646 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



sooty blotch" to the fungus Phyllachora pomigena, and "fly- 

 speck " to Leptothyrium pomigenum . No additional evidence as to 

 the identity of the two- diseases is given by the writer in the present 

 article. 



The disease is likely to prove troublesome by damaging the look 

 of well-grown apples, and thereby interfering with the practice of 

 marketing the best apples in boxes. 



Systematic spraying with Bordeaux mixture is recommended except 

 on Cox's Orange Pippin and Duchess's Favourite. — A. S. H. 



Sprays, Summer, on Apples and Peaches. By G. P. Clinton 

 and W. E. Britton (U.S.A. Exp. Stn., Conn., pt. vii. Biennial Rep. 

 1909-10; 8 plates). — Owing to serious injury from the use of Bordeaux 

 mixture experiments were undertaken to compare it with lime-sulphur 

 preparations, both as regards fungicidal value and immunity from 

 spray injury. With the commercial and self -boiled lime-sulphur sprays 

 there w^as no leaf injury worth mentioning, but with Bordeaux the 

 leaves suffered more or less serious spotting and leaf fall, while with 

 the commercial lime-sulphur sprays containing other ingredients in 

 addition considerable damage resulted in some cases. As regards the 

 fruit, the russeting resulting from the use of commercial lime- sulphur 

 sprays was never so general or so conspicuous as from Bordeaux 

 (p. 598). The results of the tests with the spraying of peaches lead 

 the writer to recommend self-boiled lime-sulphur as the best summer 

 fungicide for general use, but it should never be used later than the 

 middle of July, and in dry seasons not so late as this, on account of 

 the sediment that may adhere to the fruit at market time (p. 617). 



A. P. 



Superparasitism : An Important Factor in the Natural 



Control of Insects. By W. F. Fiske {Jour. Econ. Entom., vol. iii., 

 pt. i. ; pp. 88-89; Feb. 1910). — " Superparasitism results when any 

 individual host is attacked by two or more species of primary parasites, 

 or by one species more than once." Instances of superparasitism are 

 quoted, especially some met with in the breeding of gipsy-moth para- 

 sites in the attempt tO' control this pest by their means. The author, 

 points out that superparasitism frequently nullifies the work of the ! 

 parasite and distinguishes three classes of manifestations : 



(1) One parasite lives; the other dies, 

 (a) The survivor preys upon the other as an accidental secondary j 



parasite. Of common occurrence. 

 (5) The survivor destroys the other by bringing about premature! 

 death of host, and may or may not devour it incidentally. Of I 

 common occurrence. 



(2) Both parasites live. 



(c) Neither is the worse for the circumstances. Very rare. ' 



(d) One or both are so weakened and stunted as to bring! 

 about a material reduction in their capacity for reproduction. 

 Common. 



