- Fruits: general tree fruits
- Production Systems: general crop production
This project consisted of a comparative analysis of three orchard systems: conventional Integrated Pest Management (IPM), Alternative Insect Management (AIM, with mixed species hedgerows, alternative groundcovers, and other strategies to decrease pest abundance and foster beneficials), and System 3 (with six subsystems, ranging from conventional IPM with clean tillage to organic PERMaculture with groundcovers and inter-crops to improve biodiversity, soil quality, and income diversity).
This project was conducted in consultation with the NW Michigan Integrated Practices (IFP) Think Tank, a farmer-industry-researcher stewardship group. The IFP Think Tank helped to design the innovative orchard systems for tart cherry (Prunus cereasus) evaluated within the context of this project, actively guiding the research, education, and publications associated with the project in an advisory capacity. Finally, the project established and assessed organic tart cherry production systems on growers’ farms and perhaps for the first time on a Land Grant University Research Station in the United States.
The North Central region produces over 75% of the U.S. tart cherry crop with an estimated farm gate and value added of over $150 million, depending on the year. Fruit crops provide wholesome and nutritious food, contribute to the economy of many communities and are an important part of the “fabric” of the rural Great Lakes region. Tart cherries are grown primarily near Lake Michigan to take advantage of the lake’s effect on moderating temperature, yet orchards also contribute to the scenic beauty of the region. Tourism relies, in part, on maintaining the rural character of the state’s agricultural regions.
Ecologically sound orchard management systems have become increasingly important as tart cherry growers strive to transition to more environmentally sound and sustainable orchard production systems. While progressive growers are experimenting with various components of highly innovative alternatives, these systems have not been adequately developed, evaluated, or effectively implemented on a broad scale. In 1994, the IFP Think Tank began to investigate alternative production systems for tart cherry. Phase I was developed to identify alternative orchard floor and nitrogen management practices for existing orchards. The resulting research was located on a commercial farm. However, design of innovative orchard systems that incorporate significant changes in basic orchard design required the establishment of a new orchard (Phase II). In 1996, the Michigan Cherry Industry and the Michigan Department of Agriculture provided “seed money” to establish a Phase II orchard at the Northwest Michigan Horticultural Research Station. This research station is a fruit grower developed and governed facility, managed by MSU. The Phase II research site was immediately adjacent to the Phase I orchard.
Phase II provided a unique opportunity to enhance the partnership with the fruit production community, to design and test solutions, and to learn about holistic orchard management and potential alternative management strategies. Outreach efforts had an impact on how growers, industry representatives, and agricultural policymakers viewed the challenges involved in reducing pesticide usage and adopting increasingly sustainable systems in tart cherry production. This increased awareness was evidenced by the decision of the cherry industry to seek funding for this project to evaluate organic production methods in a series of on-farm grower trials.
Michigan Tart Cherry Industry
More than 75% of the U.S. tart cherry crop is produced in the NCR, with a farm gate and value added worth of about $150 million per year. In 1996, Michigan had 27,300 acres of bearing tart cherry trees that produced 40 million pounds of fruit for a gross farm gate value of $31.2 million (1996-97 MI Agric. Statistics). In 1996, utilization included fresh market (<1%), canned (28%), frozen (69%) and other uses (2%); and 72% of the crop was produced in the northwest region, which was the area of this research project. Cherry production is managed through use of a conventional horticultural model and is impacted by numerous key insect, disease, weed and nematode pests.
Sour cherry is susceptible to a range of pests including the arthropods cherry fruit fly (Rhagoletis cingulata and R. fausta), plum curculio (Conotrachelus nenuphar), and mites (Tetranychus urticae, Panonychus ulmi); nematodes (several species); the diseases cherry leaf spot (Blumeriella jaapi), brown rot (Monilinia fructicola), and powdery mildew (Podosphaera clandestina); and weeds, among others. A production system had evolved that relied on pesticides applied on a weekly to biweekly basis to control pests. However, growers’ concerns about environmental quality, pest resistance to pesticides, loss of important pesticides, increasing input costs and urbanization of farmland have challenged them to change the way pests are managed. In the last decade, NW Michigan sour cherry growers have made significant reductions in the number of pesticide applications necessary to produce the high quality fruit demanded by the marketplace. Reductions in pesticide use have come primarily through the implementation of intensive Integrated Pest Management (IPM) that utilizes scouting for insects and diseases, current and predictive weather information, degree day models, alternate row middle and border spraying, innovative spray application technology and biological control.
