. Annual report of the New York State College of Agriculture at Cornell University and the Agricultural Experiment Station. New York State College of Agriculture; Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). PiRE Blight of Pears, Apples, Quinces, Etc. i6i to harbor the bacteria through the winter and supply a source of infection for the following season. The whereabouts of the Blight bacteria are thus accounted for throughout the year, and it should be easy now for the grower to see where they come from in the spring. It is certain that unless these bac
. Annual report of the New York State College of Agriculture at Cornell University and the Agricultural Experiment Station. New York State College of Agriculture; Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). PiRE Blight of Pears, Apples, Quinces, Etc. i6i to harbor the bacteria through the winter and supply a source of infection for the following season. The whereabouts of the Blight bacteria are thus accounted for throughout the year, and it should be easy now for the grower to see where they come from in the spring. It is certain that unless these bacteria are introduced into the trees by insects or by the grower himself, no Blight will result. The source of infection may be in an old neglected pear or apple tree in the back yard or in the fence row. A single old tree of this sort will often serve as a source of infection to orchards within a radius of several miles. It is also worth noting that the dis- ease seldom appears in a young orchard until the trees begin to bear, that is, present blossoms for inocu- lation by insects. In a block of quinces in the nursery this season, out of 38 blossoms appearing on the trees, ^^ were observed to blight. Not all the factors which contribute to the appear- ance of this disease in epi- demic form are yet known. However, it is evident that there must be (i) a favor- able source of infection (hold-over cankers); (2) abundance of the proper dis- seminating agents (insects); and (3) favorable weather conditions (warm, rainy or cloudy) at blossoming time, and during the rapid growth period of the twigs and shoots. The proper combination of these factors together, perhaps, with others not so evident at present, undoubtedly accounts for the periodic appearance of this disease in such virulent Fig. 17.—Cankers almost always appear abotU the base of the blighted spurs or water sprouts. CONTROL OF THE DISEASE It has been pretty definitely shown that no method of protecting the trees b
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