Development of Fungal Entomopathogens for Greenhouse IPM (ANE95-23)

Final Report for LNE95-058

Project Type: Research and Education
Funds awarded in 1995: $217,763.00
Projected End Date: 12/31/1999
Matching Non-Federal Funds: $155,808.00
ACE Funds: $14,168.00
Region: Northeast
State: Vermont
Project Leader:
Dr. Bruce L. Parker
University of Vermont
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Project Information


Greenhouse ornamentals are sold on the basis of their appearance—consumers will only purchase high-quality, unblemished plants that are free of insect and disease symptoms. Insect pests, many of which also vector plant pathogens, must be regulated promptly to prevent plant damage. Chemical pesticides have traditionally been applied frequently and routinely for this purpose. Use of these synthetic insecticides is neither desirable or sustainable, and there are considerable pressures to adopt alternative, safer pest management strategies.

Integrated pest management (IPM) is increasingly advocated for suppression of greenhouse pests. When implemented correctly, IPM increases the precision of pesticide applications, minimizes control costs, improves worker safety and lessens environmental contamination. It encompasses the use of various control tactics, including biological control, in a coordinated and proactive fashion.

Broader adoption of IPM by growers in northern New England has been hindered by a general lack of knowledge of the “nuts and bolds” involved in implementation, and a lack of opportunities to acquire the necessary skills to begin IPM. Major goals of this project have therefore been to provide educational workshops on IPM fundamentals such as scouting, monitoring, insect and disease identification and management options. Workshops have also included sessions on biological control and grower-to-grower forums to encourage a free exchange of crop management information. Two workshops (one in VT one in ME) and a seminar were held in 1998, 3 workshops (in VT, ME & NH) were held in 1999 and 3 workshops are scheduled for 2000. Participants have expressed high praise for these workshops, and have appreciated the small-group, practically-oriented “hands-on” format that distinguishes these events from many other professional development opportunities.

IPM encompasses the use of many control tactics, including cultural, chemical and biological control. We are specifically focusing on the use of insect-killing fungi, which, as with other biocontrol agents, are best used in a preventative fashion within a proactive pest management strategy. This necessitates that fungal interactions with other controls be determined, to allow appropriate scheduling of sprays and the most cost-efficient use of materials. Results of our trials indicate a high degree of compatibility between fungi and the natural enemies, Orius insidiousus (a thrips predator) and Eretmocerus eremicus (a whitefly parasitoid). Fungi are also compatible with many biorational insecticides and plant-growth regulators, some fungicides are also very compatible and may be readily incorporated into a spray program with appropriate scheduling.

The project’s components serve to address stated needs in the Tri-state greenhouse industry. By providing information on IPM, hands-on demonstrations of these techniques and integration of different control tactics, growers will be able to initiate IPM programs with confidence. Our emphases have been to encourage growers to begin implementing IPM on a small scale. As their knowledge and experience in IPM grows, they can expand its implementation. As such, change will be gradual, but the long-term benefits in reduced pesticide use will be significant.

Project Objectives:

1. Establish a regional IPM Advisory Committee comprised of growers.

2. Initiation a 3-year demonstration scouting program and Tri-state training workshops.

3. Assess the compatibility of fungi with beneficials and biorational pesticides.


Research results and discussion:

Objectives 1 & 2. The Tri-state Greenhouse IPM Program was established in 1995 to coordinate IPM educational activities within Maine, New Hampshire and Vermont. By joining forces, we felt we could maximize on limited resources and provide high quality educational programs. The goal of the program is to encourage adoption of IPM practices among growers of greenhouse ornamentals and bedding plants. The Tri-state Greenhouse Advisory Committee is made up of 7 growers, 3 researchers and 7 extension/state pest specialists from within the Region (see attached list of the current members). It was formed to guide program activities and ensure that the educational needs of growers in terms of IPM were met. Grower members have provided critical insights into how to best reach growers. Over 10 meetings of the group have been held to coordinate and plan workshops and other regional IPM activities.

