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the cuttings which had been in water.

It should be noted in this connection that some investigators (16, 47,
117, 119) have treated control cuttings, checks, with water for the same
number of hours that other cuttings were immersed in a solution of growth
substance; but in the work done here, control cuttings were directly in-
serted in rooting media without any previous treatment with water for,
in practice, cuttings are either treated with a growth substance or not at
all.

Concentrated Solution-dip Method of Treatment

Treatment of cuttings by this method consists in merely dipping the
basal half inch of cuttings in a concentrated solution containing 1 to 20
mg. root-inducing substance in 1 cc. of water or mixture of water and
alcohol (49). Like the powder-dip method this reduces the time of treat-
ment to a few seconds and is said to be about as effective at optimum
concentration as the standard or solution-immersion method (49). The
last named is, of course, a matter not of seconds but of hours and this
is a point of some importance with cuttings of species which may be
injured by a prolonged soaking in a solution or even in water.



PROPAGATION OF TREES AND SHRUBS 9

Root-inducing Substances Sold Under Trade Names

These have given results not significantly different from those secured
by the use of the pure chemicals (83, 113). They improve the rooting of
cuttings of some species if properly used. That usually means as recom-
mended by the manufacturers, although their recommendations, like those
of the experiment stations for use of the pure chemicals, are probably
sometimes tentative and may not finally and in all cases prove tci be the
best (102). Rootone contains alpha naphthylacetamide and the Hormo-
dins contain indolebutyric acid. As v/ith indolebutyric acid, so with Hor-
modin A, rooting response varies with the season and conditions under
which cuttings are taken, treated, and handled (117). One B T I unit
in Hormodin A, as now made, is equivalent to indolebutyric acid 1 mg./l.,
a point of interest when a recommendation for optimum concentration of
one of these materials is being followed in diluting the other.

Treatment of Hardwood Cuttings

Hardwood cuttings of most trees and shrubs respond less to treatments
with root-inducing substances than do softwood cuttings (25, 57, 114, 130),
but rooting of hardwood cuttings of a number of species including grape
(130), Tatarian honeysuckle (40), oriental bittersweet (48), black locust
(95), poplars (65), and Deutzia (48) has been improved or hastened by
treatments. Rooting of hardwood cuttings of common privet was not affect-
ed by callusing before treatment (57), but treatment of hardwood cuttings
of pecan and some other species was more effective if cuttings were al-
lowed to callus before treatment (95). Such cuttings rooted, if, immediate-
ly after treatment, they were packed in moist san4 or sphagnum at 68° to
70° F. for a week and then planted in the field (95); and hardwood cut-
tings of apple, grape, and Hibiscus responded to treatments when buried,
after treatment, in damp peat moss at about 75° F. (58).

Deferred Treatment or Re-treatment of Cuttings

Cuttings are usuallj' treated with a root-inducing substance very soon
after they are taken if they are treated at all. If, however, they have not
rooted, either with or without treatment, cuttings of some species may be
removed from the rooting medium and effectively treated, without remov-
ing callus (48), weeks or months after they were first inserted. Such
treatments are called "deferred" if applied for the first time; "re-treat-
ments" if applied for the second time.

Rooting of cuttings of box, Japanese yew, and a variety of Camellia japonica
was improved when treatments were first applied to cuttings six weeks
to five months after they were taken (48). A treatment first applied to
cuttings of American holly after they had remained unrooted in the bench
for eleven weeks was beneficial (101). A first treatment of cuttings of
incense cedar (see page 25) with indolebutyric acid fifteen months after
they were taken was decidedly effective.

Cuttings of some species which respond little or not at all to an initial
treatment will root or root better if re-treated (61). Rooting of cuttings
of Hamlin sweet orange was improved by re-treatment three weeks after
the initial treatment (19). Re-treatment of cuttings of papaya and Camel-
lia (19), after callus had formed on the latter (61), gave similar results.
Other species which responded well to re-treatment are Japanese yew and
Pfitzer's juniper (59).



10 MASS. EXPERIMENT STATION BULLETIN 382

Use of Potassium Permanganate

Potassium permanganate has a decidedly beneficial effect on the rooting of
cuttings of some species. A solution, one pound in fifteen gallons of water,
applied to the rooting medium at the rate of two quarts per square foot,
resulted in better roots on cuttings of twenty-three out of twenty-five
species and in increased percentages of rooting of softwood cuttings of
arrow-wood, dockmackie, flowering dogwood, Tatarian honeysuckle,
Japan quince, dwarf flowering almond, Coriius racemosa, Magnolia Sou-
langeana, Viburnum Carlcsii, Mains atrosauguinca and Philadclphtis coronarius
(14). When potassium permanganate, 18 gm. per square foot, was well
worked into sand-peat before the insertion of cuttings taken here in
October, they rooted as follows:

Percentage Rooting

With Potassium Without
Permang-anate It

Eiionyyniis patens 100 80

Taxus media 93 40

Ilex crenafa 100 60

Thuja occidentalis var. Columbia 86 53

The good effects of potassium permanganate, not due to anj^ soil-
disinfecting action (26), are also marked when it is applied to cuttings of
some species rather than to the rooting medium. Rooting of cuttings of
black-alder, common privet, and Japanese j'^ew was improved by treat-
ment for 24 hours with a solution of one ounce in five gallons water (14),
and treatment of cuttings of Kudzu-vine for thirty minutes with a solution
of one ounce in eight gallons water improved their rooting more than did
treatment with an ordinary root-inducing substance (75).

