Washington State University Cooperative Extension

Areawide IPM Update

The Newsletter of Pheromone-based Orchard Pest Management

Vol. 2, No. 1 -- January 1, 1997

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.

CAMP expands in 1997

Funding has been provided by the USDA-ARS in 1997 for over 4000 additional acres of orchard where mating disruption will be used in a codling moth management program. Five new sites will receive support and three existing sites will be expanded. Funding will be available to each of the new areas for the cost of labor and supplies needed for the thorough monitoring required by this program. Unlike the first five sites, the cost of pheromone dispensers will not be subsidized.

The new sites selected are:

PROGRESSIVE FLAT, WA: This area produces mostly apples, with a few pears and cherries. It is located on a bench just above the City of Okanogan, in Okanogan County. Acreage will be between 500 and 600 acres. Codling moth pressure is light to moderate, and growers at this site have little experience with mating disruption to this point. Average orchard size is 20 to 25 acres.

BREWSTER FLAT, WA: This production area extends to the north and east of Brewster, WA. Apples dominate the production, with lesser amounts of pears and cherries. Codling moth pressure is light to moderate, but obliquebanded leafrollers have become a serious pest for many in this area. Some growers in the proposed area have had mating disruption experience, but most have not. Over 2000 acres could be involved at this site.

MANSON, WA: This site is located in North Central Washington near the town of Manson, along the north shore of Lake Chelan. The production is almost entirely of apples. The topography is hilly and the average orchard size is less than 25 acres. Codling moth pressure is moderate to high, and has been increasing in recent years. Mating disruption experience within this area is limited. Close to 1000 acres could be included at this site.

WEST WAPATO, WA: This production area is located in the lower Yakima Valley. The topography is fairly flat. Most of the production is in apples. Some of the acreage within the proposed site has been using mating disruption for codling moth control for one or more years.

UKIAH, CA: This 390-acre site began the areawide use of mating disruption in 1996, with support from the University of California-Berkeley and management provided by Dr. Lucia Varela of UC Cooperative Extension. Production is entirely of pears, mostly the Bartlett variety, with lesser amounts of Comice, Bosc and Starkrimson. Codling moth pressure is high, as is resistance to azinphosmethyl. Two applications of Isomate-C+ were used in 1996.

In addition to these five new sites, three of the original five areas have added acreage. The Lake Osoyoos site (Oroville) will be expanded by 300 additional acres along the east side of Lake Osoyoos, the Howard Flat site (Chelan) will add close to 600 acres to the north and east of Chelan, and the Carpenter Hill site (Medford) will add 100 acres.

Within the next several months, each of the new sites will put together a management board, select a coordinator and be ready to hang pheromone and commence monitoring by bloom time in 1997.

CAMP research reviews

Each year, a considerable portion of the money that the USDA-ARS distributes in support of the Areawide Program funds research to address needs or problems associated with this control approach. In 1997, 38% of the $1.5 million available will be spent in support of 24 different research investigations. Many of these research needs have been identified by growers or consultants within the CAMP sites, or by members of the CAMP Industry Advisory Committee. Within the next several newsletters, we'll review what has been learned from many of the 1996 projects.

Monitoring leafrollers with pheromone traps

Leafrollers have frequently emerged as a problem where broad spectrum insecticide use has been reduced, as in blocks using codling moth mating disruption. In many blocks, they have surpassed codling moth as the principal source of insect-caused fruit damage. Monitoring for larvae is difficult, time-consuming and often inaccurate. Ideally, the use of pheromone traps would provide a relatively simple and reliable means of both detecting leafrollers and assessing the need for treatment, in much the same way that codling moth traps are used. Unfortunately, the lures currently available commercially are very attractive, drawing in moths from outside the blocks being monitored. Trap catches can be high, of 100 or more moths per week, even in blocks where few or no leafroller larvae are found. Pheromone traps for both pandemis leafroller (PLR) and obliquebanded leafroller (OBLR) are used by most consultants simply to provide a general idea of leafroller presence and to track seasonal leafroller development.

Research into improving the usefulness of leafroller pheromone traps was led by Larry Gut of WSU-TFREC in Wenatchee. The standard lures used for leafrollers contain at least 1mg of pheromone. For this project, lures containing 10% of the standard PLR pheromone load or 5% of the OBLR standard load were provided by Trece, Inc. Traps containing both standard and low load lures were compared in 27 orchards for PLR and 20 orchards for OBLR. Leafroller larvae were monitored in each of these sites, with population densities being estimated after petal fall and again in mid-summer. Fruit was inspected at harvest around each trap for leafroller feeding damage.

Use of the low-load lures resulted in an 80% reduction in trap catch compared to the standard for PLR, and a 60% reduction for OBLR. More importantly, moth catch in these low-load traps from the overwintered generation (flight in June) was a good indicator of larval populations and fruit damage at harvest. In orchards where cumulative catch in the first flight was less than 10 moths, fruit damage at harvest never exceeded 0.2%. Interestingly, catches of both PLR and OBLR with standard lures also correlated well with larval activity, in contrast to what many consultants have reported. This may be due to the high density at which traps were placed (one per 2.5 acres in most cases) and to their placement away from block edges.

Use of low-load lures was an advantage with regard to trap maintenance as well. The reduction in moth catch meant that the trap bottoms were replaced less often than the standard. Both the low-load and standard lures had similar longevity, about six weeks in the field. Continuing this research in 1997 will allow for comparisons of spring larval numbers with the catch reported from the 1996 summer generation (flight in August and September).

