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Fruit and Nut Trees Plant Care, Propagation, Identification, Appreciation and more!

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Old February 19th, 2005, 12:15 PM
Ian McCracken
Posts: n/a
Plum Tree, flowers but no fruit

Hello BC:
I have been searching the web for "fruit tree help"and I believe this is the best forum I have come across. I have searched the forum but cannot find a query which matches my problem. I am hoping you can help me even though I am in the US.

I have two plum trees in a sunny area in San Francisco. One was in the garden already. It produces hundreds of small plums which are not the best easting but make good jam. I need your help with a Santa Rosa plum tree which I planted myself about 5 years ago. It flowers reliably with almost as many flowers as the "native". However, only about half or less, of the flowers result in green buds (sorry I do not know the technical term, but I mean the start of the plum). Within a week however, nearly all the green buds, which are about 5mm - 10mm diameter, fall off or just dissapear. (I cannot see them on the ground). The result is that there are only a dozen buds which mature and grow to be become fruit.

On the native plum tree, sorry I don't know the variety, nearly all the fowers become buds and these quickly grow to become plums.

The tree appears very healthy. Nice healthy green leaves. Good growth. I should be getting cross pollination from the native. I see bees on the tree. I prune a little in the winter. I fertilize, but I do not use a dormant spray. But I do not use one on the native either, which produces hundreds of fruit.

Could I have an "infertile" tree? Is an insect or fungus attacking the early fruit? (I see no evidence of that) Do I need to use the dormant spray (even though I don't use one on the healthy native)?

We also have a peach tree which produces a fantastic amount of fruit each year. I pay no more or less attention to this than to the plum tree. I use the same water/feed schedule and each gets the same amount of sun. As does the native plum tree.

Any advise will be very welcome.
Thank you,
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Old February 23rd, 2005, 05:02 PM
mr.shep's Avatar
mr.shep mr.shep is offline
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Join Date: Mar 2004
Location: San Joaquin Valley, California
Posts: 1,394
Hi Ian:

Why not join the UBC forums?

More than likely what you are calling a native
Plum is more apt to be a flowering Plum. We
have several types here in California that produce
an abundance of canning quality Plums as well
as fresh eating but they are just a little tart for
eating and do not get the sweetness or the size
of fruit, nor some of the exotic flavors of the
fruiting Plums.

I would need to know if your Santa Rosa is an
Early Santa Rosa, Late Santa Rosa or was just
a Santa Rosa on the label. All forms of Santa
Rosa are self fruitful meaning they can produce
fruit without any other Plums around. They
will have better fruit set if there is another
fruiting Plum nearby.

A lot of times we will get good bud set and then
much of the infantile fruit is sloughed off. Plums
require more water during the Winter and when
they are in bloom than a Peach does. I've seen
every single Plum that was pollinated fall off the
tree before when the tree did not get adequate
deep watering when the tree was in bloom. Also,
a dormant spray is rather important for a fruiting
Plum whereas for a flowering Plum a dormant
spray is not necessary.

It may be good to know where you bought your
tree as many times what homeowners thought
they were buying as being a Santa Rosa Plum
was not a Santa Rosa at all. It could be that you
have a Plum that requires a pollinizer, another
Plum to help it along to better promote fruit set.

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Old February 23rd, 2005, 05:16 PM
Ron B Ron B is offline
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Existing plum probably cherry plum (Prunus cerasifera) or another kind not closely related to 'Santa Rosa', unsuitable for cross pollination.
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Old February 24th, 2005, 08:20 AM
mr.shep's Avatar
mr.shep mr.shep is offline
Plant Collector/Home Gardener
Join Date: Mar 2004
Location: San Joaquin Valley, California
Posts: 1,394
Existing plum probably cherry plum (Prunus cerasifera)

For many years cities and municipalities used Prunus blireiana,
Prunus cerasifera 'Atropurpurea' x Prunus mume a lot for
street trees and parks back in the mid to late 70's through the
mid 90's. People loved the trees in bloom and the color of
the trees for most of the year but some people objected to the
fruit set and the clean up afterwards which led to some cities
to remove some of the trees.

Even back in the early 60's Atropurpurea were planted in
select areas usually aligned as frontal borders for properties.
I know of an old wholesale growing nursery, once very well
known, that used Atropurpureas for their rootstock for their
fruiting Plums back in the early to mid 60's . Myrobalan,
Prunus cerasifera is still used quite a bit as rootstock for
commercial Plum production varieties here but we have not
seen it per say available for sale in local retail nurseries for
many years. People seem to prefer the purple-red leaves
rather than the green leaves. Also, the fruit for preserves
is far better from the red leafed trees than the green anyway,
at least to some of us. Fruit from the old Atropupureas is
better quality for preserves and fresh eating than the
Blireianas are also.

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Old March 8th, 2005, 09:33 PM
ianmccracken ianmccracken is offline
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Join Date: Feb 2005
Location: San francisco
Posts: 1
Cross Pollination

Thanks very much for the detailed replies Jim and Ron. I will try your tips. I did water the tree once a week last year, about 1 gal per week, when it flowered but I will do that more often this year. The tree is about 12' tall and the spread is about 6'.

I have also applied a dormant spray which I did not do last year.

I have searched for the label to the tree but I cannot find it. I do believe I may not be getting the cross pollination. I did buy it at Home Depot so it may not be a Santa Rosa!

Is there any alternative to planting another plum tree for the cross pollination? I don't really have room for another tree.

Thanks again,


BTW: I have joined the forum.
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Old March 9th, 2005, 12:20 AM
Ron B Ron B is offline
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Grafting branches of other varieties onto existing tree. Fruit hobbyists do this, otherwise they'd be buying and planting a whole additional tree every time they wanted to try a new kind.
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