Insect & Mite Pests in Michigan Tart Cherry
The key insect pest species in tart cherries that directly affect the quality of cherry fruit are the cherry fruit flies [cherry fruit fly, Rhagoletis cingulata (Loew) and black cherry fruit fly, R. fausta (O.S.], and the plum curculio [Conotrachelius nenuphar (Herbst)]. A complex of Sessidae moth species [peach tree borer (Synanthedon exitiosa (Say), lesser peachtree borer (S. pictipes (Grote & Robertson), and dogwood borer S. scitula (Harris)] may damage the root systems and scaffold branches of tart cherry. Other secondary pests that effect the tree canopy or winter hardiness include leafrollers, mites, aphid, leafhoppers, leafminers, plant bugs, rose chafers and scale insects.
Conventional insect pest management in tart cherries relies on cover sprays of organophosphate (OP), carbamate and pyrethroid insecticides (Hull et al. 1997). The leading insecticide applied by Michigan growers was azinphosmethyl; an OP applied to 79% of tart cherries in 1995 (USDA-NASS 1996). Other OPs applied were imidan to 37%, chlorpyrifos to 22% and methyl parathion to 8% of Michigan’s tart cherries. The carbamate, carbaryl, was applied to 10% of the cherries and the pyrethroids, esfenvalerate and permethrin, applied to 20% and 14 %, respectively. These insecticides are broad spectrum insecticides and are applied to control the wide range of insect pests in cherries. These insecticide sprays may be applied at dormant, petal fall, as three cover sprays and a preharvest cover spray.
Mite management may require applications of superior oil at dormant growth stage of tart cherry. Two miticides (Vendex or Apollo) may be applied at pre-bloom for the plum nursery mite [Aculus fockeui (Nal. & Trt.)], at third cover for European red mite [Panonychus ulmi (Koch)] and two-spotted spider mite [Tetranychus urticae (Koch), and at post harvest for two spotted spider mite.
IPM in Tart Cherries
Growers have strived to reduce their use of insecticides to control cherry fruit fly through the implementation of IPM strategies. Current strategies in Michigan include the use of yellow sticky boards to monitor cherry fruit fly, to avoid unnecessary insecticide applications (Howitt, 1993). Alternate row and border sprays are also used to mitigate the amount of insecticide applied (Edson, et al. 1998). Many growers use new spray application technology that improves distribution and coverage of spray materials. Growers who use this technology routinely reduce pesticide use by 30% or more (Edson, et al. 1998). These efforts to reduce insecticide use have been successful, yet these systems currently rely primarily on organophosphate insecticides. Growers need economically viable and ecologically sound alternatives that will effectively control cherry pests and meet the stringent quality demands of the marketplace.
The evolution of IPM and recommendations for the future have been reviewed in a comprehensive manner by Bird and Berney (1998), Benbrook (1996), Board on Agriculture (1996) and Bird et al. (1990). The IPM system to be used in the research will be based on the conventional management system (Hull et al. 1997), but will not include the pyrethroid applications that can lead to herbaceous mite outbreaks. All pesticide applications will be applied only when weekly scouting reports indicate that management is necessary. Furthermore, most pesticides will be applied as alternate row sprays to further reduce the amount of product required to manage those insect pests that are highly mobile, i.e. cherry fruit flies (Edson et al. 1998).
Living hedgerow barriers may be an underexploited and non-chemical means to prevent the movement of insect pests into an orchard. For the past 10 years, researchers at MSU have studied key insect pest movement into and out of Michigan fruit plantings (Whalon & Croft 1986, Whalon & Croft 1985, Larsen & Whalon 1988, Mowry & Whalon 1984, Whalon & Elsner 1982, Bush & Whalon 1995, Bush et al. 1997). Several key pest species including plum curculio, fruit flies, tarnished plantbug, certain leafhoppers (particularly X-disease vectors- Paraphlepsius irroratus and Scaphytopius acutus), rose chafers, and several leafrollers orient their flight below 3 m. Many of these species (tarnished plantbug, rose chaffer, P. irroratus leafhopper, etc.) prefer to fly just above the ground cover in the boundary layer of air. Physical net or screen barriers used in field situations to significantly reduced pest immigration into test plots (Yudin et al. 1991). Wipfli et al. (1991) showed that 1.2 m-tall screen barriers were effective in reducing tarnished plantbug immigration into plots. A 6.0 m-tall physical net barrier surrounding peach plots effectively reduced the immigration of aphids and reduced the number of lepidopteran pests (primarily leafrollers) captured in pheromone traps (Bush & Whalon 1995). These barriers may keep larger mammalian pests, such as deer and unwelcome humans out of the orchard. Finally, treating the hedgerow barrier with repellents or low rates of insecticides (pyrethroids) will repel many pest species that frequently invade orchards from outside sources, i.e., leafrollers and fruit flies (Maxwell 1968, Whalon & Croft 1985, Prokopy et al. 1990).
