652 Bulletin 81. 



than upon the sprayed part. The line between the two plots 

 passes across the page from A to B. The knots were all cut out 

 after the photograph was taken. The appearance of the thicket 

 after the operation is shown in Figure 6. It will be noticed what 

 a large proportion of small branches has been removed from the 

 unsprayed part. When the value of these branches is considered, 

 the seriousness of this loss can be realized. The sprayed portion 

 lost but a very small number of such twigs and is still in very 

 good condition. The table below shows the numbers obtained in 

 the spring and those removed in the fall. By the term " new " 

 knots are meant those which appeared to have been produced by 

 a new infection ; " old " knots are those which apparently grew 

 from the mycelium which had not been removed when the knots 

 were cut in the spring. 



April 25, 1894. 



Unsprayed portions, knots removed - - - 2002 



Sprayed " <> w . . ^^^^ 



November 26, 1894. 

 Unspraj'ed portion, total number removed 3529 — new knots 3466 

 Sprayed " " " " 240 " " 165 



The above figures are full of encouragement. They show, not 

 that the black knot fungus has been held under absolute control, 

 (and what fungous disease is,) but that it issusceptible to treatment. 

 There was a large increase, nearly 57 per cent. , in the number of 

 knots cut in the fall from the unsprayed portion over those cut in 

 the spring. Had the same proportionate increase taken place in 

 tlie sprayed part, a supposition which must be allowed had no 

 applications been made, the number of knots produced would 

 have been within a fraction of 2000. Consequently, the 165 new 

 knots should be compared with 2000, and not with 1155 as 

 shown by the table. It must also be considered that this reduc- 

 tion took place in the face of circumstances which had been made 

 as favorable for the spreading of disease as possible. The 

 sprayed portion had been covered with knots during the first 

 year's treatments. It was practically in contact with a large 

 number of diseased plants. And finally, we are still in the dark 

 as to the best time of making the application, for we do not know 



