164 EXrEKLMENT STATION. [Jan. 



cultures and conii)arisons made of the two types of Monilia — 

 that on the fruit and on the stem, made by Dr. Stone — show 

 that the spores of the one on the twig are always smaller when 

 grown in any media than those of that on the fruit, and the two 

 species react quite differently chemically when grown in solu- 

 tions on different media. ^ 



On the Leaves. — In wet weather, es]>ocially. one often no- 

 tices s})ots on the leaves. These are found on Ixith the u})pcr 

 and lower surfaces, but are generally most conspicuous on the 

 ui)per. During wet, warm weather, if one examines these spots 

 carefully he will find here and there small grayish masses of 

 powder, which are in reality the conidia of the '' brown rot " 

 fungus. 



Spores. — The spores, more or less oval shaped, are one 

 celled, and their contents are quite noticeably granular. These 

 spores germinate readily in water, producing a mycelium whose 

 contents are granular, as in the case of the spores. The myce- 

 lium is broken up here and there by cross w'alls. The spores 

 are produced in chains by a sort of budding, the last one of the 

 chain being the newest one. When grown on culture media 

 (prune agar) these spores form much longer chains than on the 

 fruits out of doors. 



Means of Spore Dispersal. — The influencing factors in the 

 spreading of this fungous disease are wnnd, rain, insects (espe- 

 cially plum curculio), etc. Many minor ways in which the 

 spores are disseminated might bo enumerated, but the three 

 above-named methods are probably by far the most influencing. 



Methods of Control. — I would suggest the following ways 

 in which to lessen the attacks of this disease. Destroy all 

 " mummied " fruit w^hich hangs on the trees or has fallen to 

 the ground. Cut off and burn all twigs that are infected with 

 the fungus mycelium. Keep the trees pruned, so that there 

 wall be a free circulation of air and plenty of light, because 

 a tree which is crowded wdth cross limbs and has in consequence 

 too much foliage acts as a convenient forcing house for " brown 



' Dr. Stone hag observed this species on the twig for many years in Massachusetts, the twig 

 sometimes lieing very badly spotteci. Monilia iaalno sometimes associated with C^nrfosporjww?, 

 but the Monilin by far predominates. Where lime and sulphur has been used as a spring spray 

 these spots have been entirely absent, with a much better annual growth of the twig as a result. 

 (See Nineteenth .\nnual Keport, Massachusetts .Xiiricultural Experiment Station, p. 166.) 



