210 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
of following the persistence of copper-containing sprays should be of great 
service to agriculturists generally, especially to secure prompt correction of 
faulty spraying practices, and to serve as a practical guide in timing new applica- 
tions, especially after rainy periods. — V. G. J. 
Cost of Spraying Kale, A Study of the. By H. H. Zimmerley and Loren 
B. Smith (U.S.A. Exp. Stn., Virginia Exp. Stn., Bull. 30, Jan. 1920; 1 fig.). — 
Kale is an important crop in East Virginia, and for several years has suffered 
increasingly heavy losses from the imported cabbage worm, the cabbage looper, 
and several species of aphides. Arsenate of lead, i \ lb. powder to 50 gallons of 
water, is recommended for the caterpillars, and nicotine sulphate, 8| oz., fish 
oil soap, 5 lb. to 50 gallons of water, are used for control of aphides. 
The data included in this paper are based upon spraying operations performed 
with a two-wheel sprayer, equipped with a gasoline engine and triplex pump. 
V. G. J. 
Crown Gall of Fruit Trees. By W. A. Birmingham (Agr. Gaz. N.S.W. 
xxxi. pp. 717, 718 ; 1 plate). — Psendomonas tumefaciens attacks many plants, 
causing Crown Gall, i.e. enlargements near the crown on the roots of trees. 
No satisfactory remedy has been discovered. As the infection generally takes 
place in the nursery, it is well to guard against infection by dipping the grafts 
in copper-sulphate-iime paste before planting. — S. E. W. 
Cypress Bark Scale. By F. B. Herbert (U.S.A. Dep. Agr., Bur. Entom., 
Bull. 838, June 1920 ; 6 plates, 5 figs.). — The main cause of the browning and 
death of so many Cypress trees in California is the Cypress bark scale, Ehrhornia 
cupressi. The characteristic injury shows first on one or two limbs and slowly 
spreads to the whole tree. The foliage first turns yellow, then red or brown, 
and after a few years the tree dies. A I2| per cent, solution of miscible oil is 
the spray recommended, applied in August and the latter end of September. 
V. G. J. 
Dandelion, Spraying Lawns with Iron Sulphate to Eradicate. By M. T. 
Munn (U.S.A. Exp. Stn., New York, Bull. 466, Sept. 1919 ; 6 plates). — Experi- 
ments made at the station during the past eight years demonstrate that dandelions 
may be eradicated from lawns at relatively slight expense and without material 
injury to the grass by spraying with iron sulphate. Four or five applications 
are necessary : the first in May, one or two should follow at intervals of three 
or four weeks, and one or two more in late summer. A conspicuous blackening 
of the lawn follows each application, but this soon disappears if the grass is 
in a vigorous and healthy condition. The spray solution is prepared by dissolving 
one pound of iron sulphate in each gallon of water. The quantity required is 
approximately 4 lb. to a thousand square feet of lawn, or 175 lb. to the acre. 
It must be prepared in wooden or earthenware vessels, as it is highly corrosive 
to metal. — V. G. J. 
Date : Rot of Date Fruit. By J. G. Brown (Bot. Gaz. lxix. No. 6, June 
1920, pp. 521-529 ; 5 figs.). — It appears probable that the primary cause 
of rot and mummification of the date fruit is the attack of Alternaria. This 
attack paves the way for the entrance of saprophytic Aspergillus and Peni- 
cillium species which bring on the disintegration of the pulp. Commonly all 
three fungi appear in cultures from the same infected spot. Attack of the 
spot fungus, unaccompanied by the saprophytic Aspergillus and Penicillium, 
results in mummification without the appearance of rot. — R. J. L. 
Disease, Air Temperatures and. By J. Johnson (Phytopathology, xi. pp. 
446-458, Nov. 1921). — Experiments were made with tobacco affected by mosaic, 
and potatos affected by ' blight,' in chambers in which temperature and humidity 
could be controlled within very narrow limits. The mosaic disease increased 
up to 28-30 0 C, and developed up to 36-3 7 0 C, but thereafter the plants sent out 
normal healthy leaves, and some chlorotic leaves regained their normal colour. 
This result appears to indicate the connexion of an organism with the disease, 
since the temperature relations are those of the activities of a parasite rather 
than of an enzyme. The best temperature for the development of potato 
disease lies above 25 0 C. and below 32 0 C, while the maximum is near 36-37 0 C. 
A bibliography is appended. — F. J. C. 
" Electro-Culture." By F. J. Rae (Jour. Dep. Agr., Victoria, xviii. July 
1920. pp. 385-394). — Under this title the author includes the following modes 
of applying electricity to the growth of plants : 
1. Illumination by Electric Light said to benefit the growth of tomatos and 
lettuce. 
