. The fungi which cause plant disease . Plant diseases; Fungi. THE FUNGI WHICH CAUSE PLANT DISEASE 23 agree in the following particulars: They are yellow rod-shaped organisms of medium size, straight or slightly crooked with rounded ends. The segments multiply by fission, after elongation. They are generally less than 1 /i in diameter. The segments occur singly, in pairs or in fours joined end to end, or in clumpy masses of variable size (zooglceae), more rarely they are united into long chains or into filaments in which no septa are visible. Endospores have not been observed. The segments are
. The fungi which cause plant disease . Plant diseases; Fungi. THE FUNGI WHICH CAUSE PLANT DISEASE 23 agree in the following particulars: They are yellow rod-shaped organisms of medium size, straight or slightly crooked with rounded ends. The segments multiply by fission, after elongation. They are generally less than 1 /i in diameter. The segments occur singly, in pairs or in fours joined end to end, or in clumpy masses of variable size (zooglceae), more rarely they are united into long chains or into filaments in which no septa are visible. Endospores have not been observed. The segments are motile by means of one polar flagellum which is generally several times as long as the rod, and may be wavy or straight when stained. The species grow readily on all of the ordinary culture media, but so far as is definitely known all are strictly aerobic. None are gas producers. They do not reduce nitrates to nitrites. The yellow color appears to be a lipochrome and in the different species varies from deep orange and buff-yellow, through pure chrome and canary-yellow, to primrose-yellow and paler tints. Ps. seruginosus Del. possibly identical with Ps. flourescens- putridus Fliigge is the cause of a leaf and stem disease of tobacco in France.^^ Ps. avenae Manns, (Group number ) A short rod with round ends, to 1 /i x 1 to 2 ii. Actively motile, generally by one polar flagellum, occasionally by two or three. Gram negative. What seem to be endo- spores are found in old cultures. On agar stroke, growth very slow, fili- form, rather fiat, glistening; margin smooth, opaque to opalescent; non- chromogenic. Liquefaction occurs on gelatine in seven to twelve days. Broth is slowly clouded. Agar colo- nies, amorphous, round with surface smooth, edges entire. No gas in dextrose, saccharose, lactose, maltose, Fig. lo.—Ps^^nae. After or glycerine. Ammonia and indol not formed. Nitrates reduced to nitrites. T. D. P. 10 min., 60°, Opt. 20° to 30°. This organism was isola
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1913
