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2 BULLETIN 534, U. S. DEPARTMENT OF AGRICULTURE. 
orchard, in other sections it is only locally severe. The former is the 
case in the Ozarks of Missouri and Arkansas and in the commercial 
apple-growing sections of Kansas, while the latter is true in Virginia 
and Maryland. 
On account of the above-mentioned facts it is very difficult to com- 
pute the amount of damage caused by the disease, but it is probable 
that $2,000,000 would be a conservative estimate of the annual loss 
due to it. 
In orchards in which blotch has not been placed under control by 
spraying, the entire crop of susceptible varieties may succumb to the 
disease and the trees themselves may be severely injured, in extreme 
cases even killed. Losses of 50 to 75 per cent of the entire crop are 
common in some sections. | 
The disease is found in practically all the eastern and middle- 
western apple-growing regions from Pennsylvania, Ohio, Indiana, 
Tilinois, northern Missouri, and Nebraska southward. It is most 
serious and widely prevalent in Kansas, southern Missouri, northern 
Arkansas, Tennessee, and Kentucky. It is also a serious disease in 
fruit-growing sections bordering on or near the Ohio River. In Vir- 
ginia and Maryland it is only locally severe, but it has become much 
more prevalent during the last two years. Blotch has been gradually 
extending farther north, but should not become serious in properly 
sprayed orchards. In those sections which have been free from the 
disease and in which a fungicide such as lime-sulphur solution or 
Bordeaux mixture is annually applied to apple trees about three 
weeks after the petals have fallen, blotch should not be able to gain 
a foothold. 
DESCRIPTION OF APPLE BLOTCH. 
Blotch occurs on the fruit, foliage, and twigs of the apple. 
On the fruit it first appears as small dark, somewhat raised spots, 
which later enlarge slowly. Usually these spots have in midseason 
a dark fringed or stellate appearance, though on some varieties, such 
as Maiden Blush, the center of the spots may be somewhat more 
raised or blisterlike in appearance and of rather light color, due to 
the raised cuticle (PI. I, figs. 2 and 3). 
A later phase of this disease on the fruit is the coalescence of sev- 
eral spots, a general homogeneous darkening, with complete elimina- 
tion of the stellate configuration typical of earlier stages. On some 
varieties, notably Ben Davis, a cracking open of the fruit often in 
three directions from a central point, is very common in orchards in 
which the disease is at all serious (PI. I, fig. 1). 
A characteristic spot is raised, glistening black, with margins 
so deeply cut in and so irregular as to give the spot its commonly 
noted stellate appearance (PI. I, fig. 4). The tissues beneath the epi- 
