USING AEROSOL PHEROMONE PUFFERS FOR AREA-WIDE SUPPRESSION OF CODLING MOTH IN WALNUTS: YEAR SIX

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1 USING AEROSOL PHEROMONE PUFFERS FOR AREA-WIDE SUPPRESSION OF CODLING MOTH IN WALNUTS: YEAR SIX C. Pickel, J. Grant, S. Welter, R. Buchner, C. DeBuse, W. Bentley, C. Abbott, S. Goldman Smith ABSTRACT The Walnut Pest Management Alliance (PMA) continued work to reduce pesticide inputs in California walnuts and demonstrate and increase implementation of pest management strategies based on various formulations of pheromone mating disruption (PMD). Six long-term, area-wide projects continued in 2010 with aerosol pheromone puffers for codling moth (CM) control. Two of these sites, San Joaquin and Glenn, have successfully used puffers for six years as the primary CM management tool. The majority of the PMD acreage in this project did not need CM insecticide treatments in 2008 or 2009, but in 2010 supplemental sprays were required at two sites. Several years of using PMD over a large area demonstrate the benefits of this system including reduced crop damage, reduced CM populations which can be managed using fewer insecticide sprays, reduced broad spectrum insecticide applications, and a move to softer insecticides as supplements for PMD. As PMD becomes better understood, the focus shifts from managing the primary walnut pest, CM, to managing navel orangeworm (NOW) considered a secondary pest. The success of this program is the result of input from many collaborators including growers, pest control advisors (PCAs), UCCE Farm Advisors, Suterra LLC, Trece Inc, USDA-ARS, Ca. Dept. of Pesticide Regulation, the UC Integrated Pest Management Program, and the California Walnut Board. OBJECTIVES 1. Continue selected CM puffer trials in Glenn, Butte, Tehama, Yolo, Kings, and San Joaquin Counties. 2. Validate and refine the techniques for large-scale pheromone mating disruption in walnuts, with a new emphasis on PMD for NOW control. Evaluate and improve protocols for field monitoring of NOW to verify reliability and efficacy. 3. Continue field demonstration sites using meso-emitters for CM. 4. Continue educational efforts to promote adoption of CM puffer use in walnuts, especially where smaller neighboring orchards can be brought under PMD together in large contiguous areas. 5. Continue educational efforts to promote appropriate and effective CM monitoring practices in PMD orchards. PROCEDURES 1. Continuation of selected CM puffer sites including monitoring with traps, canopy counts and evaluation of harvest samples. Trap monitoring at the San Joaquin expansion area and at the Butte site was less intensive, fewer traps per acre. California Walnut Board 127 Walnut Research Reports 2010

2 2. Validate and refine large-scale PMD techniques with a new focus on use of NOW puffers. Both types of puffers are deployed in grid arrangements at rates of one CM unit per two acres, and NOW units at rates of between 1-2 units per acre. Navel orangeworm puffers are tested both with CM puffers and alone. The layout of the puffers is based on current understanding of distance and direction of pheromone plume movement at each site. Monitoring for NOW includes egg traps and also traps baited with virgin females moths. USDA researchers working on related projects provided virgin NOW females and training on the use of these techniques. Data collected from weekly monitoring is shared on a collective basis such that larger flight patterns can be observed. 3. Sites for testing CM meso-emitters were selected with the help of walnut industry field reps to locate areas with previous damage. The meso-emitters tested were provided by Suterra; selected sites also tested Pacific Biocontrol s Isomate rings. Both types of dispensers are installed at approximately units per acre, also in a grid pattern. Several sites were created with at least two sites each in the San Joaquin and Sacramento Valleys. The locations for the meso-emitters sites are more than one mile away from any CM puffers. The treatment blocks are as large as twenty acres and are monitored by project staff using traps, canopy counts and collection of harvest samples. Additional details and results are presented in another report, submitted by Dr. Stephen Welter. 4. Given that the benefits of the area-wide project include regional suppression, educational efforts to promote adoption of CM puffer use continue, especially where smaller neighboring orchards can be brought under PMD together in large contiguous areas. Nearby walnut growers are identified and contacted with the help of the county Agricultural Commissioner s staff. Project researchers meet with the nearby growers to ensure understanding of PMD with puffers and encourage the adoption of CM puffers. Local pest control advisors (PCA s) and Farm Advisors are also included in the educational efforts. 5. Efforts to promote appropriate and effective CM monitoring practices in PMD orchards is continued on a larger scale than #4 above to include field meetings and newsletters. Understanding how nearby PMD can affect trap catches and also instruction and encouragement of the use of the CM-Combo lure for more accurate monitoring data. To demonstrate area-wide control of CM, large areas of contiguous walnut orchards of several different varieties are treated with aerosol pheromone puffers. Sites include blocks with historically high CM pressure as well as portions with varieties with both high and low CM susceptibility to CM. Varieties include Ashley, Chandler, Hartley, Howard, Serr, Tehama, Tulare, and Vina (Table 1). The San Joaquin Lockeford site was in its sixth season of puffer deployment and monitoring in 2010 and a 540-acre Expansion area, in its third season. The Lockeford site is 600 contiguous acres of walnuts divided into 22 blocks of varying age, varieties, and pest pressure. It is owned and managed by a single farming entity. The Expansion area consists of ten contiguous walnut blocks adjacent to the Lockeford site, and is farmed by four owner/operators. The 180 acre Glenn site, consisting of a large block of Vinas and two small blocks with Tehamas and Chandlers, has had six years with CM pheromone puffers. The Butte site is 205 acres of Vinas in two blocks and just completed the 4 th year using puffers. The Butte and Glenn sites both have areas within the blocks that have greater CM pressure and must be monitored very closely. The site in Northern Tehama County has used the puffers for three years and the Yolo site is in its second year. This report also includes results California Walnut Board 128 Walnut Research Reports 2010

