PEAR BLIGHT 



REPORT OF A COMMITTEE OF THE POMOLOGICAL SOCIETY. 



lion. Marshall P. Wilder, President Amencan Pomological Society : 



Dear Sir, — The committee appointed at the last annual meeting of the 

 Society, to investigate the cause of pear blight, and, if possible, recommend a 

 remedy or preventive therefor, beg leave to submit as follows : 



The task allotted to your committee is connected with unusual difficulties, 

 as the subject is one that has for more than a quarter of a century remained an 

 unsolved problem. We therefore entered upon the performance of our duties 

 with the conviction that our efforts must fall short of doing justice to the 

 object in view. 



Pear blight assumes different forms and has conse([uently different causes 

 for its origin. One form attacks trees graditalhi ; its approach is slow and 

 may be detected for mouths, and often during the preceding season of growth, 

 before the tree is fully affected. This form, which may bo termed gradual 

 blight, is seen at all seasons during the period of active vegetation, from early 

 spring until September. Its progress is usually arrested by a liberal top-dress- 

 ing of liquid manure, so far as the roots extend, and a severe cutting back of 

 the branches. This must be done whenever the tree assumes an unhealthy 

 appearance. The cause, then, may be safely attributed to exhaustion, and the 

 remedy consists in replenishing the exhausted supply of plant food. This 

 form of blight is often noticed in orchards left unworked and where the annual 

 or biennial top-dressing with fertilizing agents has been withheld. 



Another, and this is the most fatal form, attacks a tree or a portion of it 

 suddenly, causing the affected part to blacken in a few hours after the tree is 

 struck; this is commonly termed fire Might. This form is periodical in its 

 attacks and migratory, as it seldom remains permanent in a locality, but leaves 

 an interval of from ten to fifteen years between its occurrence. Its greatest 

 intensity is on its first appearance, which occurs usually when the fruit has 

 attained half its size; it decreases as the season of vegetation advances, but 

 reappears again tlie following summer with less of its previous intensity. 

 After decimating a section of country during two consecutive seasons, there 

 will be an interval of a series of years, during which blight in its other forms 

 may occur, but there will not be a wholesale destruction as during the preva- 

 lence of epidemic blight. Every observation tends to the conclusion that fire 

 blight is caused by zymotic fungus, whose presence is not detected until life is 

 destroyed in the affected parts, This form offers a wide field for the investiga- 

 tion of microscopists, and from their future labors, we hope to arrive one day 

 at the origin of this fungoid growth. We are unable to arrive at a satisfactory 