Orchard Decline and Replant Issues
Tart cherry replant and orchard decline problems are complex and involve a range of interacting pathogenic and abiotic factors. Nematode problems associated with stone fruit production are reasonably well documented (Bird and Melakeberhan 1995). In Michigan, low soil pH and high root-lesion nematode (Pratylenchus penetrans) were the most commonly observed factors in a survey of declining orchards (Melakeberhan et al., 1993). Nutritional imbalances, however, are also common in soils with low pH, and Melakeberhan et al. (1997) demonstrated that population densities of P. penetrans associated with cherry seedlings maintained under optimal soil nutritional conditions did not increase as much as population densities of this nematode associated with cherry root-stocks maintained under an environmental with nutrient stress. Recent nematology research (Berney and Bird 1998, and Freckman and Ettma 1993) has demonstrated that the nematode community ecology relationship between non-plant parasitic nematodes (bacterial and fungal feeders, etc.) and plant pathogenic nematodes can be an indicator of overall soil quality and used to differentiate among different types of farming systems. Similar results were observed in a 1997 comparison of alternative soil nutrient management systems associated with a potato research project. It has been indicated that soil-borne diseases associated with agricultural crops may be directly related to the type of overall system used for managing soil nutrients (Walters and Fenzau 1996). Innovative Tart Cherry Orchard Systems: Design, Evaluation and Demonstration is structured in a way that will test this hypothesis.
Orchard Ground Covers
Ground covers are critical components of orchard systems, both with and without the use of herbicides. They significantly impact both beneficial and detrimental soil-borne organisms (Bird and Berney 1998). Recent research on the role of covercrops in Michigan will be used in development of the alternative orchard systems associated with this project (Mutch et al. 1998). Orchard ground cover harbors at least one-third of the arthropod and most of the plant diversity in Michigan fruit plantings (Strickler & Whalon 1985). Most pest insects, mites and pathogens spend at least one life stage in the ground cover (Mowry & Whalon 1984, Whalon & Elsner 1982). Ground cover management is an important part of sustainable IPM programs in tree fruit production systems (Bugg & Waddington 1994, Flexner et al. 1991, Klonsky & Elmore 1989, Meagher & Meyer 1990, Meyer et al. 1992, Smith et al. 1989, Stinchcombe & Stott 1983). It can also have an impact on surface water runoff of nitrate and some pesticides (Merwin et al. 1996). In some regions of the United States, growers have relied on ground cover to harbor beneficial mite species that move into the apple canopy to control European red mite and two-spotted spider mites (Croft 1982, Coli et al. 1994, Alston 1994).
Furthermore, research has indicated that fungal endophytes (Acremonium spp.) associated with perennial ryegrass (Lolium spp) inhibit insect feeding and effect arthropod populations (Clay et al. 1985, Johnson et al. 1985, Kirfman et al. 1986). We have explored a unique endophytic rye grass-ground cover system that reduces the need for insecticidal control of leafhoppers and other pests in orchards (Rahardja et al. 1992, Garcia et al. 1991). Mowing ground cover at specific times has been experimentally successful in disrupting the life cycle of some insect pests such as the tarnished plantbug (Whalon, unpublished data). Thus, phenologically timed mowing of ground cover could serve as an additional nonchemical strategy to control important insect pests of fruit trees.
Novel Pest Control Chemicals
There are novel pest control chemicals that recently entered or will enter the market that may be used by growers to manage cherry pests. The key characteristics that make these products marketable include pest specificity, environmental friendliness and novel modes of toxic action on target pests. Two potentially useful products for cherry fruit flies are spinosad (Success, Spintor by DowElanco) and fipronil (Rhone-Poulenc). Both products claim activity towards dipteran pests and spinosad has been shown to have activity against cherry fruit flies in field trials in Michigan (G. Thornton, pers. comm.). Both products plus imidacloprid (Provado by Bayer) claim activity towards adult coleopteran pests. These products may be useful for plum curculio management and imidacloprid has been shown to be effective in reducing plum curculio damage to fruit in apples (Bush & Whalon 1997). Imidacloprid is also toxic towards several sucking insects that affect cherries including aphids, leafhoppers and scale insects. The pesticide tebufenozide (Confirm by Rohm & Haas) and spinosad have activity towards lepidopteran pests. These compounds are registered for use on apples in Michigan and have provided effective control for leafrollers (Biddinger et al. 1996, Waldstein et al. 1999, Waldstein and Reissig 2000).
Attract and trapping strategies may have potential in the management of cherry fruit flies and plum curculio. For cherry fruit flies, yellow sticky traps baited with ammonium acetate are attractive and can be used to trap adults before oviposition begins. An apple maggot trap-out strategy with red spheres showed promise for maggot management with reduced or no insecticide applications. Prokopy (1991) placed sticky red spheres with a synthetic fruit odor around the perimeter of apple orchards to trap out immigrating adults and documented acceptable levels of damage without late season insecticide applications. Duan & Prokropy (1995) used red spheres treated with dimethoate, feeding stimulants, and red acrylic paint to effectively manage apple maggot in three of four orchards tested. A similar approach could be combined with the hedgerow barrier to intercept invading adults before they enter the orchard. The effectiveness of pesticide treated spheres for the control of apple and blueberry maggot has also been demonstrated in Michigan (Liburd et al. 1999, Liburd et al. 2000).
