RASPBERRY DISEASES IN MINNESOTA. 241 



mens, and giving original observations as to the prevalence of 

 diseases, the damage they cause, and the effect of soil and 

 weather conditions on the seriousness of these diseases, together 

 with the financial losses they occasion. 



Information will be sent out as it becomes available. In 

 the meantime it is important to recognize the fact that diseases 

 are important limiting factors in raspberry production and 

 that until more specific recommendations can be made the fol- 

 lowing procedure is advisable: 1. Set out healthy plants. 2. 

 Practice proper culture. 3. Cut out and burn all infected 

 canes. 4. Spray. 



No one method is sufficient, such as spraying alone, with- 

 out proper regard to destruction of infected material in the 

 field. The importance of this last point cannot be too fully 

 emphasized. In raspberry disease control, as in everything else, 

 an ounce of prevention is worth a pound of cure. Do not wait 

 until your patch is diseased before taking the necessary measures 

 to keep it disease free. Definite action toward complete disease 

 control should be begun immediately. 



Mr. Bussey: I would like to know the cause of what 

 we might term leaf riddlers. Along the middle of the sum- 

 mer the upper part of my raspberry bush leaves were riddled 

 like some flies had been at work, but I could not see any traces 

 of flies working. 



Mr. Hoerner : I have seen the condition you mention. 

 There may be two things that cause it. If it shows shothole 

 effects, as if the leaves had been punctured with fine shot, it 

 may be caused by a leaf blight. Or it may be a worm that 

 chews very rapidly. It is hard to see, but if you shake the bush 

 you will shake it off. This worm is the larva of a fly — but that 

 is out of my field. 



A Member: It is possibly a grasshopper; they will eat 

 most anything. 



A Member: Does the root gall affect anything else be- 

 sides the raspberries? 



Mr. Hoerner: Yes, sir. It is true that the same bacteria 

 that causes crown gall on raspberries also affects apple trees and 

 various kind of trees, causing the same kind of a gall on the trees, 

 although it is true that infected galls from the raspberry will 

 affect the raspberries easier than they will affect apples. 



Mr. Sauter: Last spring a man to whom I sold some 

 nursery stock showed me some apples that had the same thing 

 as the raspberries. 



Mr. Hoerner: It is exactly the same organism, and some- 

 times you find a hairy root condition on the apple trees caused 

 by the same thing. 



