A central leader form is best for dwarf tart cherries. Use a modified central leader form for semidwarf and standard cherry trees. Spreading the branches while they are young will help control height and encourage earlier bearing. After the trees reach bearing age, prune to let light penetrate to the interior of the tree. Prune tart cherries lightly each winter to stimulate new growth and thin tangled branches. Prune sweet cherries less frequently, only every third or fourth year. Cut back heavy tops on overgrown sweet cherry trees to force new fruiting wood to develop on lower branches.
Fruit cracking and hungry birds are two of the biggest problems when raising cherries. Most insect and disease problems are less severe on tart cherry trees than on sweet. For information on pest control methods, see the Pests entry.
Birds can strip all of the cherries off a few backyard trees in very little time. Covering trees with netting before the fruit starts to ripen is the most effective way to stop bird damage. You can also try planting a mulberry tree nearby that fruits at the same time as your cherries to lure birds away from the harvest. See the Animal Pests entry for more ways to discourage feathered scavengers from stealing your cherries.
Cherry fruit fly
, green fruit worm, peach tree borer, mites, and plum curculio all attack cherries. Aphids and scale can also cause problems. Sawfly larvae (pearslugs) sometimes skeletonize cherry leaves; see the Pear entry for description and controls.
Shothole borers can attack cherries and other fruit trees. They make small holes in the bark of twigs and trunk. The holes are often covered with gum. The larvae are pinkish white and about 1/8 inch long. Prevent the tiny black adults from laying eggs by painting trunk and large branches in spring, summer, and fall with white latex paint diluted 1:1 with water. These pests most often attack wounded or diseased trees, so their appearance may be a sign that your trees are in trouble and you need to consider removing them.
Pear thrips can cause disfigured leaves and blossoms. Naturally occurring predatory mites
usually provide control, but if your trees become severely infested, spray with insecticidal soap.
can be a serious problem on cherries. Watch for these:
• Brown rot and perennial canker attack cherries and other stone fruit.
• Black knot can attack cherries.
• Cherry leaf spot appears as small purple spots on upper leaf surfaces. The spots later turn brown, and their centers may fall out. Leaves turn yellow and drop before autumn. Clean up and dispose of fallen leaves each winter. Plant resistant cultivars. If leaf spot is a problem in your area, plan a preventive spray program with lime sulfur or sulfur. Lime sulfur may discolor fruits, so don't use it after young fruits begin to develop.
• Powdery mildew can be a problem on cherries.
• A number of viruses attack cherries. Buy virus-free stock and avoid planting in old cherry orchards or near wild chokecherries.
When the fruit begins to drop, it is ready to pick. Tart cherries can be left to sweeten on the tree for a day or two.
To pick cherries, gently pull off clusters, keeping the stems on the fruit. Be careful not to tear off the fruit spurs (small woody twigs to which the cherry stems are attached).