Rose habitats to enhance leafroller biological control in pome fruits

Project Overview

Project Type: Research and Education
Funds awarded in 2004: $105,149.00
Projected End Date: 12/31/2007
Matching Non-Federal Funds: $65,344.00
Region: Western
State: Washington
Principal Investigator:

Annual Reports


  • Fruits: apples, cherries, pears, berries (strawberries), general tree fruits
  • Additional Plants: native plants


  • Education and Training: demonstration, extension, on-farm/ranch research
  • Natural Resources/Environment: habitat enhancement, hedgerows, riparian buffers, hedges - woody
  • Pest Management: biological control, integrated pest management

    Proposal abstract:

    Full Proposal

    Please note: Work in the project did not begin in 2004 as money was not received until October 2005, after the season was over.

    Narrative from original proposal
    1. Outcomes-Impacts
    Background: This project will provide the pome-fruit producer community the knowledge and skills required to enhance the biological control of our key leafroller pests (Pandemis pyrusana [PLR] and Choristoneura roscaceana [OBLR]) thereby significantly reducing pesticides use in apple, pear and cherry orchards of the Northwest. A highly effective, gregarious (~25 offspring per host) parasite of leafrollers, Colpoclypeus florus, was discovered in Washington in 1992 following its introduction from Europe to Canada in the late 60s (Brunner, 1996). It has become an abundant parasite of leafrollers in parts of Central Washington but it usually produces only low parasitism in spring (and only moderate parasitism in summer) because it is unable to over-wintering in our orchards. PLR and OBLR overwinter as very small larvae and do not provide a suitable over-wintering host for C. florus. However, we have found that the strawberry leafroller (SLR), Ancylis comptana, feeding on wild multi-floral rose, Rosa woodsii, provides this missing link in the parasitoid’s seasonal biology. We have demonstrated that the presence of naturally occurring and experimentally planted rose patches near orchards dramatically enhances leafroller parasitism in the adjacent orchards. In experimental rose plantings (3 separate small gardens of 25 m2) next to orchards, spring parasitism increased from <10% to greater than 90% of leafrollers in the adjacent orchards, with a clear relationship between parasitism in orchards with distance from the gardens. Parasitism in summer generation of the leafrollers also increased in orchards near gardens. The proposed project represents the next logical step in implementing these research findings by demonstrating this phenomenon on broader geographic scale under the varied conditions that includes. This proposal is supplemented by funding from two grower groups and the EPA. a) Increased producer knowledge, awareness, attitudes and skills. . Growers will learn how to position, plant, and maintain gardens, how to infest gardens with non-pest leafrollers, and how to maximize benefits of the key natural enemies by careful stewardship of the adjacent habitat and minimum pesticide use in nearby orchards. They will also learn how to simply assess parasitism in the field when leafrollers are abundant enough to consider remedial pesticide applications. Our project will demonstrate how this alternate host habitat is a missing link in the biology of an important beneficial wasp, which will enhance producer awareness of these otherwise esoteric ecological relationships. We have seen a remarkable desire by producers to understand all aspects of the ecology of their trees and the pests that attack them and to make their product as natural and pesticide-free as possible. Parasitic wasps, including the main wasp involved here, are very susceptible to most insecticides (Brunner et al. 2001a). It has been our experience since studying experimental gardens in close collaboration with growers, that once growers understand the ecological phenomena involved, they become much more active participants and promote the idea to their peers. In the most recent statewide grower survey (Brunner, unpublished), more than 80% (160,000 acres) of the pome fruits in Washington were treated with Lorsban for leafrollers, and more than 50% used Success, Intrepid, Esteem or Bt. There is no information on how much of this use is prophylactic, nor does the industry maintain consistent records of leafroller damage on these commodities. Wherever we sample orchards intensively we find leafrollers, suggesting that if growers want to control prophylactically, they will find leafrollers in their orchards or traps that supports this desire. We have seen that familiarity with the rose gardens changes the producer’s mindset. They begin to think of the effect the sprays have on beneficials and become reticent to spray unless they have very high levels of leafrollers in the spring generation. b) Information dissemination:
    Information will be provided to producers in multiple ways. We will publish an extension bulletin or semi-technical pamphlet that details the insects and plants in rose/strawberry gardens and how to economically create and foster these habitats. We will continue to make oral presentations at producer-attended meetings and publish articles in tree fruit grower magazines and technical journals that summarize the results and overall benefits of the gardens. We will conduct field days at garden/orchard sites in Washington and Oregon and we will maintain a web page, now under construction, that will provide current research results, details on garden establishment and maintenance, and reviews how and when to assess parasitism in the orchard ( Finally, we will provide individual consultation to producers by phone and through on-site visits whenever possible.

