3 year old leaf mould containing cameraria ohridella

Carole Gadsby

We have gathered leaves onto one site for rotting down for at least 3 years. For the last 2 the trees nearby have shown clear signs of the leaf mining moth. We went on heaping them on to our heap. Now we learn that the problem is managed on the continent by burning the leaves. Is there anything we can do to kill any insects in the leaf mould without burning the whole lot?

Emma Crawforth

Dear Carole,

As you say the horse chestnut leaf miner is a moth. The caterpillars make the mines in the leaves, then pupate in there. This lifecycle takes around a year to complete. If the leaves are isolated, say in compost bags, any moths that hatch from the pupae will be kept within the bags until they die, so taking the leaves out of the bags in August is safe. If your leaf mould has not been added to for over a year, it should already be free from moths.

However, this problem is so persistent now that you shouldn't be surprised if it returns. Most trees in the South East of England seem to be infested now. I understand that good controls are being developed but these may not be available to home gardeners even when they come onto the market.

In summary, cover your leaf mould until August - if you've been adding to it in the past 10 months. Otherwise it should already be free of moths at this time of year and fine to use in your garden.

Emma

gardenersworld.com team

Wayside

Just been collecting leaf litter.  I have some ash leaves in the mix.  Can I spread die back the same way?  Would you offer similar advice?

Dovefromabove

Ash dieback is spread by fungal spores.  I wouldn't collect ash leaves from other areas ... in fact I think it's illegal to transport ash trees without a licence so leaf litter probably falls into that category too ... however we have ash trees in this garden and compost the leaves and use it as a mulch on tour veg patch here in this garden. 

I wouldn't use it in potting compost in case I passed plants in pots to friends and spread the disease that way. 

Wayside

Just leaf litter from the road out front.  It didn't really occur to me that it could be a problem.  Someone mentioned a lot of leaf fall from a nearby conker tree into their garden - my first thoughts were that the leaves could be harnessed for good - but they had a hunch that it wasn't a good idea.  Do the spores die if I compost them in the dalek?

Dovefromabove

No idea... But if you're using them in the area where they grow it can hardly be spreading the problem.