Winter Meeting. ^83 



"ii 



ovei- the trees and cut them all out. I believe it would be desirable to 

 pick the fruit of those trees which are known to be infected, and thus to 

 some" extent prevent its spread. If we can find some wash to put on 

 the tree in the winter to kill these cankers we should be able nearly to 

 control it. There are very few apples in Illinois this year, and we will 

 not be likely to have much early outbreak of this bitter rot next year, 

 I think it pretty certain that the cankers upon the limbs are produced by 

 the bruises made upon the tree at picking time. They are usually formed 

 upon some injured portion of the tree. ■ Any little bruise is likely to 

 admit the spores, which make the canker. If we want to keep down 

 canker as much as possible we must see that the trees are not carelessly 

 handled, I think one of the worst things is to let the apple buyer go 

 into the orchard and pick the apples. He is apt to club the trees, which 

 puts them into fine condition to admit the canker spores which make the 

 bitter rot. It is thought that the spores may be carried by the little 

 pomace flies, and they may be blown by the wind. This makes it more 

 important to stop its first outbreak. 



Can it be controlled by spraying? Expermients show that if the 

 fruit is actually covered with Bordeaux no bitter rot spore can get to it ; 

 but it is very difficult to keep the apples sufl.'iciently coated. It does no 

 good to put on the coat after the spore gets into the apple. There is 

 no stopping it then. Early spraying for the scab and the codling moth 

 does not seem to have much effect against the bitter rot. The spray 

 must be put on before the spore gets on the apple; but just as little be- 

 fore as possible. It is hard to meet all the conditions required. Whether 

 we can make spraying absolutely successful is very doubtful. I hope 

 it may be done. I think we will have to get up early in the morning if 

 we succeed. If we succeed we will have accomplished something worth 

 while in Illinois and Missouri. 



J. L. Erwin. — Has any effort been made to destroy the spores in 

 these cankers? 



Prof. Burrill. — That has not been successfully done, to my knowledge. 



Mr. Chandler. — Will early picking and destroying infested apples 

 avail anything? 



Prof. Burrill. — That is exceedingly desirable to keep out the very 

 first infection. Where there are not a great many of the cankers in the 

 limbs their removal has proved to be a great advantage in practical work. 



Mr. Erwin. — I observed in 1882 that trees to the windward of a 

 tree affected by the bitter rot were affected by the same disease. I 

 grubbed up and burned the affected tree. I think it may be propagated 

 upon wild crabs in the woods. 



