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 2012 season we continued to evaluate the actual field efficacy of nematode applications for borer management in apple and peach orchards. During this third year of the project trials were conducted in three stone fruit and four pome fruit commercial orchards with a history of borer problems. The efficacies of mulch and nematodes combinations were compared with grower standard borer control practices without nematodes. All treatments were applied in commercial orchards during the spring of 2012 and results were collected during the fall of the same season. The application of nematodes mixed in mulch to the trunk of trees provided comparable control of wood boring insects as the standard practices.

Objectives/Performance Targets

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 2012 season we compared field efficacy of nematode plus mulch combination with the standard grower practices for borer management in apple and peach orchards. Based on results from the first two years of the project and inputs from involved growers, the mulch plus nematode treatment was identified as the most promising for possible implementation in commercial orchard settings. The efficacy of nematode/mulch treatment was evaluated in four apple (dogwood borer) and three peach (peach tree borer) orchards. Two additional growers, previously not participating in the project activities, become also involved in the project. Unfortunately, due to a possible effect of borer’s mating disruption treatments on borer’s population, except for one location (i.e,. orchard DA, where grower applied seasonal DWB and PTB MD in the entire orchard), the mating disruption treatments were not utilized during these trials. Although use of mating disruption was originally planned to be a part of the field comparisons, the actual limited size of plots forced us to eliminate this part of the program. However, it is expected, when nematodes will be used on a larger whole orchard scale, the mating disruption, as a supplemental tactic, will again be incorporated into borers management programs.

The research and educational milestones of the project planned for this season were accomplished by:

1. The borer infestation levels were evaluated in multiple orchards and management trials conducted during 2012 season.

2. The combination of nematodes and mulch was identified by growers as the most practical venue for adoption of nematodes for borer control. Treatments were applied in commercial peach and apple orchards. The results were collected from each site and the data is being evaluated.

3. Extension publication describing the project results is being prepared for a distribution during the 2013 season.

4. Updates on the project will be presented to growers during educational meetings and additional growers will adopt this method in their orchards.

The two main challenges with a wider adoption of this tactics are related with the use of specialized mulch delivery tool (hydro-seeder) and commercial availability of nematodes. Due to changes occurred to the company providing entomopathogenic nematodes, in the future additional sources for nematodes will probably need to be identified.

Accomplishments/Milestones

Trials conducted during the 2012 season.

During the spring 2012 tree trunks in three peach and four apple blocks were treated with nematodes and mulch. The number of trees treated with nematodes varied from 90 to 660 trees per treatment. In each orchard, parts of the blocks or group of trees in adjoining orchard were designated as a control trees (from 80 to 400 trees). The standard borer management program (e.g., application of pesticides to tree trunk) was not used for the nematode treated trees. During the summer (July 2012), each single tree within all treated and control plots was evaluated for a presence/absence of fresh insect frass and pieces of bark. The results of these observations are presented in Table 1. Additionally, in late August and September samples of fresh frass were collected from trees located in both treatments. Each individual sample collected from a single tree was evaluated for the presence /absence and number of live nematodes. The process of data collection from nematode counts is still in progress at the time of writing this report (December 2012).

Large plastic delta pheromone traps (Trece, Inc.) baited with pheromone lures of either dogwood borer (apples) or peach tree borer (peaches) were deployed in each orchard to monitor borer populations. Traps in FREC, CML and CHTA locations were used for entire season, while traps in ER and DA orchards were used only during the late part of the season. The cumulative average moth captures per trap per location are presented in Figs. 1a and 1b.

Treatment Notes:
• Nematodes – S. carpocapsae (BioLogic Biocontrol Products, Willow Hill, PA.)
• Mulch consist following ingredients:
Easy Mix Mulch at 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; Turbo Technologies, Inc. Beaver Falls, PA);
• Mulch plus nematodes – entomopathogenic nematodes were incorporated with treatment of mulch for the application;

Nematode Applications:
Methods to apply nematodes in the orchard were developed and evaluated in the first and second years of this project. Based on the results of these early trials, all applications in 2012 used the entomopathogenic nematode S. carpocapsae at a rate of approximately 132,000 nematodes per liter of mulch mixture (500,000 nematodes / gal.). Nematode applications in the orchard were made utilizing a 50 gallon Turbo Turf Hydro Seeder. For orchard applications, fifty gallons of mulch were prepared as follows: Twelve and half gallons by volume, of dry ‘Easy Mix Mulch,’ 180 mL ‘Turbosorb’ (polyacrylamide gel) and 160 mL ‘Witches Brew’ (a tackifying agent) were added to the hydro-seeder with 25 gallons of water and agitated until thoroughly mixed. The hydro-seeder was then filled with water to the 50 gallon mark. The hydro-seeder 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 hydro-seeder hose aimed at the base of the tree. After some practice, the opening and closing of the nozzle was 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 received approximately 835 nematodes per square inch of treated trunk surface.

Fall 2012 nematodes count:
Trees treated with nematode plus mulch and control treatments during the spring 2012 were evaluated for the presence of surviving nematodes. All detected possible borer feeding sites with borer’ frass (if detected) were identified and frass together with pieces of surrounding bark were collected from each affected tree. Collected samples were placed in small plastic cups (1.0 fl oz) and stored in refrigerator for further nematode counts.

Nematode Recovery and Bioassays:
Techniques typically used for extracting nematodes from soil were modified to recover nematodes from collected insect frass and pieces of bark. Samples were collected from injured bark near the base of treated trees. The frass 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 2.

• NE SARE Wood boring project, graphs and tables, 2012 season

Impacts and Contributions/Outcomes

The 2012 grower trials in commercial orchards provided practical verification of efficacy of proposed application for entomopathogenic nematode S. carpocapsae. The application of nematodes mixed in mulch to the trunk of trees provided comparable control of wood boring insects as the grower standard practices (Tab 1 and Tab 2). While the nematode treatments were located in blocks with relatively high borer populations (Fig 1a and Fig.1b), the control blocks were identified based on close proximity to treated blocks and on captures of moths in pheromone traps. In result, although it was not planned, in every case the control blocks appeared to have lower borer pressure than block used for nematode tests. The commercial availability of viable nematodes and specialized equipment necessary to conduct treatments represent probably the most significant challenges for a wider grower adoption of this tactic. However, if application can be done by trained applicators, it should possibly eliminate this obstacle. Also, a long time window for effective use of nematode application should be helpful for the development of this kind of service. During the 2013 season we are planning to continue trials (i.e., demonstration plots) with a large scale applications of entomopathogenic nematodes (with and without mating disruption) in current and additional commercial fruit orchards located in various fruit growing regions in Pennsylvania.

Collaborators: