Symptoms: Affected trees bloom, send out new leaves, then suddenly collapse. Caused by heavy, poorly drained soil, and there is no cure.
Treatment: Prevent soil from becoming waterlogged.
Symptoms: Caused by fungal disease, blooms, fruit or new leaves turn brown but remain on the tree.
Treatment: For light infestations, prune out affected areas. If severe, treat with Captan or Benlate; do not apply excessive nitrogen. Badly affected trees may need to be replaced.
Symptoms: Cankers appear on twigs or tiny holes in leaves before the affected part dies. Cool, wet weather makes canker commonon the West Coast. Prunus x subhirtella cultivars are especially susceptible.
Treatment: Select canker-resistant varieties. Prune out affected branches to healthy wood as soon as cankers are visible (clean tools with a disinfectant or a 10 per cent bleach solution). Copper spray can also be used. If caught early, healthy trees have a good chance of survival.
Symptoms: Leaves wilt or yellow. Sticky honeydew on upper leaf surface, base, or stems.
Treatment: Remove new shoots or small suckers (which are magnets for aphids), or shower off with insecticidal soap (aphids can also be removed with a blast of plain water). If treated early, there is an excellent chance of survival for the infected tree.
Cherry bark tortrix moth
Symptoms: Tiny, brown pellets resembling sawdust appear in cracks or pruning cuts in spring as larvae tunnel under bark. This moth attacks weakened trees.
Treatment: There is no cure; avoid pruning unless absolutely necessary. Depending on overall health, the tree may or may not survive.
Symptoms: Noticeable web tents and foliage damage.
Treatment: Use a forked branch to wind up webs and expose caterpillars to predators. Prognosis is good, if defoliation is prevented by removal of pests.
Symptoms: Leaves are being eaten, but no visible tents. Natural predators usually keep winter moths under control.
Treatment: Apply Tanglefoot or other sticky barrier product to trunk before first cold spell. Prognosis is good, if defoliation is prevented by removal of pests.
Symptoms: Pests burrow into tree, creating tunnels through which sap leaks out. Generally affects trees in severe decline.
Treatment: Look at age and overall health of tree; if the tree is old and weak, replace.