Fertilizing Cherries

Control grass or other competing vegetation around the tree for the first few years. A heavy mulch from the tree trunk to the tree's dripline helps conserve soil moisture and control weeds. Fertilize each spring until trees start to bear. Once bearing, cherries need little irrigation or fertilizer in most areas.

If you apply nitrogen to bearing trees, wait until after the fruit has been harvested, but apply it no later than midsummer. This will give the tree a boost toward producing plenty of sugars in its leaves to ripen next year's crop. To prepare the tree for winter, it's a good idea to paint tree trunks white or wrap them with white plastic tree guards. Pull mulch away from the trunk and be sure to harden the tree off.

Be on the lookout for problems with pests and diseases. In the southern parts of the Tart (though tart means sour, tarts are usually sweet) cherry-growing area, the only worm to infest the fruit is the larva of the plum curculio, which also attacks sweet cherries. The cherry fruit fly may infest sweet cherries and tart cherries are susceptible to black cherry fruit flies. The apple maggot and peach tree borer may also cause problems.

Brown rot and cherry leaf spot affect both tart and sweet cherries. Black knot and powdery mildew are potential problems for some areas.

Prevent avians which are commonly known as birds from decimating your crop with netting, scare tactics, or barrier-type controls.

Harvesting

One mature, standard-size tart or sweet cherry tree will produce 30 to 50 quarts of cherries a year; a dwarf tree, about 10 to 15 quarts. Wait until the cherries turn fully red to harvest them; the sugar content rises dramatically in the last few days of ripening. You'll need to go over the tree every other day for about a week. Pick the fruit with stems attached, but be careful not to tear off the woody fruit spur, which will continue to produce fruit year after year. If you're using a mechanical cherry pitter, pick the cherries by leaving the stems on the trees. Use these cherries up soon after you pick them because they'll leak juice and may spoil if left out. Using a hand-cranked cherry pitter, you can pit a quart of cherries in 10 minutes.

Cause: The fungi Monilinia fructicola and M. laxa can incite both a blossom blight, a twig and branch dieback, and a fruit rot of several Prunus sp. including many ornamental and fruit trees. Fungi survive year to year on infected twigs, branches, old flower parts, or mummified fruit. Conidia are produced on infected plant debris in the tree when the temperature is above 40°F. A small, mushroomlike structure (apothecium) can be produced on fruit that drops to the ground. Wind and rain blow spores (conidia and ascospores) to healthy blossoms in spring to begin the infection process during wet weather. Infection will occur for M. laxa above 55°F. Infection may occur at any temperature above freezing with 24 hours wetness. Flowers can be blighted any time floral tissue is exposed but are most susceptible at full bloom. More spores can be produced on this tissue, initiating several more disease cycles during the spring.

Some infections may be symptomless until fruit begins to ripen. Ripening fruit also is highly susceptible to infection, and many more disease cycles can occur near harvest. Peach and nectarine fruit that fall to the ground due to lack of pollination, thinning, or overripeness can significantly increase inoculum and the amount of fruit rot at harvest. Fruit infected in the orchard may not show symptoms until it is in storage or in transit. High nitrogen fertilization also is associated with increased levels of brown rot.

Both fruiting and ornamental cherries, peaches, nectarines, prunes, plums, almonds, and apricots are susceptible. The disease is more a problem west of the Cascades. Surveys of eastern Washington packinghouses during 2000 and 2001 found very little brown rot on peaches and nectarines. Symptoms: Infected flower parts turn light brown and may develop areas of buff-color (M. fructicola) or gray (M. laxa) spores. Infected petals may look water soaked, which can be mistaken for frost injury. Flowers generally collapse as the fungus invades through the pedicel. Infected flowers often adhere to twigs and spurs through harvest or even winter. On peach, the disease continues into twigs or spurs. Lesions may remain discrete or may girdle the twig, causing all distal portions to die. Profuse gumming also may be in these areas. Again, buff or gray spores (in sporodochia) may develop on these necrotic twigs.

Fruit symptoms begin as small, dark spots that enlarge rapidly. Fruit remains fairly firm and dry relative to a watery rot caused by Rhizopus sp. Production of masses of buff-colored spores is equally rapid in the necrotic area. Peaches may have concentric rings of gray sporulation as the rot takes a few days to encompass the entire fruit.

Note zones of gray sporulation on the lowest peach. Rotted peaches mummify and may cling to the tree well into the next growing season.

Blossom infections result in necrotic lesions on the stem. Brown rot of the blossom which results in a twig canker.

Cultural control: These must be supplemented by chemical control methods especially in the wettest areas such as west of the Cascades.

- Remove and destroy infected twigs and branches in summer.

- Remove and destroy all mummified fruit in and around the tree. Cultivating or burying old fruit before the growing season will not reduce the risk of this disease. However, removing fallen fruit (due to thinning or lack of pollination) can significantly reduce the amount of rot at harvest.

