I see your rootstock is ELMA 111. It is known for burr knots on the rootstock itself. That is what the top picture looks like to me. The recommendation is deep planting with only 1-2 inches of the rootstock above ground. At this point you could mound soil up over all the burr knots until they root. After that things should be OK.

The second picture looks like hail or other injury that is healing over. Probably not fire blight, FB.

The third picture does look like something that could be FB. It strikes at the tips, usually, and the wood there looks dead or damaged. I'd prune that off if it indeed appears damaged.

Next year, now that you've studied this, you will pay better attention. FB is not that hard to recognize during the active stage.

The Fruitnut

Fruitnut,

Thank you very much for the input, things are not as bad as I feared. I would hate to lose one of my maiden trees so fast. Thanks again.

I have never had any problems with burr knots on 111. It is not an issue in the northeast as far as my own experience with 100's of trees over the decades, so I don't think you need to pile up the soil. There are several varieties like Northern Spy and Fameuse that form burr knots over the entire tree and I've never seen insects or disease use these as a weakness.

Anyone out there ever had a problem of disease or insect entry by way of burr knots? I once asked Jim Cummins about it at a lecture he was giving when he mentioned burr knots as a liability on 111. He actually seemed surprised to realize that he hadn't seen any actual problems in his experience and was apparently speaking from the literature and not experience. He was, of course, making the case for the relative advantage of the Cornell rootstocks that he helped develop.

There is a guy that lives about 1/4 mile from me that had a couple apple trees with terrible burr knots (all over the trees). Although I never saw any borers in the trees, the owner claimed he used to have borers. In fact, he incorrectly thought the borers caused the big galls, instead of the other way around. He started spraying his trees some with Diazinon (I supposed purchased before it was restricted)and apparently got rid of the borers. Last year he cut the two trees down.

We get dogwood borers here, but they are not a serious issue, usually. Northern Spy tend to be long lived trees and I manage quite a few as well as growing them in my nursery. I've never seen borers using the burr knots as an entry point which are usually well above the graft unions (the entry points, that is). I do spray them with Lorsban when I've noticed them but by this time they may have already done their damage.

Interestingly, of thousands of trees I manage, only 2 Bosc pears have been seriously injured by borers (talking about pomes, not peaches here). Both had the leaders snap off at the point of injury.

Thanks for the input, Olpea. I'm not sure what to make of your neighbors experience, however. How could you not see the injuries if the neighbor had suffered borer damage? If you saw entry points specifically at the location of the burr knots, I'd have to re-evaluate my perception somewhat of the possible liability of burr knots. Why did he cut down the trees?

Hi Hman,

Sorry for the late response. I've been pretty busy and haven't been able to check the forum.

I didn't see any borer entry points into the burr knots myself. Apparently, many years earlier some "apple guy" examined the trees and pointed out the borers to my neighbor. I had assumed the borer damage had healed over by the time I saw them. He cut the trees down because the trees weren't that healthy looking (the burr knots where so prevalent, it made the trees look unnatural). Also the trees suffered significantly from scab and rust. The owner seemed to attribute the scab and rust to general unhealthiness and cut them down. Lack of pomological knowledge is prevalent among folks in my area, even among those who try to grow fruit.

Because I keep hearing about the dangers of burr knots from Frutinut and others I finally googed around and there does seem to be a correlation between burr knots and dogwood borers as well as rosey apple aphid as Fruitnut suggested.

I read that in the east RAA is usually not a big issue becuase of natural predators. Dogwood borers are a more significant issue generally. I suspect that in home orchards it is rare that either are fatal or even a serious problem just because massive plantings tend to amplify pest pressure.

It seems to me that I manage too many trees on too many sites to have overlooked this problem if it was predominant in my neck of the woods. Has anyone out there actually suffered tree or crop loss to either of these pests?

Olpea: "Lack of pomological knowledge is prevalent among folks in my area, even among those who try to grow fruit."

Yep, its's hard to teach an old horticulturist new tricks.

Michael