Too frequently in neglected vineries the leaves and bunches of berries are more or less covered with a dense brown or mouse-coloured mould, often called Botrytis cinerea. This is one of the commonest of moulds we have in this country, and may be met with on decaying vegetable matter everywhere. It can only become a parasite in the presence of an excess of moisture and in a stuffy atmosphere. Its presence on Vines can only be attributed to gross neglect in ventilating, more especially early in the day. When the fungus once gains a foothold it is difficult to exterminate promptly, as spores are produced in rapid succession and in immense numbers, and are dispersed by wind, watering, etc. A fairly dry atmosphere is fatal to the fungus, and aided by spraying with sulphide of potassium will restore things to order (fig. 393).

Brown Vine Mildew {Sclerotinia fuckeliana).

Fig. 393. - Brown Vine Mildew {Sclerotinia fuckeliana).

1, Summer fruit on portion of a vine leaf (reduced in size). 2, Summer fruit (natural size). 3, Portion of summer fruit (magnified 300). 4, Winter fruit springing from a small black sclerotium (natural size). 5, Mode of spore formation in winter fruit (magnified 200). (Journal Royal Horticultural Society).