12 The Colorado Experiment Station. 
and a half years and which illustrates in a practical way what the 
withholding of water has done toward the eradication of the disease 
in a natural way: 
“The writer had an opportunity of studying an orchard during the 
summer of 1904, which had been without water for two and one-half years. 
The effect of this enforced drought on checking blight was very marked, 
and it also showed that pear trees can exist in this location for a consid¬ 
erable period without irrigation or cultivation. These results would prob¬ 
ably be the same in all of the pear growing sections of Colorado. * * * * 
At the time of my visit, June 25, 1904, many of the trees were still in good 
condition. This was especially true of the Winesap apple. The Jonathan 
trees were still in condition to be saved, but they were less vigorous than 
the Winesaps. Most of the Ben Davis trees were still alive, but the ma¬ 
jority of them had put forth few or no leaves. About one-half of all of the 
apple trees of all varieties were dead, as well as most of the peach, and 
plum trees. 
“But the most remarkable, was the appearance of a block of eight- 
year-old Bartlett pear trees. Most of them were still in a fairly vigorous 
condition. Some of the twigs of the previous season’s growth measured 
fourteen inches in length. The average of the current season’s growth was 
about four inches, and quite a little fruit had set on some of the trees. 
“The inspector, Mr. H. E. Mathews, had visited the orchard each 
season and he found that in 1902, blight was quite abundant in the pear 
trees and some of them died from its attacks. The following year there 
was still a good deal of blight, though there was much less damagei than 
before. At the time of my visit, June 25, 1904, there were but few twigs in 
which the disease had been active that season and the germs were appar¬ 
ently dead. * * * * These results show that the germs of blight do not 
thrive in slowly growing trees and, in fact, that the disease may be eradi¬ 
cated by prolonged drought. They also show that pear trees will remain 
in good condition for a considerable period without irrigation or cultiva¬ 
tion. But just how far this could be carried in actual pratice remains to 
be seen, but one cannot help but surmise that bearing pear orchards might 
be successfully handled without irrigation, depending upon cultivation, or 
lack of it to regulate the water supply.” 
2. With a disease working as this does in the juicy part of the 
stem between the bark and the wood, there is no chance of reach¬ 
ing the trouble by means of sprays, for, unless the chemicals come 
in contact with the bacteria, spraying is futile. 
The knife and saw remain as the only effective remedies. We 
must cut out and burn all affected tw J igs, leaves and branches, not 
only from the pear but the apple, quince and related species as well, 
so that there will be no infectious material near by for insects to 
carry into the blight-free orchard. It is very essential in cutting out 
the diseased branches to cut well below the discolored part, as the 
bacteria are usually far below this region. The discoloration does 
not appear until after the bacteria have been at work some time, so 
that eVen if all the blackened wood were removed the seat of the 
trouble would not have been reached, and the germs would live on 
in the apparently healthy stump, soon to cause another visible out¬ 
break of the blight. The affected branches should be cut back all 
the way from ten to fifteen inches below the discolored wood, and 
if the branch be a large one, more than one-half inch in diameter, 
