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University
of Rhode Island GreenShare Factsheets
Plum
Culture
Plums are an excellent tree fruit that can be used either
fresh, canned, frozen or preserved in jams and jellies. The
trees are hardy and, if given reasonable care, can be expected
to grow and produce well in the Northeast.
Plums can be divided into three different groups--European,
Damson and Japanese. Familiar varieties of the European type
are Stanley, Reine Claude (Green Gage) and the French and German
prune (Fellenburg) types. The European-type plums are best
for eating fresh and for canning.
Damson-type produce very tart fruit which is used chiefly
for cooking and preserving. Examples of Damson-type plums are
Shropshire and French Damson.
Japanese plums are generally not satisfactory in the Northeast,
due to frequent loss of crops to poor pollination and spring-frost
injury. Examples of Japanese plums are Methley, Shiro, Ozark
Premier, Burbank and Elephant Heart.
An important consideration in selecting
plum cultivars for planting is that of pollination requirement.
Trees of some
plum cultivars are capable of setting and producing a crop
if grown as single isolated plants. Other plum varieties that
do not self-pollinate require cross pollination for fruit set
and development. This means that trees of at least two cultivars
with overlapping bloom periods must be planted.
Standard
plum trees usually begin to bear fruit three to five years
from planting. The trees have a useful life of
15 to 20 years and come into full production in about 10 years.
Yields of 3 to 5 bushels per tree may be expected, depending
on cultivar.
Desirable nursery stock for planting consists of trees
3 to 6 feet tall with a trunk diameter of 3/8 to 3/4 inch.
Plum trees should be planted in early spring. Standard-size
plum trees should be spaced at least 20 feet apart in fertile,
well-drained soil.
Important cultural practices in plum production are pruning
and training, fertilizing, mulching, and pest control. Plum
trees of the European type are best pruned and trained to the
modified central leader system. In this system, several well
spaced side or lateral branches (scaffolds) are allowed to
develop from the main trunk or leader of the tree. When the
tree reaches the desired height, the central leader is cut
to a short lateral branch.
Plum trees should be fertilized annually for best growth
and development. Suggested fertilizer practice consists of
an early spring application of 1/20 pound of actual nitrogen
(8 ounces of 10-10-10) fertilizer per year for each year of
tree age.
Mulching with an organic mulch such as straw, sawdust,
wood chips and similar materials can help conserve valuable
soil moisture and help control weeds under the tree.
Common pests and diseases of plum trees
include plum curculio, European red mite, brown
rot, leaf spot and black
knot. See specific GreenShare Factsheets on these pests
and diseases for more information and control recommendations.
High quality plums are well shaped,
colored, firm and free from defects such as bruising and
insect and disease damage.
Without a good knowledge of plum cultivar (variety) characteristics,
it is difficult to detect when a plum is ripe by color alone.
Plums may be various shades of red, blue, green and yellow.
The best way to determine plum ripeness is to apply gentle
pressure to the fruit with the thumb and feel if the flesh
is beginning to soften†if so, the fruit should be ready for
consumption. If not, allow the fruit to ripen for a day or
so at room temperature. With experience with a particular variety,
one can soon correlate color with taste and judge when the
fruit should be harvested from the tree.
Ideal storage conditions for plums consist of maintaining
a temperature of 31 to 32 degrees F and a 90 to 95 percent
relative humidity. Under such conditions, storage life of plums
is from two to four weeks. For many, the home refrigerator
will be the best method of preserving the after-harvest life
of the fruit until it is consumed or preserved.
Adapted from Richard C.
Funt, Ohio State University Extension, 2000
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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