35 



dance in the spring. While the .spores will germinate almost imme- 

 diatel}^ after the}" are formed, the}" can also withstand hardships, and 

 will grow after they have been kept two 3"ears. 



The pustules or blisters just described constitute onh" the reproduc- 

 tive parts of the fungus. In the interior of the fruit may be found 

 innumerable filaments which make up the mycelium or vegetative part 

 of the fungus. 



Besides the fruit, the fungus also attacks the leaves, the flowers, and 

 the twigs. When the flowers are affected the}" become brownish and 

 rotten. In most cases it is through the stalk of the flower that the 

 fungus enters the twig, where it sometimes causes serious damage, 

 especially in the case of peach trees. The mycelium in the twigs lives 

 from year to year, and the fungus may in this way have been intro- 

 duced into the Northwest. The disease spreads nuich more rapidly in 

 damp w"eather than in dry, so that the amount of damage it does is 

 much more serious in some seasons than others. 



Remedies. — As the fungus passes the winter mainly on the mummi- 

 fied or dried up fruits, these should always be gathered and burned. 

 This treatment alone will often lessen the loss very materially. 



It is also desirable to thin the fruit so that no clusters remain. 

 W^here a cluster of fruit is left, it frequently happens that all in the 

 bunch are destroyed. 



Spraying has not yielded perfectly satisfactory results with this 

 disease on account of injury to the foliage. Two sprayings of Bor- 

 deaux — one just before the blossoms open, the other just after the 

 petals fall — are usually recommended. The second spraying should 

 be made with a Bordeaux containing a large excess of lime. Any later 

 spraying is liable to result in defoliation of the trees. 



PEAR BLIGHT. 



This disease, which was exceedingly bad in 1899 and 1900 and hardly 

 less so in 1901, may readily be recognized from the fact that the leaves 

 and twigs of attacked branches turn black, giving the tree the appear- 

 ance of having been scorched by fire, hence the popular designation, 

 "fire blight." As has been fully demonstrated, the disease is caused 

 by a species of bacteria or microscopic organism. As a result of the 

 investigations made by Waite,'^ the life history of this germ and the 

 proper treatment for it are now well understood. The attack usually 

 begins in the blossoms, less commonly in young twigs or young leaves. 

 The disease rapidly works down the cambium layer between the bark 

 and the wood, and the foliage quickly blackens. The leaves are quite 

 often directly attacked by the disease, in which case only portions of 

 them are blackened. It is uncommon for the disease to work down 

 into the twig from the leaf. 



''M. B. Waite. The Cause and Prevention of Pear Blight. Yearbooli U. S. 

 Dept. of Agr., 1895, pp. 295-300. 



