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Mount Vernon berry pathology research aids Westside growers

MOUNT VERNON, Wash. – Northwest Washington’s small fruit growers may get some help warding off two growing threats to their high-value crops, as a result of the ongoing work of WSU Mount Vernon’s new berry pathology research team.

Associate Plant Pathology Professor Tobin Peever, Post-doctoral Research Associate Dalphy Harteveld, and Ph.D student Olga Kozhar are studying the biology, ecology and epidemiology of Botrytis cinerea and Monilinia vaccinii-corymbosi, fungi which respectively cause Botrytis gray mold and mummyberry of raspberry and blueberry. These two plant diseases are infecting and posing a significant risk of loss to the Pacific Northwest’s blueberry, raspberry and strawberry crops, valued at $136 million according to the most recent annual statistical information available from the U.S. Department of Agriculture.

Tobin Peever
Tobin Peever

“For both diseases, we are focused on similar questions,” said Peever, whose research is geared to identify how and when infection occurs, under what environmental conditions infection occurs, how disease cycles can be disrupted, and how disease spreads among different berry crops. “We are interested in providing growers with a better understanding of the disease cycles of these two important berry diseases, as well as other diseases, so that control methods can be employed more effectively and in a more cost-effective manner.”

The three researchers — part of a collaboration between WSU Mount Vernon and Washington State University’s Department of Plant Pathology in the College of Agricultural, Human, and Natural Resource Sciences in Pullman — are working closely with local growers to determine how their research can address the needs of the community and the Washington state berry industry.

“Over the past eight months or so, we have met with several different grower groups and industry leaders to establish pathology research priorities,” Peever said. “These meetings will occur on a regular basis to continually update our priorities and obtain industry feedback as well as keep growers informed of our research progress.”

Dalphy Harteveld
Dalphy Harteveld

One of those priorities is to help small fruit growers more effectively deal with fungicide resistance.

“We are continuing a large survey of fungicide resistance to the major fungicides used to control Botrytis gray mold in blueberries, raspberries and strawberries, a project initiated by Alan Schreiber,” Peever said. “The objective is to provide growers with a much better idea of the status of resistance to the major fungicides used for disease control in these crops.”

According to Peever, it has been nearly 10 years since WSU has had a small fruit pathologist; and the need for berry pathology research is growing.

“Our main goal is to provide growers with increased knowledge of the disease cycles of these two diseases – Botrytis gray mold and mummyberry — and to ensure this knowledge will be directly applicable to improving disease control and allowing growers to move away from calendar-based application schedules,” Peever said. “We hope to be able to reduce fungicide use while maintaining a high level of disease control by using fungicides only when they are needed.

“Reducing the use of fungicides will have the added benefit of reducing pesticide inputs to the environment, lowering selection pressure for resistance to these fungicides and preserving their use for disease control in berries and other crops,” he said.

Peever and WSU Mount Vernon Research Center Director Steve Jones anticipate this new berry pathology team will complement the work being conducted across the Pacific Northwest — within Lisa Wasko DeVetter’s WSU Mount Vernon small fruit horticulture program; at the WSU plant pathology labs in Pullman; in the fields of WSU’s cross-border agricultural research partner, Oregon State University, in the Willamette Valley; and in British Columbia.

Olga Kozhar
Olga Kozhar

Peever’s team is collaborating with OSU berry researchers Jay Pscheidt and Lisa Jones to address different components of the Botrytis gray mold disease cycle and with the British Columbia Ministry of Agriculture and food scientist Siva Sabaratnum on fungicide resistance in B. cinerea.

“The region has been in desperate need of a berry pathology team, and we feel this is a great start to filling that need holistically,” said Steve Jones.

“Many berry pathology issues are only addressed by looking at the whole berry production system, which includes consideration of other pests and weeds as well as cultural aspects,” Peever explained. “Our pathology research intersects with many small fruit horticulture issues like plant phenology, nutrition, and irrigation; and we collaborate closely with Lisa DeVetter’s research program.”

“These are incredibly exciting times for berry research in the region, and we look forward to collaborations with researchers here as well as many others nationally and internationally during the next few years,” Peever added. “I think this influx of people researching berry problems in the Pacific Northwest bodes very well for the berry industry in Washington and the region.”

Peever and his berry pathology team’s research are currently funded by the Washington Red Raspberry Commission, the Washington Blueberry Commission, the Washington State Commission on Pesticide Registration, and the Northwest Center for Small Fruits Research.


Steve Jones, WSU Mount Vernon Research Center Director, 360-416-5210,

Tobin Peever, WSU Plant Pathology Associate Professor, 509-335-3754,

Dalphy Harteveld, WSU Mount Vernon Post-doctoral Research Associate, 360-416-5211,

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