Areawide II - 2001 Apple Annual Report

By Ted Alway, Jay Brunner, Elizabeth Beers, John Dunley and Vince Jones

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The Areawide II (AWII) program is investigating the use of new pest control and pest monitoring methods in Washington apple and pear orchards. With funding provided by the Washington State Tree Fruit Research Commission and two federal government grants, 15 apple and six pear sites were established in the spring of 2001 in major fruit growing districts of Washington (Fig. 1). The acreage and cultivar at each site is shown in Table 1. Seven tree fruit pest management consultants, with assistance by Washington State University Tree Fruit Research and Extension Center (WSU-TFREC) and the United States Department of Agriculture Yakima Agricultural Research Laboratory (USDA-YARL) personnel, collected the data on pests and natural enemies at all sites. The consultants recorded the data in the field with a PDA (hand held computer) and sent it electronically to the WSU-TFREC, where it was entered in the database from which weekly reports were generated.

APPLES

The AWII apple program was comprised of 15 orchards, each 20 to 40 acres in size, and all using codling moth mating disruption. One-half of each orchard was treated conventionally, including receiving treatments of organophosphate (OP) insecticides as needed (OP) The other half controlled pests without the use of any OP insecticides (NON-OP). The NON-OP half of the orchard controlled the major lepidopteran pests (codling moth, leafrollers and lacanobia fruitworm) with pesticides, such as Esteem (pyriproxifen), Intrepid (methoxyfenozide), Success (spinosad) and Avaunt (indoxacarb). Other pests were controlled with registered NON-OP insecticides such as Provado (imidacloprid) and Carzol (formetanate hydrochloride).

A wide array of tools was used to monitor lepidopteran pests. Adult codling moth (CM) and leafroller species were monitored with a large delta style trap and adult lacanobia fruitworm were monitored with a plastic bucket style trap. A high-load pheromone lure (Super Lure Bubble Cap by Pherotech, Inc., designated BB) and a lure containing a non-pheromone, kairomone attractant from Trécé, Inc., called the DA-lure, were used in delta traps to monitor CM adults at one trap per 2-2.5 acres. Both pandemis (PLR) (Pandemis pyrusana) and obliquebanded (OBLR) (Choristoneura rosaceana) leafrollers were monitored using traps baited with a standard (1 mg) and low load (0.1 mg for PLR, 0.01 mg for OBLR) pheromone lure at 2 trap per block. A food-based attractant for leafrollers containing acetic acid (AA) was used in each orchard, also at 2 traps per block. Both a pheromone lure and a non-pheromone lure containing a mixture of acetic acid and isoamyl alcohol (AAOH) were used to monitor the lacanobia fruitworm (LAC) (Lacanobia subjuncta) at one trap per block. All traps were checked weekly and the number of moths recorded. The moths in the DA, AA and AAOH traps were collected and transported to the WSU-TFREC for identification, counting and the determination of sex and mating status as appropriate. The BB, leafroller and LAC pheromone lures were changed every 6 weeks, AA and AAOH lures every 4 weeks, and DA lures every 8 weeks.

Field monitoring for damage was done at key times throughout the season in each orchard. Surveys were made in each block for the amount and location of damage by each of the lepidopteran pests. Leafroller damage was surveyed in late May and early August. Damage by CM and LAC was evaluated in early to mid July, and CM damage was evaluated again prior to harvest. Bins of fruit (2500 fruits per treatment) were checked for damage from lepidopteran pests and other insects during harvest.

PEARS

Six pear orchards (each from 15 to 20 acres in size) participated in the AWII program. Each orchard was divided into four treatments:

1. AgriMek and OP insecticides used (OP +AG)
2. AgriMek used, no OP insecticides used (noOP +AG)
3. No AgriMek, OP insecticides used (OP noAG)
4. No AgriMek, no OP insecticides used (noOP noAG)

The objective of the AWII pear program was to determine whether eliminating certain insecticides known to be disruptive of many natural enemies in pear orchards could improve the biological control of several key pear pests, including pear psylla, spider mites and grape mealybug.

Each orchard was monitored with pheromone traps for CM and leafrollers as described above. The DA and AA lures were also used in the pear orchards for monitoring CM and leafrollers, respectively. Traps were checked weekly and the number of moths recorded. Every two weeks, each of the four treatments in each pear orchard was monitored separately for pear pests and natural enemies by taking a 20 beat-tray sample. Leaf samples were collected at two-week intervals from each treatment from fruiting spurs (mid May through August) and top shoots (mid-June through August). These leaf samples were brushed and counted at the WSU-TFREC or the USDA-YARL. Field assessments of CM damage were conducted in all treatments in each pear orchard, and the consultants conducted harvest time examinations of fruit in each orchard (1500 fruits/treatment, four treatments/orchard).

