North American Fruit Explorers mailing list at ibiblio

[dwoodard@becon.org]

In reply to Bernie Nikolai's message #4764 of 30 September:

About 1950 the Journal of the American Society for Horticulture 
Science (?) published an article on the coldhardiness of European 
plums by a researcher the the Minnesota fruit breeding station 
(Excelsior/Minneapolis).

The hardiest of those tested was Krikon Damson (which should be in US 
collections; I think a few Canadian specialist nurseries sell it; it 
used to be in the Vineland Station (Ontario) collection and I believe 
they got it from the US), the next was Stanley (which seems rather 
prone to black knot)and Mount Royal was rated almost as hardy as 
Stanley. Yakima was rated a little less hardy than Mount Royal, but 
still one of the hardiest European cultivars.

I have no experience of Yakima and almost none of Mount Royal. The 
information I have encountered about Yakima says that it is a large 
plum of exceptionally good flavour, better than Mount Royal. It is 
usually said to be a shy bearer, although I have not acquired much 
information about it and maybe there is some combination of climate 
and pollinators that helps, as in some other cases.

I recall that the late Dr. Gus Tehrani, plum breeder of Vineland 
Station, maintained Yakima in his collection and hoped to incorporate 
its quality in a commercial plum, although I don't know whether 
Yakima figured in the ancestry of any of his named cultivars or 
numbered selections.

I believe that Yakima is considered to be related to Yellow Egg 
(English origin, mainly processing although apparently some people 
like it fresh, hints of susceptibility to brown rot) and Peach ( I 
think northwest US origin, apparently a good quality fresh eating 
cultivar). I seem to recall rather vaguely that the ASHS Journal 
article listed both as hardier than average. They would be more 
productive, probably especially Yellow Egg.

Dr. Tehrani evaluated Pershore Yellow Egg as a rootstock (it is 
considered a good plum rootstock in Britain) and told me that the 
roots seemd to grow more on one side than the other, and that it was 
somewhat susceptible to wind. I recall from a British government 
publication I read many years ago that Pershore Yellow Egg is 
compatible with peach and I think (memory a little dim here) with 
apricot. It apparently does not share the ability to let the 
cultivars grafted on it crop reasonably well in droughty summers 
which makes Myrobalan so popular in the Niagara Peninsula.

I once bought a Mount Royal tree as a gift for friends who lived 
about 20 miles north of Lake Ontario near Kingston, and in the 3 or 
so years I was able to observe the tree I noticed that it lived up to 
the usual description of Mount Royal as somewhat dwarfish with good 
crotch angles, close to 90 degrees in this case. This growth 
character made me wonder how Mount Royal would serve as a rootstock 
for European plum in cold areas. One might be able to propagate it on 
a marginally compatible nurse rootstock such as Prunus americana, and 
I have wondered how softwood cuttings would work. I don't expect to 
be able to do these experiments myself.

Mount Royal originated at Montreal around 1830-1850 with a Mr. Corse 
(?). It is often spoken of as resistant to disease, although I don't 
know how this resistance or tolerance divides between black knot and 
brown rot.

Mount Royal has survived for lengthy periods (apparently 20 years or 
so at a stretch) along with Krikon Damson, around WWII or somewhat 
before,  at the Agriculture Canada research station at Morden in 
southwestern Manitoba (Agriculture Canada zone 3b, a little milder 
than Edmonton's 3a in the rural area away from the urban climate 
effect). Mount Royal and Krikon Damson apparently did markedly better 
at Morden than McIntosh apple.

I have heard of a successful (for a while at least) small commercial 
planting of Stanley on the Gaspe peninsula - near the sea, but it 
still gets plenty cold there in winter. I think that Mount Royal 
might be a better prospect for most people than Stanley, mostly 
because of black knot, and partly because I have noticed that Stanley 
in commercial orchards in the Niagara Peninsula on peach soils has 
pretty mediocre fresh quality. I understand that the Geneva Station 
which originated it has a lot of clay, so maybe it does better on 
clay than on sandy loam. I recall that Imperial Gage was reported in 
the old books to be super-good in quality on the peach soils but 
mediocre and not worth growing on clay.

Both Mount Royal and Stanley are reputed partly self-fertile, I 
believe the damsons are self-fertile.

I would be very careful about commercial nursery trees of European 
plum in cold areas regarding rootstock hardiness. Ontario nurseries 
used to sell them on Myrobalan seedling, and in the test winter (very 
cold early, then a long warm thaw followed by severe cold with no 
snow) of 1980-81 in the Kingston area, I had some Myrobalan seedling 
rootstocks whose apricot tops had died previously, die or suffer 
severely (the roots died or were damaged, not just the tops).

I hope that you are not too bored with this long post.

Douglas Woodard     <dwoodard@becon.org>


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