The committee organized and participated in IPM workshops in New Hampshire in 1996, Maine and Vermont in 1998 and Maine, Vermont and New Hampshire in 1999 (see attached programs). The format of these workshops stressed practical hands-on training in small groups, which fostered communication among growers and between growers and researchers. These workshops focused on training growers how to recognize the different life stages of the major pests and how to survey for them. Microscopes and hand lens were provided to allow growers to see up close what to look for. Some of the training was very basic. For example, how to use a hand lens was demonstrated, a skill most growers lacked. Scouting is the cornerstone of any IPM program, and the primary goal of these workshops was to educate growers about how to establish a scouting system that was suitable for their particular operation. Without a full appreciation for the value of scouting, it would be difficult for growers to progress to adoption of other more complex aspects of IPM, such as the use of biological control. In addition to providing a full-day educational program, we also compiled a comprehensive package of educational materials, which included pest information, guidelines for safe pesticide use, data sheets for scouting, and sample scouting materials.

Each year, attendance in our workshops has increased, to the point that many potential participants had to be turned down in 1999. Over the course of this project, IPM educational programs have been presented to over 350 growers. Based on the positive evaluations from the participants, three things are clear: growers strongly favor hands-on versus lecture presentations, they prefer small groups to the large conference formats and they are eager to learn how to use biological control agents effectively. Plans are underway to offer workshops in January 2000 in the three states focusing specifically on this subject.

In addition to coordinating IPM workshops, we also supervised a Univ. of VT student intern who developed a model scouting program for a local grower. This demonstrated the greatest impediment to implementation of routine scouting by growers. It took so long to scout a greenhouse according to established protocols, it is unrealistic to expect most growers take the time. The greatest pest pressure occurs when growers are most busy. Solutions to this dilemma must be developed. Either streamlined, reliable methods must be devised that can be done by growers or a scouting program using private, independent scouts should be considered.

As the computer becomes a more common tool for communication, our two internet listservers are proving extremely valuable to growers. Thripsnet is a network focusing on thrips and tospoviruses, the two most serious pests plaguing greenhouse growers worldwide. It now has over 360 subscribers from over 30 US states and 35 different countries. This network links growers, researchers and extension specialists regionally and internationally and offers growers from this area an opportunity to gain from the IPM expertise of others all over the world. We also recently established a similar network, Greengrower, specifically targeted for growers, researchers, educators and extension personnel in northern New England.

Finally, to encourage communication among greenhouse growers, extension specialists and state regulatory agencies, we prepared a tri-fold reference guide for the Tri-state region. This provided a list of the pest specialists in each state.

Objective 3. As insect-killing fungi come to the marketplace, it is essential that information is made available to growers on how to use these materials most effectively against various greenhouse pests and on different ornamental crops. In general, fungi must be applied early, before pest populations are high, to prevent damage, and are best used within the framework of a proactive IPM program. This necessitates that fungal interactions with other control components be determined, to allow appropriate scheduling of sprays and the most cost-effective utilization of materials.

Information on the compatibility of fungi with the thrips predator Orius insidiosus was given in the 1997 Annual Report. Briefly, fungi were shown to be highly compatible with the predator when the two agents were used simultaneously on thrips-infested chrysanthemums.
A series of trials was conducted on the compatibility of two commercial formulations of Beauveria bassiana (BotaniGard™), a wettable powder and emulsifiable oil formulation, with the whitefly parasitoid Eretmocerus eremicus on poinsettia. A high degree of compatibility between the wettable powder formulation and the parasitoid was obtained, especially when parasitoid release preceded spraying with the fungus by 3-5 d. When the emulsifiable oil formulation was used, parasitism rates were significantly reduced, particularly when parasitoid release immediately followed a spray. Data indicated that the oil had a repellent effect and parasitoids avoided treated nymphs.

Tests were also conducted to evaluate the compatibility of several biorational pesticides, both insecticides and fungicides, and a variety of entomopathogenic fungal isolates. Compatibility was assessed based both on spore germination and fungal growth. Of the two fungicides tested, one displayed a negative effect on the germination of the fungi at all of the tested dosages. The other fungicide inhibited germination of B. bassiana and Paecilomyces fumosoroseus but did not affect Verticillium lecanii. There were definite differences among fungal species and isolates of the same species to their sensitivity to some of the insecticides tested. Enstar II and Margosan-O exerted the most inhibitory effects on B. bassiana. Germination of P. fumosoroseus was inhibited by Precision, whereas Enstar and Margosan-O had no effect on germination. The V. lecanii strains were not negatively affected by any of the insecticides. Fungal growth was not adversely affected by any of the insecticides tested. However, fungal growth was negatively impacted to some degree by the fungicides, though effects were less evident as dose rate decreased. Overall the data show that several commercially available biorational insecticides and fungicides can be used in conjunction with entomopathogenic fungi, though the timing of applications is critical to ensure that negative effects are minimized.

