154 



Bulletin 2y2. 



to occur. Whether it is the blighting of the blossom clustets (Fig. 6), 

 the dying of the growing tips of the twigs (Fig. 7), or the formation 

 of dead areas or cankers in the bark of limbs or body (Fig. 8), it is one 

 and the same disease — the Fire Blight. It is the same disease whether 

 it appears on the pear, the apple or the quince, and is readily and com- 

 monly transmitted from one to the other. 



History. This disease was first observed about 1780 in the Hudson 

 River Highlands by William Denning ('94), a fruit-grower of that 



section. It very prob- 

 ably occurred as a dis- 

 ease of some of the in- 

 digenous wild crab 

 apples, wild thorns or 

 wild plums of eastern 

 North America before 

 the introduction of 

 cultivated fruits. 

 From the wild fruit 

 trees it readily spread 

 to the cultivated va- 

 rieties as they were 

 introduced, and as or- 

 chards became nu- 

 merous and more con- 

 tiguous it gradually 

 worked its way west- 

 ward over the Alle- 

 ghany Mountains and 

 into the Mississippi 

 valley until in about 

 1876 to 1880 it had 

 become so destructive 

 in the orchards of Il- 

 linois and adjoining 

 states as to furnish 

 one of the chief topics 

 of discussion at the state and county horticultural society meetings 

 of that period, as witness the Annual Reports of the Illinois State 

 Horticultural Society during these years. It was for a long time con- 



FiG. 10. — ''Hold-over " canker in large limb of old apple 

 tree. Rough bark cut away to sliow limits of the canker. 

 Note the base of the sucker near the center by the blight- 

 ing of which the bacteria gained entrance to the tender 

 tissues of the bark. 



94 



Denning, 



W. M. On the Decay of Apple 

 Agriculture, etc. 1:185, 



trees. Trans. Soc. for Prom. 

 CSecond Edition 1801.) 



