844 EXPERIMENT STATION RECORD. [Vol. 41 



extending through the stoma. Moisture favors growth. The approximate 

 temperature conditions for growth are found to be, minimum 9°, optimum 20 to 

 25°, and maximum below 34° C. (93.2° F.) Strong, diffuse light is detrimental 

 to spore and color formation. The organism withstands a considerable range 

 of reaction. Translocation of starch is hindered in the infected leaves. The 

 organism may be disseminated by air currents. While field inoculations suc- 

 ceed under normal conditions in the North, these do not appear to favor 

 greatly the spread of the disease. The inoculation period requires usually 6 to 

 10 days, or longer under conditions of low humidity or temperature. The over- 

 wintering of the fungus is probably due to the longevity of the conidia, although 

 growth as a saprophyte may also be a factor. 



Bordeaux mixture is ineihcient for control of leaf mold, as are also am- 

 moniacal copper carbonate, potassium sulphid and sulphur dust. Commercial 

 lime sulphur appears to be more effective as regards prevention of plant in- 

 fection than self-boiled lime sulphur, but less effective in moist chamber ex- 

 periments. Formaldehyde gas, while apparently effective in preventing spore 

 germination, is expensive, owing to the quantity required. Fumigation with 

 sulphur, as tested experimentally, appears to be an adequate means of killing 

 spores of C. fulvum on trash and leaves. 



The occurrence of Alteriiaria^ in a characteristic apple spot, and an apple 

 rot caused by Gliocladium viride, F. J. MacInnes {Trans. III. Acad. Sci., 10 

 (1911), pp. 218-223). — The progress of a disease attacking immature apples 

 sent from Harristown, 111., for study is here noted and described, with an ac- 

 count of the fungi found in this connection. One of these shows no marked 

 disagreement morphologically with A. tenuis. Two other species of Alternaria 

 were found, one causing a core rot and one growing on the surface of the seed, 

 but apparently causing no injury. A. fasciculata, regarded as a variety of 

 A. tenuis, causes a spot not unlike the one affecting the fruit under investiga- 

 tion. It is not certain, however, that the'trouble is due to an Alternaria. 



An apple rot caused by Gliocladium viride, F. J. MacInnes {Trans. III. 

 Acad. Set., 10 {1911), pp. 223-229, pis. 2, figs. 30).— A fungus found on petri 

 dishes in which cultures had been made while isolating fungi from diseased 

 apples produced, when inoculated on healthy fruit, a dry brown rot. A study 

 was made of the organism, which may prove to belong near or within G. viride, 

 though some differences are noted. 



The longevity in the soil of the Sclerotinia causing the brown rot of stone 

 fruits, J. B. Pollock {Ann. Rpt. Mich. Acad. Sci., 20 {1918), pp. 219, 280).— 

 Facts are cited which are thought to show that Sclerotinia on mummied 

 plums may persist in sclerotial form capable of producing ascocarps for at 

 least 10 years, but that they can not persist indefinitely. 



The control of brown rot of plums and plum pocket, E. C. Stakman and 

 A. G. ToLAAS (Minn. Hort., 46 {1918), No. 5, pp. 182-186, figs. 4).— Brown rot 

 is said to have been reduced in experiments during recent years at the Min- 

 nesota Experiment Station from So per cent on unsprayed to 5 per cent on 

 sprayed trees. Plum pocket has been reduced but not completely controlled. 

 For either disease, Bordeaux mixture 3 : 4 : 50 or a commercial lime-sulphur 

 1:40 should be used at least three times (in connection with powdered lead 

 arsenate) every year regardless of the appearance of the disease. 



Sap acidity and disease resistance in grape varieties, M. D. Atti (Ann. R. 

 Scuola Sup. Agr. Portici, 2. ser., llf (1916-11), pp. 24).— The author concludes 

 his account of a study on grape varieties differing as regards locality of origin 

 with the statement that a close relation may be demonstrated between sap 

 acidity and resistance to disease. 



