112 Bulletin 313 



Marssonia populi (Lib.) Sacc. — On the leaves of the Populus. 

 Causes a spotting and a blighting of the leaves and lateral shoots. 

 Spots sviborbicular with dark margins and frequently uniting, acer- 

 vuli on the upper surface, yellow^ or flattened; conidiophores 

 branched and septate; conidia hyaline, unequally 2-celled, constrict- 

 ed at the septum, 14.9-20.0 x 5.5-7.7 /^. (Saccardo says "20 x 12.") 



687. Infected leaf of Populus alba. 688. Acervulus showing conidiophores 

 and spores, 1/12. 689. Conidia from Populus deltoides, 1/12. 690. Conidio- 

 phores and conidia from P. alba. 



Marssonia potentill^ (Desm.) Fisch., var. fragaricu Sacc. — 

 On the leaves of the strawberry. Causes small, ochre-colored or 

 reddish spots with indefinite outline or reddish margins. Acervuli 

 dark, conidia irregular, 1 -septate, cells unequal in size, 18 x 5-6 fi. 



691. Infected strawberry leaflet. 692. Conidia, 1/12. 



Marssonia rhabdospora E. & E. — On the leaves of Popithis 

 grandidentata. Causes spots visible on both surfaces. Acervuli on 

 the under surface of the leaf, flesh-colored, erumpent; conidia 

 cylindrical, slightly curved, 1 -septate, hyaline, 20-30 x 2 /*. 



693. Spores from Populus grandidentata, 1/12. 



Monochaetia MALI (E. & E.) Sacc. — On the leaves of the apple. 

 Causes small, circular white or cream-colored spots with reddish- 

 brown margins and about 1-3 mm. in diameter. Acervuli innate, 

 erumpent, sublenticular; conidia cylindrical, 5 or 6 septate, some- 

 times constricted, 20-25 x 6-7 fi, brown, apical, and basal cells, coni- 

 cal and hyaline. 



694. Infected apple leaf. 695. Acervulus, 2/3. 696. Conidiophores from 

 hanging-drop culture, 1/6. 697. Spores, 1/6. 698. Spores, 1/12. 699. Germi- 

 nating spores, 1/6. 



Pestalozzia guepini Desm. — On sunburnt leaves of Rhododen- 

 dron. Acervuli minute, convex, dark ; conidia fusiform, 3-4 septate,* 

 20 jx long, inner cells brown to olive-colored, terminal cells cone- 

 shaped and hyaline, basal cell hyaline and with 3 or 4 appendages. 



700. Conidia, 1/12. 



Pestalozzia guepini var. vaccinii Shear. — On the leaves and 

 sometimes on the fruit of the cranberry. Causes a rotting of the 

 fruit which is not easily distinguished from rots due to other or- 

 ganisms. Acervaili scattered, subepidermal, spores emerging in dark 



