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Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Fruit trees--Cross-pollination, Pyrus

I am looking for a European variety of pear tree that cross-pollinates with an Asian pear tree. I thought I'd heard that Bartlett pear trees can pollinate an early blooming Asian pear. Is this right?


The University of California, Davis Fruit & Nut Research Center indicates that European pears may be used for cross-pollination with Asian pear.
"Pollination: Asian pear varieties are partially self-fruitful but better crops are set where two or more varieties are planted together. In Fresno and Tulare counties, 20th Century or Shinseiki are known to set good crops when planted alone in large one-variety blocks. In areas with cooler temperatures at bloom-time, cross-pollination by European or Asian pear varieties will be necessary. Cross-pollinated fruit with seed tend to be larger and more uniformly round than fruit with few seeds due to inadequate pollination."

Washington State University's Tree Fruit site shows which European pears will be compatible pollenizers for specific varieties of Asian pear. (click on the plus sign to expand the information on pollination for pears)
It indicates that Bartlett will work for Chojuro and Nijisseiki.

Washington State University's Fruit Handbook for Western Washington says "pears and Asian pears are genetically compatible, so they can cross-pollinate just the same as any varieties whose bloom periods overlap. It is, however, important to note some limitations. Asian pears (...) tend to bloom earlier as a group; furthermore, not all European pears are suitable pollenizers. Conference is a good early blooming pear that can pollinate Asian pears in most years (...) Pear flowers are not particularly attractive to bees, so for good pollination when growing pears and Asian pears, try to minimize the availability of other flowers (eg., dandelions) when pears are in bloom."

Date 2018-03-01
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Plant Answer Line Question

Keywords: Fruit trees--Cross-pollination, Cornus mas

Can you tell me how to grow Cornelian cherry? Do I need more than one tree to get fruit? Also, what kind of soil and fertilizer does it need?


Cornelian cherry, or Cornus mas, is not especially fussy about type of soil, but prefers well-drained moist soil that is somewhat rich. According to Lee Reich's Landscaping with Fruit (Storey, 2009), the tree is at least partly self-fruitful, but planting a second tree (a different cultivar or clone) will increase fruit yield. I don't think there are particular fertilizer needs for this tree, but you can provide a mulch of compost in spring or fall if you wish. Reich says to "plant this tree carefully, keep weeds at bay at least for the first few seasons, water as needed during the first season and you'll have little else to do for your tree beyond enjoying looking at it and harvesting the fruits."

The local website of Great Plant Picks has information about this tree.

Washington State University at Mount Vernon's fruit research center offers a list of cultivars tested in 2007:
Cornus mas

  • "Elegant"
  • "Olga"
  • "Pioneer"
  • "Red Star"
  • "Sevetok"
  • "Yevgenii"

Date 2018-03-01
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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