THE FUNGI WHICH CAUSE PLANT DISEASE 365 



not constricted at the septum, wall pale cinnamon-brown, thin, 

 about 1 ii; pedicel cylindric, 3-5 n in diameter; pores two in 

 each cell near the septum. 



I. iEcia on apple both wild and cultivated. 



III. Telia on Juniperus virginiana and J. barbadensis. 



Destructive, particularly in East and South. 



Sporidia are matured in twelve to twenty-four hours after the 

 spore-masses expand by moisture and as soon as the sori begin to 

 dry they are carried away by wind and on suitable hosts infect 

 through the cell walls by appresoria. Two or three crops of sporidia 

 may arise in one season but the first crop is largest.^^* Each crop 

 may result in a corresponding crop of secia. The stage on apple 

 fruits shows as pale-yellow spots of pinhead size about seven 

 to ten days after infection. The spots finally become orange- 

 colored and in a few weeks the pycnia appear as black specks. 

 On leaves hypophyllous cushions 0.5-1 cm. in diameter form on the 

 spots and bear the aecia, the mature tubes of which are split and 

 recurved giving a stellate appearance. iEciospores pass back to 

 the cedar in summer and cause infection. The mycelium here 

 remains practically dormant according to Heald ^^* imtil the fol- 

 lowing spring when the telial galls first become visible. These 

 galls grow throughout the summer, mature in the fall, and give 

 rise to the teliospores during the next spring. The mycelium is 

 thus seen to be biennial. 



G. clavariaeforme (Jacq.) D. C. ^ ^ ^n 



I. Mcisb hypophyllous, fructicolous or caulicolous, usually 

 crowded in small groups 2-3 mm. across on the leaf blades, some- 

 times in larger groups on the veins, petioles and twigs, often 

 densely aggregated on the fruits and occupying part or all of the 

 surface, cylindric, 0.7-1.5 mm. high by 0.3-0.5 mm. in diameter; 

 peridium soon becoming lacerate, usually to base, erect or spread- 

 ing; peridial cells long and narrow, often becoming curved when 

 wet, linear in face view, 18-30 x 80-13 n, linear or linear-oblong 

 in side view, 15-25 fi thick, outer wall 1-2 /i thick, smooth, inner 

 wall and side walls 5-7 /x thick, rather coarsely verrucose with 

 roundish or irregular papillae of varying sizes; aeciospores globoid, 

 21-27 X 25-30 n, wall light cinnamon-brown, 2.5-3.5 /* thick, 

 moderately verrucose. 



