University:
Washington State University
Course:
BIOLOGY 401 | Plants and People
Academic year:

2022
Views:

309

Pages:

1
Author:

strofamay57

COMMON PROBLEMS OF FLOWERING CHERRY TREES April is when the flowering cherry trees are at their most beautiful. Sometime after they flower we begin to see some of the diseases and other problems they have in our area. Below are some of the more common problems of flowering cherries that we see in Skagit County. Bacterial canker is common west of the Cascades because it is favored by our cool, wet weather. Symptoms include infected buds that may fail to open in spring. Small, greasy-looking spots appear on newly opened leaves. The spots turn a dark brown and may eventually fall out, leaving a shothole appearance. In wet weather, the spots may expand and kill terminal shoots of susceptible cultivars. Shoots may appear blackened. Cankers may develop on branches. Leaves on branches may wilt during hot weather and turn brown. Cultural control includes pruning out cankered branches in summer or dry weather or in dry weather late in the dormant season. Chemical control is to apply copper products before fall rains, during leaf fall and in late dormancy just before buds open. Crown gall is a bacterial disease that lives for several years in the soil, often spreading from diseased nursery stock. The bacteria enter plants through wounds. After the bacteria have entered the wound, a small piece of DNA is transferred into the plant’s DNA and eventually causes galls. On young trees a gall may begin as a soft, spongy or wartlike gall on the crown or roots. Gall size on mature trees range from a fraction of an inch to several inches across. Galls become hard with a rough, fissured surface as they age. Gall tissues are irregular and have no definite growth pattern. To prevent crown gall, avoid injury to bark around the crown and select well-drained areas for planting. Black knot is a fungus. The fungal spores infect new shoots from budbreak through shoot elongation. These spores are produced from within two-year-old knot tissue, primarily during rain events or shortly after bloom. Knots will not appear for several months after initial infection. Elongated, corky, outgrowths or "knots" occur on shoots, spurs or branches. Other fungi or insects may colonize the knots. Knots can expand an inch or more each year. Cultural control includes removing and destroying knots by removing infected branches 2-3 inches below knots and burn infected parts. Gumming is caused by a number of things including mechanical injury, winter injury, insect damage, fungal diseases and improper growing methods. Symptoms include gum exuding from buds, branches, twigs or trunk. Pools or large deposits of gum collect beneath the bark at the crotch, on larger branches or on the trunk. Gum eventually breaks through the surface and runs down the bark. Cultural control includes controlling insects and diseases. In large cankers, cut away all dead tissue until a sound surface is exposed. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`