|Vol. 3, No. 3||March 1, 1998|
Inside this issue:
Cooperating agencies: Washington State University, Oregon State University, University of California, U.S. Department of Agriculture, and Chelan County.
Cooperative Extension programs and employment are available to all without discrimination.
Most of the serious insect pests that Washington apple and pear growers must contend with are exotics, having traveled from foreign lands to infest our orchards. The list of unwelcome immigrants includes codling moth, pear psylla, campylomma, San Jose scale and European red mite. The spread and introduction of exotic pests continues today at an accelerated rate, as more goods and people travel further and faster than ever.
The Washington State Department of Agriculture, in an effort headed up by State Entomologist Eric LaGasa, has conducted extensive surveys in Western Washington for a number of years to identify new exotic species that attack apple trees and to determine the extent of the infestations. Most of these pests are thought to have entered through ports in that region or to have moved down from British Columbia. Among those found since 1985 include the apple tortrix, native to Japan and Korea, the dark fruit tree tortrix, from Europe and Asia, and the lesser-bud moth, from Europe. The discovery of these exotics in Western Washington prompted a 1996 survey of roadside and backyard (untreated) apple trees in Kittitas and Okanogan Counties. These counties are the geographical pathways by which these pests could spread from Western Washington or the Canadian Okanogan into the commercial apple production areas of Central Washington..
The 1996 survey found more leaf feeders in Kittitas than Okanogan County. Only one of the recent Western Washington exotic finds, the lesser bud-moth, turned up east of the Cascades, in Kittitas County. This pest is similar in damage and appearance to the eye-spotted bud-moth that is already widespread in Central Washington where it is rarely reported as a problem. Most of the leaf feeders found on wild or abandoned trees were leafrollers, including the European, obliquebanded, fruittree and pandemis leafrollers. Of interest was the find in Okanogan County of Xenotemna pallorana. This leafroller species has been identified as a suitable overwintering host of the leafroller parasite Colopoclypeus florus, and could play a significant role in helping this parasitic wasp provide substantial biological control of both obliquebanded and pandemis leafrollers in orchards.
Most apple and pear pests, including leaf feeders, are suppressed by the regular use of broad-spectrum insecticides in orchards. The use of these insecticides, primarily organophosphates and carbamates, may be severely curtailed within a few years by the Food Quality Protection Act of 1996. Their use is also reduced in orchards in which codling moth mating disruption is adopted. This can provide opportunities for previously rare or unknown pests to appear and even cause economic damage. With this in mind, LaGasa and his crew from the WSDA, with the help of Dr. Peter Landolt of the USDA-ARS lab near Yakima, initiated a project in 1997 to identify leafrollers and other defoliators found within the Codling Moth Areawide Management Project (CAMP) sites in Washington and Oregon, and from other nearby sites with a history of minimal broad-spectrum insecticide use.
Leafrollers were the most common group found. Pandemis leafrollers were the only ones submitted for identification from the Lake Osoyoos CAMP site near Oroville, WA, while obliquebanded leafrollers were the only ones from the Medford CAMP. Both of these leafrollers were found in sites near Wenatchee, together with larvae of the fruittree leafroller and another similar tortricid without a common name, Sparganothis tunicana. About 15% of the leafroller larvae were parasitized, by more than seven different parasitic wasp species and a number of tachinid fly species.
Cutworm larvae were also submitted for identification by CAMP staff and other field cooperators in areas surrounding CAMP sites. By far the most common one was Lacanobia subjuncta, with much smaller numbers of bertha armyworms. The Lacanobia were found in many central and southern sample areas, showing that it is the main noctuid species found feeding in trees. Fruit damage from this pest has become more of a problem in orchards in many areas, including the Yakima Valley, the Columbia Basin and near Milton-Freewater, Oregon. Lacanobia was not found in northern sites in the 1997 project, and field staff are encouraged to watch for cutworms feeding on apple leaves in those areas in 1998. For more information contact Eric LaGasa at (360) 902-2063, or email@example.com.
