2951e

Sweet Cherries

Although climatic requirements for growing sweet cherries are exacting, home-

owners have been growing sweet cherries successfully in California for many

years. This leaflet provides information not only on climatic and soil requirements

but also on varieties, rootstocks, and pollination. Suggestions are made on

planting and care of sweet cherries.

Soil

Cherry trees grow best in deep (at least 4 feet),

well-drained loam soils. They will tolerate less

desirable soil, but may do poorly on excessively

sandy, heavy or wet soils.

Climate

Some very exacting climatic requirements must be

met to grow this crop successfully. To break dor-

mancy, the trees need considerable winter chilling

from November through February. Ordinarily they

get sufficient winter chilling in the northern and

central coastal areas, the Sacramento-San Joaquin

Valley area, and the foothills of the Sierra-Nevada

mountains. However, in southern California, chilling

is usually inadequate unless trees are grown above

2,000 feet elevation. In addition, cherries should be

grown in an area that is relatively frost-free following

the beginning of bloom. Frost can limit cherry

production at higher elevations.

Sweet cherries are not well adapted to the high

summer temperatures common to many parts of the

interior valley. High temperatures are believed to

cause double or "spur" fruit (fig. 1) which are con-

sidered "off-grade" by commercial growers and

shippers. However, such fruit may not be particularly

objectionable to the homeowner. High summer

temperatures also can cause tree stress and sun-

burning of limbs. Once limbs have been sunburned,

they are susceptible to attacks by insects and disease

organisms.

Rainfall between bloom and harvest can increase

disease problems and when rain occurs near harvest,

fruit may crack and become nearly worthless.

Fig. 1. High summer temperatures are usually considered the

cause of double and "spur" fruits. The top row of cherries

illustrate spur fruit, while the bottom row shows doubles.

of Agricultural Sciences Division

UNIVERSITY

LEAFLET

2951e OF CALIFORNIA

PRINTED FE BRUARY 1977

(Scan of Leaflet 2951. No content was updated from the 1977 printing.)

Apart from these limitations, which may discourage

some home gardeners from planting them, sweet

cherries are a rewarding and delicious crop when

grown successfully.

Varieties

Table 1 describes some characteristics of sweet cherry

varieties that have been grown successfully in

California

Pollination

Sweet cherry varieties will not set fruit with their

own pollen. Instead, they require cross-pollination

from another variety. Also, certain varieties such as

Bing, Lambert, and Royal Ann will not pollenize each

other. Table 2 is a chart showing the value of various

varieties as pollenizers for other varieties. In order for

a variety to be an acceptable pollenizer, it must be

both cross-compatible and have sufficient bloom

overlap with the variety to be pollinated.

The actual transfer of pollen is done by insects,

usually the honey bee. Therefore, trees must be

planted close enough together, usually within 100

feet is sufficient, for the insects to carry the pollen. If

only one tree is desired, a pollenizing variety can be

grafted into a major limb; to be successful, the pol-

lenizing limb should consist of at least one-fourth of

the entire tree. Another alternative, if space is

limited, is to plant two trees of cross-pollinating

varieties in the same hole and then train them as

though they were a single tree.

Young cherries may be 5 to 8 years old before they

begin to produce substantial bloom and bear signifi-

cant crops. Very vigorous trees may take even longer

to begin bearing.

Rootstocks

Sweet cherries in California are grown on one of three

rootstocks: Mahaleb, Mazzard or Stockton Morello.

These three rootstocks have somewhat different

characteristics, as described below. (For additional

information on diseases, see the disease section of this

leaflet. )

Mahaleb is the most common rootstock used in

California. This rootstock gives slight dwarfing, and

often there is some overgrowth at the graft union;

2

however, the union is generally strong. The Van,

Larian and Early Burlat varieties sometimes do not do

well on this rootstock and may be partially incom-

patible with it. Mahaleb is highly susceptible to

gopher damage and root rotting fungi. However, this

stoek is resistant to bacterial canker. This rootstock is

best adapted to light-textured (sandy to sandy loam)

well-drained soils.

Mazzard is a sweet cherry seedling and gives the best

union with the top variety. This rootstock usually

produces larger trees than Mahaleb or Stockton

Morello and trees on Mazzard are frequently slower

to come into bearing. Mazzard is moderately resistant

to oak root fungus, water-molds, and gophers but is

susceptible to bacterial canker.

