164 EXPERIMENT STATION. [Jan. 



cultures and comparisons 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 ditferently chemically when grown in solu- 

 tions on diflt'erent media. ^ 



On the Leaves. — In wet weather, especially, one often no- 

 tices spots on the leaves. These are found on both the upper 

 and lower surfaces, but are generally most conspicuous on the 

 upper. 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 " 

 fimgus. 



Spoj'es. — The spores, more or less oval shaped, are one 

 celled, and their coutents 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 walls. The spores 

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

 chain being the newest one. When grown on cidture 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 wind, rain, insects (espe- 

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

 spores are disseminated might be 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 which hangs on the trees or has fallen to 

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

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

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

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

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



• Dr. Stone has observed this species on the twig for many years in Massachusetts, the twig 

 sometimes being very badly spotted. .l/oniVi'a isalso sometimes associated with C/nrfosporn/?H, 

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

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

 (See Nineteenth Annual Report, Massachusetts Agricultural Experiment Station, p. 166.) 



