_General Notes._--The downy mildew is a fungus known botanically as _Peronospora viticola_. Its native country is the United States, but its greatest damage is done in Europe. It appears as white, downy spots on the underside of the grape leaves, which are gradually destroyed, and later on attacks the berries, which shrivel and spoil. In California the downy mildew occurs frequently on wild native grapevines, but only very rarely on the cultivated Asiatic vines. Dr. H. W. Harkness, the eminent mycologist, found it only once on cultivated vines in the Sacramento river bottom. These vines were growing close to native vines, from which the fungus had spread. There is no fear that this fungus will ever spread and cause damage in our State as long as the vineyards are given plenty of air. In France the _Peronospora_ has caused much damage, but is now being combated with bluestone and lime solutions, according to the following formula: Slake thirty pounds of lime in seven and a half gallons of water, also mix sixteen pounds of bluestone (copper sulphate) in twenty-five gallons of water. Mix the two together, and either sprinkle the foliage with it, or dilute it further with say five hundred gallons of water and spray the vine leaves on both the upper and lower sides. According to Dr. Harkness the efficiency of this spray cannot always be relied on. So far no other fungi have appeared in the raisin districts of this State, nor have we reason to fear that any will attack the vines. [Illustration: Downy Mildew (_Peronospora_), Greatly Magnified. _a._ The Fungus Growing out of a Stoma of the Vine Leaf. _b._ Transversal Section of Vine Leaf, showing Fungi and their Tuberous Mycelium.] THE VINE PLAGUE.