Diseases of plants induced by Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae diseasesofplants00tube Year: 1897 VENTUKIA. 219 })lacecl them in the genus Ventirrio. His investigations are, however, not (juite complete. The scab or black spot of apple and pear is a very familiar disease in America and elsewhere. It attacks leaves, young shoots, and fruits. Dirty greenish spots appear first, then enlarg- ing, they run together, and darken in colour till almost black. If the attack occur on young foliage, it may b
Diseases of plants induced by Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae diseasesofplants00tube Year: 1897 VENTUKIA. 219 })lacecl them in the genus Ventirrio. His investigations are, however, not (juite complete. The scab or black spot of apple and pear is a very familiar disease in America and elsewhere. It attacks leaves, young shoots, and fruits. Dirty greenish spots appear first, then enlarg- ing, they run together, and darken in colour till almost black. If the attack occur on young foliage, it may be dwarfed and killed ; the newly-formed fruit will in such cases be attacked, shrivel up, and fall. If the attack be deferred till the foliage and fruit are well advanced, theii .spotting results and the fruit remains hard, perhaps cracks. The conidia are oval, unicellular, and yellowish-brown; they are produced from short conidiophores Fig. 10'. —Venturio. {) dendritici-m forming br<mii .spijts on an apple; those still in the earlier' stages have a radiate margin and bear conidia. The enlarged section shows two rows of large-celled parenchyma of the apple, covered by a stroma of pseudoparenchyma bearing conidiophores and conidia. (v. Tubeuf del.) with warty prominences which grow on spots of leaf or fruit (Fig. 107). The perithecia (as yet described) are distinguislied by black bristles surrounding the pore, and occur on fallen leaves. The asci contain eight greenish ovoid spores with two or three cells. In addition to the injury to leaves and destruction of young fruit, the disfiguration of the apples is a cause of considerabk- monetary loss. Dilute Bordeaux or copper sulphate mixture applied before the opening of buds, and once or twice after
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