r,Q. o. DEP'ARTMENT OF AGRICULTUftE.. 449 



In all work of cutting out pear blight, a disinfectant should be 

 carried to sterilize the tools and cut surface. For this purpose, one 

 of the most convenient germicides is a l-to-1,000 solution of corro- 

 sive sublimate. A bottle of this can be carried in the pocket and 

 a sponge, tied to a string, kept saturated with this solution. After 

 trimming out the blight or removing the blight bark from a dis- 

 eased area, the cut surface as well as the instruments should be 

 sterilized before turning to another infection. It is possible with 

 proper tools such as a gouge, draw shave, or box scraper, or better 

 a specially' made scraper, to remove the bark from a blighted area, 

 disinfect the surface and thus save a large limb or the trunk of 

 the tree instead of removing the same. All small limbs which can 

 be easily spared should be cut out in removing the blight. The ob- 

 ject of the treatment of pear blight i-s to cut all blight from the trees 

 and save all the healthy parts that can be saved. Blight completely 

 kills the bark of that portion of the tree which it reaches but leaves 

 the rest of the tree wdiolly uninjured. The only exception to this 

 is where the girdling effect is produced by the blight at the collar 

 or on the branches. Very few orchardists in the east thoroughly 

 know and understand pear blight. It has been with them so long 

 that they regard it as one of the inevitable troubles of the pear and 

 in fact the apph^ as well. Still less generally known are the modern 

 methods of controlling this disease by eradication. 



Apple Scab. * 



One of the commonest apple diseases in America and an in- 

 jurious one in this section is the apple scab caused by the fungus 

 Venturia inequalis. This little fungus is reproduced by spores which 

 germinate on the flower bud, young fruit and foliage of the apple, 

 doing more or less serious damage according to the season, variety 

 and locality. The apple scab fungus requires moist, rainy weather 

 for its propagation. The spores are probably blown very generally 

 about by the wind. Infection periods or times when the spores can 

 germinate and enter the little fruit occur only at certain intervals: 

 that is, it is necessary to have periods of moist, rainy weather for the 

 infections to take place. The degree of humidity in the air. and 

 the length of time that such a humid period, with its drops of rain 

 or dew on the fruit, lasts, determines the severity of the attack. 

 On the other hand, dry, sunny weather discourages or entirely pre- 

 vents the entrance of the scab fungus into the little fruit. Apple 

 scab, therefore, is an extremely variable disease. It also varies 

 greatly in different sections of the country. It is most severe in 

 the regions of the Great Lakes. It is also very destructive in New 

 England, New York, down to Virginia, and as far westward as 

 Kansas and Missouri. Its destructive elfects, however, diminish 

 toward the southward and westward, entirely disappearing in the 

 arid regions. Again on the Pacific Coast, in the more humid parts 

 of California, Oregon and Washington they are subject to the 

 scab fungus and the related disease on the pear during the rainy 

 spring months. Where the apple scab is severe, as it is in the Great 

 Lake Eegion, the full treatment consists of about five sprayings. It 

 is useless to spray the trees before the cluster buds open exposing 



29— n— 1907. 



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