Central to an effective orchard pest management program in Washington apple orchards is a clear knowledge of the location and relative numbers of codling moth (CM). This information will become even more important if and when we lose the relatively cheap and effective broad-spectrum insecticides we have relied upon for CM control, like azinphosmethyl and phosmet. They will probably be replaced with more expensive materials that kill a smaller percentage of the pest, as appears likely with the insect growth regulators (IGRs) being considered for registration. Timing and coverage will become more critical with these new compounds. With their higher cost, growers will require more information on CM populations before deciding to treat their orchard, or just a portion of it. In addition, because of their less robust activity, more growers will be supplementing the IGRs with mating disruption (or vice versa). However, monitoring CM in pheromone-treated orchards with pheromone lures is limited by the high levels of the pheromone present in the orchard atmosphere. Fortunately, research on CM monitoring has continued and there are several promising developments.
The recommended standard lure in mating disruption orchards has been a red rubber septum loaded with 10 mg of codlemone. This has provided consistent attractiveness to male CM for about 3 weeks in the spring and only 2 weeks in the summer. Changing the lures with such high frequency to get reliable CM catch information is a burden for consultants and growers. Drs. Larry Gut and Jay Brunner, of the WSU Tree Fruit Research and Extension Center in Wenatchee, have tested several new lures that provide CM catch at least equal to the current standard and for much longer periods.
Two lures in particular stood out in their studies. An experimental "bubble" cap manufactured by Pherotech, Inc., was shown to catch as many or more than the red rubber standard for the entire 54-day study period, without being replaced once. This held true for both the first and second generations. Based on these results, this lure will easily last 8 weeks or longer. More trials will be conducted in 1998, and the company hopes to have it commercially available by 1999. Consep, Inc., manufactures a high load "biolure" for mating disruption blocks. In 1997 tests, this biolure was shown to provide consistent attractiveness for about 4 weeks, or up to twice as long as the high load red rubber septum.
The standard trap used for codling moth monitoring has been a wing-type trap, similar to the Pherocon® 1CP. In mating disruption blocks the recommendation is to place them in the top third of the tree canopy, usually too high to allow inspection from the ground, and too install them at a higher density than in non-mating disruption blocks (one trap per 2 to 4 acres versus one per 5 to 10 acres in conventional orchards). This extra effort and expense in the pheromone-treated orchards is needed to have trapping reliability similar to conventional blocks.
Several trap designs were studied by Brunner and Gut in 1997: triangular (Delta trap, Scenturion, Inc.), diamond (Pherocon IIB, Trécé, Inc.), and pentagonal (Intercept A, IPM Concepts, Inc.). The delta trap was consistently the most effective of the three. In the first generation, it caught about 50% more then the Intercept A and three times the amount of the Pherocon IIB. Catch in the second generation was almost 100% greater in the delta trap than in the other two styles. The delta trap consists of a durable plastic body with a sticky cardboard insert on the inside bottom as the catching surface. When the size of the sticky insert was cut by 33%, the moth catch fell an equivalent amount, indicating that the superior catch numbers of the delta were related to its larger catching surface relative to the other two. This improvement in catch with the larger sticky surface seems to be more important in mating disruption blocks than in non- pheromone orchards. It also appears to be more important with codling moth catch than with leafrollers, as shown in other studies.
False negatives, i.e. traps that catch few or no CM in an area with significant CM damage, continue to be a concern in both mating disruption and conventional blocks. Using recommended protocols, the incidence of false negatives is about the same (about 5%, by some estimates) in both situations in the first generation. It is often on the orchard borders where damage occurs, and where pheromone traps fail to predict it. Some consultants have had success identifying border problems in mating disruption blocks by placing traps with standard 1 mg lures directly in the edge trees. High load lures, with 10 mg of codlemone, can catch less then the standard lure in this situation, as the high load becomes less attractive in the low pheromone levels found on orchard borders. In the second CM generation, with higher summer temperatures, trap catch efficiency declines. This may be a result of the higher temperatures causing heating and convection currents in the orchard, creating a less extensive pheromone plume from the trap and a smaller active space effectively monitored by the trap. The use of a stronger, more apparent pheromone lure may be needed in the summer.
