. The fungi which cause plant disease . Plant diseases; Fungi. 42 THE FUNGI WHICH CAUSE PLANT DISEASE to decay of roots of carrot, parsnip, tumip, radish, salsify, of onion bulbs, hyacinth corms, cabbage heads, celery stalks and fruits of tomato, pepper and egg plant. Jones found no decay pro- duced in young carrot or parsnip plants, fruits of orange, banana, apple, pear, cauliflower head,* Irish potato tuber, beet root or tomato stems. ^"^ Infection did not occur unless the epidermis was broken. The rotten mass was always soft, wet, and exuded a liquid clouded with bac- teria. / \ I V^ J
. The fungi which cause plant disease . Plant diseases; Fungi. 42 THE FUNGI WHICH CAUSE PLANT DISEASE to decay of roots of carrot, parsnip, tumip, radish, salsify, of onion bulbs, hyacinth corms, cabbage heads, celery stalks and fruits of tomato, pepper and egg plant. Jones found no decay pro- duced in young carrot or parsnip plants, fruits of orange, banana, apple, pear, cauliflower head,* Irish potato tuber, beet root or tomato stems. ^"^ Infection did not occur unless the epidermis was broken. The rotten mass was always soft, wet, and exuded a liquid clouded with bac- teria. / \ I V^ Jones ^'^ in 1909 made an extensive study of the cyto- Fio. 28.—^B. carotovonis. After Jones. .... j. .i- litic enzyme of this germ. This enzyme was separated by heat, filtration, formalin, phenol, thymol, chloroform, diffusion, alcohol, and its conditions of pro- duction and action investigated. Heating the enzyme to 60° in- hibited its activity to a marked degree; higher than 63° inhibited it entirely; chloroform, th3Tnol and phenol did not retard its ac- tion. No loss was suffered through alcoholic precipitation and resolution. The dried enzyme remained active for fully two years. Its effect was greatest at 42°, less at 32° and 48°. No diastatic action was observable. In 1909 Harding and Morse,'' from an extended study of some 12,000 cultures of non-chromogenic, liquefying soft>-rot bacilli of some forty-three pathogenic strains (including B. carotovorus, B. oleraceae, B. omnivorus, B. aroidese and what Potter regarded as Pseudomonas destructans), from six different vegetables, con- clude that unless later studies of the pathogenicity of these cul- tures shall offer a basis for subdividing them, there is no apparent reason why they should not all be considered as somewhat variant members of a single botanical species. This conception would lead to the abandonment of the supposed species mentioned above and the recognition of all of them under their oldest described
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1913
