CHAPTER XI 



CONTROL MEASURES AGAINST DISEASES 



By M. F. Barrus 



It will be noticed from reading the preceding pages 

 that for some diseases the selection of seed tubers is 

 advised and for others seed treatment, crop rotation or 

 spraying is recommended. It may be necessary to prac- 

 tice more than one control measure in order to control 

 some diseases. P'or the seed potato grower, it is desirable 

 and is becoming more and more necessary that all meas- 

 ures be employed that will tend to produce sound tubers 

 free from all diseases. Detailed directions for carrying 

 out these measures are given in these pages. 



Control of curly-divarf , mosaic and leaf-roll 



As has already been pointed out, such diseases as curly- 

 dwarf, mosaic and leaf-roll, transmitted by the tubers, 

 cannot be detected by the appearance of the tuber out- 

 side or within. There is very little or no outward evi- 

 dence on tubers affected with Fusarium and ^^erticillil^n 

 wilt, bacterial wilt and net necrosis, and occasionally on 

 some tubers affected with black-leg. Even a section of 

 the stem end will sometimes fail to reveal the presence 

 of these last-named diseases. In such cases, it is very 

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