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. From the twig the 

 causal pathogene passes 

 into the larger limb 

 where it spreads out, 

 forming a canker (Figs. 

 72 and 73). The brown- 

 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- FlG> 73. _ B rown-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 