Stockton Morello is the most dwarfing of the three

rootstocks. Cherry varieties grown on the rootstock

generally are somewhat smaller than when grown on

Mahaleb. However, trees on Stockton Morello usually

are not greatly dwarfed and can still be quite large.

Varieties generally have the poorest union and

greatest over-growth on this rootstock although the

unions are normally satisfactory. The Chapman and

Early Burlat varieties are incompatible with this

stock. This is the preferred rootstock for heavy or

wet soils, although trees on Stockton Morello will not

do as well under these conditions as when planted on

good soils.

Planting

Cherry trees should be planted when they are

dormant-usually in January to March. Normally they

are sold "bare root," so care must be taken to keep

their roots from drying. Plant trees as soon as possible

after purchase. If a delay is unavoidable, cover the

roots with soil, sand, or sawdust (but not higher than

the original soil line in the nursery), and keep the

roots moist but not excessively wet. Trees 1 /2 to

1 inch in diameter, measured just above the soil line,

often grow better than smaller or larger trees.

Do not plant in soil that is too wet. The soil should

be friable and not doughy or dripping wet when

squeezed in the hand. Dig the planting hole wide

enough so that the trees' roots spread naturally

without crowding. Digging the hole a few inches

wider than needed is often desirable. Before pbnting,

cut off any broken, badly damaged or dry roots, and

cut back any roots longcr than 10 to 12 inches.

TABLE 1. SOME CHARACTERISTICS OF SWEET CHERRY VARIETIES GROWN SUCCESSFULLY

IN CALIFORNIA

Bloom'l Harvest 2 Fruit Fruit3 Fruit

Variety season season color size firmness

Bing Mid Mid Dark Large Firm

Black Tartarian Early Early Dark Small to Soft

medium

Early Burlat Early to Early Dark Medium to Soft to

mid large mod. firm

Jubilee Late Mid Dark Large Moderately

firm

Lambert Late Late Dark Large Firm

Larian Mid Early to Dark Large Moderately

mid firm

Mona Mid Early Dark Large Soft to

mod. firm

Royal Ann4 Mid Mid Light Large Moderately

(Napoleon) firm to firm

Van Mid Mid Dark Medium to Firm

large

1 Cherries usually bloom from mid March to mid April, depending on the location, variety and season.

2 Cherries usually ripen during May and June depending, on the location, variety and season.

3 Fruit size also depends on crop load and growing conditions.

4 Used mainly for processing (canning and brining).

TABLE 2. VALUE OF VARIETY AS POLLENIZER*

Variety to be Black Early

pollinated Bing Tartarian Burlat Jubilee Lambert Larian Mona Royal Ann Van

Bing 0 x x x 0 x x 0 x

Black Tartarian x 0 x 0 0 x x

Early Burlat x x 0 0 0 x x x x

Jubilee x 0 0 0 x 0 0 x 0

Lambert 0 0 0 x 0 0 0 0 x

Larian x x 0 0 0 x

Mona x x x 0 0 0 x x

Royal Ann 0 x x x 0 x x 0 x

Van x x 0 x x x 0

x means acceptable pollenizer; 0 means unacceptable pollenizer; - means value is unknown.

3

Plant the trees no deeper and preferably 1 to 2 inches

higher than they were in the nursery. Planting deep is

a dangerous practice because it enables crown rot

fungi to attack the trunk more easily and kill the tree.

Soil should be firmed but not compacted around the

roots. Water the tree immediately after planting to

prevent the roots from drying and to help settle the

soil around the roots. After watering, some additional

soil may be needed to level the ground line if settling

occurs. Do not put fertilizer in the planting hole; it

could cause root damage.

After planting, the tree should be cut off at about 24

to 30 inches above the ground to balance the roots

that were lost during the digging process in the

nursery. To prevent sunburn damage, whitewash the

trunk prior to any bud swelling or growth; the top 6

to 8 inches should be left unpainted. Take care to

paint the tree trunk down to the soil surface; if

settling exposes unpainted trunk areas, these should

be painted. Commercial whitewash materials made

for this purpose or white interior waterbase paint can

be used.

Fertilization

Usually California soils have an adequate supply of

most mineral elements needed for plant growth

except for nitrogen. Thus, yearly applications of

nitrogen usually are necessary. A full-grown, bearing

cherry tree may need about 1 pound of actual nitro-

gen per year. Small 1- to 2-year old trees need only

about 1/4 to 1/3 pound per year. Do not apply fertil-

izer in the planting hole or during the first season

until the tree is growing (usually several months after

planting). Often trees may not need supplemental

nitrogen the first year; however, if growth is weak

and the leaves have a yellowish-green color, a small

amount (2 to 3 ounces of actual nitrogen) can be

applied. The fertilizer should be applied under the

tree in a ring at least 18 inches away from the trunk.

