THE WESTERN YELLOW PINE MISTLETOE. 31 3 
cutting and providing more favorable conditions for the optimum 
development of the parasite, every effort should be made to free the 
stand entirely of mistletoe infection, although it is doubtful whether 
in certain cases the removal of lightly infected trees would be war- 
‘ranted because of silvicultural reasons. The increased activity of 
the mistletoe following the opening of the stand militates against 
leaving for a future cutting operation any but lightly infected trees, 
the infection of which is confined to the lower portion of the crown. 
Old and heavily infected trees should be cut for two reasons: (1) To 
improve the hygienic condition of the forests of the future through 
the removal of the mistletoe, and (2) to secure the maximum reali- 
zation on a rapidly diminishing growing stock or forest capital. 
Since the future productivity of the forests depends toa great extent 
upon the proper choice of seed trees or of the seed itself in the case of 
artificial regeneration, those trees used for reproductive purposes 
should be sound, healthy, and of an intermediate age class. 
As heavy a stand of healthy trees as possible should be left in order 
to compensate for the removal of diseased trees, and to maintain 
better forest conditions, reduce wind damage, and insure a denser 
stand of reproduction. Exceptional care should be taken to leave 
every healthy black jack which is free from infection. Wherever 
possible, trees should be freed from light infections by cutting off 
lower branches within reach. Transition trees and vigorous yellow 
pines, suitable for seed trees, should be left in greater numbers to 
take the place of diseased black jacks removed, to maintain better 
forest conditions, and to furnish abundant seed for the restoration 
of the stand. Small heavily infected black jacks should be marked 
wherever it is possible to have them cut under the sanitation clause 
of the timber-sale contract, or where there is a market for small 
material, such as stulls, mine props, ties, poles, posts, and pickets. ° 
Forest officers in charge of marking on mistletoe-infected timber- 
sale areas should study carefully the possibilities of increasing the 
number of healthy trees in the remaining stand. The pruning of 
infected limbs from small trees at the time of marking presents a 
practical means of eliminating light limb infections and at the same 
time increasing the number of healthy trees. Occasionally there are 
trees in a stand that are lightly infected on a low branch within 
reach of the ground. Mistletoe-infected reproduction and young 
timber below merchantable size should also be freed from the disease 
either through cutting the seedlings and saplings or by lopping off 
the infected branches. Such measures may be impracticable except 
on timber sale areas and in some cases the extra labor and expense 
involved may prove prohibitive. 
The areas of mistletoe infection should be located and mapped as a 
prerequisite to an efficient control campaign. The degree of injury 
