THE FUNGI WHICH CAUSE PLANT DISEASE 179 



and concludes that the same form of "Erysiphe cichoracearum 

 D. C, occurs on at least eleven species of the cucurbits, belonging 

 to seven genera, infection occurring in these cases in fifty per cent 

 or more of the trials. Six other species were also infected, but in 

 a smaller percentage of cases. ... It is also plain that the biologic 

 form of Erysiphe cichoracearum, occurring on so 

 many cucurbits is not entirely confined to the 

 species of this one family. Out of fifty-four 

 leaves of Plantago rugelii, a species belonging to 

 the Plantaginacese, which were inoculated, ten 

 became infected. . . . Furthermore out of ten 

 leaves of squash seedlings, inoculated with conidia 

 from plantain, six became infected . . . and the 

 sunflower, Helianthus annuus, was infected in 

 thirty-five per cent of the trials in which conidia 

 from the squash were sown on leaves of seed- 

 lings. . . . The cucurbit mildew could not be 

 transferred to asters and goldenrods nor was the 

 mildew occurring on these in nature able to in- 

 fect the squash. Neither the aster mildew nor 

 the cucurbit mildew proved able to infect a 

 goldenrod, Solidago csesia. Nor was the mildew 

 on this host able to infect asters or squashes." 



E. taurica L6v. is found in Europe, North 

 Africa and Asia on Capparis, Cicer, Clematis 

 and various other hosts. 



E. graminis D. C. ^'°: 129.— E. p-a- 



„. fe'-i ^ minis, comdial 



Usually epiphyllous, rarely amphigenous;myce- stage. After Sal- 

 lium more or less persistent, forming scattered 

 patches, at first white, then brown or gray; perithecia large, 

 135-280 fi, usually about 200 n, scattered or gregarious, cells ob- 

 scure; appendages rudimentary, few or numerous, very short, 

 pale brown; asci numerous, 9-30, cylindric to ovate-oblong, more 

 or less long-pedicellate, 70-108 x 25-40 m; spores 8, rarely 4, 

 20-23 X 10-13 n, seldom produced on the living host plant. 



Conidial form (=Oidium moniUoides) with a grayish cast; coni- 

 diophores medium tall ; conidia ovoid, white or sordid, 25-30 x 8-10 fi. 



It is found on a large number of species of the Gramineae in- 



