and 6.5-9.6 for the untreated controls and fungi only treatments. Foliar damage was less on plants from the two fungal/mite treatments than on those from all of the other treatments at 4, 5 and 6 wks post treatment. Damage, based on a 0-5 rating index, in the fungal/mite treatments was first occurred at week 2 and no increase in damage was observed over the remaining 6 wks. An average damage index of 1.2 was obtained for the fungal/mite treatments by week 6 compared to 3.7 for the untreated controls.

Growers who attended the Tri-state IPM workshops this year were asked to complete an evaluation of the event, and 87% of the respondents said they learned new techniques they intend to use in the coming year. Over 85% indicated they made new contacts and said the workshops were great for rebuilding lost contacts with growers and local specialists. Averaged over all of the individual sessions, growers gave the workshop program a ranking of 4.3 out of 5, slightly higher than the rating for last year's workshops. In general growers recognized the expertise and knowledge of all of the presenters, and appreciated the efforts we made to transfer IPM information to them. Many growers expressed a desire for more hands-on training sessions. Over 60% of those who completed the evaluation indicated they used some type of biological control; specifically, 75% used parasites, 65% used predators, 36% used nematodes, and 33% used insect killing fungi. Fifty-three percent of the respondents indicated they used some form of a plant-mediated IPM system last year compared with 41% the year before. The most commonly used system was marigolds as indicator plants (66%), followed by ornamental peppers for thrips management (59%), eggplants for whitefly control (22%), alyssum for conserving predatory mites (26%) and grasses for aphid control (19%). This suggests that growers in northern New England would likely adopt techniques we are testing using plant-mediated IPM systems in conjunction with predatory mites and insect-killing fungi, once their effectiveness is clearly demonstrated. The following topics were identified by attendees for inclusion in future workshops: energy efficiency, greenhouse sanitation, soil health, fruits and vegetables, landscape ornamentals, IPM for retail greenhouses and calibration and use of basic equipment.

Report Appendices

PDF

Final Report:

Outcomes
In Yr 1, trials were conducted to test the effectiveness of different rates of a commercially available entomopathogenic fungus within a plant-mediated marigold IPM system to manage WFT. The experiment was conducted in the lab using individual marigold plants (var. Hero Yellow) grown in pots within clear, vented plastic cages. The marigolds were grown from seed in Metromix 360 potting soil. The granular fungus was produced at the UVM Entomology Lab on millet. Granular formulations were compared with a foliar spray and soil drench of the same fungus. The BotaniGard spray was a commercial wettable powder formulation (Laverlam, USA) which was applied according to label recommendations (10.4 ml of 400-fold dilution per plant). The BotaniGard drench was applied at 10.0 ml of a 500-fold dilution per pot. The following six treatments were tested on the marigolds: a) untreated control, b) a standard soil drench of BotaniGard, c) a standard foliar Botanigard spray applied weekly for 4 wk, d) 2 g of a granular fungal formulation of B. bassiana GHA (the strain in BotaniGard), e) 4 g granular GHA, and f) 8 g granular GHA. Soil fungal treatments were applied once at the start of the experiment along with the first foliar fungal spray. Granular formulations were mixed into the upper 2-3 cm of potting soil around the plants to ensure the fungal spores would be dispersed enough so pupating thrips were likely to contact them. After 4 hr, 3 WFT from our laboratory colony were released onto the foliage of each marigold. Each week for 6 wks, plants were tapped onto a white paper to determine the relative number of thrips. Visual assessments of foliar damage were made based on a standard rating system (0 for no damage - 5 for 76-100 percent damage). At 6 wks post-application, plants were cut off at ground level and the pot was covered with a sticky lid to assess WFT emergence from the potting mix. Each treatment was replicated three times and three replications of the entire experiment were completed each year.

