A NEW SPECIES OF MYRIANGIUM ON 



PECAN 



L. E. Miles 

 (With Plate 14) 



On the living bark of the pecan, Carya illinoensis, in southern 

 Mississippi, as well as elsewhere, probably throughout the entire 

 range of the host, one finds a black fungus growth, sometimes in 

 considerable abundance. It is quite superficial in character, occur- 

 ring in the form of wart-like or knob-like tubercles on the un- 

 spotted and uninjured younger bark. But rarely, if ever, is it 

 found on the rough, scaly portions, and never has it been observed 

 growing on dead trees. It is found on all varieties of the host 

 tree, more abundantly on those trees which have suffered some- 

 what from neglect and lack of proper care, but occasionally is 

 abundant in thrifty, well-cared-for orchards. It has never been 

 observed on the hickory, though it has been seen on pecan limbs 

 and twigs which had been top-worked onto that tree. 



Though quite superficial and apparently causing no injury to the 

 host, the fungus is an object of considerable concern to growers 

 in that it mars the appearance of their trees. It is the cause of 

 numerous inquiries, and, therefore, it has been deemed worth while 

 to devote some little attention to it. Although superficially de- 

 scribed and pictured by McMurran and Demaree, 1 the causal or- 

 ganism has never been determined. 



Morphology 



The tubercles vary in size, ranging from 1 millimeter to 3 or 4 

 millimeters in diameter. The shape also varies, but isolated speci- 

 mens usually approximate the hemispherical in form. Often a 

 number of them are found crowded together, but rarely do they 

 become confluent. The color varies from a very dark reddish- 

 black to a coal-black. The surface is usually considerably con- 



1 McMurran, S. M., and Demaree, J. B. : Diseases of Southern Pecans, U. S. 

 Farmers' Bulletin No. 1129 (1920), p. 20. 



77 