    We believe that these venues will completely saturate the industry in Washington and northern Oregon based on the response to our recent efforts. In the winter of 2002-2003 over 100 growers and pest managers saw our presentations at the Washington State Horticultural Convention and many others at the Western Orchard Pest and Disease Management workshop (Unruh 2003). Still others have read a magazine article describing the results (Warner, 2003) and heard a 10-minute radio interview with the PI on the Yakima Valley Agriculture Radio network. Growers from throughout the state have called about trying this approach, showing that information is getting out.

    c) Resources -- impacts
    The Pacific Northwest produces the majority of the nation’s apples (57%) and pears (65%), most of which are destined for the fresh market. Mating disruption for codling moth control (CMMD) is a successful tactic that has been implemented in approximately 50% of the pome fruit acreage in the Northwest since 1991 and has resulted in substantial reductions in organophosphate insecticide use (Brunner et al. 2001b). Implementation of mating disruption has been a tremendous boon to organic and bio-intensive production approaches. Organic acreage in Washington State tripled to 40,000 acres from 1997 to 2001 and the major share of that increase was in pome fruits (WSDA 2002). Several 2003 studies with two newly registered formulations of codling moth granulo- virus show that, when combined with CMMD, and backed up by the emergency use of Entrust (spinosad), provide a stable pest management program for codling moth in organic apple and pear.

    The producer/packer participants of this project include the two largest growers in Washington (Washington Fruit and Stemilt) as well as some of the smallest growers operations, demonstrating that there are no barriers to implementation due to business or corporation size. Furthermore, Pac Organic fruit is the largest organic packer of tree fruits in the Northwest. We believe that these gardens could be implemented in 30-40% of the acreage in 5 years as our demonstration studies are already in 1% of the acreage and our participating producers represent over 15% of Washington’s acreage.

    d) Economics and Quality of Life Impacts
    Pesticide costs exceed $25/acre per application with more than 2 applications per year. Replacing one leafroller spray with biological control in 25% of acreage would save over $1 million per year in pesticide application costs. Our studies to date show that elevated parasitism of leafrollers in the spring generation leads to even higher parasitism in the more damaging summer generation. Hence, reduced pesticide use in early season will both enhance biological control in the second generation of leafrollers and reduce the need for second or third applications of insecticide. Similarly, reduced insecticide use may enhance biological control of other pests providing the added benefit of fewer insecticide applications for control of these pests (e.g. aphids, scale). Lorsban, the material of choice for early season leafroller control, is a disruptive organophosphate that has been found in surface waters above EPA standards in the Pacific Northwest and is targeted by EPA under FQPA guidelines. Clearly, reduced use of Lorsban will reduce the risk of ground and surface water contamination and enhance worker safety, clear quality of life issues.
    We believe that when the mindset changes, as discussed in section IIa, the use of pesticides for leafroller control will drop dramatically.

