11 



Heald (15) has established an intimate relation between the 

 bud rot of carnations and certain mites. These develop in the 

 mass of rotted petals, and the young migrate to healthy buds, 

 carrying the spores of the causal fungus with them. 



Massee (34, p. 184) has pointed out that the rapid spread 

 of apple canker in England due to Nectria ditissima, coincided 

 with the introduction of the American blight, or woolly aphis. 

 He is of the^opinion that the canker would not have been pres- 

 ent in an epidemic form had the insect not been introduced into 

 England. 



Grossenbacher and Dugger (14) have pointed out that the 

 blight of currants due to Botryosphaeria rihis may be carried 

 by several insects, the most likely of which is the American 

 currant borer, Psenocerus supernotatus. This insect was not 

 found in blight-free plantations. The authors conclude that 

 "since the imago eats the fungus and the larva lives as a 

 borer in the host, the beetle's habit of oviposition may have 

 some relation to the dissemination of the fungus and the ino- 

 culation of the host." 



The statement is made by Jones, Giddings, and Lutman (30) 

 that leaf eating insects function in the distribution of the 

 spores of the potato fungus, Phytophthora infestans. A related 

 fungus, P. phaseoU, a mildew on the lima bean, is believed by 

 Sturgis (52) to be spread by bees. This is based on observa- 

 tions in the field and on a study of the structure of the flower 

 and pod of the lima bean. 



The sooty mold of the orange and other citrous fruits, due 

 to MelioJa camelUae, follows the attacks of certain scales and 

 aphid-like insects. In Florida (Webber, 55) the trouble be- 

 comes serious when it follows infestations of the white fly, 

 Aleyrodes citri, and the fungus derives its nourishment from 

 the honey dew secreted by this insect. The amount of sooty 

 mold depends directly on the amount of honey dew present, 

 or upon the distribution of the white fly, which, furthermore, 

 acts as an agent in transmitting the spores of the fungus. 



The mosaic disease of tobacco has generally been considered a 

 physiological trouble. AUard (1) expresses the opinion, how- 

 ever, that paratitism offers the more plausible explanation of 



