756 EXPERIMENT STATION RECORD. [Vol.38 



ing to temperature and humidity, and it can not be arrested at any Btage 

 beyond its inception, at which time, however, treatment properly used is 

 absolutely effective. The primary infection develops from the bodies that have 

 overwintered, and may occur several times. The secondary infection develops 

 from the oil spots if conditions are favorable. 



The progress of the mildew in the berries parallels that in the leaves, and 

 both require thorough treatment. 



In case of a single rain, contamination in a definite manner follows in a 

 short time. In case of rains in close succession, repeated applications of the 

 treatment are necessary until the end of the rainy period, particularly if this 

 is accompanied by a lowering of temperature. Humidity and low temperature 

 favor the development of the fungus and at the same time render the plants 

 more receptive. During a certain period the young leaf or grape is par- 

 ticularly receptive to mildew, and during this time treatment should be prompt 

 and thorough, employing a copper spray not lower than 2 per cent in con- 

 centration. 



The comparative efficacy of acid and alkaline Bordeavix sprays, L. Deq- 

 BULLT (Prog. Agr. et Vit. {Ed. VEst-Centre), 38 {1917), No. 7, pp. 11,9-155, fig. 

 1). — This is a discussion of the comparative merits of acid, neutral, and allca- 

 line Bordeaux mixtures as reported recently by several investigators, giving 

 prominence to the cPaim of superiority for the allialine mixture made as a 

 result of recent tests by Vermorel and Dantony (E. S. R., 38, p. 153). 



Acid and alkaline sprays, V. Veemorel and E. Dantony {Prog. Agr. et 

 Vit. {Ed. VEst-Centre), 38 {1917), No. 9, pp. 201-2'b7).— This gives the details 

 ol the experimentation referred to above. 



One series was continued for 16 days, the other for 50 days. Copper sulphate 

 of 99.8 per cent purity was employed at 2 per cent strength in each series, 

 the acid spray containing 0.32 per cent, the alkaline 0.96 per cent, calcium 

 oxid. The greater persistence of the copper on the leaves in case of the 

 alkaline spray was very marked as compared with that of the acid spray. 



A second test employing the neutral in place of the acid spray showed this 

 to give results approximately the same as regards the persistence of soluble 

 copper on the leaves. 



Acid and alkaline sprays, V. Vermobel and E. Dantony {Rev. Vit., Jf6 

 (1917), No. 1192, pp. 285, 286). — In a statement supplementary to that above 

 noted, the authors discuss acid and alkaline sprays in regard to their actual 

 contents and qualities, so far as known. They claim that the acid preparation 

 at 2 per cent strength is actually less efficacious than the alkaline mixture at 

 half that concentration. 



Acid and alkaline sprays, A. Cadoset {Prog. Agr. et Vit. {Ed. VEst-Centre), 

 S8 {1917), No. 17, p. S94). — In 1914 the use of acid Bordeaux spray was fol- 

 lowed by the defoliation of the vines and the loss of the crop. In 1915, when 

 an alkaline spray was used, the leaves were retained and the crop was normal. 

 Lead arsenate appeared to improve the quality of adherence in the copper spray 

 liquid. 



Alkaline and acid sprays, L. Degbtjlly {Prog. Agr. et Vit. {Ed. VEst- 

 Centre), 38 {1917), No. 11, pp. 247, 248). — Noting an inquiry as to the mean- 

 ings of the terms acid and alkaline as applied to sprays, the author states 

 that the usual mixture of 2 per cent copper sulphate with 1 per cent lime 

 Is regarded as fully adequate and practically always alkaline, in spite of the 

 usual impurity of the lime. The failure of the spray noted in Armagnac, 

 where 12 or 14 sprayings are often insufficient to keep down black rot and 

 downy mildew, is attributed to the climate, which is thought to be very favor- 

 able t« mildew and black roL 



