flowers and fruit on Arbutus unedo

My Strawberry tree (Arbutus unedo) is 8 years old, and very lovely, but the hummingbirds and bees don’t seem to find it. The tree has had some blossoms over the years, but only 1 “strawberry.” Now it has many blossoms. Can I help it by hand-pollinating?

I first saw Arbutus unedo growing in Greece while on a Christmas holiday hiking trip. So I returned home with the dream of a real live tree, self- decorated with red, yellow and orange baubles! My tree is lovely and green as I look out the window, but I may need to hang the decorations. Should I be out there now with a paintbrush and hope for strawberries next Christmas?

There are several factors that affect the fruiting of Arbutus unedo. You don’t mention a cultivar name, so I’m assuming that your plant is the species, Arbutus unedo, which is usually propagated from seeds. Seedling plants are variable, unlike cultivars, which are grown from cuttings (hence, genetic clones). It’s likely that some seed-grown plants do not fruit reliably. An Australian article notes that “vegetatively propagated plants will fruit faster and more predictably than seedlings.”

Another factor is that the flowers and ripened fruits appear on the plant at the same time. Your plant has flowered sparsely until this year, so it’s possible that fruit will form in the next several months, ripening next fall.

The University of Washington Botanic Gardens blog has an entry about this plant: “The flowers are in clusters of tiny white bells (similar to its related genera Arctostaphylos, Pieris, and Enkianthus) and are present October to December while the 1” round fruits of the previous year’s pollination are ripening on the tree. The fruits take 10-12 months to ripen; from green in the spring they begin to turn yellow then orange through summer then ripen to a bright red from October to December at which time they are edible.”

Local non-profit Great Plant Picks indicates that a protected location is also a factor: “Foliage and flowers may be damaged in unusually cold winters, but it will recover in the spring. Plants in protected locations are more reliable fruit producers.” Other sources stress the need for a warm, relatively sunny location. Unfortunately, strawberry tree doesn’t transplant well, so if yours is planted in a shady location, transplanting it is probably not an option.

Even though Arbutus unedo is self-fertile, fruiting is greatly improved by planting more than one tree. On my own walks in Seattle parks, I’ve noticed that strawberry trees planted in groups of two or more seem to fruit prolifically.

Strawberry tree is attractive to many forms of wildlife but is pollinated by bees. If your garden lacks other plants that attract bees, I recommend adding bee-pollinated shrubs, perennials and/or annuals that flower earlier in the year to increase the chances that bees will remain there in fall.

Finally, does your site have what Arbutus unedo needs to grow well, remain healthy, and develop fruit? “This versatile shrub tolerates a wide variety of soil conditions including sand and clay, but it must have a well-drained location.” (Great Plant Picks). It’s drought tolerant when established but may be damaged if not given supplemental water during the very hot and dry conditions the Pacific Northwest has experienced, especially in the last several years. Even using a high nitrogen fertilizer will affect fruiting, promoting leaf and stem growth instead of flowers and fruit.

Arbutus unedo, Failure to fruit

Staghorn sumac flowers and fruit

I planted three staghorn sumacs several years ago. They have done well, and have nice fall color, but I was hoping to see the flowers and fruit. This summer, for the first time, there are flowers on one shrub. What prompted the change? Will the flowering plant have fruit?

Anecdotally, there are reports of Rhus typhina (staghorn or velvet sumac) taking a while to flower and fruit. If you don’t have flowers on more than one of your three plants, you are not likely to get fruit (unless your flowering plant is female and someone nearby has a male, in case your other two are also female). Rhus typhina and Rhus glabra (smooth sumac) are dioecious, meaning that they produce male and female flowers (yellow green upright cone-shaped panicles) on separate plants. Plants of both sexes need to be grown together, and pollen from the male flowers needs to reach the female flowers, for the the upright clusters of the fuzzy disc-shaped dark red fruit (berry-like drupes) to develop on the female plants. These fruit clusters are colloquially referred to as ‘bobs.’

You can examine the flowers on your plant closely (with a hand lens) to determine if they are male or female. Male flowers tend to be larger and have five yellow-tipped stamens, while female flowers have a three-lobed style in the center, and a calyx with five pointed lobes nearly the same length as the petals. Both flower stalks and calyx are densely hairy. [Source: Minnesota Wild Flowers field guide online] Here are additional photos to clarify the description.

Failure to flower, Failure to fruit, Flowering of plants, Rhus

Pear rust and lack of fruitfulness

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 University of Maine. It mentions possibilities such as immature tree(s), lack of sun, 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.

blueberry bushes lack of blooming and fruiting

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.

Nanking cherry and 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.”