Ornamental cherry trees, help identifying issues please

smki

Can anyone offer some diagnosis of problems we have on two cherry trees please? Google hasn't been much of a help... nothing I've read about matches up.

In the last couple of weeks we've noticed leaves on the smaller one are yellowing and dying (following 4 photos). Closer inspection found there's a dark red fungus/mildew on the underside of them. It's slightly raised. The problem has spread far, across the bottom half of the tree. 

The larger tree (which does need a good cut back) has mouldy-looking cherries this year. They're almost mummified where they hang. Only a few are actually red. Most are shriveled and white. The leaves don't look healthy either. They're covered in a sticky substance and are holey. There's white flecks on them too which I thought was a sign of a pest? I think this tree is a purple leaf plum/plum cherry but I could be wrong. 

The trees are on opposite sides of our garden and both bloomed in early spring. We love them but aren't knowledgeable gardeners so don't know where to begin with treating them! Any advice is welcome, thank you.

Lizzie27

Bumping your post up as I don't know the answer I'm afraid. I've never seen that red fungus/disease before on any tree. The yellowing leaves might either be a sign that the tree is short of water, so is dropping some leaves as a survival mechanism or it could be a sign of a mineral deficiency. The purple leaved cherry might be showing signs of wind burn/frost damage to the leaves. The white bugs are probably just whitefly which exude a sticky goo (are there also ants on the tree?) and little holes in the leaves are not a big problem.
 If your area has been very dry lately, I would water them very well, say at least 4 buckets each, slowly done so the water soaks in well and see if the trees look a bit better in a week or so. Don't feed them yet as that might cause more stress. 
Hope some other members can help.

BobTheGardener

I don't recognise the first, but suspect it is a rust of some sort.  The second tree is probably a cherry plum (Prunus cerasifera) and looks very much like it has a bad case of 'Pocket Plum' disease:

https://www.rhs.org.uk/advice/profile?pid=199

As mentioned in the link, not much is known about the lifecycle of pocket plum disease but the general approach is to remove the worst infected branches and collect and burn (or put in domestic waste - do not compost) all fallen leaves and damaged fruit.  As @Lizzie27 mentions, keeping the trees well watered going forwards is vital.  You can give them a feed of fish, blood and bone early next spring which will help as these sort of diseases have more effect on trees already weakened by drought or lack of nutrients.

It's best to prune this family of tree in mid-summer but check the local forecasts and wait until there are a few dry days due to come up.  Remember to sterilise the pruning tools between each cut (eg wipe with bleach solution) to avoid spreading the diseases further.