1082 
white cob-webby growth. Several spots 
may grow together and large patches may 
be formed. In older spots the moldy 
growth turns brown. Later in the year 
small black specks, just visible to the 
unaided eye, appear in the brown mold 
in older spots. 
The berries, when attacked on one side, 
may develop unevenly, and in severe 
cases may crack and decay. When at- 
tacked at a later stage they do not crack; 
but the presence of the mold renders them 
unsalable. 
The leaves of diseased shoots are small 
and where badly affected gradually turn 
brown. The general effect on the plant 
is to reduce the vitality and market value 
of the crop. 
Cause 
This disease is caused by a fungus be- 
longing to a group known commonly as 
the powdery mildews. These fungi are 
superficial in their growth; that is, the 
mycelium develops largely on the outside 
of the affected spots instead of in the 
tissues as is the case with most fungi. 
The mycelium sends short branches into 
the outer cells of the part of the plant 
attacked. These absorb the sap. In the 
early part of the season the summer 
spores are produced in chains on the 
erect branches of the mycelium. These 
are produced in great abundance and soon 
fall apart, giving the surface of the spots 
a dusty appearance, from which fact the 
name “powdery mildew” has originated. 
These spores are easily spread by the 
wind or other agencies and start new 
spots wherever they come to rest. This 
superficial mycelium, as noted above, soon 
turns dark and becomes thick-walled, and 
later in the season black spherical re- 
ceptacles are formed which have long 
thread-like appendages attached. These 
are called perithecia; they are hollow 
and enclose a single large sack or ascus, 
inside of which are found eight rather 
large spores. This stage, which may be 
referred to as the winter spore stage, 
serves to carry the fungus over winter. 
The perithecia, when mature in the 
spring, burst, forcibly ejecting the spores, 
which, on coming to rest upon young 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
leaves or fruit, germinate, causing the 
first spots. It is thus seen that the fun- 
gus, which remains over the winter on 
the canes of the current growth and on 
the leaves and ground, etc., serves as a 
source of infection in the spring. 
Treatment 
This disease is one of the most difficult 
among the powdery mildews to control. 
The standard remedy for years has been 
to spray with potassium sulphide, 1 
ounce to 2 or 3 gallons of water, begin- 
ning when the buds break open and con- 
tinuing at intervals of ten days until 
about seven applications have been made. 
This, wherever used thoroughly, has been 
found to control mildew. 
Co-operative experiments conducted by 
the writer in Oregon during the past 
season indicate that an application of 
winter strength lime-sulphur to the dor- 
mant branches, followed by applications 
of lime-sulphur diluted 1-30 on the fo- 
liage at frequent intervals, gives excellent 
satisfaction. On account of the slight 
deposit of lime-sulphur it may be found 
desirable to use potassium sulphide in 
the later sprayings. 
H. §S. JacKSON 
Rusr. See Currant Diseases. 
For other Diseases or GoosrcBEeRRY, see 
under Currant Diseases 
GOOSEBERRY PESTS 
Frouir Worm. See Currant Pests. 
Gooseberry Fruit Worm 
ZLophobsa grossulariae Riley 
Just before gooseberries ripen, clusters 
of two or three may sometimes be no- 
ticed which are prematurely colored and 
which are joined together by the webs 
spun by the caterpillar or a small moth. 
These caterpillars are pale greenish-white 
and sometimes have a reddish tinge. They 
live inside the berries and, when the 
contents of one berry are consumed, at- 
tack another near at hand, joining it to 
the first by a silken web. When full 
grown they fall to the ground and spin 
brown parchment-like cocoons, just be- 
neath the surface of the ground. The 
moths, which are pale grey, marked with 
dark streaks and bands, are very rarely 
