Control of Eastern Filbert Blight

Control of Eastern Filbert Blight

Summary

The management of eastern filbert blight (EFB) using DMI or strobilurin fungicides was effective. An important discovery this year was finding that the strobilurin trifloxystrobin (Flint) not only has excellent protective action in the field and 2 days kickback in the greenhouse. A model based on branch wetness used fewer applications of fungicide and was as good as or better than the standard program. This may result in more than 50% savings in costs associated with EFB control. All research and extension projects were communicated to the hazelnut industry in a wide variety of ways.

Objectives/Performance Targets

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

Accomplishments/Milestones

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 inter-planted within heavily diseased orchards during the dormant season, sprayed with fungicides during early spring growth, then tended until evaluated for EFB cankers the following year. Some experiments were shifted this year from diseased orchards to the NWREC where access to irrigation helped ensure better survival of trees. EFB inoculum was suspended from a trellis above trees.

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. The products myclobutanil (Rally) and fenarimol (Rubigan) are also effective but provide less disease control 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. Orbit and Procure seem to have the best activity at 72 hours. None of the DMI fungicides have activity out to 96 hours.

The next generation of agricultural fungicides, the strobilurins, are beginning to be registered in various fruit markets. Products such as azoxystrobin (Abound) and kresoxim-methyl (Sovran) have been evaluated in both the field and greenhouse with disappointing results against EFB. They can be used as protectants but only at high rates and do not have any kickback activity.

An important discovery this year was finding that the strobilurin trifloxystrobin (Flint) not only has excellent protective action in the field and 2 days kickback in the greenhouse. This could be the next grower standard if test continue to show good results. Also, field protocols that deploy different chemistry at different times to capitalize on each materials advantage have been encouraging.

Several products continue to be tested including Messenger (harpin) and Actigard, which are reported to stimulate host defense mechanisms. Greenhouse studies indicated that materials effective against Botrytis and might have good activity against EFB. This needs to be verified with field studies. Field studies have indicated that we may not get 72 hours kickback with DMI’s in the field. New studies need to be initiated to further characterize this effect.

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. During the first year, trees treated every 2 weeks in the North Plains location with Bravo or according to the forecasting model with Bravo and Orbit or with just Orbit alone after a long wet period did not develop cankers. The number of cankers on trees treated according to the forecasting model with Bravo and Elite were not significantly different from zero. During the second year, our trial was oversprayed by the commercial operation adjacent to the plots. This resulted in no usable information.

During the first year, all fungicide treated Royal trees planted at the Mission Bottom location had significantly fewer EFB cankers than nontreated trees. However, there were no significant differences in the number of cankers observed on Royal trees among fungicide treatments. However, Ennis trees treated with Bravo and Orbit according to the forecasting model did not develop cankers. During the second year, trees treated according to the forecasting system have better disease control than the check but did not have as good disease control as trees treated according to the grower standard.

Refinements in the model are needed which will require field verification.

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

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.orst.edu/disease.cfm?RecordID=578

http://eesc.orst.edu/agcomwebfile/edmat/html/em/em8328/em8328.html

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.

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 and 2003) 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.

Producer Involvement

The Oregon Hazelnut Commission frequently meets throughout the year to assess research results and priorities. The commission is made up of 7 grower members that greatly influence the scope and nature of this research. During this past year they include Richard Birkemeier (chairman), Wayne Chambers, Ben Mitchell, Gary Rodakowski, and George Wolf.

Several hazelnut growers provide land and services needed to maintain research plots in areas where the disease is present. They include Richard Birkemeier, Bruce and Ron Chapin, Ben Mitchell, and Bob Jossy. David and Nita McAdams have provided seed used in greenhouse experiments. Additional growers will be used in the future to test the forecasting program.

Several hundred growers attended a winter workshop in the field to learn and discover what EFB looks like and how to find it in an orchard. Several hundred growers also attend the annual Nut Growers Society (of Oregon, Washington and British Columbia) summer tour where EFB research results have been discussed. Several new shortcourses have already been planed for the upcoming year. Another 50 growers in British Columbia attended an EFB presentation at the Horticulture shortcourse in Abbotsford, BC. A recent find of EFB near the USA-Canadian boarder is of major concern to Canadian producers.

Collaborators: