12 



CONTROL OF PEACH BROWN-ROT AND SCAB. 



stools, about one-half inch in diameter, are produced from mummies 

 which have remained on the ground through two winters partially or 

 entirely covered with soil. (See fig. 1.) One mummy may produce 

 ten to fifteen of these bodies, each of which produces myriads of 

 ascospores. When disturbed by a puff of wind a little cloud of spores 

 may be seen to rise into the air from one of the cups. These ascospores 

 as well as the conidia, serve to infect the blossoms. A crop of sum- 

 mer spores is in turn produced on the diseased blossoms and some of 

 the young, green fruits become infected by these, so that there is 

 usually a great abundance of material ready for the infection of the 



mature crop of fruit, 

 even if the old mummies 

 have been removed from 

 the trees. 



It has for years been 

 recommended that the 

 rotten fruit be picked 

 from the trees and from 

 the ground and destroy- 

 ed in order to remove 

 the source of infection 

 for the following year's 

 crop. This is a good 

 practice, but it is usually 

 disappointing, because 

 the fungus is so prolific 

 in spore production that 

 the few mummies that 

 inevitably escape the 

 pickers are sufficient to 

 furnish the initial infec- 

 tion material for the en- 

 tire crop of the following year. Protection of the fruit by spray- 

 ing appears to be the only satisfactory means of combating this 

 fungus, although the destruction of diseased fruits doubtless aids in 

 checking it and should not be discouraged. 



Fig. 1 .—An old brown-rot mummy with the cup-shaped bodies 

 (apotheeia) of the fungus, in which myriads of ascospores 

 are produced. 



INFLUENCE OF THE WEATHER. 



Most parasitic fungi are influenced by weather conditions. This 

 is especially true of the brown-rot fungus. Moisture not only favors 

 the growth of the fungus and the production and germination of the 

 spores, but it also renders the fruit tender and watery and therefore 

 more susceptible to rot. In a dry season, or one with only occasional 

 rains of short duration, a peach crop may be expected to reach maturity 

 practically free from rot, particularly if the weather is cool; but when 



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