
688 Report or THE HORTICULTURIST OF THE 
received the infection during the season of 1892, and that the 
first conidia formed as a result of this infection were produced in 
June, 1893. 
A point of economic interest is also emphasized by. these 
observations, namely, that a very serious outbreak of the Black 
Knot may follow an infection from the conidia which are formed 
only during the summer months. Infection from this source is 
to be feared as well as from the ascopores matured in late 
winter and early spring. 
PREVENTING LEAF BLIGHT OF PLUM AND CHERRY 
NURSERY STOCK. 
During the years of 1891 and 1892 Mr. D. G. Fairchild, assist- 
ant in the United Statés Division of Vegetable Pathology con- 
ducted some very valuable experiments in spraying nursery stock 
at this station. The progress of the work in 1891 was noted in 
Bulletin No. 3 of the United States Division of Vegetable Patho- 
logy and a report of the work of 1892 was given in Vol. VIL, 
pp. 240-264, of the Journal of Mycology, published by the same 
Division, and also in the last annual report of this station, 
pp. 642-673. 
Since these publications are probably accessible to any who 
are interested in these investigations it will be sufficient in this 
connection to make a very brief statement of the results of the 
experiments. 
The experiment designed to compare the efficacy of the ammo- 
niacal solution. of copper carbonate and the Bordeaux mixture 
against the plum leaf blight on cherry nursery stock resulted in 
a more favorable showing for the latter. 
On Mahaleb stock, both Windsor and Yellow Spanish cherries _ 
did better under Bordeaux mixture treatment than without any 
treatment.” Fie: 
On Mazzard stock the treated cherry trees were superior to 
the untreated; the Bordeaux mixture was slightly superior to 
* Jour. Myc, VII, p. 251; Annual Rep. N. Y. State Expt. Station, 1892, p. 657. 

