Experts tackle readers’ garden questions.
Q: Can you help me identity the fungus on my lilac tree and help me to eliminate it? I want to save the tree; it was started more than 30 years ago from my grandparents’ lilac.
Tana Colburn, Carmichael
Bee garden writer Debbie Arrington: Those are turkey tail mushrooms (Trametes versicolor). Some varieties are edible, others are toxic. It is considered a white-rot, wood-decay fungus and a decomposer of dead wood.
According to the University of California’s Integrated Pest Management research, white rot breaks down cellulose in the wood, causing it to feel moist, soft, spongy or stringy and look white or yellow.
Turkey tail mushrooms are most common on alder, apple, ash, beech, birch, catalpa, cherry, chestnut, crape myrtle, elm, eucalyptus, fir, ginkgo, hackberry, holly, juniper, laurel, lilac, linden, locust, London plane tree, maple, nectarine, oak, pepper tree, poplar, redbud, sweet gum, tulip tree, walnut and willow, according to UC research.
Drought may have played a role in the appearance of this fungus, commonly found on cut and fallen wood and on wounded areas of living trees. According to UC research, it also is capable of colonizing sapwood of trees and shrubs stressed by water shortage, sunburn, freeze damage or wounding. Lilacs need good summer irrigation (at least an inch a week) and your lilac may have suffered during the drought.
Turkey tail, which causes a white, spongy rot of wood, can actively invade and rapidly kill the cambium (the tissue between the bark and wood), causing cankers with papery bark and dieback.
The solution is to cut out the deadwood, starting with the trunk that’s harboring the mushrooms. Also clean up the leaves and replace any mulch around the tree; that debris likely contains fungal spores.
Lilacs bloom on old wood grown the previous season, so severe pruning may mean no blooms for a year or two. But you need to eliminate that deadwood in order for the plant to be revived and returned to full health.
Here’s what the experts at Old Farmer’s Almanac recommend:
“If your lilac is old and in really bad shape, remove one-third of the oldest canes (down to the ground) in year one, half of the remaining old wood in year two, and the rest of the old wood in year three. Another option for old lilacs is to chop the whole thing back to about 6 or 8 inches high. It sounds drastic, but lilacs are very hardy. The downside to this option is that it takes a few years to grow back. The upside is less work and more reward, as the lilac will grow back bursting with blooms.”
The Bee’s Debbie Arrington is a consulting rosarian and lifelong gardener. Reach her at firstname.lastname@example.org, 916-321-1075, @debarrington.
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