SEEDS WEEDS. 249 



the reduction of yield, but in depreciation of the quality: Ainhrosla 

 trifida^ Lychnis githago^ Saporiaria vaccaria^ Polygonum c<m'Volv(du8, 

 Sefaria virid/H^ S. glavca, and Arena fatua. 



Killing weeds with chemicals, L. K. Jones and W. A. Orton 

 ( Vermont Sta. Rpt. 1899, pj^. 182-188).— Since the pu])lication of the 

 bulletin on the use of salt in killing the hawkweed (E. S. R., 8, p. 1)87), 

 the authors have received many inquiries as to the possibility of 

 destroying- other weeds by chemicals, which led them to make a com- 

 parative test of a number of chemicals for this purpose. Among 

 those included were common salt, copper sulphate, potassium sulphid, 

 kerosene, arseniate of soda, a mixture of white arsenic and sal soda, 

 and 2 proprietary articles. These chemicals were tested l)v marking 

 off areas on gravelly walks, roadways, tennis courts, and similar drj^, 

 beaten soils. Applications were begun about July 1 and observations 

 continued until autumn. The different chemicals were tried at the 

 rate of about 8 gal. of solution to each square rod of surface. The 

 weeds most commonly present were knotweed {Polygonum (miculare)^ 

 white clover, various grasses, purslane, plantain, dandelion, etc. Of 

 these the knotweed was most troublesome and the efficiency of the 

 chemicals in destroying this weed was considered the best gauge of 

 its value. The experiments with different chemicals are reported at 

 some length, together with notes on their cost, and the following con- 

 clusions were drawn: 



"Gravel walks, drives, tennis courts, and similar places can Ije kept free from 

 weeds by the use of certain chemicals. 



"Common salt can be used for this purpose, but very heavy applications are 

 re(]uired, and when used in such amounts it is liable to be washed into the borders 

 of adjacent lawns. Salt should always be applied in the dry form. The weeds may 

 be more fully suppressed without such danger from washing by certain other chem- 

 icals. These are to be applied in solutions, and at the rate of about 8 gal. to the 

 square rod. 



"Crude carbolic acid is a very powerful and quick acting herbicide. One pint in 

 4 gal. of water is usually sufhcient; cost as diluted, \ ct. for a gallon, 4 cts. to the 

 square rod. Its effects are not as enduring, however, as are those of the arsenical 

 solutions. 



"Various arsenical compounds are available, including arseniate of soda, a mix- 

 ture of white arsenic and sal soda, and two proprietary articles. The choice between 

 these latter becomes largely a matter of relative expense and convenience. In gen- 

 eral, the choice should, in our judgment, lie between the crude carbolic acid and the 

 arseniate of soda. 



"One or at most two applications each season of one or another of these chemicals 

 will, it is believed, suffice to keep down the weeds." 



The use of solutions of sulphate of ammonia and superphos- 

 phate for destroying weeds, Maizieres {L' Engnnx, IJ4. {1899), 3'r>. 

 36, pp. 851, 852). — The author quotes from a report of experiments 

 made by M. Georges Castel-Deletrez in eradicating weeds by spraying 

 with solutions of sulphate of anunonia. A 3 per cent solution burnt 