    2. Producer Involvement
    When submitted in 2002, this project involved 3 Washington grower-cooperators in 2 different growing districts (4 gardens). These growers invested effort as follows: they listened and learned about the ecology of the system, they cleared land, purchased, installed and operated irrigation systems for gardens which we planted. In 2003, several more growers planted their own gardens. They, in addition to making site preparations, purchased roses and strawberries and planted them. Our involvement has been to provide infested plants to allow the strawberry leafroller to establish at these sites. Currently we know of and are cooperating with 24 gardens in 6 production areas from the northern part of the Okanagon Valley in Washington to The Dalles and Milton Freewater areas of Oregon. Hence, producer involvement is high and begging to be expanded. We believe more critical to involving more growers is harnessing current involvement so that the appropriate statistical and biological comparisons are used for evaluating the results. It is wonderful that Northwest fruit growers are eager to invest in novel ways to control pests biologically, but worrisome if they do so in an incomplete way and draw unfounded negative conclusions. We will focus our efforts on the 13 growers and 24 gardens, to collect robust data form studies that are uniformly conducted. We will foster much greater producer involvement by having a unified view of the merits of this approach by well known industry representatives and presentation of these results in the venues discussed in IIb.

    3. Project Relevance to WSARE Program Goals
    This project directly addresses WSARE goal 3 with a special emphasis on reducing the use of toxic chemicals and integrating biological controls. Benefits of this approach will include reduced reliance on insecticides to control leafrollers and reduction or elimination of leafroller damage. Enhanced biological control of other pests will be an additional benefit of reduced pesticide use. Management programs without neurotoxic insecticides have shown much higher abundance of beneficial species supporting biological control in apples in Washington (Epstein et al. 2000). The method is especially suitable for use in orchards that use mating disruption for codling moth control, which is becoming a more stable system supported by other non-toxic, species specific and organically certified bioinsecticides and prasitoids. It is also clear that reliance on a self-sustaining and permanent habitat modification to replace pesticide use is a vivid example of increased sustainability of a pest management approach.

    Project objectives from proposal:

    objectives from original proposal

    Project Objectives
    We have three discrete objectives:

    1. Evaluate the impact of large gardens (ca. 75 to 200 m2) of Rosa woodsii and wild strawberry harboring the strawberry leafroller, Ancylis comptana (SLR) which supports C. florus overwinter and enhances parasitism of OBLR and PLR in adjacent orchards.
    2. Disseminate information on how to establish, maintain and benefit from these alternate habitats through traditional presentations, grower magazines, a web site and consultation.
    3. Develop greater understand of the ecology of this system, particularly how far into orchards will parasitoids disperse from gardens. And the stability of the beneficial community in gardens with rose alone versus, strawberry alone, and rose plus strawberry.

    Background: We planted 4 small (5 by 15 m) mixed gardens of mixed strawberry and rose within 50 m of orchard edges in the summer of 2000. We documented their effects in enhancing parasitism in nearby orchards in the spring and summer of 2001 and again in 2002. Late in fall of 2002 and spring of 2003, grower cooperators have planted 18 more gardens (see producer involvement), provided simple irrigation systems to support the gardens and have reduced pesticide use near gardens. Parasitism of the leafrollers in orchards adjacent to new gardens is was assessed (see below) to give a “before-garden” picture of parasitism. The new gardens have been seeded with SLR in October 2003, and with C. florus, if not already present.

    Objective 1 In 2004-2006, the effects of gardens on PLR and OBLR parasitism in orchards will be measured by sampling naturally occurring populations of leafrollers, or, if they are too rare, by exposing lab-produced leafrollers placed on tree branches at specified positions in the orchards. Positions of samples are of 3 types: 1)between 5 and 10 tree rows from the gardens, 2) as distant from garden as feasible toward the center of the orchard, and 3) within 5 to 10 rows of the orchard edge at a site distant from any gardens. This is done twice per year in the spring and late summer generations of the leafroller and if lab-reared leafrollers are deployed we do so when 3rd instar is the modal stage in the field, and deploy that stage. After exposure for 3 weeks in spring and 2 weeks in summer (or when leafrollers first begin to pupate) we collect and rear leafrollers to adulthood, individually on clean apple leaves. Leafrollers and parasites ae identified and parasitism rates are calculated.