Participation Summary


Educational approach:

Publicity for the Activities and Programs

For the workshops held in 1998 we send out announcements and registration materials to growers on mailing lists that were obtained from within our departments (around 300 in VT, 200 in NH and 400 in ME). Because no one in our tri-state region has exclusive responsibility for this area of extension, these lists were not as comprehensive as we would have liked. Therefore for the 1999 workshop we gained access to a more complete mailing list from the New England Greenhouse Conference (450 in VT, 400 in NH and 700 in ME). This list has now been updated and compiled into a database that is available to our tri-state cooperators. In addition to sending out announcements, we also submit press releases to grower newsletters in the 3 states (see attached). In addition notices of the workshop are lists on regional internet listservers and computer newsletters.

Conferences, Workshops and Meetings


• IPM for Bedding Plants – Durham, NH – June, 1997 – 59 growers attended. Coordinated by Univ. of NH Extension personnel, with input and participation by Univ. of VT cooperators and provided hands-on training in pest identification and scouting techniques.

• Greenhouse Integrated Pest Management – Manchester, ME – January, 1998 – 22 growers attended. Coordinated by the Tri-state Greenhouse IPM Advisory Committee, and provided hands-on training in pest identification and scouting techniques.

• Greenhouse Integrated Pest Management – Burlington, VT – January, 1998 – 27 growers attended. Coordinated by the Tri-state Greenhouse IPM Advisory Committee, and provided hands-on training in pest identification and scouting techniques.

• Practical Application of Natural Enemies in Greenhouse IPM – Burlington, VT – January, 1998 – 30 growers and students attended. General practical information about how to use natural enemies in greenhouses was presented by Carol Glenister, owner of IPM Labs, Locke, NY.

• Tri-state Greenhouse IPM Advisory Committee – has met 2-3 times annually since its establishment in 1995. Workshop programs and regional greenhouse IPM initiatives are developed at these meetings. Attendance of over 80% of the committee has been achieved at all of the meetings.

• IPM Scouting Seminar – Wheaton, MD – June, 1998 – 50 growers attended. Organized by the Univ. of MD Coop. Ext. Presented lecture entitled “How to Use and Evaluate the Effectiveness of Beauveria bassiana” which was a compilation of results from greenhouse spray trials conducted at the Univ. of VT.

• Seminar on greenhouse IPM in the Tri-state region. “Researcher/Grower partnerships in Greenhouse/Ornamental IPM”. Practical Partnerships, A New England Sustainable Agriculture Conference, Nov. 1997, Portland, ME.

• Entomological Soc. of America, Ann. Meeting, Nashville, TN, Dec. 1997 – Seminar entitled “Entomopathogenic Fungi: Making Them Work in Greenhouse IPM” presented at a session on Arthropod Pests of Ornamentals.

• Society for Invertebrate Pathology, Japan, August, 1998. Seminar entitled “Beauveria bassiana Plus Biorational Insecticides: a Recipe to Enhance Field Efficacy in Ornamentals?” presented results from our trials on in vitro compatibility and discussed potentially beneficial combinations of materials.

Articles in Greenhouse Industry Publications

• So Much to Do…So Little Time! Greenhouse Integrated Pest Management in Northern New England. M. Skinner, M. Brownbridge, J.F. Dill, B.L. Parker & J. Boone. The Plantsman, Dec. 1997/Jan. 1998. A publication of the New Hampshire Plant Grower’s Association.

• Insect-Killing Fungi. M. Brownbridge, B.L. Parker & M. Skinner. GrowerNotes, Spring 1998. A publication of the Society of American Florists, Alexandria, VA.

• Factors Affecting the Efficacy of Fungal Preparations in Ornamental Pest Management. M. Brownbridge, M. Skinner & B.L. Parker. OFA Bulletin, June 1998. A publication of the Ohio Florist’s Association, Columbus, OH.