WFT populations (both adults and immatures) were consistently less for the 8 g fungal treatment than the other treatments throughout the 6-wk test period. At Wk 5 the average number of WFT per plant was approximately 10 per plant for the 8 g treatment compared with 40 per plant for the control and spray treatments. WFT populations decreased significantly at Wk 6 in the controls resulting in similar numbers of thrips for that and the 8 g fungal treatment. This was because the control plants were completely dead, and unable to sustain WFT reproduction. Though overall differences in WFT populations throughout the trial were not detected between the 2 and 4 g granular fungal treatments, both were more effective than the BotaniGard foliar spray and drench treatments. WFT populations were lower on plants that had the drench than the spray treatment. Foliar damage was significantly less on plants in the 8 g fungal treatment than those for all of the other treatments at Wks 5 and 6. At Wk 5, damage in the 8 g treatment was half that of the other treatments (damage rating of 2 [feeding on 10-25 percent of the plant] compared with 3-4 [feeding on 51-75 percent of the plant). At Wk 6, 40-70 percent of WFT emerging from pots treated with the granular formulation and drench were infected with B. bassiana. Less than 6 percent of the WFT emerging from the foliar spray treatment were infected with B. bassiana, and none were infected in the control. Our results clearly demonstrated the potential of granular fungal formulations to reduce WFT populations. The treatment used once at a rate of 8 g per pot was significantly more effective than the standard recommended foliar fungal spray made weekly. Despite the promising results, WFT populations were not reduced below levels at which no damage occurred. It was hoped that the addition of predatory mites to the foliage of the marigold plants could further protect the plants from damage.
Based on Yr 1 results, the 8-g granular fungal treatment was further tested combined with predatory mites on the marigold foliage. The following treatments were tested: a) untreated control, b) marigold with a predatory mite sachet, c) marigold plant with 8 g of granular GHA fungal formulation mixed into the potting soil, d) marigold with 8 g of fungal formulation and predatory mites; e) foliar Botanigard spray; and f) foliar spray of Botanigard with predatory mites. For the mite treatments, one slow-release sachet containing 30 ml of a bran carrier with the predatory mite Neoseiulus cucumeris and bran mites as a food source (produced by Applied Bionomics, Canada) was hung on each marigold after WFT were released on the plants. The sachets acted as sustained miniature breeding units. The trial was set up and evaluated in a similar way to the Yr 1 trials over 6 wk (see above).

At Wk 6, both habitat plant treatments in which predatory mites were combined with either the granular fungal formulation or the BotaniGard spray were the most effective in terms of suppressing WFT populations, resulting in an average of 3.0 - 3.8 WFT per plant (larvae and adults), compared with 36.0 per plant in the controls. Plants with only mite sachets provided moderate suppression (average of 9.2 WFT per plant). No significant effect on WFT populations was observed for either of the fungal treatments alone, (over 36 WFT per plant). A significant increase in WFT populations was first observed in the control and two fungal treatments (spray and granular) 2 wk after infestation, and continued to rise throughout the test period, with no clear evidence of a fungal treatment effect. In all treatments with mites (mites alone or with granular fungus or fungal spray), an average of 3-6 predatory mites per plant were observed (based on tapping the flowers) with no significant difference in mite numbers among the treatments over 6 wks. This suggests that the fungal treatments had no adverse effect on mite populations, and that the mites are sustained either from the sachets or on marigold pollen and thrips for at least 6 wks, without requiring replacement of the sachet. The number of WFT adults emerging from the pots at the end of the experiment followed the same pattern as the thrips numbers on plants. The number of thrips emerging for the two fungal and mite treatments was around 1.2 compared to 3 for the mite only treatment and 6.5-9.6 for the controls and fungi only treatments. Foliar damage was less on plants from the two fungal/mite treatments than on those from all of the other treatments at 4, 5 and 6 wks post treatment. Damage in the fungal/mite treatments was first observed at Wk 2 and no increase in damage was occurred over the remaining test period. An average damage of 1.2 was obtained for the fungal/mite treatments by Wk 6 compared to 3.7 for the untreated controls, demonstrating that adding predatory mites to the habitat plant system with a fungal treatment can provide WFT control with minimal WFT damage to the crop.

