Back spots and curly leaves

philanderson213

What is causing these black spots and curling leaves on my philadelphus? Is it a fungal infection, if so can it be cured with fungicide and can it spread to other plants?

Fairygirl

They're normally pretty trouble free. How are you growing it?
They prefer a reasonable soil, enough moisture and some shade. 

philanderson213

It's in a large pot, mostly JI no3 compost I seem to recall. Against the wall on my shed which is east facing. Sun from about 9am to 2pm. Have regularly checked soil to ensure it is damp.

Fairygirl

It won't be happy in a pot long term. It's possibly struggling to maintain itself, and is therefore a bit weaker than it should be. That always makes any plant more vulnerable to any pests or diseases. 
Difficult without being able to see the whole shrub, but if it's otherwise ok, I wouldn't worry too  much. They can sometimes get a little bit of blight/fungal diseases on leaves,  but that can be pruned out. It's probably something like that. It looks fine lower down. 
Keeping the air flow  by careful pruning every few years can help prevent problems, but if you can't plant it in the ground, you'll need a very large container for it. 

philanderson213

Thanks for your thoughts. Here's a picture of the full plant. The pot is 45cm internal diameter and 40cm deep. Planting in the ground isn't really an option at least at the moment, as my garden is very small and in this location covered in pebbles on top of hardcore. The black spots seem to be effecting about 25% of the plant.

Pete.8

It looks more like some sot of physical damage to me.
Could  those branches have been hitting the fence or something and got a bit bashed about with all this weird weather?

Fairygirl

It looks fine when you see the whole shrub. I don't think you need to worry too much 

Long term, you'll need to give it plenty of fresh organic matter each year, and it would need pruned if it was staying in that pot. If you did that after flowering, it should keep it more compact, but ideally, a much bigger container will help it thrive and get to full potential. It'll depend on the variety too. 
Most of them are quite large shrubs when grown in the ground, but some are smaller.  Manteau d'Hermine, for example,  can be kept smaller more easily, as it's not as vigorous, and is a more compact variety anyway. 

philanderson213

It's a virginal, which from your comments I guess may have been a slight mistake, but it's here now and I'm learning. What sort of organic matter do you recommend?

Fairygirl

Just carefully remove an inch or two of the top layer in the pot and refresh each year with good quality compost - preferably a soil based one, as multi purpose compost isn't suitable for long term planting. It  just dries out. If you look for John Innes composts, they are simply a formula comprising loam and compost, and you'll get ones which are ideal for shrubs.  When you do that, you can add a little bit of slow release food - Blood Fish and Bone is ideal - and that will give it a boost for the season. 
Leaf mould would be excellent too, but I'm guessing you probably don't make that, and it isn't usually available as a commercial product.

Anything in a pot needs a bit more care than it would do in the ground, but as  long as you keep it fed and watered, it should be fine. It may not be as exuberant as it would be in the ground, but it should still perform well