The use attractants other than sex pheromones is a possible means to get around the problem of pheromone lures within mating disruption blocks being masked by the high pheromone levels present. A lure that could attract females in addition to males would be an advantage, as female activity is more closely linked to the risk of fruit damage.
Other methods have been used, mostly on an experimental basis. Ultraviolet light traps catch both sexes, but also catch high numbers of many other insects, require a power source and are relatively quite expensive. Passive sticky traps have very low catching efficiency, are non-selective as to the insects caught and are difficult to maintain. Bait pans containing a fermenting sugar solution, generally based on molasses, have been shown to be attractive to several insects, including codling moths, and were used by some orchardists for CM monitoring before pheromone lures were commercially available. They are difficult to use and maintain; hanging open containers of a sticky solution in the trees and refilling them frequently is not easy, nor is fishing out and trying to identify the soggy insects trapped in the goo!
Dr. Peter Landolt, entomologist with the USDA-Agricultural Research Service lab in the Yakima Valley, is identifying the compounds produced in the fermenting molasses solution that are attractive to codling moths. His goal is to develop an easily handled lure based on these attractants that can be used in a trapping system to monitor both male and female codling moths. His tests with the molasses solution have shown that many more female CM were caught than males (60% female) and close to 90% were mated. At this point, he has identified 7 different attractive compounds. In the coming field season he will continue the testing of blends and dosages of these compounds in order to develop a combination with superior attractiveness. The goal is to produce a lure that is at least equal in attractiveness to the molasses standard.
By David Granatstein, WSU Center for Sustaining Agriculture and Natural Resources, Wenatchee, WA
Consumers are clearly willing to preferentially purchase food grown with fewer pesticides, as evidenced by the 25% annual growth in organic food sales over the past five years. However, many consumers are not willing to pay high prices, and many growers are not interested in organic certification. What other options are there for growers using mating disruption?
In Europe, over 40% of the apples and pears are produced under formal Integrated Fruit Production (IFP) systems. The production standards are very detailed, consumers recognize the IFP logos, IFP fruit is preferentially sourced by supermarkets, and growers may get a premium price. Here in the Northwest, the Responsible Choice program of Stemilt Growers, Inc. and the Hood River Grower/Shipper IFP Program are modeled after the European approach.
Other "eco-label" programs, as these are often called, include California Clean Growers (soft fruit), CORE Values Northeast (apples), Partners with Nature (various crops), and Eco-O.K. (bananas). A new organization, The Food Alliance (TFA), is launching an eco-label program for fresh fruits and vegetables in the Northwest. Based in Portland, TFA has developed a stewardship program to evaluate farms for endorsement, and is working with several supermarket chains to develop a marketing program. A comprehensive evaluation of consumer reaction will be conducted during the spring as products are introduced in the marketplace. TFA is actively seeking interested growers who want to have their 1998 crop endorsed.
The Food Alliance is a non-profit organization directed by a Board representing growers, food industry, environmental and consumer groups, labor, and public agencies. A primary goal is to improve communication and understanding between consumers and producers, particularly through market based incentives.
The Food Alliance conducted national consumer research during 1996 to determine the size and nature of the "green" consumer. About half the population is interested in supporting food grown in an environmentally sound manner. One segment, the "New Green Mainstream" at 23% of the population, is very interested in eco-labeled foods and is willing to pay a premium price. The study results are published in "The Hartman Report: Phase I and II", available from The Food Alliance.
To become TFA approved, order any of their "green consumer" reports, or to receive results from their test marketing, please contact Deborah Kane, Executive Director, or Vance Corum, Marketing Director. They can be reached at The Food Alliance, 1829 NE Alberta, Suite #5, Portland, OR 97211; Tel. (503) 493- 1066; email: firstname.lastname@example.org.
Ted Alway, Editor
Phone: (509) 664-5540
Fax: (509) 664-5561
Partial Funding provided by: Washington State Tree Fruit Research Commission, U.S. Department of Agriculture-Agricultural Research Service.
WSU Cooperative Extension, Chelan County
400 Washington St.
Wenatchee, WA 98801
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