. Les champignons qui causent les maladies des plantes . Les maladies des plantes, les champignons. Les champignons qui causent les maladies des plantes 241. blanc centre de la place. En cinq heures de plus qu'ils sont assez nombreuses pour donner un aspect noirâtre. À New York, Reddick a constaté que l'asci commencent à mûrir en mai et continuent de mûrir tout au long de l'été étant toujours abondant en octobre. Les asques houle dans l'eau souvent à deux fois la longueur indiquée ci-dessus ; les spores sont renvoyées à partir de l'échéance à l'ASCI, projetés à une hauteur de 2 à 4 cm. Il est à un bout de l'Asco- spore une vésicules hyalines qui probablement le sida en le fixant à l'h

• Contributeur: Central Historic Books / Alamy Banque D'Images
• ID de l’image: PG46FB
• Taille du fichier: 7,1 MB (249,4 KB Téléchargement compressé)
• Autorisations: Modèle - non | Propriété - non
• Dimensions: 1071 x 2332 px | 18,1 x 39,5 cm | 7,1 x 15,5 inches | 150dpi

Informations supplémentaires

Cette image appartient au domaine public, ce qui signifie que le droit d’auteur a expiré ou que le titulaire du droit d’auteur a renoncé à ses droits. Les frais facturés par Alamy couvrent l’accès à la copie haute résolution de l’image.

Cette image peut avoir des imperfections car il s’agit d’une image historique ou de reportage.

. The fungi which cause plant disease . Plant diseases; Fungi. THE FUNGI WHICH CAUSE PLANT DISEASE 241. white center of the spot. In five hours more they are so numerous as to give a blackish appearance. In New York, Reddick found that the asci begin to ripen in May and continue to mature throughout the summer being still abundant in October. The asci swell in water often to twice the length given above; spores are forcibly ejected from the asci at maturity, being thrown to a height of 2 to 4 cm. There is at one end of the asco- spore a hyaline vesicle which probably aids in fixing it to the host.^^^ They germinate but slowly, requiring from thirty-six to forty-eight hours to show germ tubes. Reddick deter- mined the incubation period on fruit as from eight to twenty-one days and found that only tender leaves still growing are susceptible. The berry is susceptible even after the calyx has fallen. The pycnidial spores are said by some to show a hyaline appendage ^®^ though others by careful study fail to find it.''" These spores often live over winter.*^ The Fiq. 176.—g. bid- . , . 1.11 1 • • T • .1 wellii; 26, nearly ma- microcomdia which develop m pycnidia similar ture ascus with to those of the macroconidia do not occur so IgcoIpOTfa'i' 2«!^g"r- abundantly early in the season as they do minating ascospores, later and seem to be mainly limited to the pressoria. After fruits. Sporeless pycnidia, pycnosclerotia, also occur and may eventually develop into perithecia. Conidia on hyphse of questionable relationship to the fungus are sometimes seen. Reddick ^^° secured pure cultures in the following ways. 1. In poured plate dilution of asci; some twenty days were required. 2. By inverting a plate of sterile agar over a bunch of mature mummies floating on water. The ejected ascospores thus clung to the agar and gave pure cultures in ten days. 3. By aseptic transfer of the mycelium. 4. By aseptic transfer of pycnospores. Artificial infections have been

Recherche dans la banque de photos par tags

• bookcentury1900
• bookdecade1910
• booksubjectfungi
• bookyear1913