HORTICULTURE. 339 



capped by poor soil condition j and spring frosts. Two poplars (Popiilus alba 

 and P. halsaiiiifera suaieolens), as well as two elms (Ulmus pumila and Ulmus 

 sp.), and an upright willow (Salix sp.), all introductions by the U. S. Depart- 

 ment of Agriculture from Asia, have given considerable promise as trees for 

 windbreaks. They all come into leaf very early in the spring and appear to be 

 vigorous. 



The influence of grass upon the growth of orchard trees, B. T. P. Babkeb 

 (Univ. Bristol Aim. Rpt. Agr. and Hort. Research Sta., 1913, pp. 94-96, pis. S; 

 Jour. Bath and West and South. Counties Soc., 5. ser., 8 (1913-14), pp. 139-141, 

 pis. 3). — In view of the results secured in the earlier experiments at Wobum 

 (E. S. R., 15, p. 474) and elsewhere, showing the detrimental effect of grass on 

 fruit trees, experiments were started in 1906 under the direction of the National 

 Fruit and Cider Institute to determine whether clean cultivation for a few feet 

 around each apple tree would suiEce to lessen or prevent the injurious grass 

 effect. In some cases the cultivated area extended for a radius of 3 ft., in 

 others 4i ft., and in others 6 ft. Some of the trees were grown in grass. 



The results of these tests up to 1910, six years after planting the trees, show 

 that the growth improved with the size of the cultivated area. From 1910 to 

 1911 there was practically no gain from cultivation. The trees were then 

 given no further cultivation. Measurements made in 1913 showed a tendency 

 in many cases for trees grassed over from the start of the experiment to gain 

 slightly on those originally cultivated. The inference based on the behavior of 

 six varieties is that trees do benefit from cultivation and begin to show the 

 detrimental effect of grass as soon as the roots extend out into grassed areas. 

 Trees that have been cultivated early in life may suffer more seriously from 

 grass later on than trees grown in grass from the start. 



Similar experiments conducted in various orchards in the west of England 

 have shown the beneficial effects of cultivation. The differences between 

 grassed and nongrassed trees in the present experiments were not so marked 

 as those noted in the work at Woburn (E. S. R., 26, p. 639). 



Pruning-, F. S. Merrill (Kansas Sta. Circ. 49 (1915), pp. 14, fiffs. 9). — ^This 

 circular contains practical suggestions for pruning orchard fruits, grapes, and 

 bush fruits. 



New developments in spray materials, W. M. Scott (Amer. Agr., 95 (1915), 

 No. 11, p. 5; Neiv England Homestead, 70 (1915), No. 11, p. 3). — In order to 

 obtain a fair comparison between arsenate of lime and arsenate of lead several 

 experiments were conducted for two years in which the former was diluted 

 to contain the same amount of arsenic as the diluted arsenate of lead. No 

 differences could be observed during the summer between the two insecticides, 

 either in their effect upon the fruit and foliage or in the control of the codling 

 moth and other insects, no injury being produced and the codling moth being 

 controlled equally well in both cases. 



It is stated that in a test by F. Johnson, formerly of the Bureau of Ento- 

 mology of this Department, upon Baldwin apple trees at Westfield, N. Y., a 

 barium-sulphur preparation, to which arsenate of lime was added, gave as satis- 

 factory results as did the homemade lime-sulphur and arsenate of lead applied 

 to adjacent trees, the orchard being entirely free from scab and codling moth. 

 It is pointed out that calcium arsenate is considerably cheaper than lead 

 ai'senate and that it mixes with lime-sulphur without causing any chemical 

 reaction. By the substitution of barium for lime as a carrier for sulphur the 

 decomposition which takes place upon drying can be eliminated. Thus barium- 

 sulphur furnishes a dry material which can be redissolved for spraying purposes 

 without losing its original composition. Experiments conducted during the 



5166°— No. 4—15 4 



