286 



soil. The larval stage lasts about four weeks in summer, but becomes 

 longer as winter approaches. Birds are undoubtedly the most impor- 

 tant natural enemies of this weevil ; if possible, poultry should be 

 allowed to run on the ground after the crop has been cut and the 

 stumps pulled up. A mixture of soot and lime, or sopt, lime and ashes, 

 dibbled in with the plants when they are put out or scattered round 

 them and pricked in lightly will act as a deterrent. Where the roots 

 of a crop are only slightly attacked, they should be used as food for 

 sheep or cattle ; in heavier infestations sheep should be turned loose 

 in the affected field. This should be followed by deep cultivation, 

 and a judicious rotation of crops is also an important factor in the 

 control of this pest. 



Batchei.or (L. I).). Walnut Culture in California. — Calif. Univ. 

 Agric. Expt. Sta., Berkeley, Bull. 332, June 1921, pp. 141-218. 

 33 figs. [Received 27th March 1922.: 



In the course of this bulletin on the cultivation of walnut in Cali- 

 fornia a chapter is devoted to the pests attacking it and the methods 

 for their control. The following insects are included : codling moth 

 [Cydia pomonella, L.j, an Aphid and red spider [Tetranychiis sp.l. 

 The remedial measures suggested for C. pomonella are quoted from 

 Quayle [R.A.E., A, vih, 238^. By the addition of 1 pt. Black-leaf 

 40 to each 200 gals, of lead arsenate the spray will also be effective 

 against the Aphid. For the control of Aphids alone, nicodust is advo- 

 cated. Red spider may be controlled by dusting with three parts of 

 dry sulphur to one of lime. 



BioLETTi (F.T.), Flossfeder (F. C. H.) & Way (A.E.). Phylloxera- 

 resistant Stocks. — Calif. Univ. Agric. Expt. Sta., Berkeley, 

 Bull. 331, October 1921, pp. 81-139, 11 figs. [Received 27th 

 March 1922.] 



As a result of the investigations here described it is now possible 

 to indicate the relative value of certain stocks for most of the principal 

 grape varieties grown under conditions such as exist in the Yolo and 

 Fresno counties, which should prove useful to grape growers who 

 intend to plant P hy II oxer a -resistdint vines. 



In order to facilitate the choice of stock all the available data of 

 importance have been arranged in tabular form showing the behaviour 

 of a particular grape variety on each stock with which it was tested. 



Smith (R. E.). The Preparation of Nicotine Dust as an Insecticide. — 



Calif. Univ. Agric. Expt. Sia.. Berkeley, Bull. 336, November 

 1921, pp. 261-274. [Received 27th March 1922.] 



The first experiments undertaken with nicotine dust were made 

 in 1917 against Chromaphis juglandicola, Kalt. (walnut aphis), and 

 subsequent tests are described. As nicotine is very expensive and 

 comparatively large amounts are required in the mixtures, it is 

 necessary to produce the most powerful dust possible with a minimum 

 of nicotine. The toxicity of the dust is influenced by the form and 

 amount of nicotine used and the nature of the filler. According to 

 the author's observations the dust acts as a fumigant. The two 

 alternatives presented in utilising a given amount of nicotine are 

 that it should be as volatile as possible and give oft' the maximum 



