554 JOUENAL OF THE KOYAL HORTICULTURAL SOCIETY. 



Parasitic Diseases of Plants, A Method of Checking". By 



M. G. Potter (Journ. Agr. Sci., vol. ii. (1908), p. 102.— The author found 

 that, as with other bacteria, Pseudomonas destructans, the cause of "white 

 rot " in turnips, produced during its growth a substance poisonous to itself. 

 This toxic substance was not destroyed by heating to boiling point, but 

 the enzyme, cytase, which produced the peculiar appearance following 

 the attack of . the bacillus upon the turnip, was destroyed. When the 

 oacilli were brought into contact with the toxin their movements at once 

 ceased and they were finally killed. Treatment of diseased patches upon 

 the turnip prevented the further development of the disease. The sub- 

 stance was not toxic to Penicillium and certain bacilli, but remained 

 unchanged after these organisms had been growing upon the turnip. The 

 author has also found that Penicillium italicum, which causes rotting of 

 oranges, also produced a substance which inhibited its further growth. 



How far these discoveries may prove applicable in practical treatment 

 of plant diseases remains to be discovered, but they open out a fascinating 

 field for research. — F. J. G. 



ParthenoeiSSUS tricuspidata. By T. A. Sprague (Bot. Mag. tab. 

 8287). — Nat. ord. Ampelidaceae ; Japan and China. Shrub, climbing by 

 viscous tips to tendrils ; leaves polymorphic, simple to 3-foliate, toothed ; 

 cymes from short shoots ; flowers densely clustered, J inch across. — G. H. 



Peach Curculio, Experiment in Control of. By E. P. Taylor 



(Jour. Econ. Entom., ii. (1909), 2, p. 154). — This insect (Conotrachelus 

 nenuphar Hbst.) is one of the worst pests of peach orchards in the 

 Mississippi Valley. Spraying with Swift's arsenate of lead paste with 

 a power outfit on a block of 1,195 six-year old trees was followed by a 

 great reduction in the amount of damage done by the weevil. Far fewer 

 peaches fell prematurely, and over and above this there was a great 

 reduction in the amount of brown rot (due to Monilia fructigena) which 

 often followed the puncture of this pest. The strength of the solution 

 used was 2 lb. of the arsenate of lead paste and 4 lb. quicklime to 50 

 gallons of water. This solution sometimes caused injury to the foliage, 

 but more often when the foliage was older than when the spraying was 

 done early ; the addition of lime reduces the danger of inj ury, but it is 

 well to be very cautious in applying arsenate to peach trees, as the action 

 varies under different conditions. The spraying was best done as soon as 

 the petals had fallen. — F. J. C. 



Pecans, Notes on Additional Insects on Cultivated. By G. W. 



Herrick and R. W. Harned (Jour. Econ. Entom., ii. (1909), 4, p. 293).— 

 A list of insects with notes on their habits, supplementing the list pub- 

 lished in Bulletin 96 of the U.S.A. Exp. Stn., Mississippi.—^. C. 



Peliosanthes violacea var. Clarkii. By C. H. Wright (Bot. 



Mag. tab. 8276). — Nat. ord. Haemodoraceae ; tribe Ophiopogoneae. 

 S.E. Asia. Herb ; leaves oblong-lanceolate, petiolate, 1 foot long ; 

 racemes 6 inches long ; flowers solitary, dark purple, \ inch long, § inch 



broad.— G. H. 



