80, STATE POMOLOQICAL SOCIETY. 



beautiful and profitable to grow for the market, but often only of 

 second quality. 



*" Pear blight assumes different forms, and has consequently 

 different causes for its origin. One form attacks trees gradually. 

 Its approach is slow, and may be detected for months, and often 

 during the preceding season of growth, before the tree is fully 

 affected. This form may be termed gradual blight, and is seen at 

 all seasons during the period of active vegetation, from early 

 spring until September. The progress is usually arrested by a 

 liberal top-dressing 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 con- 

 sists 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 

 blight. 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 occurrences. The greatest 

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

 fruit has attained half of its size; it decreases as the season of 

 vegetation advances, but reappears again the 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 

 prevalence 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 investigations of raicroscopists, 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 conclusion as 

 to what peculiarities of soil and temperature induce the favorable 

 conditions for the development of this fungoid vegetation. 



In the experimental gardens of the Department of Agriculture, 

 at Washington, the following mixture is prepared : 



Place a half bushel of lime and six pounds of sulphur in a close 

 vessel, pour over it about six gallons of boiling water, adding 

 enough cold water to keep it in a semi-fluid state until cold. It is 

 used as a wash, and applied to the tree and branches as high as 

 can be reached. It should be applied two or three times during 

 the summer. Since this preparation was used no trees thus treated 

 have been lost, although small limbs not coated with the mixture 



* Report of P. J. Berkmans and Josiah Hoopes, Committee on Pear blight ; Ameri- 

 ean Pomological Society. 



