ASCOMYCETES 



191 



every fruit having perhaps some on its surface, these spores may 

 germinate, under favorable conditions in transit, and cause infec- 

 tion of the fruit in bulk, so that a shipment which showed great 

 promise as it left the orchard may reach the market in practically 

 worthless condition. 



Susceptibility of hosts. No very extensive data have been ac- 

 cumulated with reference to the resistance or susceptibility of the 

 many varieties of stone fruits in different sections of the country. 

 In general, however, it 

 would appear that among 

 peaches the sorts, densely 

 covered with hairs or down, 

 such as the Alexander, Hill's 

 Chili, and Triumph, are un- 

 usually susceptible. Among 

 the more resistant sorts are 

 to be found the Carman, 

 Early Crawford, Elberta, 

 Chinese Cling, and some 

 others. Among the plums 

 the Japanese varieties suffer 

 generally in most sections 

 of the country. The Amer- 

 ican group of plums is also 

 susceptible, and apparently 

 more susceptible at the South than farther north. The Wild Goose 

 and Marietta plums are much less affected in all regions. The 

 native cherries are more resistant than such as the Montmorency. 



The fungus. The small tufts of the fungus, commonly called 

 mold tufts, which appear on affected fruits and occasionally on 

 blighted twigs are made up of conidiophores and the numerous 

 conidia to which they give rise. The production of the aerial 

 conidia usually indicates that the substratum is considerably pene- 

 trated by the mycelium. This mycelium is light brown in color, 

 rather closely septate, considerably branched, unequal in diameter, 

 and somewhat nodulose or occasionally cellular in appearance. It 

 is often vacuolate and may contain bodies differentiated as resting 

 mycelial cells, or perhaps properly designated chlamydospores. 



Fig. 71. Section of Peach Twig affected 

 with the Monilia. (After Erw. F. Smith) 



