But why are these pics outside then? Why are you spraying them? And do you spray them in direct light?
It looks like the most extreme case of phytotoxicity i've even seen! Water can focus strong light, like a magnifying glass, burning your plants. This can be further amplified by the presence of other substances in the solution. Normally you just get some rusty spots on the margins, but this is horrific!
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And it doesn't really look like flagging damage per se, where the leaves are left to desiccate(dry out), usually appearing as dark green, dried out leaves, more at the margins than the interior blade... but desiccation coupled with spraying could burn the desiccated material, resulting in this incredible damage.