APPENDIX. 421 



The spores are produced in immense numbers and are so small and light 

 that they are blown about by the wind, washed about by the rains, and 

 carried about by birds, insects, and other agencies. Should they chance to 

 fall upon the surface of flower, leaf, or fruit, in the presence of moisture 

 and a sufficiently high temperature, the spores will germinate, the germ- 

 tube will penetrate the epidermis and the mycelium will ramify through 

 the underlying tissues absorbing nourishment and inducing those changes 

 which we call brown rot. 



Many writers have denied that the germ-tube has the power to penetrate 

 the uninjured epidermal tissues, maintaining that this must be ruptured by 

 other causes. In view, however, of the results of numerous experiments, 

 there can now be little doubt that under favorable conditions the germ-tube 

 has this power. Arthur produced the disease in cherry leaves and blossoms 

 by simply sowing them with spores and keeping them in a moist chamber. 

 Smith has infected the soundest peaches by merely sowing a few Monilia 

 spores in a drop of water upon their surface. July 1, 1895, I placed several 

 perfectly sound cherries and plums in a moist chamber and sowed a few 

 spores in drops of water upon their uninjured surfaces. July ,3 these spots 

 were slightly discolored, and by July 4 spore clusters had formed on both 

 the cherries and the plums. 



While it is evident from the above tests that the germ-tube has the power 

 to penetrate the epidermis of flower, leaf, or fruit when in the presence of 

 sufficient moisture, we have noticed that the disease rarely does attack an 

 uninjured prune until the ripening process is well under way. This is 

 probably due not alone to the resistant epidermis of the green Italian 

 prune, but also to the small amount of moisture in the atmosphere during 

 the summer months. Observations during the past two seasons have shown 

 that in nearly every instance prunes which are infested with Monilia early 

 in the season have first been attacked and the epidermis broken by the 

 larvie of the peach-twig borer, Anarsia Unratella Zell. It is these injured 

 prunes which develop the spores with which later in the season the ripening 

 crop is infected. If they were gathered and destroyed from time to time as 

 the rot developed it would undoubtedly aid materially in checking the 

 spread of the disease. 



BLIGHTING OF BLOSSOMS. 



Upon peaches and cherries the fungus usually makes its fii-st appearance 

 in spring upon the flowers about the time the jjetals fall. Galloway states 

 that at flrst a slight discoloration appears at a given point. This rapidly 

 increases in size until at length the entire blossom assumes a brownish hue. 

 After killing the flower the fungus frequently attacks the pedicle, where it 

 produces similar discoloi-ations to those described above. The dead flowers 

 usually remain on the tree for three or four weeks : then, if the weather is 

 wet. they begin falling, and as they consist at this time of a soft mass of 

 rotten tissue, they stick to any jjart of the tree with which they come in 

 contact. Careful experiments have shown that these rotting flowers are 

 highly infectious and that wherever they touch the leaves or fruit decay 

 sets in. We have never obsei-ved this blighting of the blossoms of prunes, 



