126 MASSACHUSETTS HORTICULTURAL SOCIETY. 



and cannot of themselves gain entrance into the host. They must 

 be placed within the tissues through a wound or opening of some 

 sort beyond the reach of externally applied poisons. Since the 

 bacteria survive the winter only in the cankers it is evident that the 

 careful and thorough removal of these would eradicate the disease 

 by removing the sources of infection. The destruction of all worth- 

 less old pear trees in the neighborhood is the first step. Often one 

 of these neglected trees along the roadway or on some abandoned 

 farm will serve as a source of infection year after year, devastating 

 the orchards of an entire neighborhood. As soon as the leaves 

 have fallen in the autumn all the trees in the orchard should be 

 gone over carefully and all the cankers removed by cutting and 

 scraping away the diseased bark, cutting well back into the healthy 

 tissue. The wound should then be washed out with a one-tenth 

 per cent solution of corrosive sublimate and when dry painted over 

 thoroughly with a heavy lead paint. It should be kept painted 

 until completely healed. JNIr. Frederick Cranefield, Secretary of 

 the \Visconsin Horticultural Society, reports that this treatment has 

 been most successful in repairing the injury from blight cankers on 

 the young apple trees in their experimental orchard. Waite rec- 

 ommends spraying the trees just before the buds break in the 

 s])ring with the lime and sulphur wash. This covers up any hold- 

 over cankers that may have been overlooked and when the oozing 

 bacteria come in contact with the mixture they are killed. As soon 

 as the spurs and water sprouts begin to appear on the body and 

 main limbs the trees should be gone over and these adventitious 

 grow^ths rubbed off. This will remove a very fruitful source of 

 cankers. It will probably be necessary to go over the orchard two 

 or three times during the season for this purpose. It will be time 

 well spent. All blighted limbs and twigs should be cut out during 

 the summer whenever they appear. It is well known that cultiva- 

 tion and the excessive use of nitrogenous manures is very favorable 

 to the development of blight and should be avoided as far as is con- 

 sistent with good horticultural ])ractice. 



