Non-chemical control of wood boring insects affecting apple and peach

Non-chemical control of wood boring insects affecting apple and peach

Summary

During the first year of the project we evaluated several alternative methods for borer management in apple and peach orchards. Commercial apple and peach orchards with a history of borer problems were selected for establishing research plots. The efficacies of various combinations of mulch/nematodes/water were evaluated under trial conditions and the best combinations were applied in commercial orchards for practical field evaluation against pesticide standard. The results of this test will be evaluated during the spring of 2011 season. Survey conducted during winter educational meetings (6 locations, about 400 growers) before the start of the program revealed significant initial grower interest in the results of this project but at the same time very strong current reliance on pesticidal methods for the control of wood boring insects in fruit orchards.

Objectives/Performance Targets

Performance Target – experimental/research: Document the field effectiveness of mating disruption and entomopathogenic nematodes for the control of wood boring insects as well as develop the best practical methods to incorporate those techniques into pest control practices.

Research Target – The results of the applied treatments will serve as the evidence of program success (short term effect). Tests will provide directions for growers on the best ways of adopting procedures. The decrease in borer populations will be evident in nematode/MD treated blocks (long term effect). During the second year of the project borer control will be sufficient to eliminate the need for additional treatments (i.e., insecticides).

Performance Target – educational: As a result of field demonstrations, presentations and publication of educational materials at least 30 new growers will incorporate mating disruption and entomopathogenic nematodes as primary tools for borer control.

Educational Target – Published factsheet, guidelines and on-site demonstrations will assist growers in application of this strategy for borers control on their farms. Growers will continue to use nematodes and mating as part of their borer control strategy.

During the first year of the project we evaluated several alternative methods for borer management in apple and peach orchards. After completion of initial trials and collection of results comparing the efficacies and associated economic constraints the project will enlist new growers into the adaptation part of the proposal (during second and third year). Commercial apple and peach orchards with a history of borer problems were selected for establishing initial research plots. The mating disruption constituted an integral part of the research.

The research and educational milestones of the project planned for the year 1 were accomplish by:

1. Securing the resources, identification of cooperating growers; establishing plans for experimental plots and conducting trials in apple and peach orchards.

2. The borer infestation levels were evaluated in multiple orchards and management trials were conducted during fall of 2010 season.

3. Grower participants for the large-scale comparisons planned during the 2011 season were identified.

4. Approximately 400 fruit growers learned about this project during educational meetings conducted by project personnel during the winter 2009/2010.

5. Grower surveys were conducted to establish the pre-existing practices and grower preferences related to the management of wood boring apple and peach pests.

Accomplishments/Milestones

Development of a model system

Progress on the development of alternative methods to control dogwood and peach tree borers is limited by the seasonal nature of the problem and other issues related to the biology of the species. This is particularly true when evaluating biological controls such as the use of entomopathogenic nematodes because there are limited windows of opportunity when conditions are optimum for application. Furthermore, it is time consuming to identify naturally infested trees for testing and labor intensive to recover borer larvae to determine efficacy of the treatment. Therefore, we have developed a model system that can substitute for naturally infested trees and provide a relatively quick evaluation of our nematode application methods.

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 more problematic in culture. 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 seek small protected spaces to pupate and strips of double-walled cardboard offer an ideal substrate. We have shown that cardboard strips containing these larvae can be stapled to the trunks of trees to mimic the natural galleries caused by dogwood and peach tree borer larvae.

Experiments – 2010:

Three orchard experiments were conducted during the 2010 season. Two experiments utilized the surrogate codling moth larvae system to evaluate application methods and nematode survival. The third experiment was conducted in three grower orchards to demonstrate the efficacy of S. carpocapsae to kill dogwood and peach tree borer larvae under typical growing conditions.

Treatment Notes:
• 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)
• Nematode only (Nema only) treatments were made using a 3-gallon backpack sprayer.
• Supplemental water applications were made using a 3-gallon backpack sprayer.

Experiment #1
The experiment was set up July 16, 2010 in apple orchard located in Biglerville PA. Three replications per treatment consisting of two trees per replication for a total of 30 trees.

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- Nematodes in mulch and detergent (Nema+mulch+detergent)

All treatments were applied to the lower 20 cm of the tree trunk at a rate of approximately 200,000 nematodes per tree. Treatment number 5 included 100 ml of household dish detergent to determine if the mulch could be made to foam to improve coverage. Mulch samples were collected 24 and 48 hours after application from the tree trunk and soil to determine if viable nematodes could be recovered.

