Volume 5 Issue 4
Dalphy Harteveld, WSU Small Fruit Pathology
Phone: (360)-848-6457 Email: doc.harteveld@wsu.edu
Research conducted by the WSU Small Fruit Pathology program led by Dr. Tobin Peever focuses on the ecology, population biology and epidemiology of fungal diseases of small fruit crops in the Pacific Northwest. Dr. Dalphy Harteveld, postdoctoral research associate in the program based at the WSU Mount Vernon Research and Extension Center, focuses on the epidemiology and control of fungal diseases of highbush blueberry. Mummy berry, caused by the fungus Monilinia vaccinii-corymbosi, is one of the most important blueberry diseases in NW Washington. Careful observation of the specific events in the disease cycle in each region greatly facilitates the timing of application of disease management practices.
Mummy berry symptoms can be found on flowers (flower strikes) on leaves (shoot strikes) and on fruit. In the first week of April, the first infected flowers and leaves were detected in Whatcom County. Flower strikes appear as brown, shriveled flower clusters, showing white-gray mycelial growth of the pathogen at the flower stems (Photo 1). Shoot strikes first appear as browning of the leaf midrib and veins, the browning expands and eventually includes the whole leaf cluster (Photo 2). Fluffy white-gray mycelium growth of the fungus can be observed at the base of the leaf blade. Initial fruit infections appear as pink/brown segmentation of fruit (Photo 3). Infected fruit does not progress through the normal ripening process but remains pink, shrivels and eventually forms a dried out, white, pumpkin-shaped mummified berry.
Fungal pathogens are evolving over time and have shown the ability to develop resistance to fungicides that are used regularly. In order to determine the level of sensitivity of the mummy berry pathogen to the fungicides recommended in this region, isolates from symptomatic tissues from conventionally managed fields in Whatcom and Skagit counties will be collected this spring and summer. These isolates will be tested for their sensitivity to fungicides using laboratory assays similar to what the program is doing currently with Botrytis. If you detect mummy berry symptoms in your field, even though you have used fungicides, please collect the infected tissue, record the field location and contact Dr. Harteveld. Isolates of the pathogen from these tissues will be used in fungicide assays and serve as an important source of information for blueberry producers. A better understanding of fungicide sensitivity of the mummy berry pathogen is needed to provide sustainable management recommendations for this disease.
