Grafting ponderosa pine scions on the parent root system

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July 1974

fSW FOREST AND RANGE

EXPERIMENT STATION

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SERVICES

U S D A FOREST SERVICE
RESEARCH NOTE RM-263

Grafting Ponderosa Pine Scions on the Parent Root System

Richard W. Tinus1

Describes grafting pine scions on parent rootstock. Reproductive success
is much higherthan by direct rooting, and is better distributed overthe parent
population.

Keywords: Grafting, Pinus ponderosa.

For many purposes, it is advantageous to
grow scions of desirable parent trees on root
stock of the same genotype. Usually this is ac-
complished by rooting scions directly, but most
species of pine are difficult to root (Hare 1970,
Isikawa 1968, McDonald and Hoff 1969, Mirov
1944, Watanabe et al. 1968). By age 11 years,
rooting ability of ponderosa pine has declined to
about 7 percent, and this ability is concentrated
in 10 to 15 percent of the tree population (Tinus,
unpubl.).

This Note describes a grafting technique
which has the advantages of scion rooting with-
out the incompatability problems associated
with ordinary grafting (Copes 1967). After sev-
eral years of experiments, the following proce-
dure has been found most effective.

In the spring when the ground has thawed, but
buds are still dormant, the litter and surface soil
around the base of the tree to be reproduced are
shoveled away without digging into the root
zone. The surface root system is then exposed
by digging with a screwdriver and the hands
(fig. 1). The roots should be protected from di-
rect sun and drying by digging under the shade
of a tarp. Next, scions are cut from the crown of
the tree and veneer-grafted into the side of roots

1 Principal Plant Physiologist, located at the Shelterbelt
Laboratory, Bottineau, in cooperation with North Dakota State
University - Bottineau Branch and Institute of Forestry. Station's
central headquarters maintained at Fort Collins in cooperation
with Colorado State University.

Figure 1. — Surface root system is exposed by digging with a
screwdriver and the hands.

of the same diameter as the scion. The roots
remain attached to the mother tree (fig. 2). The
union is wrapped with a grafting rubber, sealed
with grafting wax or tree sealing compound,
and the scion enclosed in a clear polyethylene
bag. The bag has been found necessary to re-
duce transpiration stress until the graft union
forms.

To prevent overheating in the plastic bags,
the grafts are covered with a conical "tent" of
brown kraft paper, burlap, or shade cloth, sup-

l

ported by lath (fig. 3) and tied to the bole of the
tree at the top. The lower edge is buried. The top
of the paper covering is left open on the north
side for ventilation. Plenty of air space must be
left between the paper cover and the scions.

Figure 2. — Dormant scions are veneer-grafted onto matching
roots of the same tree.

Figure 3. — Grafts are bagged with polyethylene. The conical
lath structure is covered with a brown kraft paper sunshade.

By midsummer the successfully grafted sci-
ons will begin to flush. When flushing begins,
the plastic bags are removed and the graftlings
cut from the parent tree. As much root below the

graft as practical should be included — usually
25 to 40 cm. The cut ends are dusted with fun-
gicide and then either potted and placed in a
sweatbox, or placed in a propagating bench
under intermittent mist. Because most of the
fine roots are lost when the rootstock is exca-
vated, the graftlings must be treated as if they
were unrooted scions. Three months is usually
sufficient for reestablishment of a new fine root
system.

In 5 years of trials, 386 grafts were made on 24
trees 8 to 13 years of age. Graft union occurred
on 247 (64 percent), and 89 graftlings became
established trees (23 percent). This is about
three times better than can be expected if scions
from 8- to 13-year-old trees are rooted directly.
Furthermore, grafting and rooting success
were well distributed over the parent popula-
tion, whereas, ability to root scions directly was
concentrated in a small proportion of the
genotypes (Tinus, unpubl.).

Literature Cited

Copes, D. L.

1967. A simple method for detecting incom-
patibility in 2-year-old grafts of Douglas-
fir. U.S. For. Serv. Res. Note PNW-70, 8 p.
Pacific Northwest For. and Range Exp. Stn.,
Portland, Oreg.

Hare, R. C.

1970. Factors promoting rooting of pine cut-
tings. North Am. For. Biol. Workshop [East
Lansing, Mich., Aug. 1970] l:n.p. (Abstr.).
Isikawa, Hirotaka.

1968. Basic studies on the formation of ad-
ventitious roots in the cuttings of the
species, mainly Pinus and Larix that have
difficulty rooting. Bull. Gov. For. Exp. Stn.,
Tokyo, Japan, p. 77-109.

McDonald, Gerald I., and Raymond J. Hoff.

1969. Effect of rooting mediums and hor-
mone application on rooting of western
white pine needle fascicles. USDA For.
Serv. Res. Note INT-101, 6 p. Intermt. For.
and Range Exp. Stn., Ogden, Utah.

Mirov^JN. T.

1944. Experiments in rooting pines in
California. J. For. 42:191-204.
Watanabe, Mosatoshi, Giro Isa, and Soichi Sano.
1968. Effects on the rooting of Japanese red
pine cuttings by misting and medium heat-
ing treatments. J. Jap. For. Soc. 50:87-92.

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