Following application, the fertilizer should be worked

several inches into the soil with a hoe or shovel or the

material applied just before an irrigation or rain.

The following amounts of various commercial fertil-

izers contain approximately 1 pound of actual

nitrogen (N):

5 pounds ammonium sulfate (21 % N)

3

6

21 urea

10 pounds 10-10-10 (10% N)

Irrigation

Irrigation is one of the most important practices in

growing sweet cherries. Insufficient soil moisture

causes poor growth and weak trees which are subject

to pest and disease attack. In addition, insufficient

soil moisture can cause smaller, poorer quality fruit.

On the other hand, excessive irrigation, especially

during fall and spring, can subject the tree to root and

crown rots.

As a rule, cherry trees in California require irrigation

during the growing season because of the variation in

rainfall and its inadequate distribution throughout

the year. It usually rains during the winter months,

but cherries require the most water for growth and

fruit production during the summer. If winter rains

do not wet the entire root zone, an irrigation should

be applied during winter or very early spring to over-

come this deficiency.

During the ~owing season, young trees with smaller

root zones need to be watered about every 2 weeks,

while older trees with more extensive root systems

require deeper, less frequent irrigations. The entire

root zone should be rewetted with each irrigation.

Merely sprinkling the surface or wetting the top few

inches of soil does little good. Trees growing in ligh t

sandy soils need more frequent irrigation than those

growing in heavier soils, since the water-holding

capacity of a light soil is much less than that of a

heavy soil. Less irrigation is needed in cooler coastal

areas and in areas of high rainfall than in hot, dry

interior regions.

Generally, mature cherry trees should be irrigated

once or twice before harvest, depending on winter

rainfall, weather conditions and type of soil. Trees

should be irrigated soon after harvest and approxi-

mately every 3 to 4 weeks through August.

Cultivation

Cherry trees in home orchards usually need no culti-

vation except for shallow hoeing or rototilling to

control weeds. Weeds compete with the trees for

moisture and nutrients and, therefore, should be kept

down. Do not hoe Of work soil that is too wet to

crumble; such handling tends to compact soil, making

it less pervious to water and root growth.

III lawns. The

and trees differ; a

well-watered lawn is irrigated too frequently for trees

11

II

and this can increase their susceptibility to root and

crown rots. Trees require deeper irrigation than

lawns. Also, the grass competes with the trees for

moisture and nutrients.

and pruning

For cherries, a vase-shaped (open center) tree is often

desirable as it allows light throughout the tree for

good fruit production and permits easy picking of

fruit. To obtain this shape, the trees should be headed

(cut off) at 24 to 30 inches above the ground at

planting.

After the first growing season, three or four main

scaffold branches usually can be selected. These

should be spaced equally around the tree and posi-

tioned about 6 to 9 inches apart vertically on the

trunk, if possible. If these limbs are 30 to 36 inches

or longer, they should be cut back to 24 to 30 inches

in length to promote secondary branching (figs. 2, 3).

Limbs that compete with these major branches and

very low limbs should be removed; weaker growth

and limbs growing more horizontally can be left to

become future fruit bearing wood.

Ideally, each primary scaffold should divide into two

secondary branches. If more than two upright

secondaries are present, these additional limbs should

be removed. Head secondary limbs at 24 to 30 inches

above the primary scaffold limbs to promote tertiary

branching. At the end of the second or third growing

seasons, other unwanted or competing limbs can be

removed (figs. 4, 5). Following the formation of

tertiary branches, very little pruning is necessary until

after the trees start bearing. Excessive pruning in the

early years after the framework of the tree has been

established can delay the time when a cherry tree will

start bearing.

Dormant pruning of young cherry trees is best done

late in the dormant period-just before or as the buds

are beginning to swell in the spring. Pruning at this

time reduces the chance of disease entering the

pruning wounds.

Bearing cherries require less pruning than most fruit

trees. However, some pruning is needed to let light

into the tree to prevent the shading out of fruiting

spurs and wood. The center of the tree should be

kept moderately open to allow sunlight to penetrate

the tree, but not so open that the limbs will sunburn.

In areas of high summer temperatures, cherry trees

should be pruned to grow relatively upright and to

5

prevent long, arched or flat limbs exposed to sunlight.

