Rob,

Captan may do the trick for you, but chlorothalonil is rated better for control of BN. Your timing was excellent though.

You won't see any knots this early. I've posted a recent Scaffolds issue below that talks about BN. To quote:

"Sometimes infections develop into knots that can be recognized as such by September. Those knots will turn black and produce ascospores the following year. In many cases, however, the only evidence of infection in autumn is a slight swelling of the twigs"

Here is a link that might be useful: They're so knotty

I pruned out black knot on my Alderman Plum last year and never sprayed it. I haven't seen anything come back yet. I was thinking pruning would be enough to get rid of it?

I had a bad black knot problem which I mostly solved by pruning the plums to be much more open. If the birds can't easily fly through you need to prune back more. Its taken several years for the lesson of how open pruning helps prevent diseases to sink in, but it finally did it.

If I get a knot on a major limb I just cut off the part sticking out and not the whole limb, and so far that has solved the problem every time. It is not perfect because the wood will have a future entry for canker etc but overall I think its a good compromise in many cases. If the canker goes all the way around there is no choice but to cut the limb off.

I have never sprayed for black knot per se but I do copper in the early spring and late fall and that helps.

Scott

Thanks olpea! I'll try to get some chlorothalonil quickly since I don't think shuck split has happened yet (I'll have to look closely this evening)and it apparently can't be used after shuck split.

Frank, I suppose it depends on the extent of the infection. If you only had a couple of knots and you got rid of everything then you might be okay. In my case, just about every branch had many knots (they probably were there the year before and I just didn't know enough to watch out for them) and even now I am still finding some knots on the ground that fell off when the tree was pruned around Thanksgiving. So, to try to prevent re-infection I need to spray.

Scott, thanks, I will look into copper spray this fall. Unfortunately, until just recently I knew nothing about care of fruit trees and I allowed it to get very tall and congested since it provided privacy from my neighbor. Now I know better.

Thanks again everyone.

Rob

I manage so many contrasting sites as far as black knot infections go it really defies easy explanation about best managment or cause.

Some sites with infected cherries nearby and no morning sun will not have a big issue and another with wide open light and no nearby native cherries will have galls almost impossible to control. I've had to cut down mature trees (goddam Methely- the ultimate gall magnate) just to save other varieties.

Scott, I wish an open tree was a panacea. Methely tends to grow leaves all along its wood and even when I keep them open and repeatedly cut out those little spurs that shade the wood I have had a lot of trouble the last couple years. Last years relentless rain just made it all the more difficult.

I have saved large trees completely overwhelmed with the cancer by doing what was mentioned- drastically heading back to pretty large wood. It was a Santa Rosa. Don't think it would work with Methely.

Olpea, I cut out galls at sites last fall where there were new galls this spring, and I even cut out the swollen early infections when I see them.

After we went over this last season I decided to follow your advice and go back to spraying with chlorothalonil. I also keep a small bottle and spray the wounds. I had stopped doing this because it seemed unecessary for a few years but when it's really wet it may be helpful.

The good news is we're having a drought spring- my prayers have been answered. Maybe in a couple weeks I'll be praying for rain. Right now I'm just hoping for no hard frosts.

Thanks harvestman. It's good to know that it at least has a chance to come back. I don't know the type of plum since it was planted long before I got there, the prior owner didn't say anything about it and my feeble efforts to identify it last summer didn't produce any results. Hopefully it's a Santa Rosa.

rweissman,
Your plum might be Stanley. It is the only plum tree I have had to prune out black knot. Are the plums blue, egg size and firm and meaty. Prune the black knot out and spray this month 2x and next 2x with chlorothalonil. Once I got rid of it it didn't come back.

Ace, I don't think it is a Stanley. It got round purple fruit with very red insides, and ripened in early July. The fruit was pretty small, but that may have been because I didn't thin it enough.

harvestman, I didn't say open pruning was a panacea, only that it mostly solved my bad problem. I still get knots, just not the "knots everywhere" kind of epidemic I used to get. In pruning this winter I found maybe half a dozen knots.

I don't know why Methley is bad, I don't have one so I don't know how it grows. I do have some plums that grow far too many branches and they are more problematic; they are getting the ruthless butcher pruning treatment from me now, which is going to negatively impact how much fruit I get, but that tradeoff works for me.

Learning to recognize the early swelling stage is good, it allows the knots to be pruned out sooner. They are much harder to spot then because of all the foilage and the lack of color contrast (they are greenish early), but if you are looking for them they can be found.

Scott

Scott, and I'm not trying to call you wrong, just to point out that what works on one site, some varieties, some years may not on another. Your advice is excellent on this point and I use your idea as well.

Ace, I'm amazed that you've only seen BK on Stanley with your extensive collection. Resistance to BK seems to be the exception. Only Italian and a numbered selection I got from Cummins has shown resistance for me, at least that I've observed so far, and I work with an awful lot of varieties.

Stanley is known as a black knot magnet. The S tree was a goner it had bad lesser borer too. 23 years old and half pruned away now and still reliable. I do get those branch galls on Metheley and on the Italian in the back yard. I shave them off to the wood. I rub copper powder on the wound. It may sprout back a little on the edges. By the second cutting its gone.

Olpea,

I went out and got some chlorothalonil at my local nursery and sprayed on Friday. I'll give it another spray in a couple of weeks. Hopefully I'll be knot free come September. Thanks.

Rob