Fungous Diseases oe Colorado Crop Peants 13 
soft and hard. Soft galls usually decay at the end of the season; 
the harder types may persist for years. Hairy root, a form of crown 
gall, is characterized by excessive production of fibrous roots. 
Control .— (i) Plant only disease-free stock. Burn all infested 
nursery trees. 
(2) Avoid unnecessary injury tO' plants. 
Bitter Pit. —A non-parasitic disease, also known as “Bald¬ 
win-spot” and “brown-spot.” Spots on the surface are more abund¬ 
ant near the blossom end. They are small, sunken, and various 
shades of brown. Affected areas may be scattered throughout the 
apple tissue nearly tO' the core. The disease may appear before ma¬ 
turity, but develops more often in storage. 
Control .— (i) Spotting of susceptible varieties cannot be en¬ 
tirely prevented. 
(2) Fruit should be stored in dry air at a low temperature. 
Jonathan Spot. —The spots, which are distributed over the 
apple surface, are usually only skin deep, irregularly circular, brown 
to almost black, and usually somewhat sunken. The disease is not 
confined entirel}^ to the Jonathan, but develops on other varieties. It 
is produced only on matured fruit and is most severe in storage and 
after taken out of storage. 
Control .—Cold storage greatly retards development. 
Powdery Miedew. —This occurs on leaves and twigs. On the 
leaf, light powdery patches are produced. These are more com¬ 
mon on the under surface, but sometimes on both. The patches are 
small at first, but later increase in size until the entire leaf is covered. 
In severe cases, affected leaves are crinkled, dwarfed, and drop off. 
Twigs are stunted or even killed in the worst cases. Powdery mil¬ 
dew does the most injury to nursery stock. 
Control.—{i) Cut out and burn infected twigs if the disease 
is severe. 
(2) Spray with Bordeaux mixture or lime-sulfur, immediately 
after petals fall and later at intervals of two tO' four weeks, depend¬ 
ing upon severity of disease. 
Rust. —One stage of this disease is found upon the cedar and 
another upon the apple. The leaf, fruit, and young twigs of the ap¬ 
ple may be affected. The spots on the leaves and fruit are at first 
about the size of a pin-head, and pale-yellow in color. Later, long 
cylindrical-shaped organs project from the surface (Plate IV). 
Fruit may be dwarfed or deformed as a result of the infection. 
On the cedar, the diseased condition is known as a “cedar ap¬ 
ple.” The cedar apple is an enlargement of the leaves and twigs 
of the ordinaiy red cedar. These enlargements may be one-half to 
two inches in diameter. In the winter the gall-like structure is hard 