Another attraction and trapping program for fruit flies are bait attractants combined with photosensitive dyes. Several combinations have been shown effective against several species of fruit flies (Bergsten 1997). In a field study, this approach was as effective as malathion baits in reducing tropical fruit fly populations (Mangan & Moreno 1997).
IPM Technologies (Portland, OR) has contacted us about Sirene, new “attract and kill” formulations that utilize a pheromone plus insecticide combination. Sirene formulations have been developed and field-tested for codling moth and another coleopteran pest, the cotton boll weevil (Kirsh 1997). Recently, grandisoic acid was isolated as an aggregation pheromone produced by the adult male plum curculio (Eller & Bartelt 1996). Our field trials show that traps with grandisoic acid were more attractive to plum curculio than traps without grandisoic acid (Coombs et al. 1997).
Avoiding or reducing the application of broad-spectrum pesticides will enhance the potential for biological control of some pests in cherries. A program based on mating disruption allowed forbuildup of natural enemies that suppress primary pest and spider mite outbreaks (Westigard & Moffitt 1984). Knight (1994) found increased numbers of leafhopper parasites, Anagrus spp., and increased incidence of parasitized leafminers in pheromone-disrupted organic apple orchards. An pest management program based on attract and kill for apple maggot encouraged the buildup of natural enemies such as leafminer parasites and spiders within the fruit canopy (Prokopy et al. 1994). Furthermore, both the hedgerow barrier and ground covers should enhance biodiversity and the abundance of predacious arthropods. Hedgerow barriers can reduce predator movement out of orchard plots and be supplemented with nectar rewards that attract insect parasitoids. The effectiveness of predacious insects and mites was enhanced by protective environmental structures (Pree & Hagley 1985, Hagley & Miles 1987). Both studies reported a reduction in the number of pesticides applied for aphid and herbaceous mite management. Inundative releases of commercially available natural enemies within barriers was explored in a low-cost pioneering effort to provide Michigan apple growers with an alternative to insecticide sprays for aphid pests (Bush & Whalon 1995).
Ground covers and hedgerow barriers may serve as overwintering sites for plum curculio and plum curculio may spend up to one month in the soil while it pupates. Both life habits lend themselves to the management of plum curculio through entomopathogens associated with the soil, ground cover and high relative humidity. Plum curculio has been reported as susceptible to the bacteria Beauvaria bassiana (Tedders et al. 1982) and B. bassiana was identified as a mortality factor in overwintering plum curculio (McGriffen & Meyer 1986). A commercial formulation of B. bassiana is being developed by Mycotech and can be applied to curculio overwintering and pupal sites in the ground cover and hedgerow barriers to better manage plum curculio. Plum curculio is also highly susceptible to entomopathogenic nematodes, particularly Steinernema carpocapsae (Tedders et al. 1982, Olthof & Hagley 1993) and Heterorhabditis spp. (Brossard et al. 1989). Both B. bassiana and entomopathogenic nematodes may reduce the abundance of the cherry fruit flies that spend nearly 10 months of the year in the orchard soil.
The goal of this project was to design, demonstrate, and evaluate innovative and holistic orchard systems for tart cherry production that are effective and practical, reduce pesticide risk and environmental impact, and sustain the economic viability of growers and their communities.
1. To utilize a grower-research-industry partnership, the Northwest Lower Michigan Integrated Fruit Practices Think Tank (IFP Think Tank), to design solutions to cherry industry pest and production challenges within the context of holistic orchard management, sustainability, and environmental stewardship.
2. To assess the potential of two alternative orchard management systems: an integrated system of alternative insect management (AIM); and System Three, a continuum of six subsystems ranging from conventional IPM with clean tillage to a PERMaculture system (PER) based on the concepts of B.C. Mollison (1995). Both were compared to an intensive integrated pest management system (IPM). The three systems were designed to promote: effective arthropod, weed, disease, and vertebrate pest management; tree vigor, productivity and fruit quality; winter hardiness; plant, arthropod and nematode species diversity; soil quality; and economic sustainability.
3. To use orchard walks, learning circles and other interactive educational processes to examine the innovative orchard management systems and their components, and to facilitate discussion about holistic orchard management among Michigan cherry growers and processors.
4. To establish and assess organic production systems on growers’ farms.
Reference: Mollison, B.C. 1995. Introduction to PERMaculture. Tagari Publications. Tyalgum, Australia. 213 pp.