HETEROSPORIUM 497 



Conidia acrogenous, fusiform, usually curved, 2-many-septate, 

 coloured. 



Practically a Fusarium with coloured conidia. 



Onion black mould. Berkeley considered that Fusariella 

 atro-virens (Berk.) was responsible for a destructive disease 

 of onions, just before the period of reaching maturity. The 

 fungus at first forms little dark-coloured dots with radiating 

 mycelium. These dots eventually coalesce and form large 

 jet-black blotches, the central portion bearing a greenish- 

 black mass of spores, which are at first involved in mucus 

 and form a glairy mass. 



Conidia cylindric-fusiform, ends pointed, 3-septate, dark 

 coloured, sometimes more or less strongly curved, often nearly 

 or quite straight, 15-18x5 p. 



The intensely black patches resemble some Torula in 

 general appearance. The fungus appears to be rare. 

 Berkeley's type, in the Kew herbarium, is the only specimen 

 I have seen. 



HETEROSPORIUM (KLOTZSCH) 



Conidiophores fasciculate, simple or sparingly septate, 

 nodulose, septate, coloured ; conidia solitary or in short 

 chains, cylindric-oblong, 2-3-septate, minutely warted, coloured. 



Often forming dingy olive patches. Only differing from 

 Helminthosporium in the epispore of the conidia being 

 minutely roughened. 



Fairy -ring of carnations (Heterosporium echinulatum, 

 Cke.) is destructive to cultivated carnations and pinks, 

 especially when the plants have been exposed to a chill, or 

 when a moist, warm spell in the spring is followed by a 

 sudden lowering of the temperature. The fruit of the fungus 

 appears in blackish dots, forming broken circles on bleached 

 spots on the leaves. Minute sclerotia form in the tissues of 

 dead, diseased leaves, and these are capable of producing 

 conidia which infect plants the following season. 



Conidia olive, minutely warted, 2-5-septate, 30-50 X 

 10-15 /* 



Pick off and burn infected leaves, and spray neighbour- 

 ing healthy plants with a solution of potassium permanganate. 

 Give good ventilation, and avoid watering the foliage. 



2 I 



