Most visitors experiencing the beauty of our historic Azalea Way flowering cherries from now through May probably have no idea of how intensive maintaining their health and prolonging their longevity truly is for the UW Botanic Gardens horticulture staff. Just ask our Integrated Pest manager, Ryan Garrison. Ryan with staff support spends many a day throughout the year monitoring and controlling the numerous diseases and insect pests our 175 plus cherries are prone to suffer from. Our rainy climate doesn’t help one bit either, especially when dealing with our most notable disease during blossom time; a fungus known as Cherry Blossom Brown Rot. Yucko! The good news is any new cherries we plant need to show a reasonable level of resistance. The not so good news is many of our older earlier bloomers, the ones extremely susceptible to the brown rot fungus, need to be protected with fungicide applications during their bloom period. As with all of our pest issues, we start with cultural and mechanical control efforts before resorting to chemical controls. The following Integrated Pest management (IPM) program discusses our best management practices for the control of blossom brown rot. If you are interested in planting cherries for your home garden, I’ve included a list of cherries recommended for our PNW climate, all have good to excellent resistance to blossom brown rot.
Cherry Blossom Brown Rot - causal fungal agent known as Monolinia fructicola. The fungus overwinters on infected twigs and dried fruit on the tree or ground. The fungal spores are spread in the spring by wind and rain through the blossoms, causing twig dieback. As part of the UWBG IPM program, moving toward our goal of eliminating the use of all synthetic pesticides is our ultimate goal.
IPM relies on many strategies to manage plant health care.
- Proper ID of the pest and its life cycle
- Regular monitoring of the plants
- The use of physical, mechanical, cultural, and biological controls
- Chemical controls used as a last resort*
- Least toxic chemicals used
* All spray applications are in compliance with WSDA pesticide regulations. Sign postings are located at all entrances and Graham Visitor Center. Spray applications are scheduled based on timing and weather. We do our best to apply when public are not present. For more information, pls contact, David Zuckerman at 206-543-8008 or dzman@uw.edu
The cherries are pruned in early fall to remove infected twigs and improve air circulation. Tree rings are given a fresh coat of mulch in the fall to bury any infected plant material that may be on the ground. In our Cherry Replacement program we are only using cultivars that are resistant to Blossom Brown Rot.
Cherries recommended for the PNW:
- Prunus‘Berry Cascade Snow’
- Prunus ‘Kwanzan’ syn. ‘Sekiyama’
- Prunus‘Pink Flair®’
- Prunus‘Royal Burgundy’
- Prunus‘Shirofugen’
- Prunus‘Shirotae’
- Prunus‘Snow Goose’
- Prunus subhirtella var. ascendens
- Prunus x yedoensis ‘Shidare Yoshino’
