Ouch, Ahmad - bad placement!
I used to spray those cuts with bleach, dunno how well it works.
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I don’t think that is black knot, peach trees can make that kind of growth when they heal over wounds. It is too dark-brown to be a black knot, and it is lighter-colored in the crevices which is not a property of black knots. I think the discolored wood is from an infection in the original pruning cut shown in the picture with the knot.
@IL847 to use a blowtorch you just need to push the button, it is remarkably easy. All you need to buy is the small propane fuel cylinder and the torch. The torch is something like
which can be found in any hardware store along with the propane cylinders. You just screw the torch on to the cylinder and press the button a couple times to get the flame going. As long as the button is held down you have a flame. Easy!
More daconil sprays would help things I expect, but I never tried to control black knot with sprays so no experience there myself. I spent about ten years just cutting them out, and now maybe 5 years doing the blowtorch off an on (now all on, too many came back so I am hitting every single cut-out knot now).
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i used daconil several times on all my trees this spring as a precaution as im in a high black knot area. the chokecherries around me are heavily infested. i guess its a good call seeing how much black knot you all are facing. now if i can convince my neighbor to prune out the many knots on his plum. told him they were killing it but hes still getting fruit and is afraid he’'ll kill the tree. cant say i didnt warn him.
I would agree.
I would also add that the discoloration of the pith could very easily just be a response to the original pruning wound as well. Discoloration just behind the cambial layer would be a sign of disease, in the heart, not so much.
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@scottfsmith @walnutclose Thanks for the encouraging feedback. I am keeping the tree till at least next year, and will see how it develops.
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This one was large and ugly. The 3rd one I removed this spring.
My mirabelle plum is a black knot magnet. I could not carve out the affected chunks on two large limbs last year. I removed those two limbs. This was after Kocide spray yearly. The tree is quite open and in full sun.
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I discovered the sun direction and the vase shape of the tree didn’t matter. Once Black knot arrives on one plum it is very short order before it strikes another. It is a horrible disease. I tried cutting out the knots, removing limbs and two of my plums were left as almost stumps due to the pruning necessary. Black knot is relentless! All plums seem to be its favorite target.
Sorry, and edit and clarification: Euro plums.
Because I manage fruit trees at so many different sites I am confronted daily with the fact that disease pressure varies a great deal from site to site and with black knot and fire blight, for reasons I find utterly unfathomable.
To say all plums are equally susceptible is counter to my experience, I even manage a type of “J.” plum Jim Cummins recommended I try and sold me 20 years ago that is immune to it, as seems to be the Blue Byrd E. plum. Clearly there is a certain range of susceptibility in other varieties I grow, but most seem to be as susceptible as Shiro among my J’s and pluots. I’ve been growing Methely for 30 years, and there is no doubt in my mind that it is much more susceptible to BK than Shiro and other J’s similar to it. I also consistently cut fewer galls from Stanley and Italian plums than other varieties I grow. However, I can only speak for my region, which is just north of NYC. Even in this I’m limited because I help manage only a couple of orchards right on the beach, which is a totally different environment than just a short distance inland.
I’ve read in university guidelines lately that the belief is that the knots that are showing up now that were not present when trees were dormant are not spreading the disease- that it is the older knots that spread the infection. It also seems that the knots showing now are the result of being infected last season with most of the spread occurring in spring. I guess that’s why it is often recommended to only remove the knots during dormancy, but I don’t trust that. Anecdotally I’ve only succeeded against this disease by cutting it out of trees as soon as knots appear. I’m not sure what that suggestion is worth, but it’s the one I’m running with.
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I have several young Japanese and hybrid plums. My Methley is growing quite large and finally flowered this year. Unfortunately, I just had to cut off several limbs with black knot. This is the first tree in my orchards to get black knot. Very disappointing, I haven’t even had fruit from this tree yet. It has a great open vase shape and gets full sun, all day.
My understanding of the life cycle of black knot is that it does not release spores until second spring.( correct me if my understanding is incorrect). First year it just grows on the branches and will not infect other trees. So theoretically, you may leave the fruits on the tree to ripen along with the black knot. You can prune the infectef branch off this coming fall.
I went the safe route and just cut the offending branches out. It needed some thinning anyway. It flowered this year but did not set fruit. It has 7 or 8 other kinds of plums to pollinate it, but they are just now getting to maturity, so maybe next year I’ll get fruit…and knots.
Methley is supposed to be self fertile. Do you think your Methley did not set fruit could be because of late freeze?
Having other varieties of J plums will definitely help. I have black knot on both J and E plums.
It was probably a combo of frost damage, sparse blooms, and immaturity. We had a lot of frost damage, but the older trees (peach/cherry) with more blooms were able to set some fruit.
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Methely is mysterious. Sometimes, some sites it takes a long time to come into bearing but more commonly it is quite precocious and a moderate to extremely heavy bearer that has branches that look like supports for vast bunches of grapes.
I plan to write something about pollinators this year- they arrived late and tended some varieties of plums well but others not at all, that is, by the time they appeared it was too late, even though they tended the flowers of varieties that either bore very lightly or not at all. I now suspect that flowers can be attractive even after ovules are no longer viable.
Methley has been my most aggressively growing tree. It looks great, or looked great before black knot. Maybe the aggressive growth makes it more prone to infection. We have plenty of black knot on wild trees in the area, so I’m probably foolish for trying plums here. So far, no knots on shiro, Hollywood, toka, prunis Americana, Byron gold, elephant heart, or any other trees.
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Yeah, it is a brushy SOB and sends out leaf growth everywhere along big wood. Where I mange them I’m constantly mopping that worthless shading growth off the big wood to let the sun hit it. However, it is difficult to get your way when a variety works so hard against you.
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Interesting….I’ll have to try clearing the branches a bit. I assume the theory is black knot has a better chance of success where leaf density promotes higher humidity? Most of my knots were on 2 year old wood. Fortunately I caught them very early. Nothing on any wood greater than .75” diameter (so far).
@mrsg47 ,
I like mirabelle plums but they get more and increasingly more black knot.
Keep finding more and more og it in just one tree!!
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My mirabelles got it too before I left. The new owners took down the entire orchard! Its so ugly. My mirabelle here is doing well. Only about twenty of them on the tree but enough for a small tart! Miss you!
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Wow, thats a lot. Start watching your other euro plums too. It takes a while but it spreads. I noticed it before I left.