3()G EXPERIMENT STATION RECORD. 



Bordeaux mixture were still green aud succulent. Seyenty-two plats 

 in all were treated, 36 receiving a 2 per cent solution, the rest a U per 

 cent solution. The experiments were divided into sets of 8 plats 

 eaeli. 



A comparison of tlie results obtained on those plats similarly treated 

 with respect to the method and frequency of application, but which 

 varied with the per cent of coi)per sulphate contained in the mixture, 

 indicates that the best results were obtained with the 2 per cent solu- 

 tion in 21 cases, and with the li per cent mixture in 15 cases. The 

 idats which gave the highest yield in each of the 9 sets in G instances 

 had been sprayed with a 2 per cent solution and in 3 instances with a 

 li per cent solution. Comparing the results obtained in each set of the 

 experiments by the different systems of application, and irrespective 

 of the amount of copper used, it appeared that in 2 sets the plats giv- 

 ing the highest yield were sprayed once only from above and below, 1 

 from above only, and from below only, the last 7 sets having received 

 2 ai)plications. A comparison of the average returns per acre shows 

 that the plats which were sprayed twice at intervals of about 4 weeks 

 from above and below gave the best results. It would appear, tnere 

 fore, that in the case of this variety of potatoes it is desirable to use a 

 mixture containing 2 per cent copper sulphate and to apply the mix- 

 ture at least twice. For those varieties which have a more tender 

 foliage than the Champion a li per cent solution will probably be more 

 suitable. The average increase of sound potatoes on all the treated as 

 compared with the untreated plats was at the rate of 104 bu. per acre. 

 In tlie case of out of 72 of the sprayed plats losses were experienced 

 varying from 30 cts. to 17.50 per acre. 



A further series of experiments were carried on at the Botanic Gardens 

 ot Glasnevin with a special view of ascertaining (1) whether any portion 

 of the copper contained in the solution finds its way into the tissue of 

 the foliage, and if so in what form, and (2) if the plant is rendered 

 practically disease proof by the absorption of copper by the tissues of 

 leaves, although all traces of the mixture may have been removed by 

 the rain. The data obtained in these last experiments seem so unre- 

 liable that conclusive results cau not be obtained, and the experiments 

 are to be repeated. 



Concerning the stimulus produced by treating potato plants 

 with copper, B. Frank and F. Kklcier {Ber. dent. hot. Ges., 12 

 (1894), Ko. 1, pp. 8-11; abs. in Forsch. Geb. agr. Phys., 17 {1894), JSfo. 3 

 and 4, pp. 348,349).— The authors refer to Rumm's' experiments with Bor- 

 deaux mixture on grape leaves, showing that the copper solution had 

 a positively l)encticial etiect upon the plant. In the case of the grape 

 tlie demonstration is admitted, and the authors have undertaken to 

 show the ettect of copper on the potato. The Phytopkthora was com- 



» Ber. deut. bot. Ges., 10, No. 2, pp. 79-93 j E. S. R., 4, p. 968. 



