s are often placed in a grafting case for rapid callusing.
This year we tried some black walnut grafts and found that they callused
in 10 to 14 days when placed in a grafting case. These were bench
grafted on piece roots, using modified cleft and side grafts. Later we
tried chestnut with excellent results. Then we made more chestnut
grafts, wrapped them in damp moss and placed them in a lab oven with a
temperature of approximately 75 degrees. These callused rapidly and were
planted immediately in the nursery. They made good growth.

We think that some adaptation of this method has possibilities in our
region. Often our chestnut grafts are damaged by late spring frosts. If
we can bench graft, callus, and then hold the grafts until favorable
weather, frost damage will be eliminated. It may be possible to handle
black walnut in some similar fashion. Then we would be dealing only with
successful grafts. A cold frame provided with heating cable should be
adequate.

Factors Affecting Nut Tree Propagation

F. L. O'ROURKE, _Department of Horticulture, Michigan State College_

Propagation of nut trees is primarily involved with the problems
affecting the perpetuation of selected clones by vegetative means. It
has been indicated by Morris (14), Reed (18), and others that trees
produced from seed are of inferior value for nut production. Seed
propagation, however, must be practiced to produce the necessary
rootstocks upon which the selected varieties are budded or grafted.

Seed Propagation

Barton (1) indicated that while some few seedlings may be produced
without prior seed stratification, after-ripening of the seed for 2 to 4
months at 35 deg. to 50 deg. F. markedly increased seedling production with
hickory and walnut. Chase (4) found that black walnut seed sown in
November yielded more and larger seedlings than when planted at a later
date. Chase (5) also reported that nuts containing larger kernels
produced larger seedlings, and that planting 1 to 2 inches beneath the
surface yielded larger seedlings than deeper placement. There have
apparently been little or no observations made on the performance of
seedlings for rootstock purposes between different parental strains
except for Chinese chestnut as reported by McKay (12).

Clonal Rootstock Propagation

The difficulty of propagating any selection of nut trees by vegetative
means has discouraged selections for rootstock purposes. Only filberts
offer such a