COLOHADO Pl.ANT DISEASES 
25 
Fire blight. An infected apple 
showing the drops of ooze con- 
taining countless numbers of 
bacteria. (Original in Colorado 
Experiment Station Bulletin 
84, by Paddock.) 
apple as on the pear. For a discussion of 
the disease see Pear. 
Scab (Ventura inaequalis) (7) — Scab is 
one of the most serious diseases of the apple 
in the eastern states. It has been observed in 
Colorado in slight quantities for the past 
three years. It will in all probability become 
more prevalent as time goes by. 
The disease affects leaves, flowers and 
fruit. On the leaves it makes its first ap- 
pearance on the lower side as irregular olive- 
brown velvety spots. Later, spots more regu- 
f Fire blight. A hold over canker in which the bacteria live over the winter. 
Small drops of a sticky liquid containing large numbers of bacteria ooze from 
such cankers in the spring. (Original in Colorado Experiment Station Bulletin 
177, by Sackett.) 
lar in outline appear 
which are on the upper 
surface of the leaves. 
On the fruit the spots 
are at first small, brown 
and smooth but later 
they become cracked 
and rough. Several 
small spots may grow 
together forming large 
scabby areas. When 
the attack is severe the 
fruit shrivels and falls. 
The fungus causing 
scab lives over the 
Apple scab on leaves winter on the dead 
