Photo and article: Joan Allen, UConn Extension Basil downy mildew, a damaging disease of sweet basil plants, has been confirmed on plants at big box store garden centers (non-locally grown plants) in the Northeast. The major symptom is yellowing of the leaves, often between the veins.  Dark, sooty-looking spores of the fungus-like pathogen (Peronospora belbahrii) are […]