Black Knot question

Hey folks, recently discovered this site and have been enjoying reading the wealth of good input and info here. I’m planning a windbreak planting on my property consisting of 5 rows. I’d hoped to have at least two rows of fruit bearing trees/shrubs. After much reading and research, I was leaning towards using chokecherry for the 1st/windward row and native plum for the last row, then I heard about black knot fungus. I live in eastern Colorado (5a), and with our dry, windy, weather and general lack of trees in the area is it something I should be concerned about or is it more of a humid climate problem? Is there a general limit to how far the spores can spread? For what it’s worth, the rows would have about 80 feet between them and have two rows of conifers between plus a row of large deciduous trees. I’d hate to spend the time and resources planting a few hundred trees only to have to cull and start over, but at the same time our options for suitable fruit bearing windbreak species are limited. Thanks in advance!


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Good question ?
I think if you don’t see black knot on wild trees ,or orchards near you,and you plant clean stock, you should be ok.
If there are infected trees upwind from you ,that is bad.
Have you seen black knot there ?

I planted plums here in wv. Never saw black Knot for 15 yrs.
My neibor , "a mile away "bought a plum tree infected with black knot.
I told him to cut it out befor it spread , he did not. And it spread to all his plum tree s ,dozens of them.they are still there ,untended.
I thought it would not travel 1mile, but it did,now I can hardly grow a plum.

Don’t let my story about my situation , slow you down,
Wv. Is wet and humid .Colorado dryer.
Black knot needs free water to infect.
May not be an issue there at all.

Not many trees where I live, mostly open pasture/range land. Pretty much the only trees in my area are windbreak trees, and most folks just do a few rows of juniper or cedar and call it good. . But your story is the situation I’m worried about. We are drier here in general, but spring time can be (relatively) damp. I’ve read about black knot in urban areas like Boulder and Colorado Springs, so I know it is capable of living and spreading in the state. Then again, I spoke with our local extension guy and he’s got chokecherries and hasn’t had a problem. I have a tendency to over-think things, maybe it’s much ado about nothing…

I have no idea what trees are suitable for your location.
I do believe in wind beaks. And it sounds like you need some.
If it was me, I would go for a diversity of things rather than a few closely related plants.
The more different things the better.
Better habitat, fruit that ripens over a longer season. Less pest ,disease ,
Better chance that somethings will do good.
I’ll bet their are a lot of different things you could stick in there,
Service berry ? Mulberry ? Buck thorn ? Mix it up

Seems like that’s kind of a rough area to grow trees. Do choke cherries and native plum grow wild there?

hi Chris, Sounds like you have a nice plan. Every place is different, of course, but we have a lot of wild black cherries here and black knot in them is common. I’ve had chums and plums in my orchard for many decades and never had a black knot in them. The wild chokecherries sometimes do, sometimes don’t. I usually figure that by planting a lot of varieties (whether fruit trees or garden crops) i’ll find out what which ones like it here and which don’t. The ones that do stay and provide good crops down the road. Have you considered interplanting with other maybe non-fruiting trees and shrubs? Diversity seems a great way to keep individual diseases and pests down. It seems to be working for me. Sue


Here is a hunch. I I suspect that unless you have a windrow of some sort of evergreen, freeze drying of your plums will be a bigger problem than the black knot. Maybe the choke cherries will be enough of a wind barrier, but my spidy senses are tingling. God bless.


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Thanks for all the great input folks. Yes, we have a rough area for growing trees. Officially we’re zone 5, though temps in the -20’s are not uncommon, we have a good bit of wind, (I think from all the 300’ tall “fans” they’ve put up around the area hehe), our soil is alkaline, and we get just shy of 20" of rain annually. I’m getting my trees through the local forest service/NRCS office seedling tree program, so my selection is limited to what they sell - in part because it’s economical but also because they’re locally sourced and generally only supply species that will actually grow in our area. Here’s my planned planting, starting from windward/North side:

Row 1 - Chokecherry
Row 2 - Juniper
Row 3 - Ponderosa
Row 4 - Bur Oak
Row 5 - Native Plum

I agree that diversity is key in a healthy, functional windbreak, and since the main reason for planting this windbreak is to provide shelter for growing, I’m thinking that I should focus on that as the main purpose more than getting fruit out of the windbreak. With that in mind, I’m thinking to limit potential for a single disease impacting two rows of my windbreak and sub out the 1st row for either lilac (proven performer in our area) or NM privet.

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Infection requires nearby trees already infected and also high humidity in spring. Pest pressure is entirely a regional issue and most pest problems experienced by growers in the humid region are non-existent in the west.

For a wind break you probably should be studying what will establish itself most quickly and then work form there. If rows are running east to west have fasted growing species on the north side and finish with flowering small trees and shrubs towards the south to help nourish pollinators. Aim for species that don’t flower when your fruit trees are. This will not only be useful for making a solid wind break (tall trees shade out their lower branches eventually reducing the wind breaking aspect as lower branches die) and help keep the bees around your property. It will also lead to a more natural looking and attractive wind break.

There are sources for very small trees and shrubs that are not expensive and with much wider selection that you can get from the NRCS. You may be surprised to find similar pricing.

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Yes and no - I’ve seen both growing in the region, though less in the high plains areas except in sheltered and/or low areas. I’m inclined to think before ranching and associated over grazing became widespread they may have been more prevalent.

IMO, that’s the upside to growing in our area. Blights, mildews, etc. that plague folks I know back east are rarely, if ever, an issue for us in our gardening. That said, I’ve read of black knot occurring in CO, and a friend of my wife’s up the road from us has described what sounds suspiciously like black knot on a peach tree they bought from one of the big box home improvement stores, though I’ve yet to see it myself.

