STATE POMOLOGICAL SOCIETY. 101 



APPLE RUST — ROSTELIA SPECIES. 



The apple rust is quite common in the Middle and Western states. 

 This fungus in one of its stages of development causes, on cedar 

 trees, what are called "cedar apples." The spores from the cedar 

 apples fall on apple trees, germinate, enter the leaves and sometimes 

 the fruit. It lives within the tissues ot the host, finally- appearing 

 at the surface when the spores are produced. The Rostelias are 

 generally believed not to survive the winter without the cedar apple 

 stage, but there seems good reason for thinking that in some cases 

 the rostelia stage ma}' be perennial. We have not seen the rust on 

 apples in Maine. But cedar apples are found, and Rostelia auran- 

 tiaca, occurs on the sugar pear. Destroying cedars near the orchard, 

 and spraying with a copper solution, just before the cedar apples 

 drop their spores, have been advised. The disease is of but little 

 importance to Maine growers at present. 



PEAR BLIGHT APPLE BLIGHT MICROCOCCUS AMYLOVORUS, BURRILL. 



By the researches of Profs. Burrill and Arthur this disease is now 

 known to be due to the species of bacteria named above. The para- 

 site is always present in actively blighting tissue and by inoculating 

 healthy branches with the organism the disease has been transferred. 

 In the East the disease is mostly confined to the pear, but in the 

 West, Minnesota, Wisconsin, Michigan and Iowa it is as bad on the 

 apple as on the pear in the East. The disease is believed to retain 

 its vitality in dead organic matter outside of the tree and the minute 

 organisms are carried to the trees by the wind. They find entrance 

 through the tender growing twigs, blossoms, or through injuries in 

 the bark caused by sun scald, cold, or mechanical injuries. The 

 parasite feeds upon the starch of the twigs causing an exudation of 

 gum and liberation of carbon dioxide. When attacked, the tree 

 appears as though fire had scorched the twigs and leaves of the new 

 growth. Hot, wet seasons, especially a series of them, favor the 

 disease. Dark porous soils are said to be favorable to the blight. 

 Cultivation, by prolonging the period of growth, is said to favor the 

 disease. If length of season increases the disease, why is it worse 

 in apples westward and northward? If excess of moisture favors 

 the plaiii, why is it worse on apples in the drier western climate? 

 We hope the pest will continue its preference for western apples. 

 We have received a number of complaints of its attacks on pears 

 but none on apples in Maine. 



