blueberry is a strain prone to purple stems, and should not be fretted over. the spots appear to be a minor calcium deff, easily fixed by a first feeding. your day temps need to come down at least ten degrees, or you'll be dealing with three beautiful males, imo, and the canoeing is a heat stress indicator...

also, every bb i've ever grown showed nute burn on the first leaves after the first feeding, and followed up with explosive growth.

i hope this helps mark...