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Elisabeth C. Miller Library

Keyword: Prunus

Prunus species in the Seattle area

I would like to know how well the following trees will do in the Seattle area ?

(1)Prunus mume var. ‘Matsubara Red’

(2)Prunus ‘Kiku-shidare-zakura’

Both species you mention should do well in the Seattle area. Prunus ‘Kiku-shidare-zakura’ is described in Arthur Lee Jacobson’s Trees of Seattle (2006). Its other common name is ‘Cheal’s Weeping Cherry.’ The Japanese name means “weeping chrysanthemum cherry.” Its form is arching and weeping from the point where it has been top-grafted. According to Jacobson, the tree tends to be gawky and a bit sparse, but the flowers are very double. It is common in Seattle.

Prunus mume is also listed in Jacobson’s book. This tree and its cultivars (such as ‘Matsubara Red’) are less common in Seattle. You might be able to see examples in the Seattle Japanese Garden, the Kubota Garden, or Seattle Chinese Garden.

Because the common name of Prunus mume is Japanese apricot, there is sometimes confusion between Japanese flowering cherries and apricots. Prunus mume does produce fruit, but they are small and “bland to somewhat bitter,” and in Japanese cuisine they are preserved in salt and used as a condiment (Umeboshi plum). The more familiar fruiting apricot tree is actually Prunus armeniaca (and its cultivars).

on spraying versus using good garden practices

We live in a heavily treed (fir and cedar mostly) condominium complex. Our shrubs are sprayed twice a year by a professional spraying company to protect against fungus and other problems. We are thinking of spraying every other year to save on expenses.

Would we be jeopardizing the health of our shrubs and small cherry trees by doing so?

Unless your shrubs and trees have a history of trouble with diseases, I can’t think of any reason they should be sprayed at all. Even if the plants were susceptible to disease, a more sustainable approach than annually applying fungicides and other pesticides would be to select disease-resistant plants that will thrive in your garden’s conditions without that sort of intervention.

Spraying, depending on what is being sprayed, can be a hazard to human health and the environment. You may be able to stop your spraying program entirely by instituting good garden practices, like cleaning up debris and providing good air circulation around the trees, and avoiding overhead irrigation.

Examples of nonchemical ways to manage fungal problems that may affect ornamental cherry are provided below, from Washington State University Extension’s HortSense website:
“Brown rot is a fungal disease which initially infects the flowers. The petals turn light brown, develop water-soaked spots and may have tan or grayish areas of fungal spores. Infected flowers often remain attached to the plant, spreading the disease to small twigs and branches. Infected twigs and branches are often observed in the summer as flagged, dead leaves and twigs. Infected branches develop cankers which may produce gumming (leaking sap) or may girdle and kill the branch. Most brown rot cankers develop with a dead twig at the center where the initial branch infection occurred. Fruit can also be infected, dry out, and hang in the tree. Tan or gray fungal spores may be found on infected blossoms, fruit, or twig cankers. Ornamental and fruiting stone fruit trees are affected.

Select Non-chemical Management Options as Your First Choice!!

  • Avoid wounding trees.
  • Clean up and destroy fallen flowers and other debris beneath trees.
  • Remove and destroy all infected twigs and branches during the summer, making pruning cuts well below infected tissues.”

Similarly, here are their recommendations for managing Coryneum blight or shothole:

  • Avoid overhead watering, as leaves must be moist for infection to occur.
  • Prune and destroy dead buds and cankered twigs if present.
  • Rake and destroy infected leaves.

Again, for cherry leaf spot:

  • Avoid overhead watering. If overhead irrigation is necessary, limit it to times when foliage can dry quickly.
  • Rake and destroy all fallen leaves and debris under trees.
  • Space plantings and prune to provide good air circulation.

shrubs and low trees that will grow in the shade

Can you suggest some shade shrubs/low trees that could be used in the bottom quarter of a huge, years-old pile of yardwaste and branches that is now a 20 foot cliff? I have started with some Vinca minor in the lower part but could use some ideas of some things to plant that might get 15 feet tall, evergreen, and grow in woods/shade or sun through trees.

