290 Journal of Agricultural Research voi. v, no. 7 



transplant of Pinus (murrayana) contorta Loud., collected at Roscommon, 

 Mich., by Mr. Schaaf, which produced a globoid gall (PL XXVII, fig. 2) 

 extending nearly around the attacked stem. This gall was 6 cm. in cir- 

 cumference and 2 cm. in diameter. Both above and below the gall were 

 irregular lesions caused by Peridermium comptoniae (Arthur) Orton and 

 Adams. The gall resembled so closely the swelling produced by Perider- 

 mium cerebrum that the junior writer thought it was this species until 

 he examined it under the microscope, when he found the typical pyriform 

 spores of Peridermium pyriforme. 



In June, 191 5, the junior writer received a fine specimen of Peridermium 

 pyriforme (P. P. 19429) on Pinus arizonica Engelm., a 3- to 5-leaved pine 

 (PI. XXVII, fig. 3), collected by Ranger J. H. Woolsey in Jacobson's Can- 

 yon, Crook National Forest, Arizona. This is the first time this rust has 

 been reported on this host. Many of the aecia of the specimen were very 

 large and unusually prominent, owing to their marked extension beyond 

 the bark. Some were over 2 cm. long and from 5 to 6 mm. in height. 

 The galls were of the effused type and were from 40 to 50 cm. long. One 

 of the branches attacked was about 2 inches in diameter where the 

 lesions occurred. Its bark was very rough and exfoliated by the action 

 of the fungus. The lesions had completely surrounded the two branches 

 for a distance of from 20 to 30 cm., but had not yet killed them. 



The writers have previously found Peridermium pyriforme only on 

 pines having two to three needles in the leaf cluster,^ and the occurrence 

 of the fungus as now reported on Pinus rigida and Pinus arizonica is of 

 interest, since it adds to the list of known hosts two pines of the group 

 bearing three needles in a cluster. Pinus rigida has three needles and 

 Pinus arizonica three to five needles. 



It is now known that Peridermium pyriforme causes three forms of 

 disease on pines; one with slight or no hypertrophy, common on Pinus 

 divaricata, Pinus pungens Michx., and Pinus ponderosa scopulorum 

 Engelm.; a second causing a fusiform or spindle-shaped swelling and 

 found on Pinus arizonica, Pinus (murrayana) contorta, Pinus divaricata, 

 Pinus ponderosa Laws., Pinus ponderosa scopulorum Engelm., and Pinus 

 rigida; and a third form, causing the formation of globose galls (PI. 

 XXVII, fig. 2) now first reported on Pinus (murrayana) contorta. 



Peridermium pyriforme, especially when weathered, superficially resem- 

 bles Peridermium comptoniae, with which the senior writer found it 

 associated near Essex Junction, Vt., where he found i specimen of the 

 former and nearly 50 of the latter species. It is quite probable that this 

 resemblance has frequently caused it to be overlooked by collectors 

 wherever two species occur together and that a more careful search for 

 Peridermium pyriforme will greatly extend the known range of the dis- 

 ease of pines caused by it. The spheroid galls of Peridermium pyriforme 

 resemble very closely the spheroid galls of Peridermium cerebrum (PL 

 XXVII, fig. 2); and unless the spores are examined, this form might be 

 easily mistaken for the latter fungus. 



2 Hedgcock, G. G.. and Long, W. H. Op. cit. 