• Making the Most of Biopesticides. M. Brownbridge. Greenhouse Grower, July 1998. Meister Publishing Co., Willoughby, OH.

• Greenhouse Biological Control of Western Flower Thrips. R.A. Cloyd, M. Brownbridge & C.S. Sadof. The IPM Practitioner, August, 1998. A publication of the Bio-Integral Resource Center, Berkely, CA.

No milestones

Project Outcomes

Impacts of Results/Outcomes

In general growers in our region do not take the time to conduct routine scouting for pests in their greenhouses. In addition to time being a limiting factor, growers also lack the knowledge of what the different life stages of the pests are, and where to look for them. Our workshops have provided hands-on instruction as well as written reference materials for them to take home. Any time a grower adopts some kind of scouting protocol, they are potentially decreasing the unnecessary use of chemical pesticides. One of the most basic but essential skills we taught growers was how to use a hand lens. Though all of the manuals instruct growers to use a hand lens when scouting for minute pests, how to use one is never given. It was interesting to notice that most growers had no idea how to use this tool properly. Those that attended our workshops now know how to use it.

Farmer Adoption

It is impossible to confirm that growers have changed their practices for the better as a result of attending our workshops. However, based on the evaluations we received from participants (see attached), they did gain practical knowledge that they planned to try out in their operations. Only 1 participant in 1998 and 3 in 1999 indicated that they learned nothing that they could use in their greenhouse in the coming year. Growers listed a broad range of IPM practices that they intended to implement in the future, including record keeping various scouting methods and sanitation. In the future we intend to conduct a survey among growers who attended our earlier workshops to determine more quantitatively how many have put new IPM principles into practice.

Feedback from Farmers

We provided evaluation forms for all growers who attended the workshops in 1998 and 1999. Results from these evaluations were summarized and reviewed by the Advisory group, and served as the foundation for developing our next workshop program. These summaries are attached. In general the comments by growers who attended the workshops have been extremely positive. They definitely recognize and appreciate the effort we put in to the events. Registration to the workshops has increased steadily every year, demonstrating that we have established a reputation for providing fruitful educational events that are worth the time and expense.

A common request from growers has been more information about biological control. However, the Advisory Group felt that it was essential that growers gain a strong foundation in the basics of IPM, i.e., scouting, pest identification and sanitation, before they were given information about biological control. Achieving successful management with biological control can be difficult, and is nearly impossible if growers have not implemented basic IPM practices.

Areas needing additional study

A. Scouting is an essential component of IPM. It enables growers to detect and treat infestations early and monitor the efficacy of a treatment. Pest thresholds for ornamental crops are badly needed to assist growers in deciding when pest populations warrant control.

B. Studies to document the efficacy and economic advantages of using spot vs. whole crop treatment is needed. Pest infestations generally originate from ‘hot-spots’ within a crop. Regular scouting allows infestations to be detected early so pesticides can be applied over a limited area to prevent a build-up and spread of pest populations.

C. It has been estimated that <1% of pesticides actually reach the target insect. With improved targeting of sprays, efficacy could be enhanced and waste and environmental waste minimized. Studies are needed to assess and refine application protocols for high- and low-volume sprayers.

D. To further encourage growers to use biological control, innovative programs are needed to instruct growers on the use of these beneficials. Growers are eager to try these environmentally friendly approaches as long as they are effective. However, without a thorough understanding of their use, growers will be disappointed with their performance. Simple strategies for assisting growers to gradually expand their use of biological control would be most helpful.

E. Scouting remains the cornerstone of any IPM program, yet few growers have the time or inclination to inspect their crops routinely and comprehensively. Strategies that provide growers with cost-effective commercial scouting services would greatly improve the pest management programs of growers in this region. Until growers see for themselves the value of routine scouting, they will not be willing to invest in this essential practice.

F. There are many cultural practices that can effectively reduce pest infestations without chemical inputs. Some are better studied than others. A full evaluation of these practices is needed so that growers gain an appreciation for their value and how best to use them. For example, the use of screening over vents can limit pest infestations from outside, and fallowing of greenhouses as certain times of the year can eliminate pests at the beginning of the growing season. Without a full scientifically based evaluation, the most effective methods can not be recommended to growers.

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Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.