44 BULLETIN 1426, U. S. DEPARTMENT OF AGRICULTURE 
could be drawn regarding any difference in infestation of the various 
plots by clover root borers. These experiments, however, indicated 
that the growth of the clover, both in roots and tops, was consider- 
ably stimulated by applications of acid phosphate, even on fertile 
bottom lands. The plots at Corvallis manifested a similar stimula- 
tion by both acid phosphate and gypsum. 
Fig. 15.—Damage to ‘clover, in its second crop year, by clover root 
borers, grasshoppers, and rodents 
REPRESSIVE MEASURES RECOMMENDED 
Adopt a one-crop system of clover culture throughout the com- 
munity. 
Plow clover sod as soon as possible after seed harvest or second 
hay crop. 
Plow and harrow badly infested clover sod after the hay crop in 
late June or July; a plow making a flat furrow and a spring-tooth 
harrow serve best for harrowing out as many roots as possible. 
Never plow badly infested clover sod in early spring; early and 
severe damage may be caused to neighboring young clover. 
Cut clover early for hay, in case of an early infestation by the root 
borer, in order that as many plants as possible of the second crop 
may mature seed before being killed by root borers. 
