Control of Eastern Filbert Blight

Control of Eastern Filbert Blight

Summary

The management of eastern filbert blight (EFB) using DMI or strobilurin fungicides alone or in combination was effective. The strobilurins trifloxystrobin (Flint) and pyraclostrobin (Cabrio/Pristine) continue to show excellent protective action in the field. A model based on branch wetness used fewer applications of fungicide and was as good as or worse than the standard program. This may result in more than 50% savings in costs associated with EFB control but with the risk of higher disease levels. All research and extension projects were communicated to the hazelnut industry in a wide variety of ways.

Objectives/Performance Targets

Objectives:

1. In cooperation with hazelnut growers, establish field and greenhouse trials designed to evaluate new chemicals for effectiveness against EFB.

2. Develop and evaluate an easy to use ascospore forecasting model in cooperation with hazelnut growers to help determine the need for late spring applications of fungicides.

3. Evaluate tree injection technology for the therapeutic treatment of trees already infected with EFB.

4. Document and describe organisms associated with EFB cankers. Evaluate the potential of various organisms for biological control of EFB.

5. Disseminate results to the hazelnut industry in a variety of user friendly formats.

Specific Results

1. In cooperation with hazelnut growers, establish field and greenhouse trials designed to evaluate new chemicals for effectiveness against EFB.

The management of eastern filbert blight (EFB) using different chemicals was investigated in the field on young trees. Healthy, 2-year-old trees were planted at the NWREC and EFB inoculum was suspended from a trellis above trees. These trees were sprayed with fungicides during early spring growth, and then tended until evaluated for EFB cankers the following year.

Many of the DMI type fungicides with locally systemic activity were effective. Products such as propiconazole (Orbit), tebuconazole (Elite), fenbuconazole (Indar), and triflumizole (Procure) have good activity against EFB when used alone. Greenhouse studies have shown this group of chemicals to have kickback activity against EFB. Many infections can be cured when these chemicals are applied up to 72 hours after inoculation with the fungal pathogen. In trials read this year, Indar seem to have the best activity at 72 hours.

The next generation of agricultural fungicides, the strobilurins, are beginning to be registered in various fruit markets including hazelnuts. Both trifloxystrobin (Flint) and pyraclostrobin (Cabrio/Pristine) continue to show excellent protective action in the field. Both have received EPA registration for use on hazelnuts due to data developed in this project.

Field protocols that deploy different chemistry at different times to capitalize on each material’s advantage were very successful. Several products have shown little to no activity against EFB including Messenger (harpin) and Quintec.

2. Develop and evaluate an easy to use ascospore forecasting model in cooperation with hazelnut growers to help determine the need for late spring applications of fungicides.

A model was developed, based on length of branch wetness due to rain, to help decide when to deploy fungicides. Last year, trees treated with various fungicide combinations in the new Newburg location were oversprayed by the commercial operation adjacent to the plots. This resulted in no usable information.

Due to the dry weather no DMI fungicides were applied to trees. The number of cankers that developed on Royal trees treated once with Bravo at bud break was not significantly different from the number of cankers on nontreated trees. Royal trees treated with 3 applications of Bravo on a protection schedule had significantly fewer cankers than nontreated trees. The number of cankers that developed on Ennis trees treated once with Bravo at bud break or treated with three regular applications was significantly different from the number of cankers on nontreated trees.

Although this model can be released, after several years testing it has not preformed as well as a simple calendar-based protection program. Fungicides can be saved but at the risk of more disease some years.

3. Evaluate tree injection technology for the therapeutic treatment of trees already infected with EFB.

Finished and reported previously.

4. Document and describe organisms associated with EFB cankers. Evaluate the potential of various organisms for biological control of EFB.

Finished and reported previously.

5. Disseminate results to the hazelnut industry in a variety of user friendly formats.

See below

Dissemination of Findings

All research and extension projects are communicated to the hazelnut industry in a wide variety of ways. Results have been communicated through various grower organizations, such as the Nut Growers Society, and grower meetings including a winter “Find It” workshop and an annual summer tour. Publications utilized include the hazelnut pest management guide (see web address below), the Pacific Northwest Plant Disease Control Handbook, and the On-line Guide to Plant Disease Control (see web address below ). The Eastern Filbert Blight Help Page has also been very helpful getting up-to-date information out on a timely basis (see web address below).

The following web sites are of direct interest to hazelnut growers wanting information on the control of EFB.
http://www.orst.edu/dept/botany/epp/EFB/
http://plant-disease.ippc.orst.edu/disease.cfm?RecordID=578
http://eesc.orst.edu/agcomwebfile/edmat/html/EM/EM8328/EM8328.html

Accomplishments/Milestones

Section 18 Emergency Use Labels for Elite 2001, Procure 2002 and Orbit 2003.

Section 3 registration of Flint (2003) and Pristine (for 2004).

Development of the forecasting system GRAMMA-CAST to time fungicide applications.

Development of data that show therapeutic treatment of infected trees with fungicides is ineffective.

Biological control of EFB may be possible but not without many more years of development. By that time, new immune cultivars would make it unnecessary.

Impacts and Contributions/Outcomes

The forecasting program combined with the registration of cheaper fungicides will have large financial impact on hazelnut growers. In general, forecasting programs using 2 applications of fungicide were as good as or better than the standard program using 3 applications of Bravo. From 1999 to 2001, the standard program would have used 9 applications of Bravo for a cost of chemical of approximately $277.02 while the forecasting program would have used 3 applications of Bravo plus one application of Rubigan plus one application of Elite for a total cost of $130.34 for chemical. A 50% reduction in cost of chemical alone should be helpful in the overall EFB battle.

Data from 2002 and 2003 still needs to be incorporated.

Farmer Adoption and Direct Impact

Finding cheaper and more effective chemistry has shifted grower use of chemicals. Emergency section 18 registrations have shifted as new information is developed and new regulatory road blocks are encountered. Requests have moved from Rubigan (1993-1999) to Orbit (1999, 2003 and 2004) to Elite (2000 – 2002) to Procure (2001-2003). Our ability to switch from product to product and maintain needed disease management tools is a direct result of the data generated by this project. Grower adoption of the forecasting program will take more time as results are still being evaluated.

Reactions from Farmers

Grower discussions during a recent Oregon Hazelnut Commission meeting indicate that this project was rated as a high priority. At an informational meeting held near Eugene, growers experienced in dealing with EFB said the use of fungicides and pruning was essential to maintain profitability.

Collaborators: