Please see the attached pictre of a leaf from our Horse Chestnut tree. I fear that the problem is Cameraria ohridella (Horse Chestnut Leafminer). However I'm hoping that it is actually the less problematic Guignardia aesculi. Can anybody help with a positive ID? Many thanks
Tough one to call from the photo; the brown patches do look a bit mine-like, but not perhaps the normal shape for Cameraria mines. Try tearing the leaf open, and see if the brown parts are hollow, filled with insect frass (droppings). If yes, the upper and lower surface of the leaf will separate quite easily, which they won't if it is Guignardia infection.
Thanks very much for your reply. Yes the upper and lower surface of the leaf do separate quite easily. I'm not quite sure if I can see the frass. Are these the black bits in the attached photo? More interestingly, there does appear to be a larvae in the attached photo (something I didn't notice just looking at the leaf first time round). This does seem to match photos of Cameraria ohridella larvae from other web sites. Thanks again
Yep, looks like you have Cameraria, unfortunately. I'm wondering how long it will take to get up here (Northumbs).
