THE FUNGI WHICH CAUSE PLANT DISEASE 129 



on plum and wild cherry, causing "plum pockets." The ovary is 

 the seat of attack. The mycelium after bud infection pervades 

 the mesocarp which hypertrophies and alone produces a much 

 enlarged fruit, usually with entire sacrifice of the other fruit parts. 

 Asci are formed over the diseased surface much as in the last 

 species. The mycelium is perennial in the bast and grows out into 

 the new shoots and 

 buds each spring. In- 

 fection also reaches 

 other shoots and trees 

 by means of the spores. 



Ascus elongate-cylin- 

 dric, 30-60 x 8-15 m] 

 spores 8, globose 4-5 /i. 

 Perennial. 



T.cerasi(Fcl.)Sad.«-" 

 produces the witches 

 broom effect upon culti- 

 vated and wild cherries. 

 It is common in Eu- 

 rope, rare in America. 

 Perennial; asci clavate 

 30-50 X 7-10 n; spores 

 8, forming conidia in 

 the ascus, oval, 6-9 x 

 5-7 1*. 



On Prunus avium, P. 

 Europe. 



T. mirabilis (Atk.) Gies.*' '* grows on leaf buds and twigs of 

 Prunus angustifolia, P. hortulana, P. americana in North America. 



Perennial; sporing on the fruits and tips of branches of the host; 

 asci subcylindric, blunt above, 25-45 x 8-10 n; spores 8, ovate. 



T. longipes (Atk.) Gies. is on Pruniis americana in North 

 America, causing plum pockets.* 



Perennial; sporing on young fruits; asci cylindric, truncate or 

 not, 30-40 X 7-10 /t; spores 8, globose or ovate, 3-4 /i. 



T. rhizipes (Atk.) Gies. Known only in North America, caus- 

 ing pockets on Japanese plums; * probably of wider distribution. 



Fig. 88. — T. deformans. Young and old asci. 

 After Pierce. 



cerasus, etc. in North America and 



