Apr. i-June 24, 1918 IlluStratlOflS VTI 



Page 

 Plate 19- A. — Photomicrograph of a small columnar intumescence on cab- 

 bage, following artificial injury. B. — Photomicrograph of a large cushion- 

 like intumescence developed after artificial injury 260 



Anthracnose; of Lettuce Caused by Marssonina Panattoniana 



Plate C. Leaf of lettuce with lesions of Marssonina panattoniana 280 



Plate 20. Marssonina panattoniana: A. — Lettuce leaves of Grand Rapids 

 Forcing variety, showing lesions on midrib and blade. B. — Lesions on 

 midrib. C. — Lesions on leaves of Black-Seeded Tennis Ball variety pro- 

 duced by artificial inoculation 280 



Stemphylium Leafspot of Cucuthbers 



Plate 21. Stemphylium cucurbttacearum: A. — Small spots on upper surface of 

 leaf with a few larger spots formed by coalescence of small spots. B. — 

 Same leaf as shown in A, but lower surface view 306 



Plate 22. Stemphylium cucurbitacearum.: A. — Large and small spots on upper 

 surface of cucumber leaf. B . — Large spots on cucumber leaf showing brown 

 centers surrounded by lighter area 306 



Plate 23. A. — Early stage of the Stemphylium leafspot on cucumber from arti- 

 ficial inoculation, showing the formation of the large mottled spots. B. — 

 Early stage of the Stemphylium leafspot on gourd from artificial inoculation, 

 showing very fine spots in groups 306 



Plate 24. Spore formation and germination of Stemphylium curcurbitacearum: 

 A. — Spores germinating in tap water. B. — Spore formation in string-bean- 

 agar culture 15 days old. C. — Portion of B more enlarged 306 



Yellow-Leafblotch of Alfalfa Caused by the Fungus Pyrenopeziza 



medicaginis 



Plate D. Alfalfa showing the yellow-leafblotch 330 



Plate 25. Pyrenopeziza tnedicaginis: Conidial (Sporonema) stage on a leaflet of 



alfalfa , 330 



Plate 26. Pyrenopeziza medicaginis: Apothecia on the lower surface of a dead 



leaflet of alfalfa 330 



An Undescribed Canker of Poplars and Willows Caused by Cytospora 



Chrysosperma 



Plate 27. A. — A small canker caused by Cytospora chrysosperma on the tnmk 

 of a tree of Populus italica, with the bark cut from around canker. B. — A 

 • tree of Populus wislizeni on the streets of Albuquerque, N. Mex., dying 

 from the attacks of C. chrysosperma. C. — Main stem of a young tree of Pop- 

 ulus italica killed by C. chrysosperma, showing young sprouts at the base of 

 the tree. D. — A branch of Populus wislizeni attacked by C. chrysosperma, 

 showing the spore horns of the fungus 344 



Plate 28. A. — Pycnidia of Cytospora chrysosperma on Populus alba after the 

 spore horns have been washed away by rains. B. — A young plant of Pop- 

 ulus italica, showing the upper portion of the stem killed by inoculation 

 with C. chrysosperma. C. — Two tubes of pure cultures of C. chrysosperma 

 on malt agar, showing pycnidia and spore droplets. D. — A propagation 

 cutting of Populus deltoides from Hays, Kans., killed by C. chrysosperma. . 344 