3 from the site in Kings County, also using CM puffers for the third year. The Southern Tehama site was not continued because the orchard was removed. This project was designed to manage codling moth with pheromones by lowering populations aggressively in the early years with supplemental insecticide treatments. After this, the insecticide treatments are reduced, eliminated, or switched to selective insecticides that are more environmentally friendly. In 2005, all first-year pheromone treated blocks at Glenn and San Joaquin (SJ) were supplemented with at least one insecticide treatment to ensure high quality nuts at harvest and reduce population levels at the start of the 2006 season. In 2006 and beyond, an emphasis was placed on managing codling moth population based on combo lure trap catches and in-season CM damage assessments Suterra CM puffers are deployed at or before the start of codling moth flight and are automatically programmed to emit a puff of pheromone at 15 minute intervals for a period of 12 hours each night. The puffers are arranged in a grid pattern at a rate of one puffer per two acres within the orchard and a slightly higher concentration along the outside edges. A 40-acre block at the Butte site deployed both CM and NOW puffers, and the remainder of the site acreage had CM puffers only. The NOW puffers were installed at the Butte site on May 28, 2010 at a density of two puffers per acre. Field workers at each site are trained to assemble the units in the field and hang in the upper 1/3 of the tree canopy. Operational aspects of the puffer units were described in previous reports. The entire Butte site was monitored for NOW moths with Biolure wing traps (Suterra, LLC) and NOW egg traps (Trece, Inc). The wing traps were baited with virgin female NOW moths sent from USDA at Parlier, California. Weekly, the traps were checked and the bait moths replaced with those from the current shipment. Egg traps were baited with a mixture of commercially available almond meal bait plus crude almond oil and also checked weekly. Traps were placed in a grid over the whole site to demonstrate trap shut-down after the puffers were deployed and to investigate how far the puffer effect may go. All trial blocks with CM puffers were monitored with Pherocon VI Delta traps (Trece, Inc.) baited with CM-DA Combo lure and hung high in the tree canopy at varying rates according to CM pressure and the needs of the grower. Monitoring blocks ranged in size from 10 to 25 acres, each with a Combo lure trap placed high in the canopy. For assurance that mating is being disrupted, additional traps with 1X lures (Trece Standard Lure) were hung low in the canopy. The 1X traps act as an early warning system : they should not catch any moths in a pheromonetreated orchard. Traps were checked weekly and the lures changed as recommended by the manufacturer. Data from Combo lure traps provides a picture of CM generations and peaks in flight, useful for timing of sprays. Seasonal total catches from these traps are also used as an indicator of CM population size. Codling moth crop damage from the second flight and subsequent generations was monitored with canopy counts performed from ground level or at mid-canopy height with a pruning tower. In each block, 500 to 1,000 nuts at random locations in the canopy were examined and percent CM damage was recorded. In-season damage surveys followed protocols available at Data collected from all monitoring activities were California Walnut Board 129 Walnut Research Reports 2010

4 shared with the grower/cooperator and the independent consulting firms providing Pest Control Advisor service to the grower. Supplemental insecticides were applied as needed using the growers choice of materials, based on field monitoring and damage in individual blocks. As in 2009, supplemental insecticides for CM control were unnecessary at many of the project locations in 2010, although sprays to control walnut husk fly (WHF) and NOW were applied at some sites (Table 2). Harvest samples were collected during commercial harvesting operations. Protocols for the collection of harvest samples varied slightly between sites due to differences in plot layout and to additional shaking and harvesting activities. At the San Joaquin sites, twenty to twenty-five 25- nut samples were collected from the ground after shaking in each test block. At the Yolo, Glenn and Butte sites, ten 50-nut samples were collected in each of the monitoring blocks/areas. At the Tehama sites, 1,000 nuts were collected from each monitoring area, and at the Kings site, 1,000 nuts were collected from each variety. At the Butte site, samples were collected again during a second shake which occurred 2-3 weeks later, because the majority of the crop remained on the trees after the first harvest. All nuts were cracked and examined to assess damage from codling moth and navel orangeworm. RESULTS Harvest samples reported here include total damage found in sound nuts (with intact kernels) and unsound nuts (with shriveled kernels) that would probably be removed and discarded during normal pickup and processing operations. Thus sample damage levels are sometimes higher than growers harvest grade results. Codling moth populations, as indicated by total seasonal CM-DA trap captures in each block, steadily declined at the San Joaquin Lockeford site from 2005 to This trend continued in 2010 with the exception of a few blocks - most notably two edge blocks (F 14/15 and F18) - where populations increased slightly, (Figure 1). Trap captures were so low in 2010 that canopy damage assessments were deemed unnecessary in all but these edge blocks. The grower elected to make a single late season supplemental insecticide treatment to Serr block 14/15 as a result of these assessments, and this block sustained unacceptably high codling moth damage at harvest, (Figure 2). At the San Joaquin Expansion site, codling moth populations declined from 2008 to 2009, but increased slightly in most blocks in 2010 (Table 3). In spite of this and 2 nd generation canopy damage assessments in that suggested supplemental sprays may have been helpful in several blocks, growers elected to apply no CM insecticide treatments in any of the blocks. With one exception (Vina, 65 acres), blocks at this site had minor CM damage at harvest, and damage levels were similar to those observed in In the Sacramento Valley, some locations had more success than others at keeping CM populations and damage low in 2010 (Table 2). At the Glenn site, damage from CM was the highest it has been in the six years of using puffers. Total seasonal CM-DA combo trap catches from each block show that populations are decreasing, or staying low, in the Chandler and California Walnut Board 130 Walnut Research Reports 2010

5 Tehama blocks. However, the CM population in the Vinas seems to be increasing despite the addition of up to ten extra puffers just outside the field edges (Figure 3). Even with a CM treatment to about ¾ of the site acreage, damage increased considerably in 2010, but insecticide inputs have been reduced overall since 2005 (Figure 4). The Butte site also received more CM damage than previous years (Figure 5) with 40 of the acres treated in 2010 and three years of zero CM insecticide treatments before that. Increases in mid- and late-season CM trap catches over the previous three years using puffers were also evident (Figure 6). This cooperator did not have, in 2010, the assistance of an intern who had performed weekly canopy counts in previous years. This situation illustrates the importance of in-season monitoring with the use of pheromone mating disruption. Other project sites, Tehama and Yolo, had no damage at harvest from either CM or NOW, the Kings site only received 0.2% CM damage and 0.1% NOW damage. No supplemental CM insecticides were applied at these three sites in 2010 The Kings location, which had not previously been included in this report, had two CM insecticide applications in 2008, one of which was Penncap-M. In 2009, two CM applications were also made, but with more selective materials- Intrepid and Belt; in 2010 no CM insecticides were used at all. Codling moth populations have been reduced over the three years (Figure 7). DISCUSSION Codling moth damage, total trap catches, and the number of sprays can be compared to previous years to demonstrate reduction of broad spectrum insecticides and a move to softer insecticides to supplement PMD. These measurements work well for managing CM, but it remains challenging to assess in-season NOW activity and population levels. Research is currently underway to develop a lure for monitoring NOW moths in the field and this project will field test, in 2011, any product that is showing promise. The grower/cooperators at the trial sites are enthusiastic about integrating aerosol puffers into their pest management program. Most of the sites began with grower-initiated implementation and all the growers now purchase their own puffer units and aerosol cans without monetary support from this project. The PMA plans to continue aerosol puffer implementation assistance, if funding allows, several more years at the more recently created sites to demonstrate the long term successes that have been seen in other crops such as pears. Several of the cooperating growers have expressed a desire to eliminate supplemental insecticides for CM and rely solely on the puffers for control from the first year on. Monitoring insect populations and in-season damage in pheromone-treated blocks will always be necessary and is especially important as insecticides are reduced or eliminated. Efforts to develop exact treatment thresholds if/when supplemental sprays are needed are ongoing so walnut growers have confidence in pheromonebased pest management programs. Also ongoing, is an effort to reduce edge damage that may be from mated females flying in from untreated orchards nearby. In a related project, Dr Van Steenwyk is investigating treatments with selected materials to only field edges to attempt to reduce this effect. California Walnut Board 131 Walnut Research Reports 2010

