10 BULLETIN 727, U. S. DEPARTMENT OF AGRICULTURE. 
$500. At Live Oak, Fla., there was a report. of a total loss cf the 
crop on one 15-acre field in 1916 due to this disease. 
To summarize, it is evident that this disease under certain con- 
ditions becomes epiphytotic and causes serious losses, especially 
among watermelons and coldframe cucumbers. On the pickle crop 
it is of less importance. Anthracnose seems to be primarily a dis- 
ease of large fields rather than small gardens, a disease which, as a 
rule, becomes a serious factor only where its hosts are grown in exten- 
sive ‘‘pure culture.’ 
DESCRIPTION. 
The symptoms of this disease vary somewhat with the different 
hosts. All parts of the host plant are subject to attack. Lesions 
tend to increase continuously in size. Acervuli are formed in 
abundance. 
On cucumber leaves the lesions usually first appear on a vein and 
become angular or amceboid in shape, owing to the more rapid 
development and consequent rhizoid extension along the veins. The 
lesion consists of reddish brown, dry, dead tissue, often surrounded in 
its earlier stages by a narrow, yellowish, translucent or water-soaked 
border (Pl. I, A). Inconspicuous acervuli are produced along the ~ 
veins on the upper epidermis of the brown center. Larger lesions 
become more circular and blotchlike (Pl. II, B). The dead centers 
crack transversely and may be beaten out by rain. Leaves being 
killed by the coalescence of a few large lesions become ragged in 
appearance (PI. Il, 6). Very numerous incipient lesions may cause 
the sudden blighting of leaves. On young rapidly growing leaves 
small lesions may cause crinkling and extreme distortion. 
Cucumber petiole and stem lesions are linear to narrowly oval, 
first slightly sunken and water-soaked or yellowish. Numerous 
acervuli are formed. The surface of such lesions later becomes quite 
dry and chalky in appearance (Pl. I, B). Cucumber stem lesions 
tend to remain shallow and superficial, and the collapse of mature 
stems at diseased points is uncommon. 
Cucumber fruit lesions appear first as more or ee circular, sunken, 
water-soaked areas. Sporulation is abundant. The surface of such 
lesions becomes buff or pinkish in color, later turning to black. On 
mature fruits the black lesions may show white central areas bear- 
ing the old acervuli as conspicuous black dots. <A dry rot is usually 
produced in the underlying tissue and the sunken epidermis may 
crack, exposing a cavity underneath. 
In the field, anthracnose of cucumbers is characterized by the 
parched or scorched appearance and spotting of the leaves. The 
chief damage is due to the destruction of the leaf lamine. Stem 
and petiole attack is not very evident and fruit injury is conspicu- 
ous only in the seed crop. 
