68 Foriy- fifth Report on the State Museum. 



The " fruit oidium," Monilia fructigena, which has recently 

 been called the " peach rot," is similar to the preceding one 

 in color but very different in structure. It also was 

 regarded by the earlier botanists as a saprophyte, but it 

 also is now known to be a real and a very destructive 

 parasite. The habitat usually ascribed to it in the books 

 is "decaying fruits," but Professors Arthur and Smith have 

 both shown most conclusively that it attacks sound and 

 healthy fruits and that it induces that decay in them which was 

 formerly thought to be a condition of its growth. My observa- 

 tions confirm what they have said of this fungus and show very 

 clearly some of the contributing causes to its ravages. It is 

 well known that its behavior is especially malignant in wet 

 weather and that it works with most destructive force on peaches, 

 plums and cherries, though frequently attacking also, apples, 

 pears and quinces. The past season, cherries with us almost 

 entirely escaped for the simple reason that dry weather prevailed 

 up to the time of their ripening. Plums and peaches on my 

 grounds were fully one-half destroyed by this fungus, but at the 

 time they were maturing wet, cloudy and rainy weather pre- 

 vailed. One plum tree maturing its fruit later than the others 

 had many diseased fruits while the wet weather lasted, but the 

 trouble was greatly diminished after the rains ceased. Then 

 even the fruit that had cracked open escaped attack. 



Insects that eat holes in the fruit are a contributing cause. 

 The only quince on my grounds that I have thus far seen affected 

 was one in the side of which some insect had eaten a small hole 

 and then left it. The aperture was very shallow, but the fungus 

 spores gained admission to the flesh by it and immediately pro- 

 duced the characteristic decayed brown spot all about it as a 

 center of infection. Yery many of the affected peaches first 

 showed the presence of the fungus on the side where small holes 

 had been made through the peel, apparently by some small insect, 

 though I was not able to detect any insect in the act. Honey 

 bees in great numbers were found sucking the juice of the peach 

 from these little cavities, and not a few striped cucumber beetles 

 were found in them feeding upon the juicy flesh of the peach. 

 Whenever peaches as well as plums were in contact, an affected 

 one would quickly transmit its disease to its sound neighbor 



