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SPRAYING PEACHES. 9 
extend from diseased fruits into the twigs. Following an outbreak 
of brown-rot on the fruit, these twig infections may become so severe 
as to give the trees a blighted appearance. 
WINTER STAGE AND SOURCE OF INFECTION. 
The affected fruits largely drop to the ground, although many of 
them hang on the trees for months. They become dried and shriv- 
eled, and at this stage are known as brown-rot mummies. The fun- 
gus passes the winter in these mummies, which form the chief source 
of infection for the new fruit crop. When moistened by spring rains, 
the mummified fruits on the trees and on the ground become cov- 
ered with fruiting tufts of the fungus, producing countless numbers 
of spores. 
After 18 months, or at the end of the second winter, about the 
time peach trees are in bloom, there arise from the mummies on the 
ground, partly or entirely covered with soil, fruiting bodies repre- 
senting the perfect stage of the fungus. These are dark-brown 
somewhat bell-shaped disks, resembling toadstools. In them are 
produced an abundance of ascospores, which rise in the air and are 
walted by the wind. These, as well as the summer spores (conidia), 
serve to infect the blossoms and young fruits. The propagation of 
the fungus being thus so abundantly provided for, it is not surprising 
that a crop of fruit may be destroyed without much warning. 
INFLUENCE OF THE WEATHER AND INSECTS. 
In sections where the brown-rot is prevalent the spores are prac- 
tically omnipresent, and only favorable conditions for their germi- 
nation and the rapid growth of the fungus are required to start an 
outbreak of the disease. The most important factor is excessive 
moisture in the form of rain, which not only favors the production 
and germination of the spores and the growth of the fungus, but ren- 
ders the fruit soft and watery, and therefore more susceptible to the 
disease. High temperatures also favor the disease, although the fun- 
gus grows readily in mild summer temperatures. Prolonged cloudy 
weather with frequent light showers is more dangerous than a hard 
rain followed by clearing. Warm, muggy weather, when the fruit is 
maturing, is often disastrous to the crop. 
Insects, especially the curculio and certain plant bugs, play an 
important part in the distribution of the spores and the infection of 
the fruit. Although the fungus under favorable conditions is appar- 
ently able to pass readily through the unbroken skin of the fruit, it 
is greatly aided by insect abrasions. In the process of feeding and 
egg laying, the curculio punctures the skin of the fruit, opening the 
way for the fungus and in many cases perhaps actually inserting the 
spores. This insect may render spraying for brown-rot partially 
82291°—Bul. 440—11——2" 
