Allotments 4 All

A friend opposite my plot grows sweetcorn year in and year out. He and his missus have never had problems until this year. The plants are still young and about a foot out of the ground,but the leaves on half of them have elongated holes in them and we have no idea what could be causing this. Its not frit fly,as they go for the growing tips in sweetcorn and its not flea beetle as they leave a rounded shaped in veg such as swede/turnips. I do not have a photo so that stretches the odds, all I can say is the holes in the leaves are along the length of the leaf and quite narrow. Anyone with any idea would be appreciated. Thank you for your time :) PS; they are protected by a windbreak so we have discounted the wind as the problem,even though we are on an exposed site. Thanks again :)

I've had that before... and always put it down to wind damage...  :-\

Had any hail stones since planting out?