Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages . ALFA The Alfalfa Leaf=blight Cercospora helvola var. medicaginis This disease has been studied by Professor F. , of Delaware, who reports that it *^ shows itselfupon the leaf as sub-circnlar, or elliptical spots of asmoky brown, or almost black color, equally visible uponboth sides, and vary-ing from one-six-teenth to oue-thirty-second of an inch indiameter. The spotsare without well-de-fined borders, which,when closely exam-ined, are somewhatirreg
Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages . ALFA The Alfalfa Leaf=blight Cercospora helvola var. medicaginis This disease has been studied by Professor F. , of Delaware, who reports that it *^ shows itselfupon the leaf as sub-circnlar, or elliptical spots of asmoky brown, or almost black color, equally visible uponboth sides, and vary-ing from one-six-teenth to oue-thirty-second of an inch indiameter. The spotsare without well-de-fined borders, which,when closely exam-ined, are somewhatirregular, shading in-distinctlv into thesurrounding leaf tis-sue. Spots coales-cing cause the leaf to turn yellow and brown, completely destroying same fungus is believed, occasionally, to attackthe red clover and scarlet clover, although it is seldom,if ever, seriously destructive to these crops. The myce-lium threads of the fungus push about between the cellsof the leaf, absorbing their contents, and causing thediscoloration of the foliage. When ready to fruit, thethreads develop abundantly at certain j^oints just beneath 217 a. FIG. 88. ALFALFA BLIGHT , Spoi-e; b, section of leaf. Magnified. >5 218 FUI^GI AXD PUXGICIDES the epidermis of the leaf, and then push out severalstalks, on the ends of which the sj^ores are latter (Fig. 88 a) are long and slender, and dividedby several transverse jiartitions. They germinate whenon moist alfalfa leaves, bv sendins: out a sleiider thread,which penetrates the skin of the leaf and starts thefunsfus anew. Treatment.—Upon this point Professor Chestersays: In case it should be necessary seriously to com-bat this difficulty, the writer would advise that all dis-eased patches or areas be cut and burned, or compostedwith an excess of lime. Literature.—The only article of importance con-cerniug this disease yet published is the one above re-ferred to, which may be found iu the Second Report ofthe Delaware Experime
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectpathoge, bookyear1896
