268 "Wilt" or "Crown-Hot" Disease of Carnations 



greenhouse, and subsequent enquiry showed this trouble to be the 

 cause of great loss of certain varieties. 



The disease he describes as showing first a yellowing of the lower 

 leaves which later become dry and dead. As it progresses the whole 

 plant becomes involved until finally death ensues. There was no sudden 

 wilting of the plants ; thus those affected resembled plants from which 

 the water or food supply was gradually withdrawn. 



In rare instances where only a portion of a plant appeared affected, 

 he succeeded in checking the progress of the trouble by removal of 

 the infected portion, but as a rule the appearance of the first symptoms 

 indicated death to the plant sooner or later. 



The stalk just below the soil showed discoloration and disintegration 

 in the outer layers, and the cambium cells were partially destroyed, while 

 permeating the wood and collecting in masses in the larger vessels and 

 ducts was a fungous mycelium consisting of delicate colourless threads. 



He finally obtained spores of the fungus on an old plant which 

 had died from the trouble and thus determined the causal fungus as 

 being a Fusarium sp. 



Pure cultures were easily obtained by inoculating culture tubes 

 with bits of the fungus-infected material. 



Sturgis succeeded in inducing the disease in plants planted in pots, 

 the contents of which after sterilisation were infected with the fungus. 

 Other pots, the contents of which too were sterilised but into which the 

 fungus was not introduced, served as controls. In a second series, 

 the contents of the pots were not sterilised but otherwise treated as 

 above. The disease also appeared in some of the control plants of the 

 first series, and he attributed its outbreak to the presence of the fungus 

 in the tissues of the original cuttings. In both cases where a decided 

 outbreak occurred in the sterilised soil, the cuttings were obtained 

 from a locality infested with the fungus and were rooted in compost 

 from the same locality. 



At the time of publication only one form of spore had been observed, 

 a spindle-shaped or fusiform spore, pointed at both ends, hyaline, 

 slightly curved, 3-5 septate and measuring 25-38ju x 3-5-4/a. These 

 spores were borne singly or in small clusters on the tips of the sides 

 of short branches of the mycelium, and seen in mass presented a pale 

 salmon pink colour. 



Under unfavourable conditions these spores were observed to pass 

 over into bodies resembling resting spores, which on germination pro- 

 duced a mycelium bearing the typical Fuswrium spores. 



