16 EXPERIMENTS IN CH ECKING POTATO DISEASE. [Sept. 1894. 



2 per cent, of copper sulphate and to apply the dressing twice at 

 least ; probably a mixture containing only 1^ per cent, of copper 

 sulphate would be more suitable for those varieties the foliage 

 of which is more tender than that of the Champion ; in no 

 instance did it appear that the foliage had been injured by the 

 strength of the mixture applied. 



The results obtained from the nine complete series of experi- 

 ments show that the average increase of yield of sound potatoes 

 on the treated as compared with the untreated plots was 2 tons 

 13 cwts. 6 lbs. per statute acre, and the average net gain on the 

 treated as compared with the untreated plots was 8s. 2d, per 

 statute acre. 



In the case of six of the 72 sprayed plots the results show 

 net losses varying from 1^. 15s. id. to Is. \\d. per statute 

 acre ; in four of the instances referred to the plots were those 

 which had been sprayed on one occasion only, all the other 

 sprayed plots in the same series of experiments showing marked 

 gains as compared with the results on the untreated plots. 



A further series of experiments was carried out at the Botanic 

 Gardens, Glasnevin, under the direction of Mr. F. VV. Moore, 

 M.R.I.A., with a special v^iew to ascertaining : — 



(1.) Whether any portion of the copper contained in the 

 dressing finds its way into the tissues of the foliage, 

 and if so, how, and in what form. 

 (2.) If the plant is rendered practically disease proof by the 

 absorption of copper by the tissues of the leaves, although 

 all traces of the dressing may have been removed by 

 rain. 



The analyses made in connection with these -experiments were 

 conducted by Sir Charles A. Cameron, Professor of Chemistry, 

 E.C.S.I., who, with Mr. Moore, afforded valuable advice and 

 assistance in arranging the details of the various experiments. 



It is stated that, owing to various unforeseen circumstances, 

 rendering the data obtained unreliable, the results of these 

 experiments at the Botanic Gardens, though carried out with 

 great care, cannot be regarded as conclusive ; it is, therefore 

 proposed to renew them during the present season. 



