Development of Fungal Entomopathogens for Greenhouse IPM (LNE95-058)

Development of Fungal Entomopathogens for Greenhouse IPM (LNE95-058)

Summary

Summary
This three-state research and education initiative worked to advance the use of insect-killing fungi within biologically oriented IPM strategies for thrips and whiteflies, key greenhouse pests.
Research 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 educational components of the project show increasing grower interest in implementing biocontrol strategies. Approximately 350 people attended eight workshops, gaining basic knowledge about scouting, monitoring, insect and disease identification and management options. The project also established two Internet list-servs to facilitate exchange between growers and pest management experts worldwide.
Evaluations of the activities by participants, and members of a diverse advisory board for the project, have been very positive.

Objectives
1. Establish a regional IPM Advisory Committee comprised of growers.
2. Initiation a three-year demonstration scouting program and tri-state training workshops.
3. Assess the compatibility of fungi with beneficials and biorational pesticides.

Project Approach, Activities and Results
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.
The Tri-state Greenhouse IPM Program was established in 1995 to coordinate IPM educational activities within Maine, New Hampshire and Vermont. The Tri-state Greenhouse Advisory Committee is made up of seven growers, three researchers and seven extension/state pest specialists from within the region. 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. By joining forces, we felt we could maximize 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 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. 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, we taught growers how to use a hand lens, 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 University of Vermont 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 lists-servs 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.
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 powder and emulsifiable oil formulation, with the whitefly parasitoid Eretmocerus eremicus on poinsettia. A high degree of compatibility between the 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.

Impacts
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, they did gain practical knowledge that they planned to try out in their operations. 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.
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.

Future Recommendations
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.
Studies to document the efficacy and economic advantages of using spot vs. whole crop treatment are 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.
It has been estimated that less than one percent of pesticides actually reaches 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.
To further encourage growers to use biological control, innovative programs are needed to instruct growers on the use of these beneficial organisms. 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.
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.
There are many cultural practices that can effectively reduce pest infestations without chemical inputs. A full evaluation of these practices is needed so that growers gain an appreciation for their value and how best to use them.
Reported 11/30/99