- Control insects that could wound and injure fruit.

- Avoid wounding fruit during harvest.

- Cool fruit rapidly after harvest.

- Use moderate amounts of nitrogen fertilizer.

- A short (2.5 min) soak in hot water (122°F) has reduced postharvest decay in nectarines and peaches. Some additives have increased efficacy of this treatment.

- Abound at 12.3 to 15.4 fl oz/A. Alternate with other fungicides. Do not apply more than 4 times/year or 2 sequential sprays. May be applied the day of harvest. Sprayers used for Abound should not be used on apples such as Gala, Cox's Orange Pippin and McIntosh. 4-hr reentry.

- Auxigro WP at 4 oz/A plus a silicone-based surfactant. For blossom blight only. Unknown efficacy in the PNW. 4-hr reentry.

- Botran 75 W at 1.3 to 5.3 lb/A. Do not apply within 10 days of harvest. 12-hr reentry.

- Bravo Weather Stik at 3.1 to 4.1 pints/A. Do not apply after shuck split. Do not use more than 20.5 pints/A/season. 12-hr reentry.

- Captan 80 WDG at 2.5 to 5 lb/A. Applications may be made day of harvest. Hi-Yield Captan Fungicide 50 WP may be used in the home garden at 2 tablespoons/gal water. 24 hr reentry.

- Echo 720 at 3.1 to 4.1 pints/A, for blossom blight only. Do not apply after shuck split. 12-hr reentry.

- Elevate 50 WDG at 1 to 1.5 lb/A. Applications may be made up to and including the day of harvest. Do not use more than 6 lb/A/season. 12-hr reentry.

- Elite 45 DF at 4 to 8 oz/A. Do not apply more than 3 lb/A per crop season. Can be applied up to and including day of harvest. 12-hr reentry.

- Immunox at 0.5 fl oz/gal water. May be applied up to the day of harvest. Do not use more than 7 times per season.

- Indar 75 WSP at 2 oz/A plus a wetting agent. Do not exceed 1 lb/A per season. 12-hr reentry.

- Microthiol Disperss(80% sulfur) at 10 to 20 lb/A. Do not use a spreader sticker. Only slight control; not recommended for use during bloom. 24-hr reentry.

- Pristine at 10.5 to 14.5 oz/A. Do not use more than 2 consecutive applications or more than 5 times/year. Can be used day of harvest. 12-hr reentry.

- Proiconazole-based fungicdes are registered. Limited to 4 applications (2 during bloom and 2 before harvest). May be used up to and including day of harvest. 24-hr reentry.

- Bumper 41.8 EC at 4 oz/A. Do not use on Stanley-type Plums.

- Orbit at 4 oz/A. Do not use on Stanley-type Plums within 21 days of harvest.

- PropiMax EC at 4 fl oz/A. Do not use on Cherry or Stanley-type Plums.

- Rally 40 WP at 2.5 to 6 oz/A. Use Eagle 40 WP at 1 to 1.65 oz/100 gal water for landscape use. Can be applied up to the day of harvest. Not as good as the manufacturer's other DMI-type fungicide, Indar. 24-hr reentry.

- Rovral 4 Flowable at 1 to 2 pint/A. Do not use after petal fall or more than twice per season. 24-hr reentry.

- Scala SC at 9 to 18 fl oz/A. Do not apply more than 3 applications alone, more than 54 oz/A/season, or within 2 days of harvest. Not for cherry—only for apricot, peach, prune and plum. 12-hr reentry.

- Syllit 65 W at 2 lb/A. Blossom blight only. Do not use after petal fall. 48-hr reentry.

- Thiram Granuflo at 3.9 to 5.1 lb/A. Do not apply within 7 days of harvest. Also serves as an animal repellant. 24-hr reentry.

- Topsin M WSB at 1.5 to 2.25 lb/A plus another fungicide with good protection activity. Do not apply within 1 day of harvest. Halt (by ferti-lome) is registered for home use. 12-hr reentry.

- Vangard 75 WG at 5 oz/A. For blossom blight only. Do not apply more than 10 oz/A/season. Tank-mix with another fungicide to improve efficacy and to manage resistance. Buffer to a pH of 5 to 7 when tank-mixing with Rovral. 12-hr reentry.

Notes: Fixed copper prodcuts are registered but due to low level of control are not recommended.

This fungal disease annually poses the greatest disease risk for fruit loss. Environmental conditions during the 2 to 3 week period prior to harvest can determine whether fruit brown rot will be a problem. Occurrence and severity of brown rot is very dependent on stage of fruit ripeness, time of occurrence of moisture, temperature, and a source of inoculum. As the sugar content increases in the fruit, susceptibility to the brown rot fungus increases. Wet, warm conditions with inoculum sources in or near the orchard during this period create a high risk. In contrast, dry, hot weather during this period greatly reduces the risk even if some inoculum is present. The preharvest/harvest period is the time when the DMI fungicides are very effective when used properly.