194 THE NURSERY-MANUAL 



punctures the tissue and thus furnishes a means of entrance 

 for blight germs. 



Fire-blight is frequently introduced into seedling blocks 

 by the use of diseased cions cut from blighted trees. The 

 seedlings budded with the diseased buds, not only blight, but 

 the bacteria are carried on the budder's knives to other seed- 

 lings. Later, at rebudding time, the budders being unfamiliar 

 with the disease, frequently attempt to rebud the blighted 

 stocks; their knives become infected and the bacteria are 

 transmitted to other seedlings. 



The shipment of cions from one nursery to another may 

 also be a means of transmitting the blight, and blight bacteria 

 have even been known to live over in cions used for grafting 

 purposes. In the winter, when the grafts were cut, the graft- 

 ing knives became infected and transmitted the blight bacteria 

 to grafts made from healthy cions. 



Control. The elimination of blight-disseminating agents 

 is an important consideration in the control of fire-blight. It 

 has been demonstrated that controlling the aphids is frequently 

 an essential step in preventing the spread of blight bacteria. 



All sources of infection should be destroyed, such as neighbor- 

 ing blighted orchard trees, and an attempt made to eradicate all 

 traces of the disease as soon as it appears in the nursery. It has 

 proved profitable to remove the blossom-buds on two- and three- 

 year-old quince trees. By removal of the buds before they 

 open, the danger of blossom infection is eliminated. Frequent 

 systematic inspections should be made and all blighted shoots 

 removed and the wounds disinfected with a solution of corro- 

 sive sublimate 1 to 1000. If the blight has extended into the 

 trunk, the entire tree should be removed and burned. 



CROWN-GALL. Crown-gall or root-gall is commonly found in 

 many kinds of trees and other plants in the nursery. Fruit- 

 trees, berry bushes and roses are frequently attacked. The 



