runner beans got sunstroke

My french beans do this  crispy leaf thing if it's been very windy, wind burn i suppose
They always seem to recover as long as you water them

Hi

I've not used soapy water as a plant spray before as this gyo hobby is still rather new to me. But I was wondering whether the sunburn is due to the fact that the soap soultion is a surfactant which acts to reduce surface tension (although you were using it here to deter the pests) but then leaves a thin film or residue of soap molecules. This then behaves as a fine magnifying glass and concentrates the rays of sunlight which leaves the leaf surface as if it was under a greenhouse - with consequential increasing surface temperature.

This reminds me of the few occasions when I've got home from work and found the seedlings keeled over on those days when I've left the seed trays outside with the clear lids on and had not expected the weather to be too warm.

Cheers.