CONTROL MEASURES OTHER THAN SPRAYING 357 



in meeting attacks of the fruit tree bark beetle of the peach. 

 Trees suffering from winter injury may, to their advantage, 

 receive a special application of nitrogen-carrying fertilizer. 



Some varieties are more resistant to disease and winter in- 

 jury than others. Thus, Tompkins King, Grimes Golden, and 

 Twenty Ounce are susceptible to collar rot about the base of 

 the trunk. Northern Spy and Mcintosh are resistant. Grow- 

 ers may sometimes resort to top-working desirable varieties 

 with weak trunk charac- 

 ters, on more hardy and re- 

 sistant kinds, as indicated 

 in Chapter VII, 'Tropagat- 

 ing Fruit Plants.'' Physio- 

 logical troubles such as bit- 

 ter pit, drought spot, and 

 cork are often decreased 

 by improving the moisture 

 conditions of the soil. 



When the balance be- 

 tween organisms is de- 

 stroyed, nature intervenes 

 to restore it. The San Jose 

 scale is the prey of many 

 species of ladybird beetles, 

 some fungi, and at least 

 nine species of Hymenop- 

 tera. However, the pests 

 are likely to make severe inroads and cause heavy losses for 

 several years, until natural enemies become abundant. Some 

 pests yield, either not at all or only in part, to s-uch enemies, 

 so that the fruit grower may not depend on natural enemies ex- 

 cept to supplement his own program of control. 



It is best to rely on the experiment stations and other public 

 agencies serving the section in which the fruit enterprise is lo- 

 cated, for the detailed information on which proper procedure 

 must be based. 



(N. Y.-Geneva Exp. Station) 

 Fig. 138. Cross section of perithecium 

 showing the spores formed, and ready 

 to emerge from leaf in Fig. 137. 



