208 ANNUAL REPORT. 



has made a speciality of the study of insects that are destructive to 

 plants. Prof. Forbes has done a good deal of work on the insects, 

 which are injurious to the strawberry, and I can refer you to his 

 reports, the Illinois Entomologist Reports. 



Mr. Tuttle. We have always considered the rust that Prof. Sey- 

 mour speaks of as being due to heat and sun-scald; I noticed two or 

 three years ago that we had very moist weather in the spring and that 

 the rust seemed to increase very much; and then when the weather 

 became dry and the rust appeared to stop, the vines took a new start. 

 This led me to think that the injury was not from sun-scalding, as 

 then the rust seemed to abate. 



Mr. Cutler. I never saw any rust on my vines until I got the Man- 

 chester, and they rusted very badly. Last summer, the season was- 

 comparatively dry and I was not troubled with it. It spread among 

 the Manchesters, but I did not observe it on other varieties; I noticed 

 the leaves were covered with dark spots. 



Prof. Seymour. Probably that was the black spot rust that Mr. 

 Earle found so destructive. 



Mr. Pearce. How do those spores circulate, in the air'? 

 Prof. Seymour. Yes, they are very easily carried in the air, as they 

 are very light. In fact they are more easily carried in the air than 

 ordinary dust. 



A Member. I would like to know how they are produced, or how 

 they germinate ? 



Prof. Seymour. They need moisture to germinate. They germinate 

 by sending out a slender thread, and if they are on the surface of a 

 strawberry leaf, they penetrate into it. 

 A Member. Do they multiply rapidly? 



Prof. Seymour. Yes, sir; quite rapidly. There would be a large 

 number of the spore bearing threads on each spot, and each thread 

 bears a spore on the end. The number is so great that one couldn't 

 count the spores; all of these produce an infinite number of spores. 



A Member. Then I would understand that the air would be literally 

 filled ■^ith these spores that are sent off? 



Prof. Seymour. If they lived on indefinitely that would be true, but 

 the}' probably do not. Probably after a length of time they would 

 not germinate. After they have been dry a few days it is known they 

 would not germinate. 



A Member. I would like to ask if there is any relation between 

 fire blight and rust? 



