PEACH DISEASES 273 
as in the case of fire-blight of pears. Twig-blight may also 
result from the spread of the pathogene from affected fruit 
into the twig by way of the fruit-pedicel. This happens very 
commonly in New York State orchards. [rom the twig the 
causal pathogene passes 
into the larger limb 
where it spreads out, 
forming a canker (Figs. 
72and 73). Thebrown- 
rot canker is a definite 
dead area in the bark, 
the surface is sunken, 
and the lesion is ac- 
companied by a flow of 
gum (Fig. 73). The 
disease is said to affect 
peach leaves, showing 
itself as a shot-hole. 
Fruits generally show 
signs of brown-rot after 
they are half grown, the 
susceptibility of indi- 
viduals increasing as 
they approach maturity. 
The lesion on the peach | 
is at first evident as a 
small, more or less circu- Fic. 73. — Brown-rot canker on peach limbs. 
lar, dark-brown, decayed 
area with a rather indefinite line of demarcation between the 
healthy and diseased portions. This rapidly enlarges, and soon 
the fruiting structures of the pathogene appear on the surface 
as grayish tufts (Fig. 71). At first these tufts occur sparingly, 
but in a day or so the original rotted spot may become densely 
dotted with the characteristic ashen mold (Fig. 71). With 
T 
