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black knot-resistant plums and cherries?

Posted by birdgardner NJ/ 6b (My Page) on
Thu, May 10, 12 at 2:32

I lost an older prune plum to black knot. There are wild black cherry trees with black knot growing here and there that aren't mine to cut down and I couldn't afford to anyway - you read about the $80 tomato - I would have the $5000 pint of cherries.

So far my young North Star cherry shows no signs of infection. Knock on wood.

I have read that President plum is fairly resistant and that Auburn University introduced Roadside plum which is supposed to be very resistant. Introduced way back in 1984.

Are they worth growing? Any other plums? Newer plums? I am especially interested in giving European-type plums a try, not much interested in prune plums.

How about cherries? Would the bush cherries be resistant or immune?

Follow-Up Postings:

RE: black knot-resistant plums and cherries?

Fruiting cherries don't suffer here from black knot. Italian and Stanley plums are pretty resistant. Of Japanese types, I find none especially resistant yet, (besides an unnamed experimental variety I got from Cummins that is no longer available) but Methely is by far the most susceptible and should be avoided in high pressure areas. It is a typhoid-Mary of black knot.

RE: black knot-resistant plums and cherries?

  • Posted by olpea zone 6 KS (My Page) on
    Thu, May 10, 12 at 8:49

I've grown Roadside and President.

Roadside wasn't very good. President was a decent flavored plum and is bigger than Roadside. Here, President was worth growing, Roadside wasn't.

President does ripen very late.

RE: black knot-resistant plums and cherries?

Ruby Queen is an excellent-tasting Japanese plum bred in Georgia. I don't know how knot resistant it is supposed to be but I have never seen a knot on my tree. In general the modern southern breeding programs are the place to go for black knot resistance; it was not something they bred much for until more recently. The AU series unfortunately seems like they focused too much on disease resistance etc and too little on flavor.

If you are regularly walking through the orchard and are keeping the trees low (for easier patrolling for knots) you should be able to keep any tree healthy. I am cutting out knots all the time and have yet to lose a major scaffold or tree to black knot.


RE: black knot-resistant plums and cherries?

I have the same [problem with black knot infested wild black cherry rampant in the woods adjoining my property. Lost an ornamental plum and ultimately a Stanley and Green Gage plum to black knot. Just returned and got worse every year despite aggressive pruning. Finally planted Shiro, Santa Rosa, and Fortune Japanese plums which (these three varieties) are suppose to be resistant. So far after 4 black knot. Sweet cherries have never shown any black knot on my property. Good luck. Black knot is devastating.

RE: black knot-resistant plums and cherries?

Table of Plum Cultivar Susceptibility to the Black Knot Fungus
Apiosporina morbosa

Here is a link that might be useful: Table of Plum Cultivar Susceptibility to the Black Knot Fungus Apiosporina morbosa

RE: black knot-resistant plums and cherries?

I would question any table if I didn't know how they came up with their evaluations (well, it if contradicted my own experience, that is). Maybe it is a question of state, but in the sites I manage Methely is much more susceptible than any of the many plums growing- this includes over 20 different varieties, including Damson.

In my nursery I have Methely growing with other varieties and over the years it is so hard to manage for black knot that I'm not going offer it anymore. You can see all the extra wounds in this variety from cutting, cutting , cutting.

In home orchards there is usually some sun blockage and if this occurs from the east the equation will be much different than on any university testing site.

I have 3 Damsons on a site with good exposure and it doesn't suffer more than other plums there. However, on that site Methely doesn't suffer a whole lot either although a bit more than the Damsons. But then, I've resisted Damson's tendency to be a dense upright growing tree- a form that makes drying difficult.

You cannot know about how easy or hard black knot is to manage unless you have managed it at multiple sites. There is huge variability on the problem that often can't even be explained by sun exposure or nearby native cherries.

RE: black knot-resistant plums and cherries?

I've had a fair amount on Santa Rosa and its labeled resistant there.

I agree that the Damson rating is probably more to do with how thick with shoots it wants to grow. It shows how tricky these ratings are.


RE: black knot-resistant plums and cherries?

  • Posted by jolj 7b/8a-S.C.USA (My Page) on
    Sun, May 13, 12 at 18:01

We have wild plums with black knot, so I will have to get the resistant plums.

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