. The fungi which cause plant disease . Plant diseases; Fungi. THE FUNGI WHICH CAUSE PLANT DISEASE 29 purplish-gray spots 1-3 mm. in diameter, ^o* Pathogenicity on this host also on cabbage was proved by inoculation. Its entrance is stomatal. Ps. malvacearum, E. F. ;'- ''• '""* This yellow organism, pathogenic on cotton, much resembles Ps. campestris but its slime is more translucent on potato and it does not attack the cabbage. It was grown in pure culture by Smith and successful inoculations were made by spraying a suspension of a young agar culture of the organism upon cot
. The fungi which cause plant disease . Plant diseases; Fungi. THE FUNGI WHICH CAUSE PLANT DISEASE 29 purplish-gray spots 1-3 mm. in diameter, ^o* Pathogenicity on this host also on cabbage was proved by inoculation. Its entrance is stomatal. Ps. malvacearum, E. F. ;'- ''• '""* This yellow organism, pathogenic on cotton, much resembles Ps. campestris but its slime is more translucent on potato and it does not attack the cabbage. It was grown in pure culture by Smith and successful inoculations were made by spraying a suspension of a young agar culture of the organism upon cotton leaves and bolls. No description has been published. Ps. medicaginis Sackett.*^ (Group number ) A short rod, X ii; filaments (1 long. No spores; actively motile with 1-4 bipolar flagella; cap- sules and zoogloea none. Agar streak filiform, later echinulate, glistening, smooth, translucent, grayish-white; no gelatine liquefaction; bouillon slightly turbid, pellicle on third day, sediment scant. Milk unchanged. Agar colonies round, grayish-white. No gas or indol. Optimum reaction +15 to +18 Fuller's scale. T. D. P. 49-50°, 10 min. Opt. 28-30°. Aerobic zymase, rennit or pepsin. It occurs as a pathogen on alfalfa and issues in clouds visible to the naked eye from small pieces of tissue of the diseased stem or leaf when mounted in water on the slide. These clouds under the high power resolve into actively motile rods, relatively short and thick. The bacteria are also found in practically pure culture in the exudate which oozes from the diseased tissue as a clear viscous liquid and collects in drops or spreads over the stem. Sackett with pure culture inoculations produced the typical disease and re-isolated the organism with unchanged characters. Re-inoculated. Fig. 15.—Ps. malvacearum. Early stage of stomatal infec- tion in angular leaf-spot of cotton. After Smith. No diastase, Please note that these images are extracted f
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1913