The closest list I could find to meet your needs is one of evergreen shrubs that will grow in shade:

Japanese aucuba – Aucuba japonica vars.

common boxwood – Buxus sempervirens

camellia – Camellia sp.

gilt edge silverberry – Elaeagnus x ebbingei ‘Gilt Edge’

Euonymus – Euonymus fortunei radicans

Japanese aralia – Fatsia japonica

drooping Leucothoe – Leucothoe fontanesiana

Oregon grape – Mahonia aquifolium

Burmese mahonia – Mahonia lomariifolia

longleaf mahonia – Mahonia nervosa

holly leaf osmanthus – Osmanthus heterophyllus vars.

English laurel – Prunus laurocerasus ‘Mount Vernon’

Japanese skimmia – Skimmia japonica

evergreen huckleberry – Vaccinium ovatum

nannyberry – Viburnum lentago

Source: The Pacific Northwest Gardener’s Book of Lists, by R. & J. McNeilan, 1997, p. 46-47

 

trees for waterlogged soils

Can you recommend some tree species (deciduous) that can have wet feet but
will also tolerate dry conditions in the summer? The recommendations should
be trees that are not too messy (no cottonwoods or alders, please) and not
too big. I would like to plant some trees near a swale in my yard – so they
could be sitting in soggy ground during the winter.

 

Following is a list of possibilities, most of which come from Water Conserving Plants
for the Pacific Northwest West of the Cascades (by the N.W. Perennial
Alliance, 1993). The list includes only trees that 1) thrive in soils
which are waterlogged in the winter, and, 2) grow to less than 40 feet tall.

ACER (maple):
A. buergeranum (trident maple)
A. campestre (field maple)
A. ginnala (Amur maple)
A. circinatum (vine maple)
CORNUS nuttallii (western dogwood)
C. douglasii (black hawthorn)
C. monogyna
C. phaenopyrum (Washington thorn)
C. x lavallei (Carriere hawthorn)
HOVENIA dulcis (Japanese raisin tree)
MALUS fusca (Pacific crab apple)
NYSSA sylvatica (black gum)
OXYDENDRUM arboreum (sourwood)
PRUNUS (prune/plum/cherry):
P. virginiana var. melanocarpa (chokecherry)
P. emarginata (bitter cherry)
PYRUS (pear):
P. communis (common pear)
P. pyrifolia (Chinese pear, sand pear)
QUERCUS (oak):
Q. acutissima (sawtooth oak)
Q. imbricaria (shingle oak)
RHAMNUS purshiana (cascara)

common diseases of plums

I have a flowering purple plum tree. For the last two years it has had
black knobby growths on the limbs. The number of these growths are
increasing and there is no sign of any type of bug involved. The tree
is healthy in all other respects and the growths remain on the limbs
all year. I cannot find anyone who knows what these are and if I need
to do anything to stop and/or remove these growths. Obviously they are
ugly but probably not fatal and do not spread to any other trees. Can
you give me a clue?

 

We can only guess from your description, and in order to get an accurate diagnosis you will need to take a sample (including both healthy and affected parts if possible) to a Master Gardener clinic. Click on the appropriate link for your local clinic through Master Gardeners / Washington State University Extension.

Meanwhile, for information about common diseases of plums in the Pacific Northwest, try searching Washington State University’s HortSense website.

The symptoms you describe are similar to 1. Crown gall, 2. Black canker and 3. Black knot. Click on those diseases for descriptions, photos, and control methods.

You can also take a look at pages like this one, on black knot of ornamental cherry and plum, from Morton Arboretum. See if the images resemble what you are seeing on your tree.

fruit trees and lack of fruits

I planted numerous fruit trees about 7 years ago. These
included almond, pear, apple, hazelnut, and plum. The almond and apple
trees have done really well.

The pear, plum, and hazelnut trees have
never even bloomed, let alone borne fruit. Am I doing something wrong or
do I just need to be a little more patient?

