616 



SCIENCE 



[N. S. Vol. XXXIV. No. 879 



In tlie two other cases where I have seen 

 bacteria reported as being associated with 

 gummosis of the cherry, the first, that re- 

 ported by Brzezinski' contained very little in- 

 formation concerning the morphological and 

 cultural characteristics of the organism and 

 all attempts at a comparison of Brzezinski's 

 and my organism were abandoned. In the 

 second instance, that reported by Aderhold 

 and Ruhland," more detailed information was 

 given and I have tried to determine the re- 

 lationships of the two organisms. The mor- 

 phology of Bacillus spongiosus' resembles that 

 of my organism very closely. A difference, 

 however, has been noted in certain of the cul- 

 tural features. I have not been able to obtain 

 the " vacuolated " or " spongy " appearing 

 colonies in agar or gelatin containing grape 

 sugar, a feature which Aderhold and Ruhland 

 regarded as important, and upon which they 

 based the specific name of their organism. In 

 addition, a chromagenic feature appears when 

 my organism is grown on certain media, 

 namely a greening of the agar in plates, stabs, 

 and slants; in gelatin plates and stabs which 

 are liquefied as well as in old broth cultures, 

 a feature which is not attributed to B. 

 spongiosus. 



1 would have preferred to do at least another 

 year's work before publishing the cultural 

 characteristics and describing my organism 

 as a new species. However, as I have severed 

 my connections with the investigation, I feel 

 it necessary to at least tentatively describe and 

 name my organism as follows : 



Pseudomonas cerasus n. sp., an actively, 

 motile, rod-shaped schizomycete, bearing one 

 or two polar flagella, 1.5fi to 2.5ju, long, and 

 from .5^ to .8ju, in diameter. The rods are 

 usually found in pairs and no long chains 

 have been noted. Spores have not been ob- 

 served and cultures heated at 80° C. for 15 



^ Brzezinski, P. J., ' ' Etiologie du chancre et de 

 la gomme des arbres f ruitiers, ' ' Comptes Sendus, 

 134 (1902), No. 20, pp. 1170-73. 



- Aderhold and Euhland, ' ' Ueber der Bakterien- 

 brand der kirchbaume, " Fl. No. 39 der Kaiserl. 

 Biolog. Anstalt. fiir land- und Forstw., Berlin, 

 1906. 



minutes are killed. The organism stains 

 readily with the common stains, is Gram neg- 

 ative and is not acid fast. It grows on all the 

 ordinary cultural media mentioned in the So- 

 ciety's Descriptive Chart excepting Cohn's 

 solution and silicate jelly. It did not form 

 gas in any of the media tried and it prefers 

 an acid medium to one all^aline. The group 

 number is Ps. 211.2322433. 



The manner of infection and method of 

 prevention is yet to be worked out. Ordi- 

 narily the fruit spur blight is not serious or 

 abundant enough to justify cutting out, but 

 if the generalized form of gummosis should 

 prove to be of a similar specific origin, syste- 

 matic cutting out, sterilizing of the wounds 

 and burning of the diseased cuttings would be 

 necessary. 



Cherry trees weakened through gummosis 

 fall easy prey to various saprophytic fungi, 

 Schizophyllum commune, Polyporus sp. and 

 Polystictus sp. being the most common. One 

 of the imperfect fungi, which appears very 

 frequently in the gummosis cankers, but whose 

 identity has not been fully determined, may 

 prove to be at least semi-parasitic in nature. 



The growers have found by experience that 

 top working resistant stocks will to a great 

 extent prevent the disease from appearing on 

 the body, or crotch of the tree. The Mazzard 

 seedling is most often used for this purpose 

 although the Morello, Duke and a native 

 western cherry have been successfully utilized. 

 The method is to plant the seedling in the 

 orchard in the usual manner and then top 

 work the branches, preferably by budding at 

 least twelve inches above the crotch, when the 

 trees are two or three years old. This elimi- 

 nates the gummosis factor from the trunk 

 and crotch, but the disease may later affect 

 the fruit-bearing wood. 



The Royal Ann, Bing and Lambert, which 

 are the principal commercial varieties, are all 

 susceptible to gummosis; the Lambert being 

 the most resistant. 



F. L. Griffin 



Department op Plant Pathology, 

 Oeegon Experiment Station, 

 CoRVALLis, Oregon 



