6 BULLETIN 658, U. S. DEPARTMENT OF AGRICULTURE. : 
surveyed, and along with careful notes of the estimator upon the 
diseased areas and upon data secured by means of a few small sample 
plats a very close 
estimate of the cull 
percentage to be ex- 
pected can be had. 
Checks can be made 
upon the estimator’s 
work by the expert 
cruiser. Members 
of the Office of In- 
vestigations in For- 
est Pathology can 
render excellent 
service by aiding 
each unit crew in 
the field in becom- 
ing familiar with 
the various diseases 
and their causes. 
If properly ad- 
Fic. 6.—Typical rot of the velvet-top fungus in the end of a justed, this work 
white-pine log. Note the cubical character of the rot. would cause no va- 
riations in the amount of linerun per day by the unit crews. The junior 
