346 



Ziekten en Beschadigingen van Tomaten. [Diseases of and Injuries 

 to Tomatos.] — Verslagen en Meded. Plantenziektenk. Dienst, 

 Wageningen, no. 26, April 1922, 30 pp., 2 tables, 4 plates. 



This bulletin issued in view of the increasing cultivation of the 

 tomato in Holland, deals with the commoner diseases and pests — the 

 latter including wireworms, the Nematode, Heterodera radicicola, 

 the whitefly, Asterochiton (Aleurodes) vapor arionim, and scale-insects — 

 and with recognised means for combating them. 



Degrully (L.) . Deux vieux Ennemis de la Vigne : le Ver gris, I'Altise. 



— Progres Agric. et Vitic, Montpellier, Ixxvii, no. 18, 30th April 

 1922, pp. 413-419. 



The winter and spring treatments for cutworms in vine3^ards are 

 discussed. One of the most successful and least expensive methods 

 is to make five or six holes nearly two inches in diameter and about 

 six inches deep around the base of each vine stock, keeping the edges 

 ver\' smooth. Numbers of cutworms are caught in this way and can 

 be crushed with a stick. Carbon bisulphide injections are useful in 

 the \\inter, but only before the cutworms come to the surface ; a few 

 holes should be made in the ground in December or January to make 

 sure that cutworms are present before: the treatment is given. 



The preparation of arsenical mixtures for use against Haliica spp. 

 is described. 



Gattefosse (R.-M. & J.). Un Nouveau V6hicule du Pyr^thron. 



— Jl. Agric. Prat., Paris, xxxvii, no. 17, 29th April 1922, 

 pp. 349-350. 



The insecticidal value of extract of Chrysanthemum cinerariaefolium 

 has been abundantly proved. It has been found, however, that the 

 usual commercial soft soap is not the best vehicle for applying it. 

 The oleoresin of pyrethrum, which the Japanese chemist Yamamoto 

 has named pyrethron, is a volatile ether accompanied by resin, and 

 resins, acids and ethers are miscible with soap and become more easily 

 soluble in water according to the degree of saponification by alcohol, 

 either free in the soap or added. It is not proved, however, that the 

 resino-alkali combinations and the products of decomposition of the 

 ether are as active as the original substance. The authors have been 

 led to use a neutral vehicle that is itself an insecticide owing to the 

 sulphur it contains, and is entirely miscible in water. It is a sulphonated 

 oil, which is now being manufactured and is patented ; it dissolves 

 pyrethron entirely and does not seem to produce saponification, 

 even after long contact. 



There are a number of other vegetable ethers and oleoresins, the 

 value of which as insecticides is touched upon ; in particular lavender 

 is the basis of certain sulphonated products that were used with success 

 in war-time against infestations of lice and mites. Pure pyrethron, 

 which is usually extracted in the proportion of 6 per cent, of the 

 pyrethnim flowers, is an expensive substance (costing about £5 per lb.), 

 and, therefore, fresh sources are being tried for obtaining it. In many 

 cases the oleoresins obtained from French and exotic plants, although 

 valuable as insecticides, are accompanied by a very strong odour, 

 which might detract from their usefulness. The actual proportion 

 of oleoresin in pyrethrum-soap is about 1 per cent. ; this is a small 

 proportion considering that the sulphonated oil now used will dissolve 



