On my way to work this morning I heard a brief story on NPR about the impact of the current late blight epidemic on local farmers.
One organic farmer explained how he would suffer a total loss this year without spraying some sort of fungicide on his crops. Unfortunately, to keep his organic certification, his best option was to spray copper, a naturally occurring chemical
(inset: copper strip-mine in NM).
He said he would usually only have to spray copper on his land in October but because of the intensity of the current epidemic, he has been spraying it every five days.
Picture what impact it has on his local ecosystem to have that amount of heavy metal pollution introduced to it. It would be more sustainable to use a modern synthetic fungicide that has very limited non-target toxicity and rapidly decomposes when exposed to sun and water.
Copper is a "biocide," meaning it hurts all organisms, and it lasts forever...