494 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
by Sclerotinia smilacina Dur. ; Damping off of seedlings caused by Pythium 
Debaryanum Hesse ; Papery leaf-spot, caused by lack of shade and due to dryness ; 
Nematode root-gall, caused by Heterodera radicicola (Greef) Muller. For control 
measures, see above. — A. B. 
Grape Manure {Queensland Agr. Jour. Nov. 1915, p. 259). — Excellent results 
have been obtained in South Australia with a yearly application of 1 cwt. super- 
phosphate, J cwt. sulphate of potash, J cwt. sulphate of ammonia to the acre, 
applying about 3 oz. of the mixture to each vine. — C. H. H. 
Grape Varieties in the Vinifera Regions of the United States, Testing. By 
George C. Husmann (U.S.A. Dep. Agr., Bull. 209, 157 pp. ; 10 plates). — The 
greater part of this bulletin consists of a table dealing with the relative behaviour 
and value for different purposes of grape varieties tested by grafting on resistant 
stocks and growing on their own roots in eleven experiment vineyards in Cali- 
fornia. About 350 varieties are dealt with on various stocks of native species 
and hybrids. In this State more than 200,000 acres of once nourishing vine- 
yards have been destroyed by disease, mainly through Phylloxera, and after 
all known remedies have been tried it is considered that the only way to re- 
establish vinifera vineyards is by growing the vines on Phylloxera-resistant 
stocks (p. 12). — A. P. 
Grapes, Powdery Mildew of, and its Control. By D. Reddick and F. E. 
Gladwin (Rep. Inter. Congress of Viticulture, California, 1915). — Dusting vine- 
yards with flowers of sulphur as a method of controlling the powdery mildew of the 
vine was followed in 25 cases out of 30 by very serious damage to foliage &c. 
The authors consider that peculiar climatic conditions contributed to the burning 
which followed the application of the sulphur, and offer two or three alternative 
explanations of its cause. — F. J. C. 
Green Manures, Relation of, % to the Failure of Certain Seedlings. By E. B. 
Fred (Jour. Agr. Res. v. pp. 1161-1176 ; March 1916 ; figs.). — The germination 
of certain seeds in soil to which 1 per cent, of fresh chopped clover had been 
added was studied, the amount of green clover being about that added to the 
soil in green manuring. Buckwheat, castor bean, peanut, flax, hemp, white 
mustard, sunflower, cotton, soy bean, white lupine, oats, maize, and wheat were 
used in the experiment. The germination of many of the seeds was injuriously 
affected by the presence of the clover, especially during the first stage of de- 
composition of the latter. Oily seeds were generally more injured than starchy 
ones, and the damage was traced to fungi which develop in great numbers 
during the few weeks immediately following the introduction of the clover to 
the soil. Small applications of calcium carbonate seemed to increase the injury 
to germination. — F. J. C. 
Growth of Forest Tree Roots. By W. B. McDougall (Amer. Jour. Bot. 
vol. iii. No. 7, July 1916, pp. 384-392). — This paper describes a series of ob- 
servations, extending over two years, upon the growth of the roots of certain 
forest trees in Illinois. The trees used for experiment were Acer saccharinuni 
L. ; Tili a americana L. ; Carya laciniosa (Michx. f.) Loud.; and Quercus alba L. 
Two methods were used for making observations on the same roots at intervals 
during the growing season : (1) the horizontal glass-plate method, and (2) the 
vertical glass-plate method. For the first, the earth was removed to expose 
some healthy roots. These were covered with a square of glass one foot square ; 
over this was placed a square of felting, and the whole was then covered with 
soil. When observations were made the glass was removed, and then the earth 
and glass were replaced. At each observation a chart was made and the 
position of each fresh-looking rootlet indicated ; at the same time its length 
was measured and recorded. 
The vertical plate method was similar to the first, but the square of glass 
was placed vertically over the roots which were deeper in the earth. The glass 
was covered with felting to exclude the light and held in place by wooden props. 
The following conclusions were arrived at : 
The root growth of forest trees begins as early in spring as the soil becomes 
warm enough for absorption, and ceases in autumn when the soil becomes too 
cold. 
There is not necessarily a summer resting period. 
When there is a summer resting ^period, it is due to a decrease in the 
water supply and not to any inherent tendency towards periodicity. — A. B. 