RESULTS

APPLES

Within the 30 treatment-block combinations (15 orchards with two treatments [OP and Non-OP --previous have used Non-Op as a designation] each), six had a total average catch for the year in pheromone traps that exceeded six moths per trap, while 13 averaged less than one moth/trap. There was no significant difference in the average CM captures between treatments in the first or second flight periods in either the high or low-pressure orchards (Figs. 2 and 3). Second generation catch of CM in pheromone traps was much lower in most orchards, reflecting reduced populations or reduced efficiency of pheromone traps in this generation (Table 2).

The DA lures attract both sexes of CM. All moths caught in these traps were collected and are being dissected to determine sex and mating status. These data will be presented later. There appeared to be a correlation of CM catch between the pheromone and DA lures, e.g. blocks with high catch in pheromone lure-baited traps tended to have high catch in DA lure-baited traps. Average catch in DA lure-baited traps in the first generation was less than in the pheromone lure-baited traps. The average second-generation catch in DA lure-baited traps (although less than the first generation) was greater than the catch in the pheromone lure-baited traps (Table 2). This is possibly a reflection of the declining efficiency of pheromone lure-baited traps later in the summer. The DA lure-baited traps show promise as a better indicator the risk of damage to fruit, especially in the second CM generation. There was no significant difference in the average moth catch between treatments in the first or second flight periods in either the high or low-pressure orchards (Figs. 4 and 5).

Leafroller: A wide range of leafroller populations was noted in the AWII blocks (Table 3). PLR tends to be the dominant species in North Central Washington and the Yakima Valley and was trapped in 11 of 15 orchards.

OBLR predominated in the Columbia Basin and Brewster areas, but was found at all sites. Capture of OBLR moths tended to increase in the second generation, while PLR did not. The number of orchards in which OBLR predominated increased from eight in the first generation to eleven in the second; PLR declined from dominance in four orchards in the first generation to two in the second. Two Brewster area growers used leafroller-mating disruption in their Non-OP treatment-blocks resulting in very low or no capture of moths in the pheromone traps. There was no significant difference in the average capture of moths between treatments in the first year for either leafroller species (Figs. 6, 7, 8 and 9).

Low load lure-baited pheromone traps for both OBLR and PLR were used at each site (Table 4).

Traps with these lures were used to investigate whether capture of moths in them better reflected in-orchard populations of leafrollers and the risk of fruit damage. Trends in moth numbers captured in the low load lure-baited pheromone traps were similar to those observed in standard load lure-baited pheromone traps, but the average catches were 80-90% lower. Correlating trap catch with damage was complicated by the use of insecticides that contributed to very low leafroller densities.

The AA (acetic acid) lures contain a food-based attractant for leafrollers. All leafrollers caught in these traps were collected for identification to species and sex. These data will be available at a later date. AA lures were also used to determine if capture of moths in traps would provide a better correlation to in-orchard leafroller populations and the risk of fruit damage compared to the pheromone lure-baited traps. Capture of moths in traps with AA lures increased dramatically in the second generation (Figs. 10 and 11), corresponding to similar increases in leafroller pheromone captures. Total moth captures in AA traps were less than 5% of the standard lure-baited traps.

Lacanobia fruitworm: This relatively new pest was monitored with both a pheromone and a food-based attractant (AAOH) lure. There was a wide range of populations as reflected in the pheromone lure-baited trap captures among the 15 orchards, though all orchards captured some moths (Table 5). Eleven of the 30 AWII orchard blocks had seasonal catches exceeding 1000 per trap, while 11 caught less than 500. Catches in pheromone lure-baited traps tended to be lower in the second generation. There was no significant difference in the average capture of LAC moths between treatments in either generation (Figs. 12 and 13).

The AAOH lure attracted several species of noctuid (cutworm) moths, and often very high numbers were collected in the bucket traps in a week. The collected moths are currently being identified to species and this information will be available at a later date.

Field Damage Surveys The AWII apple orchards were surveyed for damage by lepidopteran pests four times during the growing season: late May (leafroller feeding on shoots), early July (codling moth damage to fruit and lacanobia/cutworm feeding on shoots), early August (leafroller feeding on shoots), and late August/September (codling moth damage to fruit). The surveys showed the wide range of pest densities among the AWII orchards (Table 6).

