B- ''■ I-'l- V. !•. ,.. I.-,,,. 



A DISEASE OF THE AVIIITE ASH CAUSED IIV POLY- 



POKUS FIIAXIXOIMIILUS. 



INTRODUCTION. 



The white ash is uttac-ked hv a iiuinl)or of fuiious parasites, which 

 g-roAv on the living leaves and do more or less injury. ArctfUinii fra.r- 

 ini Sell., the orange rust, is perhaps the one licst known, as it otuws 

 . on almost all speeies of ash. even the introduced forms. It occurs 

 with varying frequency in successive years, and. so far as known, 

 has appeared in epidcMuic form l)ut once (iss.j). Among the funo-i 

 whicli grow as parasites on leaves are several species of (Thirosporium. 

 and SjiJuhi-npsis, as Avell as Sej^tora/ fra.r!/n' and l*h>jlh,f<t'H'fa fraxini 

 Ell. & Mart. Sphaevmeina .y}/)/(( Berk, c^c Rav. grows on vountv 

 twigs, and kills a good many now and then. 



The fungi mentioned above, to which several others might ])e added, 

 rarely appear in sufKcient numbers to do very much harm to the trees 

 affected. 



WHITE ROT. 



There is one fungus, Polt/jHrrmf raxinojj/ulus Pk., which grows in 

 the heartwood of the trunk and 1)ranches of the white ash. This fun- 

 gus changes the hard Avood of the ash into a soft, pulpy, yellowish 

 mass (PL I), making it unfit for lumber purposes. Diseased trees are 

 ultimately blown down by windstorms. In regions where this disease 

 is conmion the ash never grows to be a very large or very old tree. 

 During the last year numerous inquiries have been made as to the 

 causes of the white rot and how it could be prevented. In Forest 

 Park, St. Louis, nearly all the white ash trees were diseased, and 

 many were blown over ]»y the wind. 



A diseased tree is readily recognized by the large, conspicuously 

 colored sporophores, which usually occur in considerable numbers, one 

 or more at every branch stub. Polypxjrus fraxino;philus has been 

 studied by the writer, particularly in Missouri, where it occurs in 

 great numbers on the ash. It has been found elsewhere in the United 

 States and has been reported from as far east as Albany County, N. Y.« 



«Peck, C. H. Thirty-fifth Report, New York State Museum. 



