240 NEBRASKA STATE HORTICULTUKAL SOCIETY. 



been scorched. The entire killed portion of the twig may not 

 be infected by the bacteria, for if the cells in the lower portion 

 of the twig are killed the upper portion will die. In severe 

 cases the smaller limbs may be attacked but usually only the 

 young succulent growths. The disease was first a disease of 

 the pear tree, later going over to the apple. 



How Spread: The disease is undoubtedly spread by the wind 

 and by insects of various kinds. Insects may puncture the di- 

 seased parts and carry the bacteria to healthy twigs. Little 

 drops of sticky sweet sap come out on the diseased twigs and 

 bees and flies are attracted to these carrying away with them 

 many bacteria to other twigs and flowers, the stigma of which 

 afford an excellent culture medium for their growth. 



Mr. A. F. Woods, of the United States Department of Agri- 

 culture, says: 



"The disease is considered to be extremely infectious, the 

 bacteria being carried in the form of dust from tree to tree by 

 the wind." 



Treatment: The best remedy, so for as yet known, is the re- 

 moval of the diseased parts and their destruction by fire. The 

 twigs or branches should be cut off a few inches below the 

 lowest point of infection. 



BROWN ROT. 



Cause: The organism which causes this disease is commonly 

 'known as Monilia fructigena, an imperfect fungus, but the cup 

 stage has been found growing on the mummied fruits, and the 

 fungus is now known as Sclerotlniafructigena. 



Description: The germinating spores form threads which 

 penetrate the cells of the the fruit, come to the surface and 

 form long rows of spores, either single or multiple. The di- 

 sease attacks the young apple and prevents its ripening. The 

 apple in this case remains hanging on the tree often through- 

 out the winter. Such apples are commonly spoken of as 

 "mummy apples." 



How Spread: When warm wet weather comes the spores from 

 the fungus carried over the winter by the mummy apples, are 

 carried to other apples by wind, rain, or insects, and there 

 they germinate. 



