Article by Thean Phey – In my ungoing quest to actually get a decent harvest of plums off of my ever expanding hybrid plum and chum section I read whatever I can find about plum pollination trying to understand it. I realize I’m not alone in this situation (many trees, few fruit) and a lot has been said on GF, but there has to be a better way than just continuing to add varieties and hope for the best. This year should have been a bumper crop for me – only one frost in early June and 3 days of beautiful sunny weather when all of the plums and chums were in full beautiful bloom (the longest stretch we had with no rain all season) and they were full of pollinators. I had great expectations. I had a handful of fruit. The only trees that didn’t bloom were the, it sounds like, very important American Plums which are too young yet, plus some new grafts of even more hybrids. The only years (two) that I’ve had a somewhat reasonable crop I also had a Pembina blossoming. Unfortunately that tree died a few years ago.
This summer the newsletter of the Canada DGB Fruit Growers Group had an article by Thean Phey on Plum Pollination (I’m always on the lookout for articles by Thean Pheh and Bernie Nikolai for interesting ideas on growing fruit in colder regions). It doesn’t give any easy answers, no answers really, but it was interesting. I’m wondering what others more knowledgeable than I think about his ideas here? The plum article is down the page below the Budding and Grafting one.
Neay article and newslwetter, lots of interesting info in there! I also liked the piece on cotoneaster as understock for pear…
I use p Americana as pollinators for my hybrid plums and it seems to work out. At the plum trial at our cooperative extension farm, they have a small isolated block of Hansen hybrids and haven’t gotten good fruit set, I told them they needed to add in some p americana…
Wow, Sue, great information in those articles for the cold-weather types! I picked up a lot of tips on various subjects that I hadn’t come across before. Thanks!
I see plum pollination as having multiple factors and these factors vary with each growing zone, so a cure all for poor pollination in my opinion doesn’t exist. Plums seem to need to be fairly mature, maybe 5 or 6 years too before drawing any conclusions. I have good pollination here, it took 5 years. I don’t have any native plums either. I don’t have a lot of trees either, Satsuma, Nadia and 4 pluots. All fruited this year, first time ever. Most were loaded with plums. I have added about 8 more as grafts this year, so I need another 5 years before I can make good observations on them.
In the colder zones Konrad knows his plums he is on Garden Web, and won’t come here. I’m not in a warm zone, but not in zone 3 either so my experiences in zone 5b/6a only apply to those zones and only in the Midwest in my opinion.
I think the fact I grow many plants that attract bees, and other beneficial made the most difference for me. Flowering herbs, nasturtium, borage, zinnia, sedums, lily’s, raspberries, etc. My yard is buzzing with bees all year. And they come back looking every year too. Many solitary bees probably live in the yard now. Some research does support that they help in stone fruit pollination. Nasturtium,columbine and borage self sow, only planted once. I germinate Zinnias every year, I really like them, the flower lasts for weeks and it produces ton’s of them. Easy to harvest seeds too. The others are perennials.
One of the biggest attracting plants to native bees I have observed is strawberries, native to all of North America. And they flower early, right with the plums.
To muddy the waters even more… in a cold zone you can have significant damage to the female bits of the plum flower, but seemingly have fully functional pollen-shedding male bits. This has been my experience the last two years with my Suprerior and Alderman plums. Both years the majority of ovaries have been killed by spring freezes, but have had pollen and nectar, and have been visited by some sort of native mason or other native grey-colored bee. However, my fruit set has been bad because of the dead female parts.
Not much you can do, well you can heat them with lights etc, but I find that so impractical. I’m lucky as the lakes buffer those late freezes and most years we are good. Once in awhile a bad one happens anyway. I noticed last week at my cottage which is farther north than my house that it was warmer there. The lakes are warm and warm the local air. The cottage is 100 yards from the river. Warm is relative, say 50F or above the water is right now.
I just came across another interesting piece on hybrid (salicina) plum (and chum) pollination. I thought knowledge of using American Plums for pollinating hybrid plums, and the problem of hybrid plums not pollinating each other, was rather recent but apparently not. This is a bulletin from Univ Minn 1951 - “Pollination Studies with Stone Fruits”. A nice, easy to read and understand report. Wish I’d read this 15 yrs ago! Can’t wait for my AmeriPlums, and a South Dakota graft, to start flowering. Sure be nice to get a real harvest of plums one of these years. Sue
Several years ago I ordered a Prunus Nigra from Forest Farm. I believed it to be a pure Prunus Nigra, not a named variety like “Bounty.” A few years later I noticed they no longer sold Prunus Nigra, but only sold “Bounty.” It had a different item # than the one I ordered (I still have the old catalog somewhere), but I am a little worried it was really Bounty all along…but it is possible that I MIGHT have a pure Prunus Nigra tree. I’ve been waiting for it to fruit so I can verify it but PC got the few fruits that formed last year. IF I can verify that is the real Prunus Nigra, I should be able to offer some scion wood or seeds next year. It is supposed to be a good pollinizer for Hybrid plums.
I planted some native plums near my other mostly non-producing, but large plum trees two years ago. I was hoping I could learn this spring if that was a successful venture, but after the -31F last week, the plums may be on vacation this summer.
You should be able to locate some seeds if you’re ambitious enough. Either a wild grove or a post on the trading sight might land you one…i could also give you a cutting from mine next summer.
An update - Last year (2018) my plums were as they have been (see top post) - great bloom, few fruit. This year I had for the first time a few blossoms on two of my young AmeriPlums (14 and 7) and a few on a South Dakota graft. Everything else blossomed in thick profusion, pollinators overall were scarse except bumblebees but they were plentiful and busy. I didn’t expect much if any fruit. But to my surprise I got 43 plums off my oldest Gracious and 22 off a 3-graft, plus a dozen Sapalta. Not a lot to be sure but this is the most fruit I’ve seen since my Pembina died four yrs ago. Not a for sure conclusion but it does implicate the AmeriPlums. Have my fingers crossed for this year.
On the Sapalta Chums the years of excellent harvest were when I also had an unknown seedling chum flowering or an unknown plum, sucker from a friend that I’m guessing from years later memory maybe was a Pembina.
The Wanetas had a crop, but the others were sparse. No blooms on the American plums yet. I didn’t get all the Wanetas eaten, so planted the remaining rotting ones to see if they would produce any rootstock. I try to remind myself that this is just a hobby.
It had 3 fruits last year but they had plum pocket disease so I had to dispose of them. I’ve never had that on any other plums but I spray my other plums for other fungal problems. This tree is in a seperate location, so I usually don’t spray it with anything. Maybe I’ll hit it with immunox in a few days.
Ever confirm what strain of Prunus nigra you have? Any fruit yet? Also what color are the blooms? Plum pocket is also an issue in the native stands around me.