. oQOOpp Fig. 71.âSphaerotheca castagnei. Epiphytic mycelium on epidermis of Spiraea UL'iiiaria. Thi'ee haustoria are embedded in epidermal cells. Two conidiophores are shown, from one of which a conidiuni has become detached. A hair of Spiraea is shown at one side. (v. Tubeuf del.) Podosphaera. This genus is distinguished from Sphaerotheca by its upright perithecial appendages, which branch dichotomously towards their extremities. Podosphaera oxyacanthae D. C. Apple powdery mildew, also occurring on pear {Pyrus), hawthorn {Crataegus), mountain ash {Pijrits Aucujjaria), and medlar {Mcspilus).
. oQOOpp Fig. 71.âSphaerotheca castagnei. Epiphytic mycelium on epidermis of Spiraea UL'iiiaria. Thi'ee haustoria are embedded in epidermal cells. Two conidiophores are shown, from one of which a conidiuni has become detached. A hair of Spiraea is shown at one side. (v. Tubeuf del.) Podosphaera. This genus is distinguished from Sphaerotheca by its upright perithecial appendages, which branch dichotomously towards their extremities. Podosphaera oxyacanthae D. C. Apple powdery mildew, also occurring on pear {Pyrus), hawthorn {Crataegus), mountain ash {Pijrits Aucujjaria), and medlar {Mcspilus). In America this disease is very injurious to ;^ It attacks chietly young seedling plants, stunting their growth and causing them to lose their leaves. P. tridactyla Wallr, This causes injury to leaves of various species of Prunus (cherry, plum, and sloe)^ (Britain and America). -Account by M. B. Waite [ Department of Ayriculture, Report for 1888); notes on treatment in Fairchikl's experiments (-Journal of Mycology, vii. p. 256), and elsewliere (Edit.). â * Halsted Zeitschrift f. Pflanzenkrankheittn, 1895, p. .338) gives as additional hosts: Apple, Crataegus Oxyacantha, Amelanchier canadensis and Spiraea (Edit.).
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectparasit, bookyear1897
