kilmarnock willow...

my old mum has this growing in her back garden, is nice, but eack year gets ripped by some sort of pest or disease... they're like tumourous lumps on the leaves... when i saw them i thought the obvious... that something had laid eggs (like wasps on a holly bush kinda thing ?)... however, when you break these hard things open, it looks like organic plant growth rather than an insect nest... any ideas guys ?

 

Sounds like galls from gall mites or from sawfly larvae. The sawfly galls are brightly coloured bean shaped galls.

 

thanks hornbeam... any idea what she can treat them with ?