    Similar exposures were completed in 2003 both for the new gardens prior to being infested by SLR (pre-garden exposures) and at 6 sites with gardens established in 2002 or before. Phenology and abundance of the SLR in rose/strawberry gardens and the extent of parasitism by C. florus and other parasites will be monitored in the gardens each winter providing the critical measure of garden productivity. Fruit damage by leafrollers will not be assessed by us but cull records for our test blocks compared to other orchard blocks will be provided by cooperators. We will critically compare before garden parasitism to after garden parasitism in the 1st through 4th year after gardens were infested, depending on the age of the garden, We expect parasitism of leafrollers in orchards near gardens to increase at all new sites across years and remain high in sites planted in 2000 and 2002. Nonparametric methods (Kruskal Wallace) methods will be used to detect significance of close or far from garden and interior and far from garden. Simple paired r by c contingency tests will be used to detect before an d after effects. Spring and late summer generations will be analyzed as separate experiments.
    Finally, in winter we will sample rose and strawberries in gardens each year to asses the stability of the SLR host population and the extent of overwintering parasitism. Forty rose stems and 4 0.25 m sections of strawberry will be destructively sampled and SLR abundance and parasitism rates measured.

    Objective 2. We will develop for growers a “how-to-do-it” pamphlet that describes methods of planting, maintaining, and infesting gardens located near orchards. An enhanced version of the pamphlet will be available a web site at ARS Wapato ( Several oral presentations will be made to the grower community (horticultural conventions and other meetings) and the approach will be presented in the Good Fruit grower magazine that enjoys wide readership in the Northwest (years 2 and 3). ARS Research Magazine will be presenting a feature article on the method in the November 2003 issue. Regionally appropriate demonstration sites will be used as backdrop for field days demonstrating the method of planting and management the rose– strawberry leafroller habitat and the simple method of assessing parasitism rates in the field. In 2004 an emphasis will be placed on summarizing past results, web page development, and large-forum presentations. In 2005 and 2006 we will include field day demonstrations.

    Objective 3. At 4 or 5 gardens selected because linked orchards are large and, ideally, have high leafroller populations, we will measure parasitism rates related to distance from the garden. Methods follow Obj. 1 except we will make collections along multiple transects extending from the gardens. Analyses will be simple regression of distance from garden to

    In an experimental orchard (The USDA-ARS farm in Moxee Washington) we will examine another factor: the importance of rose, strawberry or the combination of the 2. We have planted 3 rose alone gardens and 3 rose/strawberry gardens in 2003. In 2004 we will add 3 strawberry gardens. We will infest all gardens with SLR and C. florus through the summer of 2004. We will assess population densities of the SLR and parasitism each winter and midsummer through 2006.

    Expected results:(Modified fro proposal)

    1. Summer parasitism in orchard prior to garden planting will be low generally and Colpoclypeus florus will be absent or in trace amounts. Tachinidae will dominate the pre-garden parasite complex. Gardens will be established and will be infested with the strawberry leafroller in the nid-late summer. In fall C. florus will find attack these leafrollers and subsequently go into overwintering diapause
    2) In spring, parasitism in orchards near gardens will show elevated levels of parasitism by C. florus and this will result in greater parasitism again in summer. Through this season and the next the abundance of the strawberry leafroller in the gardens will increase with the increasing maturity of the rose plants. In subsequent years the parasitism by C> florus will also increase both in spring and summer generation of the Pandemis and oblique banded leafrollers.
    3) Growers will experience reduced fruit damage within 2 to 3 years of garden planting in those orchards showing high parasitism of leafrollers and concommitant drops in leafroller density. Website and field days will cover the success in reaching these outcomes and

    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.