I 



FOES AND FRIENDS OF THE PLANT 213 



apples.' ' An unusual abundance of fruit sets, but does not 

 grow to full size (figure 122). Spraying at the right time is 

 the best remedy. (Idaho Experiment Station, Bulletin 40; 

 Oregon, 38.) 



Woolly aphis. This attacks bark, roots, and stems. The 

 injured places on the stems have a marked woolly appear- 

 ance. In the early spring these may be touched with a swab 

 dipped in gasoline, and if this be done early enough and often 

 enough, it will check the aphis. The attacks on the root 

 may be checked by putting lime around the roots. (Oregon 

 Experiment Station, Bulletin 38; New Mexico, 68; Utah, 55, 

 65; Washington, 65.) 



Phylloxera. The phylloxera is a very small insect 

 (less than the size of a pin head) which attacks the 

 roots of grapevines. It usually kills the European 

 grapevine, which is the one mostly planted in Cali- 

 fornia. Spots in the vineyard attacked by phylloxera 

 may be known by the low growth of the vines and may 

 show in the center some dead vines; outside these, 

 vines which make little growth and produce no grapes ; 

 outside these, vines which do not make the usual growth, 

 but may bear more than the usual amount of grapes ; 

 and outside all these, healthy vines which will become 

 affected in course of time, if the spread of the insect is 

 not stopped. 



Various ways of checking the insect have been tried ; such 

 as flooding the vineyard for a time and putting carbon bi- 

 sulphid in the soil. These are giving way to the use of 

 resistant roots. These are roots of American grapes which 