 

All of your trees should be mature enough to flower and bear fruit, given
the right conditions. There are many potential causes of failure to
flower. Are your trees that have not flowered in a location that receives
high nitrogen fertilizer (such as near a lawn)? This would lead to lots
of leafy growth at the expense of flowers. Cold winter weather can also
damage buds and lead to no flowers.

The lack of fruit could be due to lack of pollination in addition to the
causes listed above. Do you have two or more pears (Pyrus) and hazelnuts (Corylus)? Is your
plum (Prunus) a variety that needs a pollenizer, or is it self-fertile? Raintree Nursery has information on flowering and fruiting for Corylus that says”Two different varieties or seedlings of similar flowering period,” are needed, and that “European Filbert flowers winterkill at -15 F. Others are hardier.”

Oregon State University Extension has fruit pollination charts, and there is an example from Burnt Ridge Nursery for European pears.

General information from University of Vermont Extension on failure to flower and failure to bear fruit from Washington State University Extension.

managing brown rot on ornamental cherry trees

We have a mature ornamental cherry or plum tree that suffered
from brown rot last year. We removed all affected branches and leaves. We were told that we might need to do something else this winter or spring–spray the tree with something, possibly. Can you advise us on how to keep our tree healthy?

 

I consulted The Organic Gardener’s Handbook of Natural Insect and Disease
Control edited by Barbara Ellis (Rodale Press, 1996), and this resource
recommends doing what you already did, by removing and destroying
affected parts of the tree. At the beginning of the growing season (early
spring) you can spray sulfur to control this fungal disease on blossoms.
If you were growing fruit, you would spray again later in the season to
protect the fruit, but since this is an ornamental tree, it isn’t
necessary. Copper sprays are also used to control the disease. Washington
State University Extension recommends preventive measures, such as
avoiding wounding trees (damaging bark with string
trimmers/weed-whackers/lawnmowers, or making bad pruning cuts). Avoid
wetting the blossoms and leaves, and keep the tree pruned for good air
circulation in the canopy. Avoid excessive nitrogen fertilizer. While the
tree is in bloom, check it frequently for symptoms, and destroy any
diseased parts as soon as you notice them.

I found sources for less toxic (but still not hazard-free) versions of
these fungicides from Peaceful Valley Farm & Garden Supply, but they may
be available at your local garden center as well. Some of these require a
pesticide handler’s license.

Lime Sulfur Fungicide

Copper Sulfate

controlling aphids on prune trees

My prune tree has tons of aphids in the leaves (also a lot of ladybugs to eat them but I am not sure the ladybugs will win out). Do I need to try to rid the tree of the aphids? If so how?

 

The question of whether to control aphids in your prune tree really depends on how bad the infestation is and if the tree is otherwise healthy enough to outgrow them. Often infestations like aphids are a symptom of a larger problem. The tree may be stressed out by root competition from grass or too much or not enough water, too much or not enough nitrogen. A stressed out tree is attractive to aphids, who in turn attract lady bugs.
My own mature prune tree gets covered in aphids every year. The leaves get distorted, and lady bugs come in droves. Some years I get a good harvest and some years I do not. I choose not to worry about it (I have other plants to fuss over). But if you feel the need to do something, see the HortSense website from Washington State University.

Garden Tip #15

A common question gardeners have is when to prune. “When the shears are sharp!” is the often-heard answer. In reality there are a few timing guidelines that do matter.

First of all, certain trees are known to “bleed” when pruned while the sap is rising in late winter and early spring. Maples, dogwoods, birch, elm, walnut and honey locust are the most common.
Bleeding usually won’t hurt the tree, but the pruning cuts are slower to heal which may leave susceptible trees vulnerable to infection. These trees should be pruned right after leaves fall off in autumn.

Cherry trees are at risk from the destructive cherry bark tortrix. The tortrix is attracted to fresh pruning cuts, so cherry trees should not be pruned between May and August when the tortrix is active.

Spring flowering shrubs should be pruned immediately after flowering so that the new growth has time to form next year’s flower buds. Summer flowering shrubs may be pruned in winter because flowers are formed on this season’s growth.

Pruning resources online: