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Fhe c%\icornsln fitorticulturist. 
VOL. VII.           OCTOBER, 1902.                No. 8. 
APPLE BUGHT. 
Numerous inquiries have recently been received at the station re- 
garding injury to apple and pear trees. Affected twigs have usually 
been enclosed which were black and shriveled, the attached leaves 
being browned as if by fire. The injury in every case was caused 
by "blight." 
What is blight? The disease known as "blight," "pear blight"
and "fire blight," is a contagious bacterial disease attacking
the 
apple, pear, quince and allied fruits. It frequently attacks the 
wild crab and is occasionally found on the mountain ash. 
What it does: Blight assumes two different modes of attack 
known as twig blight and blossom blight, the cause of the two being 
the same. In the former the new shoots, growth of the current 
season, are affected; in the latter the blossoms and fruit spurs are 
destroyed and commonly a portion of the adjoining main branches. 
The conditions that favor blight: A wet season favors blight; 
a dry season hinders it; a very dry season entirely checks it. The 
blight microbe soon perishes when exposed to drying conditions. 
Unfortunately, conditions that favor the growth of the tree favor 
blight. Heavy pruning, during the dormant period induces a 
strong growth of new wood and favors the development of the 
blight germ. Trees heavily manured with barn yard manure are 
apt to be more affected than those not so well fed. Trees that are 
well cultivated often blight more than those growing in sod;