214 MINNESOTA STATE HORTICULTURAL SOCIETY. 



a nature that you could draw no definite conclusions from it. Mr. 

 Waite has a big orchard where he- is doing this experimenting on 

 what he calls his theory, and he is using the saw and the knife to 

 see what the result will be. You will see that this blossom feature 

 is the most dangerous. Now, if the gentlemen who want informa- 

 tion will ask me questions I will be glad to tell them all I know. 

 There may be a good deal of theor}- about this matter, but I have 

 given you simply all that I have been able to obtain on the whole 

 subject. 



Mr. Parks : Have you found anything in your research in re- 

 gard to the scab or blight on the fruit that we have been troubled 

 with this summer? 



Prof. Robertson : That is a different growth entirely, and what 

 I spoke about was simply the apple blight. There is lots of literature 

 on the subject, and there has been lots of work done on that kind of 

 blight. The fruit can be infected with the blight. You can in- 

 oculate the fruit with the blight so it will blight. 



Mr. Kellogg: In your researches did you find anything that 

 will protect from blight? Would a good circulation of air be any 

 protection ? 



Prof. Robertson : I said a good circulation of air would tend 

 to keep the moisture off. Blight is always more active in moist and 

 warm weather. 



Mr. O. W. Aloore : Can you give us any light on what we call 

 "spur blight" at blossoming time? 



Prof. Robertson : That is the same thing. They speak of blos- 

 som blight, twig blight, spur blight and fire blight, and they are all 

 the same thing. These gentlemen have taken the flower and in- 

 oculated it and left it for a certain length of time to watch the result. 

 These bacteria start in on the blossom and work down through the 

 spur into the limb, and they can trace the exact distance it goes down. 

 Sometimes it stops at the blossom and fruit spur, and if everything 

 is favorable they can tell the exact number of inches it goes down. 

 At the Delaware station they made tests, and in some cases they 

 found that it had worked down as much as fourteen inches. 



Mr. Mitchell : Sometimes it stops at the end of the blossom 

 stem, and the gum exudes where the stem joins the limb. 



Prof. Robertson : It does often stop there. 



Mr. Mitchell : How does it get introduced from one orchard 

 to another? 



Prof. Robertson : By the bees and other insects working from 

 one orchard to another, and in that way it might easily be carried 

 a mile or a mile and a half. The sap starts early in the spring 

 season, and only a few of these ^bacteria live over the winter, but you 

 find them very actively at work until quite late in the fall. They 

 begin to multiply very early in the spring, and they cause exudation 

 of the gum which results from their feeding, and Mr. Waite has 

 found insects feeding upon them so that within a mile or a mile and 

 a half insects could easily carry the infection. Mr. Peffer mentions 

 an instance where trees were affected within two days where the 

 conditions were favorable. A gentleman in California appointed 



