356 Report of the Horticulturist of the 



limbs of a pear tree with cultures of Sphaeropsis obtained from 

 cankered apple-tree limbs. The details of the experiment are 

 given on page 336. The fungus grew readily at all points of in- 

 oculation and though the culture material was inserted between the 

 bark and wood it did not attack the cambium layer, but made 

 its gi'owth in the outer bark. Here dead sunken areas were pro- 

 duced similar to those that are so common on the trunks and 

 larger limbs of pear trees. These definitely outlined and sunken 

 areas of dead bark commonly known as body blight, have long 

 been thought to be due to the action of the pear blight bacillus; 

 however, there seems to be no definite reason for such belief. 



But little attention was given the matter at the time since it was 

 not then known that Sphaeropsis occurred on these blighted areas. 

 In the spring of the present year, however, a Sphaeropsis was 

 found to be comparatively abundant on the diseased bark of pear 

 trees in the Station orchards. Since that time a large number of 

 pear trees from many localities affected mth body blight have 

 been examined and in neaidy every instance a Sphaeropsis was 

 present though not in sufficient quantity to account for many of 

 the blighted areas. Macrophoma malorum (Berk.) Berl. et Vogl. 

 is commonly present in large quantities on the dead bark and 

 since Sphaeropsis is able to produce body blight may not this 

 closely related fungus be an important factor in producing the 

 diseased condition? 



Fifty successful inoculations made this spring with cultures of 

 Sphaeropsis in mature pear trees confirm last year's results. An 

 attempt was also made to grow the Macrophoma artificially, but it 

 made an indifferent growth on all of the media that were tried 

 and produced no fruit, consequently inoculation experiments with 

 this fungns could not be undertaken at that time. 



THE PACIFIC COAST APPLE-TREE CANKER. 



After the publication of the paper, An Apple Canker, the writer 

 received inquiries concerning the canker from the secretaries of 



