22 MANUAL OF FRUIT DISEASES 
difference in susceptibility. Under nursery conditions there 
is evidence that the Yellow Transparent, Golden Russet, 
Sutton, Fameuse, Wagener, Tompkins King, Rhode Island 
and others are more affected than Ben Davis, Red Astrachan, 
Oldenburg and. Gravenstein. In New York and neighboring 
states such varieties of the commercial orchard as Tompkins 
King, Baldwin, Grimes, Alexander and others are susceptible. 
In Virginia, the York Imperial and Grimes are most likely to 
show fire-blight. In this and other regions one of the serious 
troubles in connection with apple-growing is a form of fire- 
blight known as collar-blight, collar-rot, or crown-rot. In 
many cases this type of trouble is a form of winter-injury. 
Symptoms. 
Large cankers may be developed on the collar of bearing 
trees, although these do not constitute the first noticeable signs 
of the disease. The leaves appear yellowish and smaller on one 
or more of the larger limbs, this effect developing gradually in 
contrast to the sudden darkening of the foliage of twigs infected 
with fire-blight. Premature defoliation is induced. The 
canker is of variable size, depending on its age, and shows a 
dark, sunken, smooth surface. Cankers in which the pathogene 
is advancing do not exhibit a distinct margin as is the case with 
older infections. The lesion develops until midsummer when 
its growth is arrested, but is renewed the following season. 
Ultimately complete girdling and death of the tree may result. 
Usually the canker extends up the body of the tree into the 
branches; it may also extend down into the lateral roots. 
In case the collar-rot is due to weather conditions there is no 
progressive dying as is found in this type of fire-blight. Fur- 
thermore winter-injury is first seen at the beginning of the 
growing season, whereas ‘collar-blight is not observed until 
midsummer. Fire-blight cankers are known to develop com- 
monly at the base of water-sprouts about wounds of various 
kinds on limbs and body. 