Codling moth surveys revealed very low levels of fruit damage in July, with only 4 of 30 treatment-blocks with any detectable damage. Pre-harvest surveys showed more damage, with some fruit damage found in 7 of 30 treatment-blocks. Most of the fruit damage was found in the four blocks with over 1.0% damage. In these blocks the great majority of fruit damage was confined to the block borders. In orchards where fruit damage was detected in late summer there was no pattern that would support a conclusion that the OP or NON-OP supplemental treatment program provided better fruit protection. Overall there was no significant difference in CM damaged fruit between treatments. In the leafroller surveys in May ten blocks showed damage, with three having over 1.0% of shoots with feeding damage; however, there was no difference between treatments. Leafroller damage was slightly higher in August counts, with the OP treatment-blocks tending to have more damage than NON-OP treatment-blocks. The damage levels attributed to lacanobia were highly variable in the July survey. Seven blocks had over 2.0% damaged shoots, while seven other blocks had no detectable damage. There was no difference in the average shoot damage between treatments.

Harvest Fruit Exams During harvest fruit was checked for damage from major lepidopteran pests and other secondary pests (Table 7 and Fig. 14). Codling moth damage was detected in 12 of the possible 30 treatment-blocks. In five orchards damage was detected in both treatment- blocks. The level of fruit damage was low and exceeded 0.2% in only three blocks. Overall there was no difference in the average percent CM damage between treatments. Leafroller feeding on fruit was detected in 17 of the 30 possible treatment-blocks. There was significantly more damage detected in the OP treatment-blocks, in line with the higher leafroller feeding found in the August field surveys. Four OP treatment-blocks had fruit damage exceeding 0.5%, and could face significant risk of damage in 2002. There was little cutworm damaged fruit and no treatment differences were detected.

Damage by other pests occurred infrequently. Stink bug damage was found in four blocks. The damage was less than 0.2% in each block and was associated with nearby native habitats. Lygus damage was reported from five blocks and never exceeded 0.1%. Damage by campylomma was reported from six blocks. Damage was a particular concern in NON-OP blocks of 2 Golden Delicious orchards. No San Jose scale was found in any of the 30 treatment-blocks surveyed. Thrips damage was found in only one orchard.

Pesticide Use
Foliar applications of pesticides are summarized in Table 8.

All AWII apple blocks used CM mating disruption, generally at rates close to 200 dispensers/acre. For the summary, CM mating disruption was counted as one foliar pesticide application with cost based on the number of dispensers per acre.

The main organophosphate (OP) insecticides used in the OP treatment blocks were chlorpyrifos (Lorsban) [13 of 15 blocks] and azinphosmethyl (Guthion) [eight blocks], with a limited amount of phosmet (Imidan) [three blocks] also used. For the control of lepidopteran pests the NON-OP blocks relied upon methoxyfenozide (Intrepid) [14 of 15 blocks] and spinosad (Success) [six blocks], with lesser use of pyriproxifen (Esteem) [two blocks], indoxacarb (Avaunt) [two blocks], and Bacillus thuringiensis [one block]. The use of the more selective "soft" insecticides was not limited to the NON-OP blocks; five OP blocks also received methoxyfenozide and eight were treated with spinosad.

The number and cost of pesticide applications were not significantly different between the OP and NON-OP treatment programs, with far greater variability between sites than within sites (Table 8). The total number of sprays varied with the cultivar (e.g. mildew-susceptible varieties received more mildewcide applications) and the pest pressure at the site. For example from zero to four codling moth sprays were applied depending upon trap counts and history.

PEARS

SUMMARY

A high degree of variation was found in the populations of CM, leafrollers and LAC across the fifteen apple orchards. Pest monitoring programs seemed to provide good estimates of pest pressure and growers and consultants responded to these data with appropriate control actions. The same monitoring systems will be used in the next two years to build a base of knowledge on how to use the new methods.

At orchards where there was a significant risk of damage from CM based on monitoring information there were no control failures and the NON-OP programs supplementing mating disruption provided acceptable levels of fruit protection. There was an apparent advantage to the NON-OP programs in the suppression of leafroller and LAC densities as noted in lower levels of feeding damage on foliage. This was reflected in lower levels of leafroller damage to fruit at harvest in the NON-OP blocks. It seemed that there was no disadvantage from eliminating the chlorpyrifos application in the NON-OP blocks in the first year of the project. However, the long-term effect of such a strategy is yet to be determined.

There were no surprises relative to secondary pests or their natural enemies in any orchards. This is not unexpected in the first year of a project like this. It often takes two to three years for either negative or positive effects of altered programs to be expressed. The continuation of the AWII project at all apple orchard sites is critical in order to determine the full impact, positive or negative, of supplementing codling moth mating disruption with NON-OP controls.

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