135 



one fruit, (lllusti-ation.) The disks are liglit brown, at first companulate, 

 becoming cup-shaiiecl, averaging about one-halt to three-fourths of a centi- 

 meter broad when full grown. The stipes are comparatively slender and 

 usually about one to two centimeters long, where that is sufficient to bring 

 the disks above the surface: 



In every case there was reason to suppose that the fruits bearing the 

 ascus stage were not from the crop of the inmiediate preceding season, but 

 that they wore one year older. In a recent conversation, Prof. Norton con- 

 firmed this opinion. Schellenberg^ has found this to be true, also, of two 

 other species of Sclerotinia in Europe. The length of the period required 

 for the development of the apothecia is doubtless the factor which is re- 

 sponsible for their scarcity, since it affords so much time and opportunity 

 for the mummied fruits to be destroyed or removed from the vicinity of the 

 trees. The above collection in a trash heap shows that development takes 

 place wherever the dried rotted fruits are covered by soil or humus a suf- 

 ficient length of time, but in such a location it is only by accident that they 

 \vould be discovered. 



While the ascoporic form is so excedingly rare, the conidial form is 

 just the opposite. As the cause of the b7-oum rot of peaches and plums, 

 it is the most common and destructive enemy of these crops. 



In 1905 it was estimated that brown rot caused a loss of one-fourth 

 of the peach crop in the southern counties of the State. In 1906 the rot 

 hfis been reported from twenty-six counties representing all parts of the 

 State. Estimates as to the amount of damage vary from 10 to 50 per cent, 

 of the entire crop. In the northern half of the State the early varieties 

 seemed to sustain almost double the loss of the later ones. This is an il- 

 lustration of the rapidity with which the rot spreads when the weather 

 conditions are favorable. The fungus is dependent for a start at the be- 

 ginning of a season chiefly upon conidiospores produced upon the mum- 

 mied fruits lying on the ground or hanging in the trees. Warm, moist 

 weather in August, at the ripening time., caused such a production of coni- 

 diospores from these nmnnny fruits that the fungus spread and caused 

 more notable effects at that time tlian later, when the weather conditions 

 were less favorable. 



Plums in all parts of the State have been attacked during the present 

 season, and a loss amounting in many instances to 75 per cent, of the crop 

 has been suffered. 



*H. C. Schellenberg, Ueber Scheratinia Mespili und S. Ariae, Centr. f. Bak. 17:188-202, 

 pis. 1-4, 1906. 



