My attention has been called a number of times to the unsatisfactory
records and directions concerning the grafting of herbaceous plants.
There appears to have been very little attention given to the subject,
and the scant discussions of it are mostly copied from one author to
another. A few years ago I made some attempts at herbaceous grafting,
but it was not until last winter that experiments were seriously
undertaken. The work was put in the hands of J.R. Lochary as a subject
for a graduating thesis.
The experiments were undertaken primarily for the purpose of learning
the best methods of grafting herbs, but a secondary and more important
object was the study of the reciprocal influences of stock and cion,
particularly in relation to variegation and coloration. This second
feature of the work is still under way, in one form or another, and we
hope for definite results in a few years. As a matter of immediate
advantage, however, herbaceous grafting has its uses, particularly in
securing different kinds of foliage and flowers upon the same plant.
There is no difficulty in growing a half dozen kinds or colors, on
geraniums, chrysanthemums, or other plants from one stock of the
respective species.
Six hundred grafts were made in our trials last winter. It was found
that the wood must be somewhat hardened to secure best results. The
very soft and flabby shoots are likely to be injured in the operation
of grafting, and union does not take place readily. Vigorous coleus
stocks, three months old, gave best results if cut to within two or
three inches of the pot and all or nearly all the leaves removed from
the stump. Geraniums, being harder in wood, made good unions at almost
any place except on the soft growing points. The stock must not have
ceased growth, however. Most of the leaves should be kept down on the
stock. Cions an inch or two long were usually taken from firm growing
tips, in essentially the same manner as in the making of cuttings.
Sometimes an eye of the old wood was used, and in most cases union
took place and a new shoot arose from the bud. The leaves were usually
partly removed from the cion.
Various styles of grafting were employed, of which the common cleft
and the veneer or side graft were perhaps the most satisfactory. In
most instances it was only necessary to bind the parts together snugly
with bass or raffia. In some soft wooded plants, like coleus, a
covering of common grafting wax over the bandage was an advantage,
probably because it prevented the drying out of the parts. In some
cases, however, wax injured the tissues where it overreached the
bandage. Sphagnum moss was used in many cases tied in a small mass
about the union, but unless the parts were well bandaged the cion sent
roots into the moss and did not unite, and in no case did moss appear
to possess decided advantages. Best results were obtained by placing
the plants at once in a propagating frame, where a damp and confined
atmosphere could be obtained. In some plants, successful unions were
made in the open greenhouse, but they were placed in shade and kept
sprinkled for a day after the grafts were made. The operation should
always be performed quickly to prevent flagging of the cions. Or, if
the cions cannot be used at once, they may be thrust into sand or moss
in the same manner as cuttings, and kept for several days. In one
series, tomato and potato cuttings, which had flagged in the cutting
bed, revived when grafted. And cuttings which had been transported in
the mail for three days grew readily, but they were in good condition
when received. The mealy bugs were particularly troublesome upon these
grafted plants, for they delighted to crawl under the bandages and
suck the juices from the wounded surfaces.
Although it is foreign to the purpose of this note, it may be worth
while to mention a few of the plants upon which the experiments were
made. Sections were taken of many of the grafts and microscopic
examinations made to determine the extent of cell union. Coleuses of
many kinds were used, with uniform success, and the cions of some of
them were vigorous a year after being set. Even iresine (better known
as _Achyranthes Verschaffeltii_) united with coleus and grew for a
time. Zonale geraniums bloomed upon the common rose geranium. Tomatoes
upon potatoes and potatoes upon tomatoes grew well and were
transplanted to the open ground, where they grew, flowered and fruited
until killed by frost. The tomato-on-potato plants bore good tomatoes
above and good potatoes beneath, even though no sprouts from the
potato stock were allowed to grow. Peppers united with tomatoes and
tomatoes united with peppers. Egg plants, tomatoes and peppers grew
upon the European husk tomato or alkekengi (_Physalis Alkekengi_).
Peppers and egg plants united with each other reciprocally. A coleus
cion was placed upon a tomato plant and was simply bound with raffia.
The cion remained green and healthy, and at the end of forty-eight
days the bandage was removed, but it was found that no union had taken
place. Ageratums united upon each other with difficulty.
Chrysanthemums united readily. A bean plant, bearing two partially
grown beans, chanced to grow in a chrysanthemum pot. The stem bearing
the pods was inarched into the chrysanthemum. Union took place
readily, but the beans turned yellow and died. Pumpkin vines united
with squash vines, cucumbers with cucumbers, muskmelons with
watermelons, and muskmelons, watermelons and cucumbers with the wild
cucumber or balsam apple (_Echinocystis lobata_).
Another interesting feature of the work was the grafting of one fruit
upon another, as a tomato fruit upon a tomato fruit or a cucumber upon
another cucumber. This work is still under progress and it promises
some interesting results in a new and unexpected direction, reports of
which may be expected later.--_Cornell Station Bulletin_.
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