Non-chemical control of wood boring insects affecting apple and peach
During the second year of the project we continued to evaluate alternative methods for borer management in apple and peach orchards. Commercial apple and peach orchards with a history of borer problems were treated with research treatments. The efficacies of various combinations of mulch/nematodes/water applied during the 2010 season were evaluated under trial conditions and the best combinations the spring of 2011 season. Additional treatments were applied in commercial orchards during the spring of 2011 and results were collected during the fall of the same season.
During the second year of the project we continued to evaluate several alternative methods for borer management in apple and peach orchards. The efficacies of various treatments were evaluated in three apple (dogwood borer) and two peach (peach tree borer) orchards. After completion of initial trials and collection of results comparing the efficacies and associated economic constraints the project enlisted growers into the adaptation part of the proposal. Commercial apple and peach orchards with a history of borer problems were selected for establishing research plots. Due to the small size of experimental blocks, the mating disruption treatments were not utilized during these trials .
The research and educational milestones of the project planned for the year 2 were accomplish by:
1. The borer infestation levels were evaluated in multiple orchards and management trials conducted during 2011 season.
2. The nematode counts conducted in the fall of 2011 season provided assessment of project treatments efficacies and identified the best practical option for implementation during the 2012 season.
3. Grower participants for the large-scale comparisons planned during the 2012 season were identified.
Utilization of a model system
The model system uses codling moth larvae as a surrogate for dogwood and peach tree borer larvae. Codling moth was chosen because we have years of experience raising this insect in the laboratory and can produce large numbers of larvae when needed whereas dogwood and peach tree borers have proven to be difficult to maintain in laboratory colony. An attempt to establish the colony of DWB during the spring of 2011 was unsuccessful, mainly due to high mortalities of collected larvae. Extensive testing under controlled conditions has shown that the entomopathogenic nematode Steinernema carpocapsae will infect and kill codling moth larvae as readily as dogwood borer larvae under the same conditions.
The codling moth larvae were utilized for the evaluation of nematodes isolated from treated trees during the fall of 2011.
Trials conducted during the 2011 season.
During the spring 2011 (May) samples were collected from 3 orchards (two apple and one peach) with various treatments applied during the fall of 2011 and nematode counts in mulch, bark and frass found on treated trees were completed. An additional, commercial apple and peach orchards were treated during the summer of 2011 with similar set of treatments. During the fall of 2011 (last week of August), samples of soil, mulch, bark and/or frass were collected from all treatments at all experimental sites, including sites treated during the fall of 2010. If present, frass was collected from all trees as sign of borer feeding, while in the absence of frass, samples of mulch or bark were collected to assess the presence of nematodes. The bark samples were collected only from treatments on apples without mulch, while the soil samples were collected only from peach trees treated with nematodes, pesticides and control treatment. Samples of isolated nematodes from all treatments were utilized in a model system with codling moth larvae to evaluate the presence of entomopathogenic nematodes (late fall 2011).
• Nematodes – S. carpocapsae (BioLogic Biocontrol Products, Willow Hill, PA.)
• Mulch – prepared as follows:
Easy Mix Mulch two and a half 5-gallon buckets by volume (Turbo Technologies, Inc. Beaver Falls, PA); 180 mL Turbosorb (Turbo Technologies, Inc. Beaver Falls, PA);
160 mL Witches Brew (Turbo Technologies, Inc. Beaver Falls, PA); 50 gallons water;
• Mulch applications were made using a 50 gallon Turbo Turf Hydro Seeder (model HS- 50 P);
• Mulch plus nematodes – entomopathogenic nematodes wee incorporated with treatment of mulch for the application;
• Nematode only (Nema only) treatments were made using a 3-gallon backpack sprayer;
• Supplemental water applications were made using a 3-gallon backpack sprayer.
Methods to apply nematodes in the orchard were developed and refined in the first year of this project. Based on the results of early trials, all applications in 2011 used the entomopathogenic nematode Steinernema carpocapsae (BioLogic Biocontrol Products, Willow Hill, PA.) at a rate of approximately 132,000 nematodes per liter of mulch (500,000 nematodes / gal.). Nematode applications in the orchard were made utilizing a 50 gallon Turbo Turf Hydro Seeder model HS-50 P (Turbo Technologies, Inc. Beaver Falls, PA).
For orchard applications, fifty gallons of mulch were prepared as follows: Twelve gallons by volume, of dry ‘Easy Mix Mulch,’ 180 mL ‘Turbosorb’ (polyacrylamide gel) and 160 mL ‘Witches Brew’ (a tackifying agent) (Turbo Technologies, Inc. Beaver Falls, PA) were added to the hydroseeder with 25 gallons of water and agitated until thoroughly mixed. The hydroseeder was then filled with water to the 50 gallon mark. The hydroseeder was kept continuously agitated to prevent settling of the mulch mixture. Nematodes (25 million per packet) were kept separate in a cooler and one packet was added to the mulch shortly before application allowing enough agitation time for the nematodes to become thoroughly incorporated in the mixture.
