DEPARTMENT OF AGRICULTURE 

 Vol. VI Washington, D. C, May 22, 1916 ' No. 8 



HYPODERMA DEFORMANS, AN UNDESCRIBED NEEDLE 

 FUNGUS OF THE WESTERN YELLOW PINE 



By James R. Weir, 



Forest Pathologist, Office of Investigations in Forest Pathology, 



Bureau of Plant Industry 



INTRODUCTION 



In the summer of 191 3 the writer's attention was drawn to what 

 appeared to be a very serious needle disease of the western yellow pine 

 {Pdnus ponderosa Laws.) in parts of Idaho, Washington, and Montana. 

 That the disease has become more prevalent is shown by the receipt at 

 the Laboratory of Forest Pathology at Missoula, Mont., of many collec- 

 tions of the fungus from localities where it was not before known to 

 exist. These collections represent material from trees of all ages and 

 show the youngest needles as badly diseased as the oldest ones. The 

 first suspicion that the fungus might be of some economic importance 

 arose through the discovery of a serious infection of young reproduction 

 over a large area in the Whitman National Forest, Oregon. From the 

 fact that the fungus causes a conspicuous hypertrophy by the extension 

 of its mycelium into the tissues of the twigs and also through the destruc- 

 tion of the youngest needles, consequently causing in some localities 

 much damage in the forest, it seems desirable to make known its char- 



TECHNICAL DESCRIPTION OF THE FUNGUS 



Since the fungus does not agree with any known member of its genus, 

 it is described as new. 

 Hypoderma deformans, n. sp. 



Apothecia black, shiny, averaging lo mm. in length and i mm. in breadth; may- 

 extend as a black line the entire length of the sheath side of the needle or be broken 

 up into a series of shorter apothecia, usually arranged along the middle line of the 

 needle, but may appear at either side and be very rarely confluent with the more 

 medially arranged apothecia; opening with a longitudinal medial split. Asci fusiform 

 (26) 26.1 to 43. sm by 159.5 ^o 207. 2/i (27.3 to 29.o,u by 171. 5 to 186. 4,u). Spores parallel 

 or obliquely arranged in the ascus, very generally slightly curved, uniform breadth, 

 rod -shaped, ends blunt, i- septate when mature, septum very conspicuous, cells 

 often apparently separated, pale olive, almost hyalin, eight to an ascus (40) 6.2 to 



Journal of Agricultural Research, Vol. VI, No. 8 



Dept. of Agriculture, Washington, D. C. May 22, 1916 



dn G — 79 



(277) 



