66 
A DISEASE OF ALMOND TREES. 
By Newton B. Pierce. 
(Plates XI-XIY.) 
During the early part of August, 1891, while engaged in work on the 
vine disease of southern California, the writer observed a number of 
almond trees east of the village of Orange, Orange County, severely 
affected by a fungus infesting the leaves. This parasite is Cercospora 
circumscissa , Sacc., a form also occurring on Primus serotina , the wild 
black cherry of the East. 
The affected trees observed were large and old, but, according to Mr. 
Moore, the manager of the place, were unfruitful. The leaves were riddled 
by the fungus. Several trees had lost most of their foliage, which 
thickly carpeted the ground. Owing to the perforations of the parasite 
most of the fallen leaves looked like strainers. It seemed probable 
that they had fallen earlier than they would had the fungus not been 
present, but owing to the lack of previous observations I could not 
then speak positively. The observations of Mr. Ellwood Cooper given 
below confirm this opinion. 
After these observations many others were made throughout the re¬ 
gion. Scattered trees were seen in many orchards, and all were more 
or less affected. Later in August I visted Florence, Los Angeles 
County, and there observed the same effects, but less seriously devel¬ 
oped. In the latter part of the same month I conversed with Mr. L. 
Thurston, at Santa Ana, in relation to this disease. The Thurston 
place has one of the most profitable almond groves of Orange County, 
and is near Arch Beach. At the close of September, Mr. Thurston 
wrote an account of the disease in his orchard, saying that the leaves 
remaining on the trees were seriously affected, while those already 
fallen, comprising most of the foliage, were completely riddled by the 
parasite. Mr. Ellwood Cooper, State horticultural commissioner, who 
has large almond interests near Santa Barbara, Cal., writes as follows 
respecting the disease : 
The disease here has been very had for several years; I can not recall its first ap¬ 
pearance on my place. 1 have over 10,000 trees. They generally cast their leaves 
in June and July. The first appearance of the disease is a yellowish brown spot on 
the leaf. * * * Very soon the round piece falls out and the leaf falls from the 
tree. Sometimes there are a number of such spots in each leaf. [ This is nearly 
always true.] It causes the leaves to fall too soon and before the woody portion has 
been perfected, and hence an insignificant crop the coming year. The blight does 
not seem to get any worse, but it is bad enough to cause great loss in crops. 
