in Cuba. In Florida the disease is known as " foot rot," 

 and in Italy as " mal-di-gomma." Its presence is indicated 

 by the exudation of masses of gum near the base of the 

 trunk. The diseased patches are small at first and gradually 

 increase in size. The disease spreads to the crown and 

 main roots and in many cases girdles the tree ; the bark 

 splits and peels off. 



In mild cases a tree may recover, but more commonly it 

 dies in about two years after infection has occurred. 



Good drainage is essential for combating the disease. 

 The soil should be removed from the base of the trunk 

 and the diseased patches cut away with a sharp knife, the 

 wound thus made being sealed with a mixture ol coal tar 

 and clay. It is of the greatest importance that treatment 

 should be applied as soon as the disease makes its 

 appearance. 



Diagnosis. — Sporodochia gregarious, confluent, white ; 

 hyphse spreading, branched, septate ; conidiophores 

 erect or ascending, oppositely or alternately branched ; 

 conidia very variable, acrogenous, continuous, or septate 

 at the middle, or 2-3-septate, oblong, or fusiform, slightly 

 curved, attenuated, slightly constricted at the septa, 

 hyaline, 26-27 by 2"4-2"8 microns. 



Webber and Swingle : U. S. Dept. Agnc, Bull. No. 8, 

 1896 



Massee : Text-Book of Plant £>is., p. 332. 



MYCELIA STERILIA,* 



OZONIUM AURICOMUM, Massee. 

 (Root Rot of Cotton.) 



Has proved itself a serious enemy to the cotton growers 

 of Texas and of the Southern States of North America. 

 It attacks the roots of the plant, destroying the young 

 rootlets and the external surface of the older roots, 

 especially the tap root. The roots become surrounded 

 with a weft of brown strands of mycelium, and the plant 

 wilts, turns black and dies. 



The fungus travels in the soil, spreading in all directions 

 from the point first attacked. 



Numerous forest and orchard trees have suffered from 

 root disease caused by Ozonium, but members of the grass 



* Including those fungi which possess sterile mycelium only. 



58 



