NOTES AND ABSTRACTS. 



267 



April 1908). — A summary of investigations into the cause of a leaf -spot 

 very generally prevalent in apple orchards east of the Rocky Mts. is 

 given. The disease is shown to be due to the fungus Sphaeropsis 

 malorum Pk., which produces circular (or irregular) reddish-brown spots, 

 an eighth of an inch or more in diameter, on the leaves. Other fungi 

 occur quite commonly on the leaves, but do not appear to be parasitic. 

 This fungus in very prevalent on dead twigs or apples, &c, and on canker 

 spots on the branches, &c. The spot is very similar to that described in 

 R.H.S. Joukn. xxxiii. p. 500, but the spots are usually smaller than 

 those caused by Cladosporium. 



The trouble has yielded well to spraying with Bordeaux mixture 

 twice, the first time just after the petals have fallen, the sec md about 

 four weeks later. A third may be necessary in very wet districts. 



F. J. C. 



Apples, Respiration of. By F. W. Morse (U.S.A. Exp. Stn. 

 New Hampshire, Bull. 135, February 1908 ; figs.). — Respiration occurs 

 in apples during storage. The experiments detailed showed that at 

 32° F. 1 kilogramme of apples exhaled, on an average, in one hour, 

 5-2 milligrammes of carbonic acid gas ; at 50° F., 13 2 mg. ; and at 

 68° F., 21*8 mg. This C0 2 is produced at the expense of the substance 

 of the apple itself ; and the experiment emphasizes the need of cooling 

 the apples to a low temperature as soon after picking them as possible. 



F. J. C. 



Arsenical Salts as Insecticides. By H. Grosjean (Le Jar din, 

 vol. xxii. No. 510, p. 158, May 20, 1908). — Another valuable report on 

 the use of arsenic as an insecticide. M. Grosjean considers that there is 

 no danger in its use, because it is applied in the very early stages of 

 plant growth. It is, however, prudent for the operator to wash himself 

 carefully and brush his clothes after handling it, and it should be kept 

 away from children. If applied to pastures or orchards no cattle should 

 be allowed to feed there for some time, nor should fruit trees be treated 

 in the vicinity of vegetables.— F. A. W. 



Arsenical Treatment of Plants. By J. Vercier (Le Jardin, 

 vol. xxii. No. 509, p. 142, May 5, 1908). — This article gives an interesting 

 account of arboricultural experiments with preparations of arsenic during 

 the last thirty years. By a curious anomaly the sale of these prepara- 

 tions as insecticides by French firms is not permitted in France, for fear 

 of a deleterious action on the fruits or vegetables treated with them, but 

 American firms are allowed to sell the same preparations in the country, 

 avowedly for the same purpose ! Lead arsenate seems to be the most 

 efficacious, but is also the most dangerous. Schweinfurt's green is 

 therefore recommended, in the proportion of 300 grammes to 300 of 

 carbonate of soda and 100 litres of water.— F. A. W. 



Asparagus, Tube Culture of. By J. M. Buisson (Rev. Hort. 

 April 1, 1908, pp. 158-9 ; 3 illustrations).— Deep planting and banking up 

 of asparagus is deprecated as injurious to vitality and contributing to 

 delay in growth. The production of an earlier crop is obtained by means of 



