FIRE BLIGHT 169 



satisfactory, and the smoothing up of the wound may be done 

 with a knife or a heavy chisel. 



Third, the trunk and branches of the trees should be care- 

 fully sprayed whenever an application of any fungicide is made 

 to the orchard. In particular they should be given a thorough 

 spraying before the buds start in the spring. 



These three lines of attack will generally keep things fairly 

 well under control, though cases are found where the attacks 

 are so bad as to make the task of cleaning up the trees almost 

 hopeless. 



Sooty Blotch and Fly Speck. These two diseases are very 

 similar, the difference in appearance being that suggested by 

 the names. Some observers have even considered them as two 

 forms of the same fungus. They are both superficial, with very 

 little attachment to the host, and can frequently be entirely 

 rubbed off with a cloth. They injure the appearance of the fruit 

 so as to render it unsalable. There is usually little or no trouble 

 with them in orchards that are sprayed for scab, but occa- 

 sionally a later spraying may be necessary. 



Fire Blight. This is one of the most serious diseases of the 

 pome fruits, both because it injures the trees so severely and 

 because the methods of eradicating it are so expensive. It 

 attacks pears, apples and quinces, as well as many allied plants, 

 such as mountain ash, hawthorns, and crab apples. The dis- 

 ease is most noticeable where it attacks the tips of vigorously 

 growing shoots. Here it works rapidly, killing both leaves and 

 twigs and causing them to turn brown and eventually nearly 

 black, especially on the pear. It will; also, on bearing trees, 

 attack the fruit spurs, where it does more serious, though less 

 spectacular, damage, because new terminal shoots are easily 

 grown, but new spurs are grown with great difficulty. By follow- 

 ing down the spur or twig the disease frequently becomes estab- 

 lished on the main branches or even the trunk, where it produces 

 what is popularly known as " body blight. " 



The Cause The disease is caused by a bacterium which 

 works in the tender parts of the twig, largely in the cambium 

 layer, and during the actively growing stage the organisms may 