That’s in line with much of what I’ve read for planning a multi-row windbreak planting, and aside from the phased-flowering pollinator angle, was what I was going for. Bee-keeping is on the list of future projects, so that’s definitely something I need to keep in mind. Since the success of our future fruit growing endeavors will depend on the snow retention and wind protection provided by the windbreak, and finding species that can get established and thrive in our area has been very much a trial and error process, I’m really thinking now that the windbreak is not the place to experiment or try out different things. We’ve got about 11 acres to work with, and I figure if we can establish something to keep blossoms from getting blown off the branches long enough to set fruit, it’ll open up a whole new world of possibilities for us :slight_smile: I did find elsewhere on this site a list of nurseries, and have been looking at some for potential sources for small trees beyond what’s offered by NRCS. We’ve got a smaller juniper/pine windbreak we started a few years ago closer to our house towards the southern side of the property that’s been doing great, if funds permit this year after the new, larger windbreak planting, I’m thinking to put in a 400’ row of a variety of crabapple and Malus sieversii to see how they do

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I wonder how the Romance series bush cherries would be for an outside row? They say they get taller than first expected, like 10-12 feet. They grow fairly rapidly and are quite hardy. The blossoms are lovely in the spring. They would be more useful than chokecherries.


i too am worried as i got a juliet and carmine jewel I’m putting in next spring and i do have wild chokecherries with black knot up wind of my property. we have a lot of cold wet springs here. can you spray for black knot? i could go prune the black knot from the infected chokecherry on the abandoned property next door before i plant out my cherries. would it make a difference? apologize for hijacking.

Yes ,pruning it out will help, (cutting at ground level may be best ?)
Usually takes about 3yr to prune all of it out.
And I believe it can be controlled with a good spray program .
I do not spray, so I don’t know current recommendations.
Pruning it out is the first step, and it’s important to get it all.
I would not try to control it by spraying alone.

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Black knot doesn’t affect peach. The peach tree may have canker, which can look like black swellings, which could sound like black knot.

One other thing to consider is that if you ever want to plant any other fruit trees, your wind break can be a host for some significant diseases which affect other fruits. For example, choke cherries can be a significant host of X disease which can affect peach, cherry, and some plums (but not American plum). Junipers can be a host for cedar/apple rust for which many apple cultivars are susceptible.


I don’t live near where you live, but I do live in the windiest province in Canada. We planted a windbreak too, and are very glad of it now. Have a look around at what is growing where you live, and stuff that is doing well in an exposed site.
Just because local Forestry or Natural Resources has it, doesn’t mean it’s the best for the outside row.
What grows where roads were widened or power lines cut through? How about things like wild rose, or rugosa rose…thicket forming, nice hips for jam, able to take a lot of drying winter wind…pioneer species.
What is clump forming or thicket forming and wild in your area…things you see out in the open, in range land?
And, yes, DO mix it up a little.
As an example, we could get forestry seedling for austrian pines, so we planted a bag of them, 50…and as soon as they got to 20 feet or so, they broke off in a storm, 2 inches below ground level. There are perhaps 7 left now, all the rest came down by ones and twos in a high wind, as soon as they were big enough. Would any of the more windfirm nut trees grow where you are…heartnuts, perhaps?
How about elms? What about poplars and Manitoba Maples…Acer nugundo?


I battle black knot on my Euro plums constantly but have never seen it on any of my tart cherries, sweet cherries or peaches.


We have black knot on all the wild pin cherries here, and some of the european plums, but not on tart or sweet cherries either. Since we are humid here, coastal, and the peaches don’t get it here either, I’d say they are pretty resistant.

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At one really terrible site for BK I’ve got an apricot tree pretty infected. It is only a problem because the tree is not vigorous (site is too wet and client doesn’t adequately maintain planting mounds, that settle over time). Peaches are equally non-vigorous but never show the least sign of BK- nor does a sweet cherry right next to the infected cot.

Hi Chris,

What are some of the goals of your windbreak besides improving your microclimate? Do you want to be able to harvest usable fruit for processing? Wildlife food/habitat? Bee forage? Wood products?

My experience is living on the Front Range and I realize there are unique challenges on the plains. You might try Buffaloberry for a native fruit-producing shrub -12’ or so (perhaps best to avoid its cousins Russian Olive and Autumn Olive which are invasive). It is a native drought-tolerant pioneer species that fixes nitrogen and has palatable small berries. Black Locust is a proven tree that grows on the high plains (though with its small leaves might not make the best windbreak), is also a drought-tolerant, nitrogen-fixing pioneer that can be coppiced for firewood, fence-posts, animal forage and makes good bee forage. Russian (white) Mulberry, hardy Apricots (Manchurian or Siberian) and wild plums were all used very widely and effectively as windbreaks throughout the Great Plains that may produce usable fruit (and could perhaps be grafted over to preferred varieties when established). I gathered wild plums in CO, some of which were pretty decent for eating straight, and they make great wine/mead. The bush cherries (from Saskatchewan) should do decently there but may be slow to establish (and I’ve never seen any indication of BK on them).

You may also be able to grow native American Hazelnut (or even the improved hybrids). Potentially, improved varieties of Carpathian Walnuts could be grown there as well (Mesa is a variety developed in Northern NM that is resistant to sunburn and may be adapted). Siberian Pea Shrub should be well-suited and has some edible and bee forage uses along with NM Locust. Boxelder is a very tough shrub or tree that should survive (it can be tapped for sap/syrup like sugar maple though has more like a 40:1 ratio than 30:1) that bees also utilize in the early season.

If you already have an established windbreak elsewhere on the property, that might be a good place to trial unproven stuff including hardy wild relatives of fruit trees like some of the crabapples, Ussurian pear, etc.

Keep us posted!