1917] FIELD CROPS. 339 



With reference to methods of conducting germination tests it is concluded that 

 germinating between blotting papers is best for most kinds of grass seed and 

 that light is necessary for the germination of the seed of some species. A 

 constant temperature of 20° C. witliout light was suited to the germination of 

 only a few grasses, but a change of temperature from 20° for 18 hours to 30° for 

 6 hours gave good results with many different kinds. A constant temperature 

 of 30° proved nnsuited for grass seed germination. A. pratensis and F. pra- 

 tensis germinated in the light and also under the temperature changes, and it is 

 suggested that in seed control work both these methods be applied in testing the 

 seeds of these species. 



[The examination of beet seeds], M. Heinkich (Landiv. Vers. Stat., 87 

 (1915), No. 6, pp. 381-394). — Four methods of beet seed examination for the pur- 

 pose of securing samples for making germination tests, referred to as tho 

 count, weight, count-percentage, and count-weight methods, respectively, are 

 described, and tests of the relative reliability of the methods are reported. 

 The sources of error are discussed and means for the reduction or elimination 

 of inaccuracies are proposed. 



The size relation between dry and soaked seed of clover and dodder, M. 

 Heinrich (Landiv. Vers. Stat., 87 (1915), No. 6, pp. 395-.'f08) .—This article re- 

 ports the results of measurements of air-dry and soaked seeds of clover and 

 dodder, compares the differences in size, and points out how soaking may be 

 employed in tlie removal of dodder seeds. 



It was observed that air-dry red clover seed from different sources showed 

 differences in the average measurements which disappeared in part when the 

 seed was soaked. Seed of Cuscuta trifoUi, when air-dry, was clearly distin- 

 guishable from red clover, white clover, and alsike clover seed on account of its 

 smaller size, while air-dry seed of C. siiaveolens was found also perceptibly 

 smaller than seed of red clover but of equal size with seed of white clover 

 and alsike clover. Soaking increased size differences between the seeds of 

 clover and dodder to such an extent that a difference in size between the seeds 

 of C. suaveolens and those of white clover and alsike clover was also plainly 

 perceptible. A method for the removal of dodder seeds from lots of clover seed 

 by means of soaking is described. 



[Cooperative experiments in weed eradication] {Ann. Rpt. Ontario Agr. 

 Col. and Expt. Farm, 41 (1915), pp. 16, 17; Rpt. Min. Agr. Ontario, 1915, pp. 

 18, 19). — The results of four years' cooperative experiments in weed eradication 

 showed that perennial sow thistle and twitch grass may be eradicated by good 

 cultivation followed by rape sown in drills rather than broadcasted. As com- 

 pared with buckwheat, rape was the more satisfactory for use in destroying 

 twitch grass. It is further stated that deep cultivation in fall and spring fol- 

 lowed by a well-cultivated, hoed crop will destroy bladder campion. Mustard 

 may be prevented from seeding in oats, wheat, and barley by spraying with a 

 20 per cent solution of iron sulphate without any serious injury to the crop or 

 the fresh seedings of clover. 



[Pteris aquilina. — Life history and eradication], G. P. Gordon (Trans. 

 Highland and Agr. Soc. Scot., 5. scr., 28 (1916), pp. 92-106, figs. 11).— The dis- 

 tribution, including the extent and method of spreading, the life history, and 

 the nature of the damage due to the growth of this plant is described, and the 

 results of experiments to determine the best methods for its eradication are 

 reported. 



It was found that the plants propagated mainly from the rhizomes, and that 

 spraying them with a 5 per cent solution of sulphuric acid as compared with 

 cutting the plants results in their destruction with greater economy and efh- 

 81075°— No. ^1^17 i 



