APPENDIX. 423 



During the dry summer months, although the spores may be and proba- 

 bly are present, the disease does not spread rajiidly because the spores do 

 not readily germinate under the conditions which then prevail. But here 

 and there the skin of a prune becomes broken, allowing the spores free ac- 

 cess to the moist interior. Thus it is that we have the occasional "moldy" 

 prune to which we have previously referred as being ijresent during the 

 time of green fruit shipments. Through the agency of winds, insects, etc., 

 the almost innumerable spores produced on these early infected fruits are 

 constantly being distributed to other fruits. In the absence of moisture 

 myriads of these spores fail to germinate, and if these conditions unfavor- 

 able to germination should prevail throughout the ripening period and 

 while the fruit is being gathered, little or no damage would be done by 

 brown rot. 



But it often rains during this period ; and even though it does not rain, 

 there are many days when the air is highly charged with moisture. If at 

 the same time the temperature is sufficiently wai'm the conditions for the 

 germination of the spores are almost perfect and the disease spreads with 

 exceeding rapidity. 



WHERE THE FUNGUS PASSES THE WINTER. 



Considerable of the rotting fruit was left in the orchards last fall and may 

 now be seen hanging to the trees and lying upon the ground. Fig. I, PL I, 

 shows some of these •' winter mummies, " which were taken from an orchard 

 in this vicinity late in February. In another orchard we discovered several 

 bushels of rotted fruit which had been culled from that sent to the drier, 

 and instead of being destroyed had been dumped upon the ground in the 

 orchard. Countless millions of spores were present upon this fruit, and 

 there is abundant evidence that such winter spores will retain their vitality 

 until spring. In addition to these spores which were developed in the fall, 

 and which, as stated, retain their vitality until the following spring, the 

 fungus has another method of surviving the winter. Smith has shown that 

 the mycelium which ramifies through and through the tissues of the fruit, 

 disintegrating the cells and causing rot, may remain dormant throughout 

 the winter in the " winter mummies," and with the advent of warm, moist 

 weather in spring, will again push forth an abundant crop of spores. Hum- 

 phrey and Chester have demonstrated the presence in these " winter mum- 

 mies " of certain thick walled moniliform threads and single cells which 

 they consider to be resistant resting spores which further insure the sur- 

 vival of the fungus through the winter. Should the weather conditions be 

 favorable for the germination of the spring crop of spores at the time the 

 trees are in bloom, these spores may be the cause of a more or less serious 

 blighting of the blossoms, and even of the young tender shoots of the peach, 

 but whether this occurs or not, the spores will be present to infest the fruit 

 whenever the conditions of heat and moisture do become favorable. 



REMEDIES. 



The disease is one of those by which the prune grower is forced "to 

 prove his faith by his woi'ks." It spreads so rapidly when the conditions 



