THE NATIONAL NURSERYMAN 
218 
ORCHARD ENEMIES 
BLACK-KNOT 
A fungus, the spores of which are carried from tree to 
tree by the wind and thus spread the infection, is'dhe cause 
of this disease. The same fungus also affects plums. Cut 
out and burn all knots before leaves appear in the spring. 
See that the knots are removed from all plum and cherry 
trees in the neighborhood. Cornell Bulletin 8i. 
BLACK-ROT 
This is the most destructive fungous disease of grapes in 
this state. It is carried over from one season to the next 
chiefly in old rotted berries or “mummies” that fall to the 
ground or cling to the vines. Remove all mummies that 
cling to the arms at trimming time. Plow early, turning 
under all mummies and diseased leaves. Rake all refuse 
under the vine into the last furrow and cover with the grape 
hoe. This cannot be too thoroughly done. The disease is 
favored by wet weather and weeds or grass in the vineyard. 
Use surface cultivation and keep down all weeds and grass. 
Keep the vines well sprouted; if necessary, sprout twice. 
Spray with Bordeaux mixture, 4-4-50, until middle of 
July, after that with ammoniacal copper carbonate. The 
number of sprayings will vary with the season. Make the 
first application when the third leaf shows. Infections 
take place with each rain, and occur throughout the grow¬ 
ing season. The foliage should be protected by a coating 
of the spray 6^/or^ every rain. The new growth, especially, 
should be well sprayed. When the foliage becomes dense 
the clusters should be sprayed with a “trailer” or hand 
spraying device. Four applications of Bordeaux mixture 
should be made. In exceptionally wet seasons two applica¬ 
tions of ammoniacal copper carbonate will be necessary. 
Apply 50 to 60 gallons of spray to the acre. Use 100 to 
140 lbs. pressure; use a 1-16 inch hole in the disk of the 
nozzle. (Cornell Bulletins 254 and 266.) 
BROWN-ROT 
This is the most serious fungous disease of stone fruits 
in this state and one of the most difficult to control. Plant 
resistant varieties. Prune the trees so as to let in sunlight 
and air. Thin the fruit well. Spray with self-boiled lime- 
sulfur, 8-8-50, to which add 2 lbs. arsenate of lead to 50 
gallons. Spray first about time shucks are shedding from 
young fruit; second, 2 to 3 weeks after first, using same 
combinations as for first; third, about one month before 
fruit ripens, with self-boiled lime-sulfur, 8-8-50, omitting 
the poison. U. S. D. A. Bureau of Entomology, Circular 120 
p. 6-7. 
FIRE-BLIGHT 
This is the same as fire-blight of apple, but it is more 
destructive to pears. It kills the twigs and branches, on 
which the leaves suddenly blacken and die, but do not fall. 
It also produces cankers on the trunk and large limbs. 
Prune out blighted branches as soon as discovered, cutting 
6 to 8 inches below the lowest evidences of the disease. 
Disinfect with corrosive sublimate solution, i to 1000. 
Clean out limb and body cankers as described for fire-blight 
on apple trees. Disinfect all large wounds and cover with 
coat of paint or gas tar. Cornell Bulletin 272. Plant the 
varieties least affected. 
PEAR PSYLLA 
These minute, yellowish, flat-bodied, sucking insects are 
often found working in the axils of the leaves and fruit early 
in the season. They develop into minute, cicada-like 
jumping-lice. The young psyllas secrete a large quantity 
of honey-dew in which a peculiar black fungus grows, giving 
the bark a characteristic sooty appearance. There may be 
four broods annually and the trees are often seriously 
injured. After the blossoms fall, spray with kerosene 
emulsion, diluted with 6 parts of water, or whale-oil soap, 
I lb. in 4 or 5 gals, of water, or with one of the tobacco 
extracts. Repeat the application at intervals of 3 to 7 days 
until the insects are under control. Cornell Bulletin 108. 
{Continued on page 221) 
SPRAYING MIXTURES 
In the Popular Edition of Bulletins Nos. 319 and 320 of 
the New York Agricultural Experiment Station, Geneva, 
N. Y., by L. L. Van Slyke and P. J. Parrott, the harmful¬ 
ness of magnesian lime in the composition and use -of lime- 
sulphur washes is shown by the following: 
“It is believed that the inferiority of these field-made 
mixtures is due to the presence of magnesium oxide in the 
lime used; for other laboratory tests have shown that the 
magnesium compounds in the presence of boiling water 
decompose the higher sulphur-lime compounds, set some 
of the sulphur free entirely, throwing it into the sediment, 
while more of the sulphur combines with hydrogen from the 
water and forms the foul-smelling gas, sulphuretted hydro¬ 
gen. The odor of this gas is noticeable wherever the 
sulphur-lime mixtures are being made from magnesian 
limes, and often in orchards where such mixtures are used. 
This gas is not only disagreeable, but to some extent 
poisonous, causing loss of appetite and nausea. 
In the laboratory the use of magnesium oxide instead of 
calcium oxide with sulphur in the effort to make the spray¬ 
ing mixture resulted in a complete failure. Practically 
none of the sulphur became soluble, but quite a little 
escaped in form of gas. When a quantity of magnesium 
oxide was added to a quantity of a standard spray mixture 
made by diluting one of the laboratory-made concentrates, 
the odor of sulphuretted hydrogen was immediately 
noticed. After allowing the mixture to stand, it was 
analyzed. The soluble sulphides were found to have 
decreased from 9.70 lbs. in 50 gallons to 8.65 lbs., a loss of 
more than one tenth; while the free sulphur had increased 
from nothing to nearly half a pound. Perhaps the most 
important lesson taught by this series of studies is that 
impure lime should be avoided in making sulphur washes, 
especially magnesian lime, since the magnesium oxide is 
worse than useless,—is a positive detriment. 
Have you made arrangements to head for St. Louis 
June 12 or 13? 
