TWO HITHERTO UNREPORTED DISEASES OF STONE 
FRUITS 1 
By C. C. Lindegren, Field Assistant, and Dean H. Rose, Pathologist, Fruit 
Disease Investigations, Bureau of Plant Industry , United States Department of 
Agriculture 
BOTRYTIS ROT OF PEACHES 
In August, 1923, during the inspection of peach shipments from California, on 
the Chicago market, numerous fruits were found which showed a rot that was 
apparently due to Botrytis. On nearly all of these fruits there was a scanty 
growth of white to gray mycelium, and on a few of them the characteristic spore 
clumps of Botrytis could be seen. The varieties found attacked were Elberta 
and Lovell. 
Cultures made under aseptic conditions from the advancing edge of the rotten 
■spots yielded a Botrytis which was apparently very similar to B. cinerea. Positive 
^evidence of the pathogenicity of the organism isolated was obtained in an experi¬ 
ment carried out as follows: Ripe healthy peaches were immersed for two 
minutes in 50 per cent alcohol, then rinsed thoroughly with sterilized distilled 
water; four of the peaches were inoculated by wounding with a flamed needle 
and forcing mycelium into the wound, four others were inoculated by merely 
laying a fragment of mycelium on the uninjured peach surface. For controls, 
four peaches were used which had received no treatment other than sterilization, 
and four others which after sterilization had been merely wounded with a flamed 
needle. All four of these lots were placed in moist chambers and held at room 
temperature. Within three days all of the peaches in the two inoculated lots 
showed light brown rotten spots about 2 cm. in diameter; by the end of eight 
days the spots had reached a diameter of 10 cm. Cultures from these 
spots yielded a Botrytis which was apparently identical with the one used for 
inoculations. 
Similar results from inoculations were obtained in several other experiments 
’■conducted in the same way. The controls in all of the experiments failed to 
develop rot of any sort. 
The noteworthy fact which these experiments establish is that Botrytis is able 
■to penetrate the uninjured skin of the peach and that when it does so it can 
produce rot as rapidty as if the fruit had been wounded. 
In lesions caused by Botrytis, peach tissue, both skin and flesh, is firmer in 
Lexture and lighter brown in color than in lesions caused by either Sclerotinia or 
Rhizopus. The skin around the margin of the lesion slips easily under pressure 
from the finger somewhat as in Rhizopus rot, but the decayed tissue does not 
liave the marked sour odor characteristic of Rhizopus rot. As a matter of fact 
it has no definite odor of any sort. So far as noted there is no tendency to 
^wrinkle and mummify. 
ALTERNARIA ROT OF CHERRIES 
During the summer and fall of 1923 the most conspicuous, although probably 
mot the most destructive, disease of cherries on the Chicago market was a brown 
decay with abundant olive green, sporulating, aerial mycelium. Bing sweet 
cherries from Yakima and Wenatchee, Washington, and Lambert sweet cherries 
from Emmett, Idaho, showed a large amount of this rot. It was also found on 
1 Received for publication Apr. 1, 1924. 
. Journal of Agricultural Research, \'ol. XXVIII, No. 6 
^Washington, D. C. May 10, 1924 
Key No. G-405 
96036—24f-10 
(603) 
