Ornamental cherry trees were given to the United States by Japan in 1914 as a gesture of friendship. They symbolize the coming of spring and are renowned for their ornamental, sometimes fragrant, spring blossoms. "Okame" cherry trees are a hybrid cherry species growing 20 to 30 feet tall and wide with shiny, reddish-brown bark. They are prone to potentially fatal diseases and are more vulnerable to them with improper care.
"Okame" cherry trees are susceptible to cankers, two of which can be deadly. Bacterial cankers produce large, indented patches on the bark that ooze sappy liquid. Bot cankers produce similarly damaged areas, but their oozing tends to be thicker and gum-like. They both cause yellow leaves and infection of plant tissue beyond the initial site. To prevent and treat moderate cases, raise the soil of the pH. Being careful not to allow any lime to contact exposed skin -- as it can be very irritating -- mix 10 pounds of hydrated lime in 5 gallons of water. Then sprinkle the solution in the soil around the base and under the branches. Water the area thoroughly to allow the solution to penetrate. In two weeks, sprinkle 10 pounds of common garden lime under the tree and, again, water thoroughly.
Improper Site Selection and Planting
"Okame" cherry trees must be planted at the proper site, in the proper way and at the right time to have the best chance of thriving. It may lose vigor or die otherwise. Plant this tree in the fall -- and not during its spring bloom -- to give it time to establish in cool weather. Summer heat stresses the plant and might weaken it if the roots are not yet strong enough. Choose a site with at least six hours of daily full sun, but with filtered afternoon sun in hot regions. Dig a hole two to three times wider than the root ball, but at the same depth of the root ball. Backfill it with native soil -- not compost or potting soil, as this may shock the tree.
Improper care can cause the "Okame" to lose vigor, produce inadequate blooms or die. After planting, add 2 to 3 inches of mulch around the base to help conserve soil moisture, keep temperatures moderate and prevent damage from mowers and weed trimmers. Okames" have very thin bark, leaving them susceptible to mechanical damage -- when then makes them more vulnerable to disease. Water it an inch a week while it is establishing and irrigate it during dry spells. Wait one year after planting before applying fertilizers.
It is easy for inexperienced gardeners to have the wrong expectations for "Okames." These cherry trees are among the few that change form; they are upright, vase-shaped, quickly growing trees when young and slower-growing, rounded specimens when older. There are a wide variety of cherry tree species, which produce different blossoms, grow in different patterns and to different heights and widths. Be aware of which species you have chosen. "Okames" only live around 20 years and produce vibrant pink flowers that bloom in early spring -- unlike the weeping-form "Pendula" Higan cherry tree, which has pink and white flowers, or the short and wide "Shirufugen" Japanese cherry, which has only white flowers.