90 MASSACHUSETTS HORTICULTURAL SOCIETY 



(25) Scott-Elliott, G. F. Experiments in curing plant diseases. 

 Gardeners' Chronicle, 1910, page 82. 



(26) Chewyreuv, Ivan. La nutrition extraraciniare des arbres 

 malades. St. Petersburg, 1903. (In Russian. An excellent 

 review of this fundamental paper is to be found in Forestry 

 Quarterly, vol. 2, pages 164-166, 1904.) 



Discussion. 



Ralph W. Curtis of the Arnold Arboretum was asked to give his 

 experience with the chestnut bark disease in the Arboretum. He 

 exhibited specimens of branches affected and said that he simply 

 brought in these specimens thinking that some one might like to see 

 the disease fresh from the field. The branch was cut from the top 

 of a young tree about fifteen feet high showing the leader entirely 

 killed by the disease, and also a side branch girdled during the 

 past summer on which the dried leaves were still hanging. He 

 said this shriveling of the leaves was a great help in locating the 

 disease. 



Mr. Curtis said further that the shriveling is due to the girdling 

 of the branch and the girdling may be done by the disease or by 

 something else. A boring insect may girdle a branch and produce 

 the same effect or the branch may have simply been broken; but 

 in any case it is worth investigating; it might be the disease. 



Dr. Metcalf has said that the production of suckers just below 

 the point of attack is a constant feature of the chestnut bark 

 disease. This is exactly the case with the specimen in hand. Just 

 below the infected area on the stem the tree has thrown up a strong, 

 vigorous sucker during the past summer in an effort to replace the 

 top killed by the disease last winter. The two sections of wood cut 

 from the stem show that the disease spreads just as Dr. Metcalf 

 explained in his lecture. The leader was already dead last winter 

 and did not bud out last season. When the warm moist days of 

 spring came the diseased area at the base of the leader commenced 

 to push out millions of spores through the small eruptions or pus- 

 tules in the bark. These were washed down by the rains spreading 

 the disease into any break in the bark that they reached. These 



