Only small limbs need removal. For larger limbs and trunks cut out all the bad wood with a good carving knife and then cauterize. I don’t cauterize the small limbs I cut out, just cut back several inches from the end of the knot. Dispose of all the wood out of the orchard.
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I’ll be damn. Never knew this was a thing. I’m trying chlorothalonil early in the year , now I’m using sulfur as cover sprays. Next season I’m replacing the sulfur with T.Methyl.
What ever knots do pop up ill do this technique. I appreciate the tips.
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Am I wrong in assuming you need to be fairly scrupulous about picking up and getting rid of the pieces and slices you carve away when doing this to larger branches?
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Spread an old sheet or tarp underneath. You definitely don’t want to spread infected shavings around your garden.
I have found the black knot far worse this year than others. I guess that’s because of the extremely wet spring we’ve had. Most of my trees are small form espallier, so at least it’s easy to spot it and remove it in the very early stages.
It sure pisses me off though because I lost 3 grafts from last year as I removed the entire limb to be safe. I didn’t spray at all this year, but I may return to spraying in the fall to keep things more under control.
For many years (20+) black knot was only a minor anoyance, but I guess somewhere close by there is some vector spreading it now.
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Optimally the shavings should be collected. I usually don’t have the time for that and just try to kick them under the mulch.
This year for me only Satsuma has knot. It is one of my worst varieties but others that often get it are clean this year.
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This is very timely topic for me. I have grown J plums in 2015 and E plums in 2016. Both have developed black knot after 3-4 years. J plums were in a shade area and I removed the trees a few years ago.
My E plums are in full sun. They seem to attract more black knot than J plums. At present, I have two multi grafted trees left. The worst variety for black knot is mirabelle Parfume de Septembre.
The number of black knot on these trees has increased each year. I have removed them by cutting infected twigs and branches out because BK mostly encircled those branches.
Last fall and this spring I removed all infected branches my E plums that I could find.
By the end of May, I have seen so many black knot (probably developed since last year but become very noticeable now). So many of them to the point that I am likely to remove both trees.
I can tell you that fungicide like myclobutanil, Indar and Lunar do not work on black knot. I do not know if I want to add Chlorothalonil to my spray schedule.
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Man…I’m sorry for your loss. That’s like losing a family member after fighting all that.
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I am a slow learner. I will likely replace plums with another stone fruit like sweet cherries 
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I think sweet cherries get BK too.
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I have grown sweet and sour cherries. They died of canker before black knot showed up. I am not worried about black knot on cherries.
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Seriously considering cutting my Methley plum tree down because of black knot. Freeze has gotten the plums for the last 4-5 years. Only plum tree that I have.
Back about 14 years ago I googled plum trees. Everybody said plant Methley. So that is what I did. It was good until it got black knot. From what I have read is that if the black knot is not cut out that the limb will die and then after a while the entire tree will die. Did they not know about black knot years ago?
FWIW, for the past 6 years I’ve been growing the European varieties Bluebyrd and President with no sign of BK. I’m adding Empress, which is a descendant of President.
I’ve also been growing the American hybrid Alderman for 7 years with no sign of BK. I tried Black Ice as a pollinator but it develops some BK so I’m removing it. I’m trialing LaCrescent and Toka as pollinators.
I had disappointment with Asians and other Europeans.
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Empress sounds interesting. Cummins says it will store for 8 weeks. If that’s true I think I’d like to try it too. Seems like there are some good reviews on here for it as well.
I didn’t know Empress is related to President. I have both, both are very good. Empress is earlier. I haven’t had BK on Empress yet, but I only have a few vigorous grafted branches of it. Fingers crossed that it maintains some resistance.
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A member @PlumHill of Vermont who grew many plums rated Empress very high in most, if not all categories, taste, disease resistance, etc.
I bought a bareroot tree last year from Schlabach. It set 3 fruit this year. I had a graft of it in the past. I like the fruit.
@Auburn I also like Spring Satin. I tagged @thecityman here because I know he has a black knot issue in his orchard.
I don’t know if his Spring Satin gets Black knot or not.
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Think I’ll try these two varieties next. Thanks for the tips.i prefer the darker color fruit of plum varieties so any tips on good varieties is appreciated also. but I’ve also never eaten a tree ripened plum of the lighter color flesh so not sure what to expect. I’ve always been disappointed with lighter colored plum flesh varieties.
Where are you in zone 7?
Technically I am zone 7 along lake Erie. It’s the new zone here. Was 6b.
I don’t know what’s the weather is like there. If it is not hot and humid in the summer, you can grow several varieties with less diseases.
I love French Improved E plum but if it rains near ripening time, this plum will crack 99% of the fruit.
Gage plums have light color and are tasty. There are many threads talking about plums. Like this.
Very humid and hot here. We get tons of rain.