Ok, so it turns out I needed more than just one dose of wood ash to control the cherry slug. While it did work beautifully, it didn’t last as the cherry slug returned. I can only assume more eggs were laid and hatched. I applied the wood ash over the tree again and it worked again but after a few days the cherry slugs returned yet again so I thought I needed to add something else to the mix. I thought I would give horticultural glue a shot, or actually a cheap homemade version of it.
Horticultural glue is applied in a band to the trunk of the tree near the base and acts as a sticky barrier to prevent the adult sawfly climbing back up and laying more eggs. I remember reading once that it was possible to just use vaseline instead.
So I liberally smeared a band of vaseline around the base of my pear tree and now I’ll wait to see if the cherry slugs return….interestingly they haven’t returned to my cherry tree so I haven’t applied any vaseline there and we’ll see if they do return eventually. So thats my not very scientific experiment!
I also treated my existing satsuma plum tree as I noticed a few cherry sluf larvae there too! As I was applying to vaseline I noticed ants moving up down the tree. The vaseline barrier prevented them doing this so I guess it has a good chance of stopping the sawfly too. I did feel sorry for the poor ants and so made a leaf bridge for them to get down which I then removed the next day 🙂
Also, as I’ve had to apply the wood ash 3 times now the whole garden is getting a bit of a coating of ash and I was worried that it wouldn’t be brilliant for the soil as it already has a high pH. So I read that you can use flour instead, so I’m going to use that from now on. You just need to use anything that will dry out their juicy sluggy bodies. As a bonus the garden smelt reminiscent of a bakery briefly while a was throwing flour about!