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INSECT AND FUNGOUS ENEMIES OF THE APPLE. D5 
into growth, the fungus becomes active, producing large numbers of 
spores, which are discharged into the air and carried to the young 
leaves, blossom buds, and later to the young fruit. If there is sufh- 
cient moisture present these spores germinate, producing infections 
that develop into the characteristic scab spots. Summer spores are 
soon produced on these spots, and through them the fungus may 
readily spread to other fruits and leaves. 
The period of greatest infection is from the time the first apple 
leaves appear until about four weeks after blooming. The fungus 
thrives best in cool, moist weather, such 
as is likely to occur during this period. 
Hot weather is very unfavorable to it, 
and infections rarely take place after 
summer sets in. However, in the New 
England States a second infection period 
sometimes occurs during September, and 
from these late infections small seab spots 
may develop after the fruit is picked and 
stored. 
TREATMENT. 
Scab was one of the first apple diseases 
to receive attention by investigators, and 
its successful treatment was worked out 
as early as 1891. Until quite recently 
spraying with Bordeaux mixture con- 
stituted the remedy for it, but owing to 
the injurious effect on both fruit and 
foliage produced by this otherwise excel- 
lent fungicide, especially during wet 
seasons, dilute lme-sulphur solution is 
rapidly coming into use as a substitute 
for it. Lime-sulphur solution has about = yg. 14——The scab: fungus on 
the same fungicidal value as Bordeaux apple leaf. 
mixture in the treatment of apple scab and produces decidedly less 
injury to fruit and foliage. 
Lime-sulphur solution may be purchased from several manufac- 
turers or it may be prepared at home. (See pp. 38-40.) Taking a 
solution that registers 32° on the Baumé hydrometer as a standard, 
the strength to use in spraying for scab is 1} or 13 gallons to each 50 
gallons of water. On varieties seriously attacked by scab and in 
localities where the disease thrives the greater strength should be 
used, but in order to reduce the danger of injury to a minimum the 
weaker spray should be used where only slight outbreaks of scab are 
expected. Arsenate of lead at the rate of 2 pounds to each 50 gallons 
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