Small trees resistant to Wetwood
Hello, In the last year Norway maples and Cottonwoods have been diagnosed with Wetwood on my property and next door neighbors property. The cottonwood had become hazardous with main trunks dying, and threatening three houses. What small trees and shrubs can I plant to replace the 65 ft cottonwood that are more resistant to wetwood, and other root decay that is displaying in a Weeping willow, and other unknown maples growing on the slope leading down to the creek below our properties? The neighborhood and creek were regraded over 25 years ago as part of a storm sewer and flood contol project. The Oregon Ash in standing water have some leaf disease, trees are not dying, so maybe Anthracnose or Verticillium wilt. The soil is very heavy clay, and the creek path is artificial without any rock base, however, Douglas Fir, Hawthorne, Filbert (with eastern filbert blight), Blackberry and slowly native plants are returning. It just seems the entire watershed is heavily diseased, and I want to help as finances allow without using toxic chemicals impacting the aquatic or avian life. Photo 1. with the striped bark is from the cottonwood that Washington County Master Gardeners said was Wetwood. Photo 2. Stump 36" x 42" is the cut down cottonwood stump also diagnosed by WCMG. Thank you.
Washington County Oregon
Wetwood is commonly diagnosed in standing trees when “bleeding” or oozing is seen from trunk wounds, cracks or other injuries. Sometimes the fluid is foamy and/or smells. In general, wetwood is a chronic disease which may cause a general decline. Affected trees often survive for many years in spite of the infection.
“Bacterial Wetwood” describes and illustrates wetwood and the similar slime flux: http://www.ext.colostate.edu/pubs/garden/02910.html
Because your site is streamside, I suggest you contact the Tualatin Soil & Water Conservation Service to determine if they might have planting suggestions appropriate to your site. Phone 503-648-3174.