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686 Report oF THE HorTICULTURIST OF THE 
SOME OBSERVATIONS ON THE LIFE-HISTORY OF 
PLOWRIGHTIA MORBOSA (Scuw.) SACC. 
At the request of Mr. James Love, a nurseryman of Geneva, 
N. Y., the Horticulturist inspected a block of plum trees in his 
nursery June 28, 1893. The plums were budded in June, 1891, 
and the buds began to grow in the spring of 1892, so that this 
year the trees made: their second season’s growth. According to 
the usual custom of nurserymen, before the buds started to grow 
the entire tops of the stocks on which the buds were set were 
cut off close to the ground just above the insertion of the bud. 
The trees as they now stand have therefore no wood that is two 
years old above their union with the stock close to the surface 
of the ground. 
The block of young plum trees is bordered on one side by a 
row of Bavay’s Green Gage plum (Reme Claude de Bavay) in 
bearing, every tree of which is very badly diseased with the 
plum Black Knot, Plowrightia morbosa (Schw.) Sace. The 
Bavay’s Green Gage are thirty feet apart in the row and their 
branches overhang the outside row of the plums in the nursery, 
which are of the Gueli variety. After the foliage had fallen last 
autumn the knots in the Bavay’s Green Gage trees were cut out. 
On June 28, 1893, nearly every tree of the young Gueii trees in 
the adjacent nursery row standing under the branches of the 
Bavay’s Green Gage showed an outbreak of Black Knot either 
on the trunks or branches. The greater the distance of the Gueii 
trees from the Bavay’s Green Gage the less Black Knot was 
found, and the portion of the nursery row midway between two . 
Bavay’s Green Gage trees contained but an occasional specimen 
of the Black Knot. The owner at first declared that no trees in 
the nursery row were affected with the Black Knot except those 
in the row adjacent to and overshadowed by the diseased 
Bavay’s Green Gage, but careful inspection disclosed an occa- 
sional specimen of the disease in other rows. The conclusion 
was irresistible that the infection came from the Bavay’s Green 
Gage trees. 

