42 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



cause it, even in healthy trees." This calls for no further reply 

 than that given to the first paragraph. 



Finally, the author states that " Canker commences with an 

 enlargement of the vessels of the bark, more apparent, by the 

 way, in apple than in pear trees, and continues to increase until 

 in the course of a year or two the alburnum dies, the bark cracks, 

 rises in large scales, and falls off, leaving the trunk dead, and 

 ready to break off with the first wind if not before removed. 

 The canker shows itself quickly, and if the cause be sought for 

 it will often admit of a remedy. The most usually effective is a 

 good supply of nourishment to the trees affected, together with 

 the removal of the parts injured." I confess that the preliminary 

 symptoms described as the enlargement of the vessels of the bark 

 have escaped my observation ; but there appears to be some 

 contradiction in the statement ; as while the first symptoms of 

 the disease are described as extending over a year or two, further 

 on it is stated that canker shows itself quickly. However, 

 although I differ so much from the writer of the article in the 

 "Pomona" as to the causes of canker, we are agreed on the 

 remedy, namely, " a good supply of nourishment to the trees." 



In 1886 my attention was specially directed to | plant food, 

 having been requested to write a paper on that subject for the 

 Birmingham Gardeners' Association. In the same year, having 

 noticed that a number of apple trees in my collection had become 

 unsightly through canker, I marked about a dozen of them for 

 destruction ; but while studying the subject of plant food, which 

 involved the consideration of the analysis of various plants, I was 

 very much struck with those of the fruit and wood of the apple 

 in Wolff's " Aschen Analysen," the great authority on plant 

 analysis. I found that the fruit contained an exceptionally large 

 proportion of soda, and the wood of lime. This at once suggested 

 the idea that my soil might not contain sufficient of one or both 

 of these elements to supply the wants of the apple tree ; therefore 

 I resolved, instead of destroying the marked trees, to give them 

 and all my apple trees a good dressing of a complete artificial 

 manure which contained full proportions of soda and lime. In 

 the following season, 1887, which was exceptionally hot and dry, 

 either through the drought, the manure, or some other cause, 

 not a spot of active canker could be found ; all the edges of the 

 old wounds on the marked and other trees, almost as badly 

 affected, had put out granulations and healed over, and the trees, 

 many of which had previously ceased to extend, made healthy 

 and vigorous growth. Last winter the trees were again dressed 

 with the same manure ; this season they have been exposed to 

 the most unfavourable conditions : the soil to a great depth was 

 almost dust dry when they were making their first growth, while 

 an army of caterpillars ruined what foliage was made. Then 

 followed the most continuous cold weather and rain experienced 



