NOTES ON THE POWDERY MILDEWS OF OHIO. 



Bruce Fink, 



Miami University. 



My interest in the powdery mildews dates from 1884, when 

 I was a student of the first class-room teacher of mycology, the 

 late Dr. T. J. Burrill, of the University of Illinois. My first 

 publication on fungi dealt with this group, and my interest 

 has never abated. My collecting in Ohio began shortly after 

 entering the State in the summer of 1906, and two of my 

 students, Mr. E. E. Duncan and Miss Esther Young, have 

 spent a considerable amount of time in studying the group in 

 my laboratory. Miss Freda M. Bachman and Mr. W. G. 

 Stover have also aided considerably with the collecting and 

 determinations. 



Mr. A. D. Selby pubHshed ''The Ohio Erysipheae" in a 

 Bulletin of the Ohio Agricultural Experimental Station for 

 1893, and Mr. W. C. O'Kane pubHshed "The Ohio Powdery 

 Mildews" in The Ohio Naturalist for May, 1910. The last 

 paper follows the nomenclature of E. S. Salmon and furnishes- 

 keys and short diagnoses. This publication will still be found 

 useful in studying the powdery mildews of Ohio, and I only 

 hope, in the present paper, to supplement it by additions of 

 localities, hosts, and species not previously reported from Ohio. 



The mycelia of powdery mildews usually occur on the 

 leaves or the small stems or twigs of seed plants, and these 

 fungi are easily collected by those who are accustomed to 

 observe small fungi, provided that the mycelia are fairly con- 

 spicuous. In summer and autumn, these parasites may be 

 observed on the leaves of goldenrods, asters, sunflowers, yard 

 grass, ragweeds, verbenas, roses, willows, oaks, lilacs, and 

 other herbs, shrubs, and trees. Less conspicuous mycelia 

 occur on yellow sorrel, grapes, hackberry, tulip poplar, Ohio 

 buckeye, maples, elms, chestnut, and other seed plants. In 

 order to know whether the perithecia (Fig. 1) are in good 

 condition and to see the inconspicuous forms at all, one should 

 collect with a hand lens at hand. Previous consultation of a 

 host index will add greatly to the success of the collecting trip. 



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