946 Summary of Agricultural Experiments, [fee. 



Globe. The weight of crop produced was, however, higher in the case 

 of the Yellow Globe, so that in total dry matter produced per acre 

 Golden Tankard had only a slight advantage. The percentage of 

 sugar in the roots was also found. 



Weeds and Plant Pests. 



Growth of Tobacco for Nicotine Extraction (Wye Jour., No. 19, 1910). 

 — Within the last few years the value of nicotine as an insecticide has 

 become fully appreciated by growers of fruit and hops, with the result 

 that the price is now almost prohibitive. The experiments described 

 by Mr. Garrad were designed to test the possibility of growing tobacco 

 and extracting nicotine from it in this country. An account of the 

 results obtained in 1910 appeared in this Journal, August, 191 1, p. 378. 



Charlock Spraying (Univ. Coll. of N. Wales, Bangor, Agric. Dept., 

 Bull. 1, 1910). — Demonstrations in 1910 were carried out at fourteen 

 centres with solutions of 15, 20 and 25 lb. of copper sulphate in 50 

 gallons of water, forming 3, 4 and 5 per cent, solutions. These char- 

 lock spraying demonstrations are now concluded, having been conducted 

 at about one hundred different centres in various parts of North Wales. 

 They have shown that in the moist climate of the district 4 and 5 per 

 cent, solutions of sulphate of copper, applied at the rate of 50 gallons 

 per acre, practically destroy all the charlock. The 3 per cent, solution 

 has only proved effective when the conditions have been particularly 

 favourable. 



A Bacterial Disease of the Potato Plant in Ireland (G. H. Pethybridge 

 and P. A. Murphy, Proc. Roy. Irish Acad., Vol. 29, Sec. B. } No. 1, 

 February, 191 1). — This paper contains a complete account of the inves- 

 tigation of the disease called Black Stalk-rot, carried out for the Irish 

 Dept. of Agric. by the authors. A shorter report on the work was 

 published in the Jour, of the Dept. of Agric. and Tech. Instr. for 

 Ireland, and was summarised in this Journal, August, 191 1, p. 420. 



Observations on Parasitic Fungi causing " Fairy Rings " (Jour. Econ. 

 Biol., Vol. 6, No. 4, Oct., 191 1). — The well-known "Fairy Rings" in 

 grass land may be caused by several different fungi. In this paper 

 Dr. J. S. Bayliss records observations made on the growth of rings 

 formed by Marasmius oreades, Fr., and Clitocybe gigantea, Sow. 

 Three distinct zones in the ring itself are distinguished, in addition 

 to the disc of poor grass inside the ring — (1) an outer ring of dark 

 green grass ; (2) a zone of dead grass ; and (3) an inner ring of dark 

 green grass. The outer zone is usually overlooked, perhaps because 

 it is, at the beginning of summer, only an inch or so in width, and 

 by the time it has attained its full width of several inches, the grass 

 of the field generally has deepened in colour, and the contrast is not so 

 marked. The soil under all these three zones was found to be well 

 penetrated with the mycelium of the fungus to a depth of about a foot, 

 though it was most abundant under the ring of dead grass, and it is 

 in this part of the "fairy ring" that the sporophores ("toadstools") 

 appear when conditions are favourable. The soil in the centre of the 

 ring showed no trace of fungus mycelium. Practically all the common 

 pasture grasses, clovers, and weeds were killed by the fungi, though 

 docks and sorrels seemed able to resist the attacks. The ring is 

 constantly growing outward, and what is the outer zone of one year 



