mahonia- all that rust!

I have only just looked closely at my mahonia and noticed that there are an awful lots of branchesttes with loads of rust on them. As this is evergreen what can I do about it. If i prune them all off there will just be big huge gaps in the branches which is going to look a bit silly. I have bought some stuff to spray them with but i guess thats to preventit not to del with whats already there?

 

Bit early in the year for rust to appear. Its a fungus and the "rust" is its spores. You can remove and burn the affected leaves, but as it has appeared so early in the year it could really have got hold and become systemic. That means it is present throughout the plant's system and not just on the leaves. If that is the case (and early showing suggests it is) then no amount of leaf burning or spraying will help. If you can't live with rusty mahonias you might have to dig them up.

On a brighter note, the rust might just be superficial and the result of malnutrition or lack of water. Personally, I'd burn the rusty leaves, water it, put some garden compost or similar around it, give it an organic liquid feed and then watch and wait to see if it recovers or the rust re-occurs.

 

whoops!!! just how wong can a person be. Its not rust its blackspot! I was getting very confused. do the same principles apply?

 

Black spot is far less serious - so that is good news! It is not a fungus, but a bacteria (Pseudomonus. It is spread by insects and even rain splashes. It is unsightly and heavily infected leaves on roses will fall and spread the bacteria. Best thing is to remove all infected leaves now so that the mahonia can put out clean fresh ones.