1908.] PUBLIC DOCUMENT — No. 33. 23 



The report calls attention to two apparently new diseases : 

 one affecting asparagus, and apparently caused by a species of 

 fusarium ; and another affecting the peony, the cause of which 

 has not been determined. No remedy for either of these troubles 

 can at present be suggested. 



During the past year the botanist has made careful compari- 

 sons between a number of combinations of fungicides and in- 

 secticides for potatoes. These experiments were carried out 

 in connection with fertilizer work of the agricultural depart- 

 ment which is designed to throw light upon the relative value 

 for different crops of seven difierent potash salts. ^ There was 

 little or no blight during the season, and all of the combina- 

 tions tried seemed to possess nearly equal merit as insecticides. 

 From the standpoint, however, of their ability to adhere to the 

 foliage and their qualities in other respects, the botanist ranks 

 the different combinations used in the following order : — 



1. Soda bordeaux and Paris green. 



2. Bordeaux and sodium benzoate. 



3. Bordeaux and disparene (arsenate of lead). 



4. Bordeaux and Paris green. 



6. Copper phosphate and disparene. 



In connection with the variation in fertilizers for the potato 

 crop in this series of experiments, ^ an important influence on 

 the prevalence of scab was noted. The proportion of badly 

 scabbed tubers was much greater where potassium-magnesium 

 carbonate was the source of potash than on any of the other 

 plots. 2 The proportion of scabby tubers was smallest where 

 the muriate and nitrate were the potash salts employed ; but 

 the dift'erence between the proportion of scabby tubers on 

 these fertilizers and on the other potash salts was relatively 

 small. 



The report of the botanist discusses mosaic diseases of to- 

 bacco and the tomato. He finds an important difference be- 

 tween the two diseases in two respects. Healthy tobacco 



1 For a full account of these experiments, see report of the agricultural department, 

 page 39. 



« The fact that scab is more apt to prove serious in soils which are alkaline has been 

 frequently noticed. The potash-magnesia carbonate is a strongly allialine fertilizer. Dr. 

 H. J. Wheeler has frequently called attention to this point in reports and bulletins of the 

 Rhode Island Experiment Station and elsewhere. 



