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Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Failure to fruit, Vaccinium, Plum, Prunus

We have three blueberry bushes of different varieties that have been bearing just fine over the last several years. This year one of them bloomed heavily and looks like it's generating a good crop. The other two only had a few flowers. What could account for this? Is there anything we should be doing to encourage blooming and fruiting?

I am also wondering when we will ever see fruit on the Italian Prune tree I planted several years ago. It was already pretty big when we bought it, and now it is about 2 inches caliper near the base and is about 12 feet tall. Is there anything we can do to encourage some fruit on this? I do not even remember seeing it bloom this year. Could it have something to do with the weather patterns?


One problem might be a lack of bees. There could also be other reasons, such as Botrytis blossom blight, and blueberry shock virus.

Here is a page from Oregon State University which has some good general information on growing blueberries .

Is it possible that the blueberries have become dense and twiggy? If they are not pruned, they may become unproductive. The information below is from University of Florida Cooperative Extension:

Pruning mature blueberry plants is largely a matter of cane removal or cane thinning. The objective of pruning mature bushes is to stimulate the proper balance of vegetative and reproductive growth, and limit plant size. Pruning stimulates the development of new canes which are more productive than older canes. A general rule is to remove about 1/4 to 1/5 of the oldest canes each year (usually one to three of the oldest canes). This will result in continuous cane renewal so that no cane is more than three or four years old. Pruning to reduce the number of flower buds may also be required on some southern highbush cultivars which set heavy crops such as 'Misty'. Flowers should always be removed from one and two-year-old plants by pruning or rubbing them off before fruit set occurs. Most pruning is usually done immediately after harvest during the early summer. Removal of some of the flowers buds to adjust the crop load is usually done during the late winter just before growth begins.

As for the Italian prune, a plum tree may not begin to bear until it is 3 to 6 years old.

You may also want to visit a Master Gardener Clinic with your questions. You can locate a Master Gardener Clinic within King County on this website.

Date 2017-09-27
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Plant Answer Line Question

Keywords: Failure to fruit, Fruit trees--Cross-pollination, Pyrus, Fungal diseases of plants

I have a 'Rescue' pear which has gotten pear rust. It is about 3 years old. I also have an 'Orca' pear tree that so far this season does not have rust. Last year we had terrible rust. We thought maybe it came from a secondary host, because there were Juniper bushes. Now those bushes are all gone and I did clean up the leaves from last year to try and avoid contamination from the rust.

Also, I have never gotten any pears on either tree. The Orca tree is a bit older, about 5 years old. They both were bought from Raintree Nursery.


Sorry to hear about your pear with rust, and about the lack of fruit. Washington State University's HortSense website says there are two types of rust that affect pears in our area:
"Two pear rusts which occur in Washington are Pacific Coast pear rust and pear trellis rust. Both require an alternate host. The rust fungus causing Pacific Coast pear rust is also found on hawthorn, apple, crabapple, serviceberry, quince, and mountain ash. The alternate host is the incense cedar (Calocedrus decurrens), which develops witches' brooms. Infected fruits of pear are deformed and drop prematurely. On the surface of the fruit, yellowish spots with cup-shaped pustules develop. Leaves and green shoots may also be infected. Symptoms are most obvious after flowering and before July. Pear trellis rust may also infect pears, causing reddish to orange blotches on leaves. The alternate host is juniper, which develops elongate, swollen galls along branches."

The only controls they recommend are cultural:

  • Avoid susceptible varieties such as 'Winter Nelis'.
  • Collect and destroy fallen fruit beneath trees.
  • Plant resistant varieties such as 'Bartlett'.
  • Prune out and destroy rust-infected tissues in pears and alternate hosts.
  • Remove alternate hosts in the vicinity of pear trees, when practical.

Here is an article from British Columbia Ministry of Agriculture and Food on managing this disease in the home orchard.

It sounds as if you are doing everything you can to prevent a recurrence. The web resource above also states that fungicide is probably not a worthwhile approach to managing rust on pears or junipers.

As for the lack of fruit on your trees, Raintree's pollination chart shows that 'Rescue' and 'Orcas' should cross-pollinate. It is possible that the 'Rescue' pear is not mature enough, or that its bout with disease slowed it down. Here is an article about failure to produce fruit, from MSU Extension. It mentions possibilities such as immature tree(s) and frost damage to flower buds.

I have an 'Orcas' growing without other pears in the garden, and yet it produces fruit, so I wonder if something else may be happening. Do you have a good number of bees and other pollinators in your garden? Do you or nearby households use pesticides that might interfere with pollinators? Here is information on protecting and encouraging pollinators, from U.S. Fish and Wildlife.

I also recommend contacting Raintree to see if they have any advice.

Date 2018-03-14
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Plant Answer Line Question

Keywords: Prunus tomentosa, Failure to fruit, Fruit trees--Cross-pollination

I have had a Nanking cherry bush that I planted 3 years ago. The first year, as I expected, it didn't produce flowers or fruit. The second year, it produced some flowers and about 4 small green cherries, which disappeared off from the bush in about a week. This year, it had a lot of flowers, but only produced 2 small green cherries, which also disappeared in about a week. I only have the one bush, and it seems very healthy otherwise. Is it due to being so young still? Do I need a second plant? Any advice would be greatly appreciated.


According to the Arbor Day Foundation, Nanking cherry (Prunus tomentosa) "is not self-fertile. Two or more shrubs should be planted within 100' of each other to ensure cross-pollination."

Information from Alberta, Canada's Agriculture and Rural Development website (no longer available online) has some suggestions on cross-pollination:
"Nanking cherries need cross pollination, for fruit production, therefore more than one plant is required, or an early flowering plum such as Brookgold, Bounty or Dandy. Mature plants reach heights of up to 2 m. Plant in rows 3 m apart with 2 m between the plants in the row. Prune annually to prevent shrubs from becoming too dense. Remove no more than one-third of the total number of branches at one time. This allows the plant to replace older wood with young, vigorous wood."

There is a chapter on Nanking cherry in Lee Reich's Uncommon Fruits Worthy of Attention (Timber Press, 2004) in which he states clearly that cross-pollination is needed (some information on the web says that it is self-fruitful...which might be true to a small extent, but you will have a much better crop with cross-pollination). Some key points: Nanking cherry does well in sun and well-drained soil. Full sun is preferable, but it will still bear fruit in a shadier spot. It grows vigorously, and can live 50+ years. "Annual pruning, though not a necessity, brings out the best in any Nanking cherry in terms of yield and fruit quality. Prune in late winter with the aim of keeping a bush open so that all branches are bathed in sun and quickly dried by breezes. Accomplish these goals by shortening some branches, removing others entirely, and leaving still others untouched. This pruning will also stimulate a steady supply of young, fruitful branches each year."

Date 2017-05-05
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May 23 2018 14:32:42