6 These successful demonstrations are creating more interest and confidence in integrating pheromone mating disruption into walnut pest management programs as shown by increasing adoption: in 2009 there were CM puffers on approximately 10,000 walnut acres, and in 2010 that acreage increased to 15,000. Table CM Puffer Project Sites. LOCATION # YEARS ACRES # BLOCKS VARIETIES San Joaquin Chandler, Hartley, Howard, Serr, Tulare, Vina Lockeford SJ Expansion Chandler, Hartley, Serr, Vina Glenn Chandler, Tehama, Vina Butte Vina Tehama-N Vina Yolo Chandler Kings Serr, Vina, Chandler Table 2. Sacramento Valley and Kings County Sites. Number of codling moth sprays applied, season total trap catches, and percent damage at harvest Sprays to control pests other than CM are not included. Location COMBO TRAP TOTALS Moths/trap # CM Sprays Harvest Damage % CM Harvest Damage % NOW Glenn % of acreage Butte % of acreage Tehama-N Yolo Kings California Walnut Board 132 Walnut Research Reports 2010

7 Table 3. In-season and harvest codling moth damage, number of CM insecticide treatments applied, and seasonal CM-DA Combo total trap captures for eleven walnut blocks in San Joaquin Expansion areawide pheromone puffer site Canopy damage assessment% CM damage % CM damage No. CM Total seasonal Combo trap Year End 1 st End 2 nd at sprays capture, generation generation harvest applied moths/trap Hartley 45a Chandler 45 a @west half Vina 44 a Chandler 20 a Serr 30 a Chandler 60 a Hartley 55 a Vina 65 a Chandler 68 a Not included in 2009, 2010 Chandler 40a California Walnut Board 133 Walnut Research Reports 2010

8 Serr 40 a Not done Not done Table 4. Glenn puffer site five years data including CM damage at harvest, total annual moths/trap, and number of CM insecticide sprays VINA % harvest Trap totals, moth/trap # of CM sprays 1 spot treat TEHAMA % harvest Trap totals, moth/trap # of CM sprays CHANDLER % harvest Trap totals, moth/trap # of CM sprays California Walnut Board 134 Walnut Research Reports 2010

9 Figure 1. Total CM-DA Combo lure-baited trap capture, all blocks, San Joaquin Lockeford puffer demonstration site. Average (1 to 4 traps/block) trap capture per block, Total Seasonal Trap captures COMBO Lure Moths per trap F1 F2 F3 & F20 F4 F5 F6 F7 F8 F9 F10 F12 F13 F14 & F15 F18 F19 F22 F23 F24 F25 California Walnut Board 135 Walnut Research Reports 2010

10 Figure 2. Percent codling moth damage at harvest, 2009 and 2010, at Lockeford Ranch pheromone puffer demonstration site. Blocks with no values shown had no CM damage in 2009 and California Walnut Board 136 Walnut Research Reports 2010

11 Figure 3. Total CM/DA Combo Trap Catches from Glenn puffer site. Average (2 to 4 traps/block) trap capture per block, Total Moths Vina Tehama Chandler Figure 4. Codling moth insecticide applications , acres in block X CM treatments per block. Only CM treatments shown. Acres Treated Chandler 30 ac Tehama 37 ac Vina 110 ac California Walnut Board 137 Walnut Research Reports 2010

12 Figure 5. Percent codling moth damage at harvest at Butte puffers Field 24 Field 25 4 % CM Damage Figure 6. Graph of codling moths/trap/day at the Butte puffers Data shown are from a selected treatment block which had high CM damage Moths/Trap/Day /1 3/22 4/12 5/3 5/24 6/14 7/5 7/26 8/16 9/6 9/27 Figure 7. Graph of CM/DA Combo trap totals at the Kings puffer site California Walnut Board 138 Walnut Research Reports 2010

13 Total DA Combo Total DA Combo Total DA Combo /28 4/28 5/28 6/28 7/28 8/28 California Walnut Board 139 Walnut Research Reports 2010