505 



by Royal Edict, provided that, when offered for sale, it is coloured by 

 an addition of 5 per cent, of chromate of lead. The properties and the 

 preparation of this poison as a spray, as well as the advantages derived 

 from its use, are briefly outlined. 



IvERSEN (Karsten) & Rostrup (Sofie). Forsog vedrorende Klover- 

 alens smit teevne. [Experiments regarding the mode of infection 

 of Tylenchus devastatrix.] 106. Beretnimj fra statens F&rsdgs 

 virksomhed i Planiekultm, Copenhagen, 1916, pp. 424-441. 



Tylenchus devastatrix is common in Denmark in clay soil, both on 

 the islands and in Jutland, the injury caused by it every year being 

 very considerable. The attack is the more serious, the more frequently 

 red-clover is cultivated in the same field. This is a natural consequence 

 of the life-history of this Nematode. The best method of control is 

 to starve it by eliminating clover from the rotation for five or six years. 

 The method of starvation, however, does not invariably give satis- 

 factory results and this suggests that the fields thus treated become 

 infected again later, independently of the earlier infection. Experi- 

 ments were therefore made as to the method of dispersal from one 

 locality to another. Soil in which the debris of infected plants had 

 been buried in the autumn transmitted infection to clover sown 

 the following spring. Hay or green plants which had been buried in 

 manure heaps, on the other hand, soon lost their power of infection, 

 though hay, stored dry, proved to be a certain source of infection. 

 The evidence goes to show that Tylenchus devastatrix may also be 

 spread with the crop from the infected fields. If, for instance, grass 

 or clover from these is dropped on other fields during transport to the 

 stack, these fields may become infected. On the other hand, if infected 

 grass or clover is kept in a manure heap for at least one month there is 

 no danger of infection, though when placed on top of a manure heap 

 for a short time it retains its ability to spread infection. The most 

 certain way to control this eel-worm is to drop clover out of the rotation 

 for a time and substitute Lotus corniculatus, bird's-foot trefoil. 



Sylven (Hj.). Margborrfaran for vara tallskogar. [The danger to 

 our pine forests from Myelophilus 'piniperda and M. minor'], 

 Skogen, 1916, pp. 153-161, 3 figs. 



The author points out that danger from these beetles is underrated 

 in Sweden, many people considering it useless to attempt any methods 

 of control. He suggests that for every tree felled a certain small sum 

 should be put aside and spent in order to protect the forest from them. 

 Details relating to their biology and development are given, and the 

 removal of the bark from the trees and stumps before the larvae pupate 

 is strongly recommended. 



Saalas (Uunio). Vara grannars fiender bland skalbaggarne. [The 

 beetle enemies of the spruce.] — Uppsatser i Skogsbruk redigerade 

 av Finska Skogsvardsforeningen Tapio. [ Papers on forestry 

 abstracted from (the journal of) the Finnish Foresters' Associa- 

 tion], Helsingfors, 1916, no. 6, pp. 91-95 ; nos. 7 & 8, 1916, 

 pp. 110-116, 9 figs. 



During his investigations on the beetles found regularly on spruce, 

 the author has discovered, in all, 289 different species, which are more or 

 (C327) B 