In Yr 3, the most effective marigold plant-mediated system based on lab trials in Yrs 1 and 2 was selected for testing in commercial greenhouses containing bedding plants. The following treatments tested were: a) untreated control (no mites or fungus), b) mites only, c) granular GHA with mites. The granular formulation was applied to the top 3 cm of potting soil around the marigold plants at a rate of 13.2 g per 201.1 sq. cm. pot. Thrips and mite abundance and foliar damage were determined every 2 wks for 10 wks. Three crop plants around each habitat plant were also sampled to determine the number of thrips and mites and damage level. Blossom samples were taken every 2 wks. Soil samples for fungal persistence were taken at Wk 10. Higher numbers of thrips were observed on the controls than the fungus and mite treatments. Thrips control was similar among treatments with mites only and the one combining the granular fungus and mites. This suggests predatory mites play a key role in WFT suppression in the marigold habitat plant system. Fewer thrips were detected on randomly inspected plants around marigold habitat plants (with fungal and mite treatment) than on the marigold habitat plants themselves, suggesting thrips were attracted to the marigolds and the treatments effectively prevented their spread. Damage on plants around the marigolds and on marigolds was less than 10 percent. Fewer thrips were found in flowers of marigold treated with the mites and fungus than on control plants and those treated with mites only. Predatory mites were rarely detected with plant tapping, but were found with flower sampling. Mites were found at similar levels in all mite treatments. Soil samples showed that the fungus persisted throughout the experiment duration.

Throughout the project, 1-d grower workshops on IPM were held in ME, NH and VT. This was a collaborative effort with Extension specialists, Dept. of Ag personnel and University researchers from the three states. Results from this project and other IPM subjects were presented. B. Krug and C. Smith, Univ. of NH and B. Watt, Univ. of ME, covered disease and nutrient deficiency diagnosis and IPM, M. Skinner and C. Frank, Univ. of VT, presented data on using fungi and predatory mites within a plant-mediated system. A. Eaton from Univ. of NH discussed insect pest id. Speakers from other areas were invited to give presentations on IPM including: A. Kutz-Troutman, Sound Horticulture, WA, spoke about compost tea and its benefits; R. Valentin, Biobest, Canada, spoke about greenhouse biocontrol; T. Gilbert, Highfields Ctr for Composting, VT, spoke about compost production and use; Steve Wraight, USDA ARS, spoke about effective use of fungi for greenhouse pests. Each year growers were recruited to take part in Grower-to-Grower sessions to encourage exchange of ideas among growers. Handouts describing plant-mediated IPM systems and other subjects were distributed.

Impacts
Safeguarding human health and the environment: Thrips remain the number one pest in greenhouse ornamentals and pesticides continue to be applied frequently in an effort to reduce their damage. Growers continue to complain that the most commonly used chemical pesticide, Conserve, does not work, strongly supporting the assumption that most thrips populations have developed resistance to this compound. Without it, growers are even more dependent on non-chemical approaches such as the habitat plant system. The results from the greenhouse trial were promising. Two of the 3 locations did not need to apply any chemical insecticides to control thrips populations throughout the duration of the experiment. By providing marigolds with thrips and fungi, insecticide use was reduced bettering the overall health of the workers, consumers and the environment. Further development of this habitat plant system could significantly reduce growers use of chemical pesticides, and thus their exposure to these toxins.

Economic benefits: This project has a direct impact on the economics of producing ornamentals. If growers plants are heavily damaged by thrips, the plants must be discarded, reducing revenues significantly. Our research has already made significant gains towards perfecting it using biological control products currently available commercially. Our results clearly demonstrated the potential of combining either a granular or spray fungal formulation of GHA (Botanigard) and predatory mites to reduce WFT populations and minimize damage in both laboratory and greenhouse trials. Greenhouse growers did not need to throw away any plants that had evidence of thrips damage. In the laboratory trials, it was promising to find that a fungal spray was almost as effective when used in combination with mites as the granular formulation. Our results could lead to grower implementation of this dual biological control strategy, despite the current unavailability of a granular formulation. It should be noted however that the combination of granules and mites are easier to apply to the habitat plant system than the foliar spray. This ease of application would further reduce costs by taking less of the growers time for treatment. Growers often complain that the costs of biological controls are too expensive, especially shipping. This system would help reduce the costs of expensive biological controls by providing a system for ongoing predatory mites. These results showed the effectiveness of the fungal/mite combination for suppressing thrips. It also demonstrated that it has a lot of potential as a habitat plant system that can attract the WFT away from the crop and protect the crop plants from damage while at the same time suppressing the pest. Several of the growers who took part in the greenhouse trials are now independently using marigolds as a trap plant based on the observations they made during the experiments. Over $650,000 of federal and non-federal support was leveraged through this project in the form of funding to continue the research, in-kind grower contributions for greenhouse and meeting space; and corporate sponsorship of the workshops.

