Mildew

Mildew (A.S. Meledæw, 'honey-dew'), a general name applied to numerous diseases of plants caused by or associated with the parasitism of certain fungi. The name is obviously most appropriate in reference to those fungi which form white mealy patches on the plants. Some of the most important are species of Erysiphe, and are common both on leaves and green stems of many Dicotyledons and a few Monocotyledons. The filaments of the fungus branch and spread over the epidermis of the plant, sending suckers every here and there into the cells. They multiply by the asexual formation of spores, and in most cases also from sexually produced fructifications. Among the common forms may be noted: Erysiphe lamprocarpa on Compositæ, Plantago, Verbaceum, Labiates; E. graminis on grasses; E. martii on Umbelliferæ and Leguminosæ; E. communis on Polygonum, Rumex, Convolvulus, Teasel, Ranunculus, &c.; E. (or Oidium) tuckeri on the vine; Podosphaera kunzei on Prunus; P. castagnei on hops. These are all nearly related, but the mildew or rust of corn (Puccinia graminis or Æcidium berberidis), whose life is divided between barberry and cereal, belongs to a distinct series. See FUNGI.