488 DISEASES OF CULTIVATED PLANTS 



Coffee leaf spot (Cercospora coffeicola. Berk, and Cooke 

 Ramularia Goeldiana, Sacc.) causes damage to the coffee 

 industry in Brazil, by causing a partial defoliation of the trees. 

 The parasite forms large blotches on the leaves ; these blotches 

 begin on the upper side and become greyish and dead in the 

 centre, but are at first dark brown, and finally show on the 

 under side as corresponding, clear brown spots. The fungus 

 also forms spots on young twigs, and on the young fruit, 

 which becomes arrested in its growth. The fruit of the 

 fungus appears as small, black spots on the diseased portions. 



Spores elongated, thickened, and rounded at the base, 

 tapering upwards to a sharp point, many septate, almost 

 hyaline, length very variable, averaging 70x5*5 p. Sporo- 

 phores septate, more or less crooked or kneed, 170-200x6 p, 

 springing in dense tufts from a stroma-like mass. 



Noack, F., Zeitschr. Pflanzenkr., n, p. 196 (1901). 

 Several other coffee diseases are noticed in this article. 



Potato leaf spot. Potato leaves attacked by Cercospora 

 concors (Sacc.) present somewhat the appearance of those 

 infested with Phytophthora infestans (De Bary), and may 

 often be mistaken for the latter unless carefully examined. 

 The disease often assumes the proportions of an epidemic. 

 Yellowish-green, yellow bordered spots appear, which are 

 covered on the under side with very fine, greenish-violet 

 down. These spots often run into each other, forming large 

 patches, which become brown. 



The slender conidiophores emerge from the stomata on 

 the under side of the leaf; conidia narrowed to a point, 

 straight or slightly bent, almost hyaline, i-4-septate, i2-5oX 

 5-6 p. 



Lagerheim, Landt. handL och Tidskr., 1903, p. 6. 



Violet leaf spot. Two or three distinct fungi form dry, 

 whitish spots on the leaves of the sweet violet ( Viola odorata], 

 which present a somewhat similar appearance, and can only 

 be discriminated with certainty by microscopic examination. 

 Cercospora violae (Sacc.) is one of these, and often ruins 

 whole batches of forced violets. When the plants are grown 

 in the open air the disease is rare, and never assumes the 

 proportions of an epidemic. 



The fungus forms rounded, bleached spots that show 