Implementation of IPM: Over the course of this 3-year project, two IPM strategies were validated through on-farm trials for managing western flower thrips (WFT): 1) a plant-mediated IPM system combining a fungus and predatory mites on marigolds and 2) marigolds as trap plants for early detection of the pest and to draw WFT out of the crop. One-day workshops on IPM for greenhouse growers were held annually in Maine, New Hampshire and Vermont, reaching a total of over 450 growers, landscapers, Extension agents, state Agriculture personnel and others involved in greenhouse production. Approximately 81 percent of the attendees were greenhouse growers. All attendees to the workshops received a complimentary copy of the Greenhouse Managers Guide to IPM in Northern New England and a hand lens to encourage their efforts to scout their crops. Each year, all participants also received a folder containing at least 20 handouts covering the following subjects: fact sheets on various exotic and invasive pests; keys to identifying greenhouse arthropod pests, diseases and nutrient disorders; summaries of research on plant-mediated systems; lists of useful websites and references on greenhouse IPM, reports of customer surveys conducted in the area, IPM posters and brochures to distribute to customers; compatibility charts for pesticides and biological control agents. Workshop attendees were asked each year to complete an exit questionnaire from which key information on the usefulness of the session was gathered. Overall, attendees gave the workshop a ranking of 4.2 out of 5.0. Many commented that these events were the most useful educational event they attend during the year, and that they preferred a hands-on format over the standard lecture presentation. They liked the small size of the workshop. Registration to these events is limited to 50 attendees per state, and the group is divided into smaller sub-sections for some of the presentations. An average of 83 percent of the attendees indicated they had made new contacts that would help them with IPM in the future. Many noted that they valued the opportunity to reconnect with fellow growers at these workshops. This encourages interaction between the attendees and presenters. Averaged over the 3 years, 90 percent of the attendees indicated they learned new IPM tactics they intended to implement in the coming year, including using pH and EC meters, referring to nutrient and disease keys to diagnose their plant problems, and banker plants to manage aphids. Attendees listed the following topics they would like included in future workshops: scouting, watering, fertilizers, biofungicides, nematodes for biocontrol, compatibility, more in-depth info on specific pests and diseases, disease id, sustaining biological control agents, mealybug control, energy efficient greenhouses, sanitation, soilless mixes and soil health in general, fruits and vegetables, landscape ornamentals and turf, IPM for retail greenhouses, calibration and use of basic equipment, calibration and use of EC and pH meters; IPM for ornamentals grown outside; ID of pests and beneficial; solutions for the pests and diseases that plague growers. Over 58 percent of the attendees used biological control and 39 percent used some form of a plant-mediated IPM system in their operations. When growers were asked if they had implemented any IPM tactic they learned about from our workshops in the past year, many indicated they had tried some form of a plant-mediated IPM system, most commonly marigolds or eggplants as traps for thrips. It is impossible to credit this project alone for their use of IPM, though, many growers have told us that the workshops we have held over the past 14 years are largely responsible for their increased implementation of IPM.

We also developed and expanded the UVM greenhouse IPM website that highlights topics covered in these workshops and summarizes our current research in greenhouse IPM: www.uvm.edu/~entlab/Greenhouse%20IPM/greenhouseipm.html

Three growers took part in the greenhouse trials conducted through this project. Two had previously used some form of biological control, one completely relied on conventional pesticide-based control. The two who were familiar with using biocontrol now use marigolds routinely in their operation for early detection of thrips and to trap them out of the crop. The grower using conventional control has now dramatically changed his management approach. He has initiated a biocontrol program and dramatically reduced his reliance on pesticides. He is extremely satisfied with the conversion, and looks forward to working with us in the future on further reducing his use of pesticides.

In addition to reporting results of this work to attendees at the annual Tri-state greenhouse IPM workshops, a presentation was also given to approximately 100 people at the 2010 New England Vegetable and Fruit Conference.

Report Appendices

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