204 Report OF THE BOTANIST OF THE 
clay loam. Since the variety was a choice one which the owner 
desired to propagate extensively, the trees were cut back severely 
in the spring of 1897 to induce a vigorous growth. In August 
of the same year all wood available for buds was cut off; and in 
each subsequent year the trees have been cut back in August to 
get buds for propagation. With the exception of the gumming 
of the fruit, the trees appeared healthy although they made very 
little growth during the past two years. 
What caused this gumming is not clear. It was certainly not 
the work of any insect or fungus and probably not of bacteria. 
At our request Mr. H. A. Harding, the Station Bacteriologist, 
made Petri-dish cultures of the diseased plum tissue on glucose, - 
lactose and peptone gelatin and lactose agar. In several of. the 
cultures no growth whatever appeared. In others, a few colonies 
of fungi and bacteria developed, but they were of diverse kinds 
and evidently foreign to the disease. 
We suspect that it was partly the effect of the severe summer 
pruning. Beach? has reported a case in which summer pruning 
of a cherry tree caused a severe gumming of the trunk; and ina 
German periodical on plant diseases*® there is given an account 
of some experiments which indicate that summer pruning of the 
stone fruits is favorable to the production of gum. However, in 
the present case there is certainly another factor to be accounted 
for: because an unpruned tree of the same variety in the same 
garden showed traces of the disease as did, also, some other 
varieties there; and the same disease occurred in a mild form at 
Geneva on German prunes which had ,not been pruned to any ex- 
tent for at least two years. . 
MiscELLANEOUS Disnases.—Neither orchard trees nor nursery 
stock were much injured by leaf blight (Cylindrosporium padi). 
Black knot (Plowrightia morbosa) ‘is a serious enemy of plums in 
Western New York, but it did not spread much last season. 
Double fruits of plum were common. We found a few specimens 
of crown gall on nursery stock. No specimens of .plum pocket 
Beach, 8. A. Gumming of Stone Fruits. Am. Gardening, 19 : 606. 
8Zeitschrift fir Pflanzenkrankheiten, 6 : 58-59. 
