PEAR GROWING IN CALIFORNIA. 



345 



While all the symptoms oivcn arc valual)le in the detection of pear 

 blight the experts who are trained for the work of control are al)le to 

 pick out obscure cases some time liefore death takes place and l)efore 

 there is a marked discoloration. The first symptoms are wiltiu.u: of 

 the foliaii'e of a diseased twip:, bark slisihtlv discolored or blackenc'l in 



Fig. 14;- 



Bli^litod pear twiss. Note tho beads of gum in front of arrow. 



spots, an abundant flow of sap which may alrc^ady have oozed from the 

 twig, and a discolored cambium as described. 



Iloldovei' blight either above or below ground may be detected by 

 the presence of dead, more or less sunken, area.s of brown and black- 

 ened bark. The discoloration of the cambium in such cases may 

 readily be seen extending back for a short distance bevond the dead 



127 



