Cherry trees are dual purpose plants in the landscape. They provide attractive flowers in spring and delicious fruit in early summer. Sour or tart cherries are delicious in pies and other desserts. Sweet cherries are often eaten fresh or used in salads, main dishes and desserts.
Cherries perform best in moist, well-drained, fertile soils. Avoid wet, poorly drained sites. Cherries are susceptible to root rots in wet, poorly drained soils. Trees should also receive full sun. Sites must receive at least 8 hours of sun each day. Sweet cherries bloom earlier than sour cherries. As a result, the flowers on sweet cherries are more prone to damage from late spring frosts. When selecting a planting site for sweet cherries, avoid planting in low spots where cold air settles on calm nights. Also, avoid southern and western exposures that encourage early bloom.
Sour or tart cherries are self-fruitful. Self-pollination occurs when pollen is transferred from the anther to the stigma on the same flower, from another flower on the same plant, or from a flower on another plant of the same variety (cultivar). Only one sour cherry tree needs to be planted for pollination and fruit set. Many sweet cherry varieties cannot produce fruit from their own pollen and are considered self-unfruitful. These plants require cross-pollination for fruit set. Cross-pollination is the transfer of pollen from one plant to the flower of a different variety. When planting self-unfruitful cultivars, at least two different sweet cherry trees (varieties) must be planted for fruit production. While most sweet cherry varieties are self-unfruitful, there are a few self-fruitful cultivars.
'Northstar' and 'Meteor' are two of the best performing sour cherry varieties in Iowa. Both cultivars were introduced by the University of Minnesota and possess excellent cold hardiness. 'Northstar' is a dwarf tree that commonly grows 8 to 10 feet tall. Its fruit have a mahogany red skin, red flesh, and are 3/4 inch in diameter. 'Meteor' is a semi-dwarf tree. Trees may eventually reach a height of 10 to 14 feet. The fruit of 'Meteor' are slightly larger than 'Northstar' and have bright red skin and yellow flesh. Another possibility is 'Mesabi.' 'Mesabi' is a cross between a sweet and sour cherry. Its red-fleshed fruit are sweeter than 'Northstar' and 'Meteor.'
'Gold,' BlackGold, and WhiteGold are sweet cherry varieties that can be successfully grown in the southern half of Iowa. 'Gold' has yellow skin. It is self-unfruitful. Another late blooming sweet cherry variety must be planted for pollination and fruit set. BlackGold and WhiteGold are self-fruitful, mid to late blooming cultivars from Cornell University in New York. BlackGold has dark red skin, while WhiteGold is light yellow with a reddish blush. Other possibilities for southeastern Iowa include 'Hedelfingen' (self-unfruitful, red fruit), 'Kristin' (self-unfruitful, purplish black fruit), 'Sam' (self-unfruitful, dark red fruit), and 'Van' (self-unfruitful, reddish black fruit).
As with other fruit trees, sour and sweet cherries must be pruned properly for maximum fruit production and to prolong the lives of the trees. Proper pruning practices for sour and sweet cherries are outlined in PM-780 "Pruning and Training Fruit Trees."
Insect and Disease Pests
There are several insect and disease pests that occasionally attack cherry trees. However, the damage is usually minor. As a result, it's usually not necessary for home gardeners to spray cherry trees.
The most common plant disease is cherry leaf spot, caused by the fungus Blumeriella jaapii. Infected leaves develop small, purple-brown spots before turning yellow and falling off. Cherry fruit may be affected by another fungal disease called brown rot, caused by Monilinia fructicola. Fruit with brown rot develop round, light brown spots that expand and rot the fruit within a couple days, often with visible tufts of gray "fuzz". Wounded fruit are especially vulnerable. The fungi that cause both of these diseases survive in infected debris, so good sanitation (removing fallen leaves and any mummified fruit that persist on the tree) can give adequate disease control in the home garden.
Cherries have occasional insect and mite pests, the most serious being cherry fruit flies, Rhagoletis spp. Cherry fruit flies lay eggs on developing cherry fruit in May. Damaged fruit appear shrunken and shriveled when ripe, and usually contain one off-white maggot that is slightly longer than one-quarter of an inch.
Cherry fruit fly damage varies greatly from year to year. It may be more practical to tolerate some damage and loss of usable fruit than to attempt effective preventive control. To prevent maggots from appearing inside the fruit the tree most be thoroughly sprayed with a labeled insecticide when the adults emerge and before the females lay their eggs inside the young fruit. Because the flies emerge over an extended period of time, several sprays will be needed. You can monitor fruit flies with yellow sticky traps hung in the tree in early May. Check traps daily after the first fruit fly is caught and repeat the spray application until flies no longer appear. Check for home orchard sprays and other insecticides at your local garden center. Read and follow label directions.
Birds love cherries. Either share the fruit with the birds or cover the trees with plastic netting. To be effective, the netting must cover the entire tree canopy and be secured to the tree trunk or ground to prevent birds from entering from below. If netting is not feasible, it may be possible to reduce the amount of fruit eaten by birds by placing scare devices, such as aluminum pie tins or inflatable balloons, in the tree.
Sour or tart cherries should be harvested when the fruit are full-flavored, somewhat soft, and juicy. Harvest sweet cherries when the fruit have attained the proper size, are uniformly colored, and possess their characteristic flavor. For immediate use, the cherries can be picked without the stems attached to the fruit. However, quality is best retained during storage if the fruit are harvested with the stems attached. Store cherries immediately after harvest. Place cherries in perforated plastic bags and store in the refrigerator at a temperature 32 to 35 degrees Fahrenheit.
Cherries are short-lived trees in Iowa, especially in poor sites. Sweet cherries seldom survive more than 10 years. Sour or tart cherries may survive for 20 to 25 years. When selecting a planting site, be sure to choose a well-drained location.