19 



This brings iis to the least definite feature in our knowledge of this 

 parasite. Since its summer spores cannot live long or endure cold, 

 how does it survive the winter? Doubtless, b}' the hibernation of its 

 threads in potato-tubers, as just described ; but this method alone 

 seems hardly certain enough to constitute the sole reliance of the 

 plant, or sufficient to account for the phenomena of its sudden and 

 abundant appearance. Most of Ihe mildews, the nearest relatives of 

 our plant, produce, in the stems and leaves of their host plants, pecu- 

 liar resting spores which can live and resist cold or dryness for a long 

 time and finally germinate and reproduce their respective fungi when 

 warmth and moisture return. But, although certain botanists have 

 stoutly claimed that the potato fungus produces such spores, their 

 existence has never been satisfactorily proved. 



A preparation which has given remarkable results in the preven- 

 tion of grape-vine mildew, when sprayed upon the vines, would 

 probably prove equally efficacious in protecting potato plants against 

 the rot, if it can be applied in time. This is the so-called Bordecmx 

 mixture, prepared as follows : 



A. Dissolve 6 lbs. sulphate of copper in 16 gals, water. 



B. Slake 4 lbs. lime with 6 gals, water. 



C. When cool, mix A and B, stirring thoroughly. 



As the preparation is a mixture and not a solution, some form of 

 spraying apparatus with an attachment for keeping it thoi'oughly 

 stirred is required for its application. But few attempts at fighting 

 the potato-rot have been made, and it is impossible to say how 

 effectual the above treatment will be ; but, as it has proved so valu- 

 able in other related diseases, a thorough trial of it is earnestly 

 recommended. The chief difficulty will be in making the application 

 promptly enough. To ensure this, the materials should be kept on 

 hand, and* the mixture applied on the first signs of the trouble in any 

 part of the field, or in any field in the neighborhood. To determine 

 the utility of the application, a j)artof the field should be left untreated 

 as a " control-experiment." A comparison of results on the treated 

 and untreated plants will show the efficacy of the treatment. 



The writer wishes to render all possible service to the farmers, 

 horticulturists, and florists of Massachusetts, in dealing with fungus 

 diseases of plants, and will be glad to answer all requests for infor- 

 mation and advice as promptly and as fully as possible. 