Improving codling moth monitoring with high-load lures in mating disruption blocks

Many growers and consultants are using traps baited with lures containing 10mg of codling moth pheromone to monitor codling moth in mating disruption orchards. Many feel that the reliability of these traps in indicating the potential for fruit injury, and the need for supplemental treatments, is suspect. Too often there have been "false negatives," traps that catch few or no moths in an area with fruit damage of close to 1.0% or more. Many have also been frustrated by the expense of changing the red rubber septa (lure) as frequently as needed to maintain high attractancy (three weeks in spring, two weeks in summer). These needs have encouraged research into ways to both improve overall heromone trap reliability and extend the lure's attractive period. In 1996, 43 different CAMP orchard blocks were used to research these subjects, in a project led by Larry Gut.

Lure Type: Two experimental high-load lures were tested, in comparison with the standard 10mg red rubber septum: a plastic membrane biolure from Consep, and a luretape from Hercon. The Consep biolure outperformed the other two lures, remaining as attractive as the standard for 4 weeks in both spring and summer. A longer lasting lure, such as the high-load Biolure, could provide substantial savings in monitoring costs.

Trap Type: Four trap types were compared with the industry standard in the Northwest, the "wing" trap: a large, plastic delta trap with a sticky bottom of 8" by 8"; a cardboard cylinder "ice cream carton," or IOBC trap; the Multipher, a plastic, non-saturating trap without a sticky surface that kills moths attracted within it with an insecticide strip; and the plastic cylinder trap manufactured by Hercon.

The delta trap was the most effective over the season, being equal to or better than the other trap types throughout both flights. The Multipher and ice cream carton were generally equal to the wing trap in effectiveness, and the Hercon cylinder was below the rest. A more effective trap, like the delta, could improve trap performance, especially during the second generation when trap performance tends to decline. The Multipher trap, although less attractive, is the easiest to service. In 1997, Gut and crew plan to test versions of the Multipher trap with modified openings and different knockdown materials in an attempt to improve its performance.

Secondary pests and their natural enemies: the impact of areawide codling moth mating disruption

One of the anticipated benefits with the use of mating disruption (MD) is improved biological control of many secondary orchard pests. With a reduction in broad spectrum insecticide use, it was hoped that natural enemy populations would flourish, provide enhanced control of many pest species, and help offset some of the costs associated with the use of mating disruption. A group of researchers and cooperators, led by Elizabeth Beers of WSU-TFREC in Wenatchee, has been monitoring pests and natural enemies in both mating disruption and associated conventionally-managed (CONV) blocks. In 1996, a total of 108 blocks were intensively monitored, both within the five CAMP sites and at additional sites in Central Washington. Mating disruption was the main control measure in 71 of the blocks and 36 were managed primarily with pesticides. Both apples and pears were included.

Apples

Of the pests sampled, there was a general trend for lower pest populations and less fruit damage in MD blocks. Natural enemy populations tended to be higher.

Leafhoppers: MD and CONV blocks had similar overwintering egg densities, but egg parasitism was higher in the MD blocks. Differences in nymph counts were seen when parasitism exceeded 30% in both types of blocks.

Aphids: In general, aphids were not a problem in 1996 in either type of block. Populations were higher in CONV blocks, but this difference wasn't directly related to the number of aphid predators found. Similar levels of predators were found under both management regimes.

Leafminer: No consistent difference was found between the CONV and MD blocks in terms of leafminer infestation or parasitism. No control treatments were applied in any case. Leafminer problems are often associated with the use of organophosphate (OP) insecticides used for leafroller control. These applications can disrupt the control provided by the main leafroller parasite, Pnigalio flavipes.

Campylomma: Populations varied widely between sites and blocks. Blocks in the Oroville area consistently had higher Campylomma population levels than other sites. No differences in nymph population or fruit damage were found between MD and CONV blocks either in Oroville or the other four sites.

Leafrollers: Leafroller populations frequently increase in MD blocks. Higher levels of shoot infestation by leafrollers were found in the MD blocks both at mid-season and prior to harvest. In spite of this, there was generally a lower level of damage at harvest in the MD blocks.

Mites: Integrated mite control is the norm for most Northwest apple blocks. Generally, this held true for MD and CONV blocks in this study. However, of the three blocks that did build a significant late summer mite population, all were conventionally managed.

Codling Moth: Codling moth is the main target of most fruit growers, and of the CAMP project in particular. Codling moth damage was consistently lower in the MD blocks sampled -- only 7% had more than 0.5% damage at harvest, versus 31% of the CONV blocks.

Pears

In addition to codling moth, the main pests of concern with pears are pear psylla and mites. Pears were sampled at three of the five CAMP sites (Parker, Medford and Randall Island). This study showed good indications of better integrated control in the MD blocks of each of these two key secondary pests, both of which have a history of developing resistance to insecticides.

Pear psylla: Counts of both adults and nymphs were consistently higher in the CONV blocks. Psylla predators were low at all sites studied, with no significant difference between regimes.

Mites: Mites were significantly higher in the CONV blocks. The only predatory mites found were in MD blocks.

True bugs (stinkbug and lygus): Damage levels varied widely from site to site. This study found no significant difference due to management regime, although there was a trend for more damage in MD blocks.

Leafroller: No significant difference found, although leafroller damage was higher in the Randall Island MD blocks and lower in the Parker MD blocks. Codling moth: Overall, no difference in damage between MD and conventional management.

Ted Alway, Editor
Phone: (509) 664-5540
Fax: (509) 664-5561
e-mail: alway@coopext.cahe.wsu.edu

Partial Funding provided by: Washington State Tree Fruit Research Commission, U.S. Department of Agriculture-Agricultural Research Service.

AREAWIDE IPM UPDATE
WSU Cooperative Extension, Chelan County
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Wenatchee WA, 3 January 1997
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