strange 'plums'

Hi, I'm new to the forum and am hoping someone can help. I've inherited a neglected plum 'tree' that was originally fanned against a wall I think, but has overgrown. Last year, some branches had some plums on them but the main branch had dozens of little hard round 'plums'- except they weren't plums. I'm wondering what they are and what to do this year to prevent them growing and encourage the others. Ihope this makes sense and thanks in anticipation!

Has a plum been grafted onto a wild species that has now taken over? Or do the branches that produced the odd ones look any different, diseased or different leaves or manner of growth

Thanks for these replies. The odd looking 'plums' (and they are plum in colour and appearance except they are round hard balls, almost like very large marbles), are off the main central stem but the normal plums are on thinner lower stems. All the branches/stems look the same except the central one's much bigger in diameter. There are no other fruit trees in the garden except for a quince at the other end- about 80ft away.They don't look anything like a quince.  Don't know if that clarifies it at all...

One thing I can tell you, Plums cannot be grafyed on to Crab apples. they are different , Prunus for Plum and Malus for Apple. they are both Rosaceae but not compatible for grafting.

Does sound like the tree has reverted to wild plum which is what the original tree would have been grafted on to.

The only other thing is a condition called' pocket plum' But in this the faulty plum is mishapen rather than small.

When I saw the subject was going to suggest you went on Embarrasing Bodies

Ha Ha .   Thanks for the replies again!

Perhaps it has reverted to wild plum, as you say Berghill, as they aren't mishapen at all. I'm not sure what to do with it now. Do you think I should attempt to dig it out (it's prbably been there for many years) ? 

Personally I would wait and see if the other branches produced normal fruit before I did anything. Indeed the small fruit may only be a reaction to the poor weather last year.

You could wait to see if the samae thing happens again this year. If it does, you could remove the branches carrying the bullets. Only ever prune a plum tree in July as it can develop silver leaf which ultimately kills the tree. It is possible that with the aawful weather last year it is a case of incomplete fertilization, if the weather is better this year you should have a full crop of proper plums.

Thanks for your reply Joyce- and others. Its hard to explain but if you imagine a fan- the lower branches that fan out from the thick central branch/trunk had ok plums on and the top shorter branches that all tufted out from the top of the main trunk had the mystery ones on. I guess I can just cut those off this year as they start to grow.The trouble is, I don't really know how to deal with plums that have been trained in thisway....I need to look it up.....

My main concern is that if you start cutting off branches or twigs of any size, at any other time than July, your tree will develop silverleaf  infection and within a few years your tree will die.

It sounds as if your tree was trained to grow flat against the fence, called fan training. Go to some garden centres and look for books on training fruii trees where you will find diagrams and pictures of what to do. Some books make it complicated but there are some very good ones which are easy to follow, the thing about having a book is you can take it out in the garden and have it next to your tree as you shape it and prune it.

http://apps.rhs.org.uk/advicesearch/profile.aspx?PID=626

All you need to know is on that link, there's also a  link at bottom for pruning mature fans. Doesn't cost a penny, and if you need it in the garden just print it off.