Posted: 05/06/2016 at 15:27
My first thought on seeing that is weedkiller damage. Is there any possibility that wind could have carried weedkiller spray onto them, perhaps from a neighbour or council kerbside weed control?
There are a few nutrient deficiencies which can look similar but it is rarely that severe and usually affects all the leaves and not just ones on the outside.
Another possibility is that you sprayed the bug killer in strong sunlight. I have seen bug sprays cause damage to young foliage which is one of the reasons I try not to use them (apart from the obvious one of them killing friendly wildlife such as ladybirds as well as the pests.)
Last edited: 05 June 2016 15:30:16