FORTIETH ANNUAL REPORT. 165 



and moisture, these spores germinate, producing a fungous growth, which 

 ramifies and kills the tissues. These dead tissues turn brown, and the 

 fungus breaks through the surface, producing another crop of spores. 

 The process is ver}' rapid, only a few days intervening between one gen- 

 eration of spores and another. 



DAMAGE TO THE PEACH. 



Although the young fruits soon after the petals are shed may become 

 affected, as a rule no marked outbreak occurs until the fruit is half 

 grown or larger, and the greatest destruction is wrought at harvest 

 time. The fruit crop may reach maturity in perfect condition and 

 yet be destroyed before it can be picked. Moreover, the fruit may become 

 affected in transit or after reaching the market. It is no uncommon 

 experience among peach growers to have a carload of peaches leave the 

 orchard in apparently good condition and arrive on the market specked 

 and practically worthless, owing to the brown-rot fungus. Through 

 handling by pickers and packers some fruit in every package may be- 

 come contaminated with spores from a few diseased fruits in the or- 

 chard. Enough moisture usually develops in the car to germinate the 

 spores, and if the refrigeration is poor the fruit is likely toi go down in 

 partial or total decay before reaching the consumer. 



The fungus also attacks the blossoms and extends from these into the 

 fruit-bearing twigs, often girdling them. In a w*et spring the fruit 

 crop may thus be materially reduced, although this form of attack is 

 only occasionally serious. In like manner the fungus may 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 shriveled, and at 

 this stage are known as brown-rot mummies. The fungais 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 covered 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 entireh^ covered with soil, fruiting bodies representing the 

 perfect stage of the fungus. These are dark-brown somewhat bell- 

 shaped disks, resembling toadstools. In them are produced an abund- 

 ance of ascospores, which rise in the air and are wafted by the wind. 

 These, as well as the summer spores (conidia), serve to infect the blos- 

 soms 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 practi- 

 cally omnipresent, and only favorable conditions for their germination 



