PLANTS IN THEIR RELATION TO DISEASE. 69 



the Frencli Commissioner visited Amherst and inspected the 

 vineyards there, then suftcring from the attacks of the phy- 

 loxora, he said the vines were the best he had seen. He 

 found a satisfactory explanation of it when he was told that 

 the vines were fed and the phyloxora were also fed ; so that by 

 an excessive supply of food the vines were given a stimula- 

 tion which enabled them to successfully resist the effects of 

 the parasite. 



Mr. . How large is the phyloxora? 



Prof. Penhallow. It is about the size, if I remember cor- 

 rectly, of the green aphis Avhich lives on the rosebush. 



Question. I would like to ask the professor if the fungus 

 mould that is found upon the grape is not the same which 

 causes the cracking in pears? I find, especially upon grapes 

 under glass, that the fruit will crack very much as the pear 

 cracks. We can cure that with sulphur, where we can con- 

 trol the air under glass. I find the same cracking upon my 

 Flemish Beauty pears that I find upon the grape. I would 

 use sulphur if I saw the same cracking upon my grapes, but 

 the pear being out of doors I cannot control the fumes of the 

 sulphur so as to make them eflfective. 



Prof. Penhallow. I do not think it is the same funras. 

 I think the action of the fungus upon the fruit might be likely 

 to cause the same result, although it might not be the same 

 fungus. , 



Mr. . I have had some trouble with the cracking 



of the bark of apple trees and some of my trees are dead. 



Prof. Penhallow. That is the same blight to which I 

 referred as occurring in the orchard of Fameuse apples in 

 Montreal, where twenty-three per cent, of the trees were 

 involved in the same season. In that particular case, the 

 condition of the soil seemed to be one of the principal causes 

 at work. The sul^soil was a very compact clay and the soil 

 above was very thin, and there was no natural drainage ; and 

 from the distribution of the disease in conformity with the 

 character of the soil, it seemed to me very evident that that 

 was one of the principal causes at work. It may be possible 

 that something of the same kind may be operating here, 

 although other causes may be at work. 



Question. Is there any better management for an apple 



