on the outer side). The organism is unable to grow when the tissues 

 are lignified or woody. 



Life History of the Pear Blight Germ. The organism which 

 produces the disease is a small motile bacillus, which increases with 

 great rapidity in the succulent parts of affected trees. (Fig. 4). The 

 microbe is of microscopic size, so .'mall that 25,000 placed end to end 

 would only measure an inch. They are able to live and multiply in 

 the nectar of the blossoms, from whence they are carried to other 

 flowers by bees and insects which visit the blossoms for honey and 

 pollen. From this locality the germs extend into the tissues and then 

 downward into the branches by way of the inner bark, girdling the 

 limbs and causing a large amount of damage. The blight germ also 

 gains entrance to the plant through the tips of growing shoots, thus 

 producing twig blight. The organism is not killed by the winter 

 frosts, but lives in the bark in a dormant condition until spring. As 

 soon as the plant tissues become gorj^ed with sap in the spring the 

 microbes, which have remained alive all through the winter, start to 

 grow and extend into the new bark. This new blight which develops 

 in the spring can be recognized by its moist and fresh appearance 

 from the blighted, dead and dried bark of the previous summer. A 

 large amount of gum is exuded from the affected bark, and runs down 

 the tree and attracts to it bees and other insects, which carry the 

 microbes to the early blossoms, and from these first flowers it is 

 carried to others, and thus the disease extends. 



The germ has never been discovered in the soil, although careful 

 search has been made ; hence the impo/tance of recognizing the winter 

 form of the disease, for if these affected portions of the tree are cut 

 out and destroyed, the pear blight question is solved, for without the 

 microbes there can be no disease. 



Conditions Affecting the Spread of the Disease. Fire blight differs 

 in severity in different localities, and there are a number of conditions 

 which affect the character and progress of the disease. 



Every tree of the pome family is subject to the blight, but 

 pears and quinces are more susceptible than plums and apples. The 

 mountain ash, service berry and hawthorn are frequently diseased, 

 but not to such an extent as the first named trees. There is a 

 difference in the susceptibility of varieties. Thus, among pears, 

 Clapp's Favorite, Flemish Beauty, and Bartlett are more liable to 

 the disease than Keiffer and Duchess, and amongst apples, the Crab 

 varieties are the least resistant. 



