DISEASES OF PLANTS. 151 



Spraying experiments and apple diseases in 1913, W. J. Morsk (Maine Sta. 

 Bill. 223 (1914), pp. 2Jf, pis. ^).— This bulletin constitutes a fourth report of 

 a series on orchard spraying experiments (E. S. R., 29, p. 145) and gives the 

 results of the experiments and observations of 1913. 



Plats of apple trees were sprayed with Bordeaux mixture, various treatments 

 of lime-sulphur solution, soluble sulphur, atomic sulphur, arsenate of lead, and 

 arsenite of zinc used In connection with the lime-sulphur solution. The effect 

 of the different fungicides on the foliage and fruit was carefully noted, and the 

 results obtained stippleuient those previously given for 1912. 



In 1913 the efficiency of the first spray application was not as marked as in 

 1912. It was suggested in the previous account that a dilution of lime sulphur 

 20 per cent stronger than the standard could be used on Ben Davis trees with 

 little danger of injury and greater efficiency, and the results in 1913 confirmed 

 the conclusion based on the previous year's work. The use of Bordeaux mixture 

 resulted in a smaller percentage of scabby apples, but a larger proportion of 

 those which were russeted. The use of lime sulphur gave a very efficient con- 

 trol of scab and the fruit was less injured than where Bordeaux mixture was 

 employed. Soluble sulphur used at the rate of 2 lbs. to 50 gal. of water pro- 

 duced severe leaf injury, although it appeared to be fairly efficient so far as the 

 control of apple scab was concerned. The use of atomic sulphur was followed 

 by satisfactory results, no spray injury being observed, but the author does not 

 consider its recommendation warranted without further test. 



A description is given of the use of arsenate of lead as a fungicide, and where 

 2 lbs. of dry arsenate of lead was used in 50 gal. of water the control of the 

 scab was better than on the other trees except those sprayed with Bordeaux 

 mixture and the stronger lime-sulphur solution. This would indicate a strong 

 fungicidal action for arsenate of lead, and it is thought probable that efficient 

 scab control with a minimum of fruit russeting might be obtained by its use, 

 supplemented by Bordeaux mixture or a strong lime-sulphur solution used as 

 a dormant spray. 



An account is given of investigations on the source of spring infection by 

 apple scab, previously noted (E. S. R., 30, p. 542). 



Notes are also given on the observance of Nectria ditissima in Maine. 



Some observations on the anatomy and other features of the black knot, 

 A. Stewart {Amcr. Jour. Bot.. 1 (IBUf), No. 3, pp. 112-126, pis. 2).— This is a 

 more detailed account of work reported previously (E. S. R., 30, p. 150). 



Court-noue, S. Barry (Prog. Agr. et Vit. (Ed. VEst-Centre), 35 (1914), A"o. 5, 

 pp. 146, 147). — The author, giving briefly his experience in grape culture, cover- 

 ing some 50 years, states that while some vines under his care have been some- 

 what subject to court-noue for many years without very serious damage, others, 

 including some vines of later planting, have suffered severely. A portion of 

 the latter are now being given a trial with the coal tar treatment. 



The downy mildew of the grape, G. H^ron (Jour. Agr. Prat. Vit. et Econ. 

 Rurale Midi France, 109 (1913), No. 5, pp. 192-204). — ^An account is given of 

 the author's experiments for the control of the downy mildew by the use of 

 Burgundy mixture. 



On the basis of the results which he secured, he recommends the use of a 

 freshly prepared mixture containing 2 per cent copper sulphate, or in very 

 humid years a 3 per cent mixture. For successful control frequent applications 

 of the fungicide shoulci be made at the beginning of the appearance of the dis- 

 ease, and it is stated that the different sprayings may be profitably alternated 

 with treatments with copper acetate or a simple solution of copper sulphate. 