The treatments were applied under very poor weather conditions for nematode survival. The temperatures were in the mid-nineties and it was dry. However, one reason for setting the experiment up under these conditions was to determine if the mulch could provide protection for the nematodes when conditions were less than optimal.

Results and Discussion:

Mulch samples collected from the tree trunk and soil 24 hours after application were moist to the touch but almost dry after 48 hours. The samples were soaked in water and teased apart to determine if viable nematodes were present. All samples yielded some live nematodes but fewer live nematodes were found after 48 hours than after 24 hours. This evaluation was not quantitative but only to determine if live nematodes were present.

Cardboard strips containing the codling moth larvae were collected after four days and incubated in sealed plastic boxes for an additional 7-10 days. The cardboard was carefully taken apart and the larvae and pupae present were collected for examination. It was also evident that some pupae had completed their development since there were adult moths present in the boxes and empty pupa skins in the cardboard. 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 S. carpocapsae.

Results of this experiment documented that adverse environmental conditions at the time of application can severely impact the survival and efficacy of S. carpocapsae even if supplemental water is applied following application.

Experiment #2

The experiment was set up September 28, 2010 in an apple orchard located in , Biglerville PA. Three replications per treatment consisting of two trees per replication for a total of 24 trees.

Treatment 1- Mulch with out 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)

All treatments were applied to the lower 20 cm of the tree trunk at a rate of approximately 300,000 nematodes per tree. Temperatures were moderate and the sky was overcast. Mulch samples were collected 24 and 48 hours after application from the tree trunk and soil to determine if viable nematodes could be recovered.

Results and Discussion:

Mulch samples collected from the tree trunk and soil 24 and 48 hours after application were moist to the touch. The samples were soaked in water and teased apart to determine if viable nematodes were present. All samples yielded similar numbers of live nematodes. This evaluation was also not quantitative but only to determine if live nematodes were present.

Cardboard strips containing the codling moth larvae were collected after four days and incubated in sealed plastic boxes for an additional 7-10 days. The cardboard was carefully taken apart and the larvae and pupae present were collected for examination. As in the first experiment, it was also evident that some pupae had completed their development since there were adult moths present in the boxes and empty pupa skins in the cardboard. 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.

Result of this experiment indicate that higher levels of larval infection can be attributed to applying nematodes at a slightly greater inoculum rate and under more favorable conditions. The results also show that larvae treated with a nematode / mulch application have a much high infection rate than by nematodes alone.

Experiment #3
The experiment was set up October 25, 2010 in two apple orchards to determine the level of dogwood borer control and one peach orchard to determine the level of peach tree borer control with nematode / mulch treatments. Prior to setting up the experiment these orchards were scouted to identify borer infested trees which were marked for treatment. The protocol in each orchard was the same as in experiments 1 and 2.

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

All treatments were applied to the lower 20 cm of the tree trunk at a rate of approximately 200,000 nematodes per tree in the apple blocks and 400,000 nematode per tree in the peach block.. Mulch samples were collected 48 hours after application from the tree trunk and soil to determine if viable nematodes could be recovered. Borer mortality data for this experiment will be collected in the spring of 2011. Sections of the bark that have been identified as potential borer galleries will be cut to recover larvae for evaluation.

Impacts and Contributions/Outcomes

The trials conducted during this first year of the project provided very valuable information for the incoming during the second year more applied, grower orchard based portion of the project. Results from initial treatments involving nematodes emphasized the importance of moisture for survival of the entomopathogenic nematodes applied in the orchard conditions. Our approach utilizing mulch as the moisture holder surrounding the borer infestation sites provided encouraging results. Also, during the commercial size trial, the utilization of hydroseeder to deliver mulch and nematodes to the target area without harm to entomopathogenic nematodes proved a practical approach. It is expected that results of the Experiment #3 conducted during the fall of the 2010 season utilizing commercial scale plantings will provide the final information needed for practical implementation planned for the Year 2 of this proposal. Commercial apple and peach orchards located in Adams County, PA were identified for practical application of the treatments during the 2nd year of the project.
Survey conducted during winter educational meetings (6 locations) before the start of the program revealed significant initial grower interest in he results of this project but at the same time very strong reliance on current pesticidal methods for the control of wood boring insects in fruit orchards.

Collaborators: