rotting plums

Well just looking at your photo there seems to be a cupressus leylandii growing through the tree plus some other rubbish. The tree area around a fruit tree needs to be kept clean and clear of any other growth, you may also need to prune out some of the branches of the plum tree. Rot occurs when the fruit starts to ripen gets moist and receives no air or proper sunlight.

The plum tree is on the sunny side of this hedge, I HATE IT, and it is sooo invasive, there is nowhere else for me to put the plum tree, the plan eventualy is to put a fence behind it would that help with the air circulation?

the whole hedge faces south, this side. and gets sun for the whole day really, it is a little sheltered from the wind in this corner of the garden .
You prune plums in the summer don't you, can I do this now?

Thanks moon grower for the info

Is the hedge yours? If so prune back hard to the trunks of the conifers to get air to the plum tree and get rid of all the grass growing through the tree. To be honest I'd prune the hedge back hard even if it isn't yours - we do this to our neighbours hedge every year. Here is the info on pruning http://www.gardenaction.co.uk/fruit_veg_diary/fruit_veg_mini_project_march_2d_plum.asp

It is next doors abomination if twas mine it would have been ash a long time ago it grows so quickly, what you can see there has grown since i trimmed it back at the begginig of the year, oh for some of that mould that kills it!!!

Try injecting Roundup into the stems - seriously! Oh and keep cutting back as often as you need to right to the trunk of the trees!

I won't ask how you know that!

A tree nurseryman who is a friend told me :-)

Cutting back can only be done (legally ) to the boundary line of your property 1 inch further inside than that and youre liable for damages,go figure!