Areawide II - 2002 Apple Annual Report

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

Washington State Univeristy Tree Fruit Research and Extension Center

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 6 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.

Fig. 1. Location of the apple and pear AWII sites in Washington, 2002.

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). 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 lures, with one lure of each type being placed in a trap in each treatment-block. A food-based attractant for leafrollers containing acetic acid (AA) was used in each orchard, at a density of one trap per ca. 2.5 acres. A pheromone lure was used to monitor the lacanobia fruitworm (LAC) (Lacanobia Subjuncta) at a density of one trap per black. all traps were checked weekly and the number of moths recorded. The moths in the DA and AA traps were collected and transported to the WSU-TFREC for identification, counting and the determination of sex and mating status as approriate. The BB, leafroller and LAC pheromone lures were changed every 6 weeks, AA 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-block) were checked for damage from lepidopteran pests and other insects during harvest.

RESULTS

APPLES

Based on trap data, CM populations in 2001 declined significantly between the first and second generations, and these populations were kept low or reduced further in 2002 (Table 3 and Fig. 2). The average seasonal codling moth catch in pheromone traps in 2002 declined 70% from 2001 levels (7.2 moths/trap to 2.1 moths/trap). In nine of the 15 orchards there was a decline in their seasonal catch and in the six orchards in which no decline was observed the average catch for the season was low, 1.4 moths/trap or less.

The DA lures attract both sexes of CM. All moths caught in these traps were collected and were dissected to determine sex and mating status. Capture of moths in the DA lure baited traps was low. In the first generation, captures in the OP and NONOP blocks averaged 72% and 70% males, and in the second-generation males accounted for 67% and 63%, respectively. The percent mated females was slightly lower in the OP compared to the NONOP blocks in the first generation, 32% versus 50%, and percent mated females increased in the second generation to 80% and 78%, respectively. Catch in DA traps was correlated with pheromone trap catch, 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 similar to the pheromone lure-baited traps. The average second-generation catch in DA lure-baited traps (although less than the first generation) was slightly greater than the catch in the pheromone lure-baited traps (Table 3).

Leafroller:
A wide range of leafroller populations was noted in the AWII blocks (Table 4). OBLR is the main species captured in the Columbia Basin, Quincy and Okanogan orchards. PLR tends to be the dominant species in North Central Washington and the Yakima Valley.

There was no significant difference in the average capture of moths between the OP and NONOP treatments for either leafroller species Catches of both species were 30-50% greater in the second generation.

Low load lure-baited pheromone traps for both OBLR and PLR were used at each site (Table 5). 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, with average catches 25-45% of the standard trap averages. The low-load LR traps also showed a higher second generation catch, with an average increase of over 115% for OBLR and 80% for PLR.

OBLR catches in standard-load lure-baited pheromone-bated traps were similar in 2002 to those in 2001 but tended to be higher in the low-load lure-baited traps in 2002 (Table 6 and Fig. 3). PLR catches were significantly higher in both standard- and low-load lure-baited pheromone traps in 2002; all ten orchards having at least ten PLR moths/standard lure-baited trap/season in 2001 had higher catches in 2002, with an average increase of over 100%.

The AA (acetic acid) lures contain a food-based attractant for leafrollers. There was nearly a 50:50 ratio of males and females captured in the AA baited traps. So few moths were captured that dissection of females to assess mating status was not done. Capture of moths in traps with AA lures showed little or no increase on average in the second generation (Table 7), in contrast to increased catch in pheromone baited traps. Total moth capture in AA traps was less than 2% of the standard lure-baited pheromone traps.

Lacanobia fruitworm: This relatively new pest was monitored with a pheromone lure. There was a wide range of populations shown by the trap captures in the 15 orchards, though all orchards captured some moths (Table 8). There was no significant difference in moth capture between the OP and NON-OP treatments in either generation. Lacanobia catches were lower on average in 2002 (lower in 12 of the 15 orchards) than 2001 in the AWII orchards

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 a range of pest injury among the AWII orchards (Table 9).

Codling moth surveys revealed very low levels of fruit damage in July, with only 5 of 30 treatment-blocks with any detectable damage. Pre-harvest surveys showed only slightly more damage, with some fruit damage found in 7 of 30 blocks. In no block did damage exceed 1.0% and in only one block was damage greater than 0.5%. CM damage was largely confined to block borders. There was no significant difference in CM damaged fruit between treatments. Leafroller surveys in May detected shoot damage in only 5 of 30 blocks and there was no significant difference between treatments. Leafroller damage was somewhat higher on average in the August samples, with damage found in 14 of 30 blocks. Again, there was no significant difference between the OP and NONOP treatments. Shoot feeding damage by lacanobia or other cutworms was found in 23 of the 30 blocks in the July survey. Damage levels were not high, never exceeding 3.2% of shoots with damage.

Fruit and shoot damage levels in field surveys showed several changes between 2001 and 2002 (Table 10 and Figs. 5a and 5b).
Codling moth damage to fruit was significantly lower in the pre-harvest samples in 2002 when compared with 2001 in both the OP and NON-OP treatments. Leafroller shoot damage in 2001 had become significantly less in the NON-OP treated blocks by the August sample. This difference was again apparent in the May 2002 samples, but by August there was no difference found between treatments. Shoot feeding by lacanobia (cutworms) in July was lower in 2002.