On such limbs, excessive fruit doubling is likely to

occur, and sunburning of limbs can be a problem.

/\ tree should be to confinc it to its

allottcd space and desired in the How-

ever, if a vigorous tree is planted in too small a space,

excessive pruning may be necessary to hold the tree

in bounds, and few cherries may be produced under

these conditions. Trees that have gTown too high or

too wide can be shortened by cutting the limbs back

to short lateral branches. Often this method is better

(especially on older trees) than cutting limbs off at a

given length and leaving a stub, which may continue

to die back. Cutting out limbs larger than 2 inches in

diameter should be avoided as much as possible.

During pruning, remove dead, diseased, broken and

interfering limbs.

Harvesting and handling

Cherries with dark skins and flesh (such as Bing) can

be picked when the fruit reaches a solid to dark red

or nearly black color. The longer the fruit is left on

the tree (until it begins to shrivel), the better the

flavor. However, the longer the fruit is left on the

tree, the more subject it becomes to bird damage and

rotting. Cherries usually are picked with the stem

attached to prevent injury to the fruit. Take care not

to break or remove the spur (fruiting twig) from the

tree; the spur is required for crops in future years.

Avoid bruising or injuring the cherries during har-

vesting and handling. Moisture can be lost more

rapidly from such injuries, and fruit rotting organisms

can enter even minute breaks in the skin. Damaged

cherries may deteriorate more rapidly.

Keep the harvested fruit as close to 32° F as possible,

without freezing the cherries, to slow deterioration

and rotting. Also, refrigeration under a fairly high

relative humidity lessens moisture loss and fruit

shrivel.

Pest control

Compared to many other fruit crops, cherries are

relatively free of insect pests. For information on the

control of insects that attack sweet cherries, refer to

Leaflet 2249, "How to Control Insects and Diseases

in Your Home Orchard", available from University of

California Cooperative Extension (farm and home

advisor) offices located in most counties.

Fig. 2 (left). Sweet cherry tree at the end of the first growing season before pruning. Fig.3(right). Same tree as fig. 2 after

pruning. Primary scaffold limbs have been selected and headed to encourage the formation of secondary branches. Low and·

interfering limbs have been removed.

Fig.4(1eft). Two-year-old sweet cherry tree before pruning. Fig. 5(right). Same tree as fig. 4 after pruning. Secondary limbs have

been selected and headed to encourage further branching. Again, low and interfering limbs have been removed.

6

Bird damage to sweet cherries is often severe and

there is no good, ecollomical way of preventing it.

Noise or scare devices may help but often cannot be

used in populated areas. A tree or two in the home

orchard can be covered shortly before harvest with a

net for bird protection; a frame can be constructed

over the tree, and a net placed on the frame. How-

ever, this practice often is difficult and expensive.

Pocket gophers can injure or kill a cherry tree,

particularly a tree on Mahaleb rootstock, by feeding

on the roots or on the crown of the tree close to the

soil line. If they completely girdle the tree, it will

soon die. Trapping usually is the best method of

controlling gophers in the home orchard. For infor-

mation on controlling gophers, refer to OSA-n30

(Leaflet 2622), "Controlling Pocket Gophers and

Moles," (also available from University of California

Cooperative Extension farm and home advisors

offices).

Some common cherry diseases

Buckskin-one of the more serious diseases of cherry.

This disease is caused by a small, virus-like infectious

agent (mycoplasma) and is found both in the central

valley and coastal areas north of San Francisco.

Buckskin can kill or severely reduce the productivity

of trees. Affected trees on Mazzard and Stockton

Morello rootstock have fruits that are smaller in size

and fail to mature as well as being conical in form,

insipid to taste and typically buckskin colored.

Leaves are chlorotic and pale in mid-summer, and

affected limbs lack new growth. Trees on Mahaleb

rootstock are affected more rapidly and may die

within several weeks (similar to the effect of girdling

by gophers). The disease is spread by leaf hoppers

(insects) which often build up in the hedges.

Control is difficult, but a couple of precautions may

be helpful: avoid planting cherries near privet hedges

and keep insects under control. Planting the Mahaleb

rootstock and then grafting the sweet cherry variety

into the Mahaleb scaffold branches is helpful, because

loss may be limited to individual limbs rather than

the entire tree.

Bacterial canker-also known as gummosis or soursap.

This disease can kill young cherry trees. Trees in their

second to eighth