Check out this .pdf if you haven't already. Doesn't look like a horrible problem, but something to watch out for.

http://agbiopubs.sdstate.edu/articles/FS936.pdf

Thanks for the info Frank. I think I will try lime sulfur spray to help prevent. But now I am more worried, it looks like it can attach to apricots and peaches? I thought it was only cherry disease. I hope I dont have to worry about it on my peach trees and apricots.

Troman:

Black knot is frequently a disease of plum trees, but not exclusively. I have lost a Methley plum to black knot. Bacterial canker has been a more serious problem for me, not only on cherries, but on peaches and apricots as well. Initial symptoms of canker include yellowing of the leaves, progressing to areas of sap leakage on the branches, followed by dieback.

Since I began dormant spraying with copper (Kocide DF) I have seen no symptoms of bacterial disease on the stone fruits at all. Seems like an effective preventive measure. I never felt that I was accomplishing much with lime/sulfur, and I don't use it any more.

Don Yellman, Great Falls, VA

Troman,
Interesting that my peach trees are at the same stage as yours. Back to the black knot. Every other wild cherry here has black knot. My Stanley plum and green gage gets it and I just cut it back. I use the kocide now and hope that keeps it at bay. Don, sorry to hear the Methley gets it since I just planted one.
Jerry

I had black knot on wild cherry trees till I pruned it all away. On my fruit trees I use copper/Chlorothalonil in the winter and Captan in the growing season. I believe around May is when the black knot spores emerge from the canker. This is the time for fungicide. Check with your local nursery.

Thanks for all the help!

I did call a local nursery and they told me that lime-sulfur would help prevent black knot, but I think I am going to check into the copper spray too.

Its funny that your plum trees are affected, there are many plum trees around here and I have never seen it on a single one, but almost every wild chokecherry tree has the disease.

I also read somewhere that black cherry's are not effected. I will be planting black cherry trees, Kristen and Black Gold. Does this make sense?

I lost a Burbank Plum to black knot, it hasn't bothered
my cherries, peaches, apricot. I also have a stanley
plum that it hasn't got yet. When my burbank got it, it
really spread fast. I culdn't cut it out fast enough. I
dug it up and burned it.

Don,

As far as spraying copper on cherry trees for bacterial canker, when should you apply the first spray?

I have read that the best time is early fall when there are still leaves on the tree. Additionally, I read that you should mix in vegetable oil with the copper to lessen leaf damage after spraying.

Does this make sense?

I am in the SF Bay Area and my tree holds its leaves until well into November.

thanks!

letsski:

I am on thin ice here, since your climate is so different from mine. I spray in mid-winter (Jan. or Feb.) and again just before bud break. It may be that for your SF climate, a fall spray is better.

I don't understand how vegetable oil could help prevent leaf damage, but I never spray copper when there are growing leaves on the tree precisely to avoid leaf damage. For me, it is a dormant spray only.

Don Yellman, Great Falls, VA

thanks!

please people help me since my Chemistry class was Oh well I never studied Chem.

many of you talk many and/or different strange names; Kocide, Captan , Copper, etc.
Do you really buy those sprays under those names and where do you buy them, or are they under diff. names.

Also, what is Copper sulfate ? When I was in the nursery place I did see a small bag with the name Copper sulfate, it is blue in colour something like almost like powder but not like powder and there are no instructions on it.

where and how do you use it, what for.

Thank you all

Chokecherries seem to be prone to black knot. Depending on your climate, it could be a problem to you. I've got chokecherries that grow among pie cherries and plums in a bit of a jungle. Many of the older chokecherries have some cankers, and on occasion it will show up on a cherry. I don't recall seeing the plums showing any signs. But--I am in a very dry climate where moisture to aid in the spread of the disease is fairly uncommon.

Since it has never bothered me, I've never done anything about it--didn't even know what it was until fairly recently. So, depending on your climate and the specific susceptibility of your trees, you may or may not have a problem. Still, if it is present in your area, you may want to take preventive measures. Otherwise, you could risk an infection, remove it as soon as you find it, then start treatments going forwards.

Kocide is used as a foliar spray as a bacterial disease preventive/inhibitor on some crops, though it may be used at a lighter rate than when you dormant spray. Kocide doesn't cure an infection, so you must apply it before the infection takes hold to inhibit the initial infection or slow its spread. This means it is usually applied earlier in the growing season or just before the time the tree is most susceptible to infection.

Nude Gardener: Many of the names listed are the trade names you would purchase the product under. Often they are capitalized. The chemical names are usually not capitalized, and sometimes, though not always, sound more "chemical-like". Many of these chemicals are sold in the garden sections of your favorite local stores and the big box stores, plus at garden centers/nurseries. If in doubt, do an internet search on the term and you'll find out pretty quickly whether you have a trade name or a chemical name, and you can quickly get the other name. Also read the label to see what crops and uses it is registered for. Unlike medicines, if the use you have planned is not labeled, it is illegal to use it for that crop/purpose. The blue stuff is copper sulphate, which is the active ingredient in Kocide. The crystals are not as easy to dissolve in water, but they do work in drains to kill tree roots. Kocide is formulated so that you can easily get the proper concentration of copper sulphate in water and to ease application.

Some of these products are not sold for the home market. Sometimes they present a greater safety risk, so they will not be sold to homeowners who are not expected to have any knowledge in proper use and safety with pesticides (I'm not saying home users don't use them properly, but nothing says a home user HAS to know how to use the product, so mis-use is more likely). Others will not be sold to the homeowner because the companies deem the market to be too small, or the EPA is trying to limit exposure potential to the general public. Commercial formulations will be packaged in larger quantities and concentrations for use by commercial growers. However, if the product is labeled for the crop you have and will use it on, it is perfectly legal to purchase it from a farm supply. The main drawback is that it will generally come in packages that will treat a number of acres, which means a 20 year supply for the home gardener. If you are purchasing a commercial grower's product, you may need a private applicator's license, depending on your state's laws. If you do, the cooperative extension service in many states handles the training and/or testing for these licenses, so you can check with them to get certification and a license. The private applicator's license where I am is pretty common. It takes about a half day of classroom instruction on the safe use of pesticides, calculating application rates, reading labels, etc.

beeone, thank you very much for so good explanation.
I am trying to be as careful as possible. I have boots , mask,
coverall , hat, gloves, and after spraying I take shower.

I would like to be able to buy a bit better sprays like those ones available for commercial growers and/or spraying companies because this staff that I am using does not seem to be as affective as needed.

I just use Wilson fruit spray.

Thank you very much.

NG, You must know what you are spraying for so that you are using the right product, otherwise you may not see any results. Then you must read the label and apply exactly as stated. Too much/too little spray and/or at the wrong time and you have managed to waste money. If you put on too much, you could damage/kill your plant.

Pesticides are poisins. Use them wisely, OR not at all. Many people grow fruits without pesticides, or at least only use things like dormant oil, koalin clay, insecticidal soal, etc. which are organically approved in most cases, and do a good job.

I have black knot on Shiro plums mostly, although one unnamed red variety also has some, but four other varieties do not so they seem more resistant. And the infection is along my fence lines in the wild cherry trees, but not in my cultivated cherries.

Each place/climate/management is different and will show different evidence of pest problems.