14 V. OF X. H. AGR. EXPERIMENT STATION [Bulletin 227 



Mosaic symptoms remained perfectly obvious throughout the ex- 

 periment in the plants of Series 4; in Series 3 the leaves became normal 

 as regards margin and smoothness of blade but remained faintly mot- 

 tled; in Series 2 mosaic symptoms were faint though recognizable; in 

 Series 1 mosait symptoms were not recognizable. At the close of the 

 exjieriment the croj) was harvested and the following yields obtained: 



Tubers per plant 

 Mean weight in grams 



Series 1. Plants heated 4 hours 45. 10 



Series 2. Plants heated 2 hours 41 69 



Series 3. Plants heated 1 hour 37.57 



Series 4. Plants not subject to heat 36 06 



Spraying and Dusting Potatoes — (Hatch Fund) 



In continuation of previous work a study was made by 0. Butler 

 of the relative value of hand dusting and spraying for the control of 

 potato diseases. The sprayer used was the Vermorel Eclair, and the 

 dusters the Vermorel double-action Torpille and the Niagara blower. 

 An 8-4-50 Bordeaux mixture was applied every two weeks with the 

 sprayer. Sanders dust containing 8.6 per cent metallic copper was 

 applied both weekly and fortnightly with the Niagara blower, and 

 weekly only with the Vermorel Torpille. 



During August the potatoes in all the plots suffered severely from 

 tip-burn. On Aug. 22 the plants in the non-treated plots were dying, 

 and those in the plot dusted every two weeks were also in very bad 

 condition. The plots dusted weekly and the sprayed plot were, how- 

 ever, still fairly green. On Aug. 29 the ]U)tatoes in the non-treated 

 plots were dead; the i:)lants in the plot dusted fortnightly were also 

 dead; the plants in the plots dusted weekly and in the sprayed plot 

 were, on the other hand, still slightlv green, but died shortly after 

 Sept. 3. 



The plots were harvested in October. The amount of copjier ap- 

 plied and the yields obtained were as follows: 



Copper per Yield per 

 acre acre 



No treatment 222 . 6 bu. 



Sanders dust weekly, Niagara blower 43.0 lb. 279 8 bu. 



Sanders dust fortnightly, Niagara blower.. 14.6 lb. 225 7 bu. 



Sanders dust weekly Vermorel Torpille . . 39.1 lb. 253.0 bu. 



Bordeaux mixture 8-4-50 fortnightly 16.9 lb. 247.5 bu. 



It will be apparent from the figures given that the efficiency of the 

 unit copper in Sanders dust is low and does not compare favorably 

 with the unit copper in Bordeaux mixture. 



Effect of Differently Cut Potato Seed and Siccatives — (Hatch Fund) 



Observation having suggested that seed pieces cut from the stem 

 end of potatoes might be more s(Misitive to adverse conditions than 

 those from the apical halves, the following experiment was imdertaken 

 by 0. Butler. Certified seed potatoes were cut in half across the 



