32: 



PLANT DISEASES 



CARNATION MACROSPORIUM 



{Macrosporium nobiie, Vize.) 



As seen with the naked eye, this fungus forms minute, 

 dark-coloured spots on the stem and both surfaces of the 

 leaves of cultivated carnations. The spots are irregularly 



Fig. 88. — Macrosporimn nobiie. i, portion of a car- 

 nation showing the disease ; 2, two conidia, x 300 ; 3, 

 portion of a conidium germinating, x 300 ; 4, Fjis- 

 arium spores, x 400. 



scattered, and the mycelium is widely diffused in the 

 tissues before these spots or clusters of conidia appear 

 and burst through the epidermis. The conidia are large, 

 pale olive-brown, and consist of many cells joined to- 

 gether. Later in the season numerous minute black 

 sclerotia are imbedded in the diseased parts of the plant. 