Secondary Pests and Natural Enemies
Personnel from the WSU-TFREC visited each orchard several times throughout the season to sample specifically for a number of secondary pests and natural enemies. These samples included:

1. Campylomma - beating trays at bloom and pheromone traps in late summer
2. Aphids - infested shoot leaves in June and July, as well as aphid predators on shoots
3. White apple leafhopper - overwintering eggs and parasitism in early April, and nymphs per leaf in late May
4. Western tentiform leafminer - larvae per leaf in early June and mid July, and parasitism in June
5. Mites - tetranychid predator and apple rust mites per leaf in early June, mid July and mid August

There were no significant differences found with any of the above pests in either treatment. Most secondary pest populations were low and did not require control with pesticides.

Harvest Fruit Exams
During harvest fruit was checked for damage from major lepidopteran pests and other secondary pests (Table 11). Codling moth damage was detected in only 9 of the possible 30 treatment-blocks. The level of fruit damage was low and exceeded 0.2% in five blocks. Overall there was no difference in the average percent CM damage between treatments. Leafroller feeding on fruit was detected in 13 of the 30 treatment-blocks; only in five blocks did the amount of damaged fruit exceed 0.2%. There was no significant difference between treatments. Fruit feeding by cutworms was seen in eight blocks but only in one did it exceed 0.2%; there was no difference in damage levels between treatments.

Damage by other pests was sporadic and rare. Stink bug damage was found in only one block and was associated with the border area. Lygus damage was reported from four blocks and never exceeded 0.2. Damage by campylomma was reported from only two blocks (at 0.04 in each). No San Jose scale was found in any of the 30 blocks surveyed. Thrips damage was found in only one orchard of Grannies (0.2 fruit with marking in the OP block, 0.3 in the NONOP). One orchard of Golden Delicious had grape mealybug on the fruit at harvest (1.4 infested in the OP block, 0.8 in the NON-OP).

Fruit damage levels in 2002 were quite low and similar to the levels found in 2001 (Table 12 and Fig. 6). Only in one case (leafroller damage in OP blocks) was there a significant decline in damage.

Pesticide Use
All AWII apple blocks used CM mating disruption, generally at rates close to 200 dispensers/acre. For the summary, CM mating disruption is included as a single foliar pesticide application with cost based on the number of dispensers per acre. Applications of carbaryl (Sevin) for chemical thinning are also included as foliar pesticides. Foliar applications of pesticides are summarized in Table 13.

The main organophosphate (OP) insecticides used in the OP treatment blocks were chlorpyrifos (Lorsban) [12 of 15 blocks] and azinphosmethyl (Guthion) [six blocks]. For the control of lepidopteran pests the NON-OP blocks relied upon methoxyfenozide (Intrepid) [11 of 15 blocks] with lesser use of pyriproxifen (Esteem) [two blocks]. The use of the more selective "soft" insecticides was not limited to the NON-OP blocks; six OP blocks also received methoxyfenozide, generally applied soon after bloom for leafroller control. Spinosad (Success) was used mostly in the OP blocks for leafroller control (five OP blocks, one NON-OP block). Chloronicotinyl insecticides were used in both treatment blocks, but to a greater extent in the OP blocks: imidacloprid (Provado) in eight OP and six NON-OP blocks, thiamethoxam (Actara) in two OP and one NON-OP block, and acetamiprid (Assail) in two OP and two NON-OP blocks.

The number and cost of pesticide applications were not significantly different between the OP and NON-OP treatment programs, although the NON-OP blocks tended to be lower in both areas. The total number of sprays varied with the cultivar (e.g. mildew-susceptible varieties received more fungicide 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.

In 2002 the total numbers of sprays and the cost per acre, for both treatment types, were reduced from the levels of 2001 (Table 14and Fig. 7). This drop was most pronounced in the NON-OP blocks in which the reduction in sprays and costs was significant. In 2001, the NON-OP treatment-blocks applied on average more sprays applied and at greater cost than the OP blocks; in 2002, this order was reversed.

SUMMARY

Apples: All treatment-blocks, both OP and NON-OP, maintained low pest populations and had very low damage levels at harvest, in most cases lower than in 2001. The average number of pesticide applications and the cost per acre also declined, significantly so for the NON-OP blocks. The reduction in sprays probably stems from increased confidence in the efficacy of the new insecticides, primarily methoxyfenozide (Intrepid) and pyriproxifen (Esteem), used for codling moth and leafroller control in the NON-OP blocks.

The thorough monitoring of codling moth, leafrollers and lacanobia fruitworm provided growers with the information needed to respond with well-timed control measures where needed. Catches in the codling moth pheromone (BB) and DA lure-baited traps accurately represented CM populations; ongoing research with the DA lure will show how it can best be used to supplement monitoring with pheromones. Leafroller monitoring with standard and low-load pheromone lures showed similar population trends. The AA lure attracted very few leafrollers and will probably not be used in the AWII orchards next year.

There were no surprises relative to secondary pests or their natural enemies in any orchards. It often takes two to three years for either negative or positive effects of altered programs to be expressed. In Year 2 the NON-OP treatment blocks were able to, on average, reduce costs and further reduce already low fruit damage levels. This is especially noteworthy in a year when many growers around the state encountered increased damage, especially from codling moth. 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.

Updated January 21, 2003

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