H; WORMALD 195 



they began to burst through the bark during December and many well- 

 developed pustules with viable pulverulent conidia were to be seen by 

 the middle of January. 



Although it has been noticed that in some cases spurs showing the 

 typical symptoms of the Blossom Wilt in the summer failed to develop 

 Monilia pustules in the winter, this condition is exceptional, and where 

 cankers have been formed these invariably have produced the conidial 

 stage of the fungus. The results of the artificial inoculations too 

 demonstrate that a spur showing the wilt condition in summer is almost 

 certain to produce pustules of conidia before the following spring. The 

 danger of allowing such spurs and cankers to remain on the trees until 

 the next flowering season is obvious. 



(c) Inoculation of Twigs through Wounds. 



Twigs on trees of the Newton Wonder variety, which is known to be 

 susceptible, were inoculated with mycelium from a plate culture of 

 the same strain which produced wilting of the blossom in the inoculations 

 made on the Warner's King variety. A A-shaped cut was made through 

 the bark, the triangular portion turned back, and agar bearing vigorously 

 growing mycelium was placed between the wood and the bark ; the 

 latter was then gently pressed back and the wound covered with sterile 

 tinfoil which was secured in place by means of raffia. Three wounds 

 were treated in this way and three others, as controls, were not inocu- 

 lated. The inoculations were made on May 30, that is, at the time when 

 cankers were in process of development on trees infected through the 

 flowers. When examined some months later all the wounds were 

 covered with callus and no trace of canker was to be found on any of 

 them. 



The result suggests that the fungus does not readily (if at all) produce 

 cankers by infection through wounds on the branches, and agrees with 

 observations in the open where, so far as my own experience goes, a 

 canker produced on an apple tree by this Monilia invariably originates 

 in a spur that has been infected through the flowers. 



(d) Inoculation Experiments on the Fruit. 



It has already been pointed out that the Monilia which causes the 

 Blossom Wilt may occur on the young apples. It will also grow readily 

 on apples approaching maturity and on ripe apples after picking, as 

 artificial inoculations have proved, although under natural conditions 

 instances of its occurrence on the mature fruit appear to be rare for 



