Aug. 2, 1920.] Agricultural Gazette of N.S.W. 595 



Bordeaux Powders v. Home-made Bordeaux 



Mixture. 



So many enquiries have from time to time been received regarding the 

 efficiency of Bordeaux powders, that it was decided to test one of the brands 

 as against home-made Bordeaux mixture. Further, it has been claimed that 

 these powders are efficient in the dry form as a preventive of downy mildew — 

 a statement contrary to general experience. It was recognised, however, that 

 if these powders were reasonably useful in checking fungoid diseases oE the 

 vine, they would be of great benefit to the smaller growers and householders 

 who had not the convenience to make their own Bordeaux mixture. A series 

 of experiments designed to determine the points at issue was thei'efore 

 carried out during the past season, under the direction of Mr. H. G. White, 

 Superintendent of the Viticultural Nursery at ISTarara. The following is a 

 condensation of Mr. White's report : — 



" Thirty-nine rows of young Muscat Hamburgh vines were selected for the 

 tests, which compared Bordeaux mixture 6-4-40, with a proprietary Bordeaux 

 mixture powder — (1) in a pure dry state ; (2) in a dry state, plus 50 per cent, 

 lime ; (3) in the proportion of 6 lb. to 50 gallons of water ; and (4) in the 

 proportion of 4| lb. to 50 gallons of water. The trials were commenced on 

 15th January, and were continued, except for the applications of (1) and (2), 

 until 19th March. x\pplications of foramlfe (1) and (2) were discontinued after 

 thirty-seven days, as it was found that downy mildew was not being checked 

 by the application of the Bordeaux powder in the dry form ; indeed, the 

 upper portion of the vines had lost a large proportion of their leaves — 

 sufficient evidence that the pure powder, and the powder with 50 per cent, 

 lime, were not effective. 



" Sprays (.3) and (4) were practically no different in their effect to Bordeaux 

 6-4-40, and on the appearance of the vines to date it seems that the smaller 

 quantity of the powder is as effective as the larger. 



" As the tests were not made until after the vines had been treated several 

 times with Bordeaux 6-4-40, furthei tests seem called for, and it has been 

 suggested that these should take place next year, when each formulae could be 

 applied from the commencement of the season to rows previously untreated 

 in that season. 



"The rainfall from the beginning of July, 191fi, to the end of March, 1920, 

 was 2,611 points, and for the actual period of the tests it was 8 06 inches." 



From the foregoing it will be seen that the main facts have been fairly 

 well established, namely, that in the di-y form the powders are of little benefit, 

 but when made up with water and sprayed on to the vines there is no 

 apparent difference between them and the home-made Bordeaux mixture. 

 The question of relative cost should be estimated during another season, when 

 the experiment should extend throughout the season. The experience of 

 vine growers in County Cumberland last season should cause them to pay 

 considerable attention to spraying in the future. — H. E. Laffer. 