Applications were made using a vertically positioned fan nozzle on the hydroseeder hose aimed at the base of the tree. With practice, the opening and closing of the nozzle could be timed to deliver approximately one-third gallon of mulch around the base of each tree (approximately 167,000 nematodes per tree). A tree with a circumference of 20 inches and mulch applied up to 10 inches on the trunk would receive approximately 835 nematodes per square inch of treated trunk surface.
Spring 2011 nematodes count:
Trees treated with various treatments during the fall 2010 were evaluated for the presence of surviving nematodes. Bark and mulch was collected from all treatments and evaluated for the presence and the number of nematodes. If present, the samples of frass with or without larvae were also collected and checked for the presence of nematodes.
Evaluated treatments in three commercial orchards included:
Treatment 1 – Mulch without nematodes (Mulch only);
Treatment 2 – Nematodes without mulch (Nema only);
Treatment 3 – Nematodes in mulch (Nema+mulch);
Treatment 4 – Nematodes in mulch followed by supplemental water applications 24 and 48 hours post nematode application (Nema+mulch+H2O);
Treatment 5 – pesticidal control (Assail @ 8 oz/100 gal of water applied at 1gal/tree;
Treatment 6 – untreated control.
Nematode Recovery and Bioassays:
Techniques typically used for extracting nematodes from soil were modified to recover nematodes from mulch. Mulch samples were collected from the bark and soil near the base of treated trees. The samples were weighed and teased apart in water. The samples were transferred to Baermann funnels and allowed to soak for 48 hours before the nematodes were recovered. Extracted nematodes were transferred to petri dishes and counted under a dissecting scope at 40X.
The results of our observations from this trial are presented in Table 1.
Summer nematode applications.
A block of apples and block of peaches in commercial orchard located in Waynesboro, PA were treated in July with treatments as described below and the nematode data was collected in the fall 2011. Unfortunately, no control (untreated) block was available for evaluation at this location.
Treatment 1 – Nematodes in mulch (Nema+mulch);
Treatment 2 – Nematodes in mulch followed by supplemental water applications 24 and 48 hours post nematode application (Nema+mulch+H2O);
Fall data collection:
During the fall of 2011 samples of bark, mulch, soil and frass were collected from all treatments located in all evaluated orchards. The nematode recovery and bioassays were conducted as described previously. The summaries of results are presented in Tables 2 and 3.
Mulch naturally becomes infested with free-living nematodes that inhabit the environment and therefore it was necessary to confirm that S. carpocapsae was among the recovered nematodes. However, isolating and identifying individual nematodes is labor intensive and severely limits the number of samples that can be processed. Since it was important to determine if S. carpocapsae was present but quantitative data was not critical, it was decided to evaluate the samples using the model system bioassay technique with the codling moth larvae that was developed in the first year of this project.
Recovered nematodes were transferred to petri dishes lined with moist filter paper. Cardboard strips containing codling moth larvae were placed in the dishes and incubated for two weeks. The cardboard was then carefully taken apart and the larvae and pupae were collected for examination. Some pupae had completed their development as indicated by the presence of adult moths and empty pupa skins in the cardboard. Remaining larvae and pupae were determined to be alive if they showed movement when touched. Dead larvae and pupae were dissected to determine if they were infected with Steinernema carpocapsae.
The data related to presence of specific enomopathogenic nematodes in collected samples is still being evaluated and will be available for the year three report.
Impacts and Contributions/Outcomes
The trials conducted during the second year of the project provided practical verification of our proposed methods of application for entomopathogenic nematodes. The real world applications and data collection revealed challenges with proposed methods and expected efficacy of tested treatments. The evaluation of results is extremely time consuming and, as presented in attached tables, provides wide spectrum of results. Although the results suggest strongly good survival of nematodes in treatments with addition of mulch and additional moisture source, the exact species composition in collected samples still need to be determined. The specialized equipment necessary to conduct treatments also poses a challenge for a wider grower adaptation. Despite those potential pitfalls, due to expressed grower interest, wide scale three demonstrational plots in commercial orchards (both in apple and peaches) are planned for the 2012 season to be conducted in various parts of the Pennsylvania.
Assistant Professor of Plant Pathology
PSU, Dep of Plant Path. FREC
290 University Drive
Biglerville, PA 17307
Office Phone: 7176776116
Professor of Agricultural Economics
Pennsylvania State University
214-A Armsby Building
University Park, PA 16802
Office Phone: 8148638638