10 



DISEASES OF ECONOMIC PLANTS 



of Denmark improved upon these methods by develop- 

 ing his hot-water treatment, which has since proved of 

 great vahie, not so much for its 

 primary use, in which it has been 

 superseded by formahn, but ow- 

 ing to its apphcabiUty to those 

 loose smuts which cannot be suc- 

 cessfully treated by surface disin- 

 fection. Similar seed treatments 

 have been extended to the potato 

 by Bolley, and to cabbage by 

 Harding.^ 

 «r. The production, by breeding, of 



^ MkL i^ew and disease-resistant varieties 



jH|^k,. is one of the latest and most prom- 



J^^^^^^n!' ising methods of combating plant 



V^^^^HllHl^g diseases. Grapes resistant to Phyl- 

 ^Hj^^^^^Hp loxera were produced by Mil- 

 ^"^^^^^ lardet ; others resistant to coulure 

 by Pierce ; cotton, cowpeas, and 

 watermelons resistant to wilt by 

 Orton. 

 No small part in the progress that has been made in the 

 prevention of plant disease is due to the improvement of 

 appHances, dusters, pumps, nozzles, etc., for distributing 

 the disinfectants upon the plants. This progress is well 

 illustrated by comparing the broom of Millardet with the 

 knapsack, barrel, or power sprayer of to-day. 



Fig. 2. — -An improved brush 

 for distributing Bordeaux 

 mixture. After Lodeman. 



' Harding, H. A., and other.s, N. Y. (Geneva) Agr. Exp. Sta. Rpt. 2.3, 

 pp. 62-78. 