Cuttings should not be treated with both potassium permanganate and
a root-inducing substance, for the former has a somewhat inactivating
effect on the later (109).

Use of Sugar

Sugar, common table sugar, alone or in combination with a root-inducing
substance, is of benefit in the rooting of cuttings of some species. Treat-
ment for 24 hours with a sugar solution (one pound in seven gallons water)
improved the rooting of cuttings of black-alder, common privet, and Jap-
anese yew (14). October cuttings of ninebark produced longer roots
after treatment with sugar and a root-inducing substance than after treat-
ment with the latter alone (37). Cuttings of white ash and white pine lived
for a longer time if, after treatment with a root-inducing substance, they
were immersed for three days in a 5 percent sugar solution (109). Cut-
tings of Picea glauca var. conica which were taken here in December rooted
39 percent without treatment, 64 percent after treatment (24 hr.) with
indolebutyric acid 50 mg. in one liter of water, 84 percent after that treat-
ment followed by treatment (24 hr.) in 2.5 percent sugar solution, and 84
percent after treatment (24 hr.) in a solution of 50 mg. indolebutyric acid
in one liter of 2.5 percent sugar solution. Cuttings were in all cases well
rinsed in water upon their removal from sugar solutions. Rooting of
November cuttings of Pfitzer juniper and two varieties of Chamaecyparis
obtusa was more improved by treatment for 20 hours with indolebutyric acid



PROPAGATION OF TREES AND SHRUBS 11

50 mg./l. in 2.5 percent sugar solution than by this concentration of the
acid in water. Similar cuttings of Taxus media rooted in equally large percent-
ages after treatment for 17 hours with indolebutyric acid 100 mg./l. in wa-
ter and in the sugar solution, but cuttings given the latter treatment had
better roots. Rooting of cuttings of two varieties of arbor-vitae and three
varieties of Norway spruce, however, was no better after treatment with
solutions containing both sugar (2.5 percent) and indolebutyric acid than
after treatment with a solution of indolebutyric acid only.

Acetic Acid
Vinegar or dilute acetic acid has long been recommended in horticul-
tural literature as a treatment for cuttings or rooting media. It may have
somewhat improved the rooting of cuttings of some species but, if so, the
improvement was probably slight compared with that which, with some
species, results from the use of such growth substances as indolebutyric
acid (3); and in the work of other investigators (48, 113), acetic acid
has been totally inefifective.

Rooting Media

Sand or a mixture of sand and peat moss are most commonly used.
The latter, referred to as sand-peat, sometimes consists of equal parts of
sand and peat moss, but it gave better results and was usually made and
used here in the proportion of sand two parts (by volume, in all cases)
and peat moss one part. There is probably no better rooting medium
than sand-peat for cuttings of ericaceous plants, although, for some
species, their native soil may be as good, and sand-peat is a better rooting
medium than sand for cuttings of the majority of woody plants (58). But
softwood cuttings of many species, including a number of those named
below, have rooted better in sand than in sand-peat.

German peat moss is now practically unobtainable. Some native peats
will do as well, but, lacking both, more use might well be made of sandy
soil. Sandy soil, a mixture of sand two parts and sifted loam one part,
is a good rooting medium for cuttings of some, not all, species of woody
plants (27). It is also sometimes used as a rooting medium for cuttings
of some herbaceous plants, but the risk of attack by soil fungi in that
medium, unsterilized, might be greater with them than with cuttings of
woody plants and only the latter are here considered.

The good effect of loam in a rooting mixture (27) may be due to the
presence of indoleacetic acid (34) or other root-inducing substance. Soil
fungi in an organic medium are known to produce auxin (86), and the
reaction of plants to applied hormones was less marked in good soil than
in sand (34). Nutrients in loam may also be a f?.v.tor. Their application
to sand improved the rooting of cuttings of Norway spruce (36) and a
honeysuckle (40). It is possible too that vitamins are involved. Cut-
tings of Asiatic sweet-leaf and Pfitzer juniper rooted better in the sandy
soil which was used here than they did in sand and these are both species
the cuttings of which responded to applications of vitamins to sand
(98, 103).

It should be noted, in this connection, that Vitamin Bi has had little
if any effect on the rooting of cuttings not previously treated with a root-
inducing substance (103, 109, 114), and that treatment of cuttings with
Vitamin Bi after their treatment with a root-inducing substance did not



12 MASS. EXPERIMENT STATION BULLETIN 382

affect their rooting (50), but that when a solution 1:1,000,000 was used to
water sand in which treated cuttings of Japanese yew and Pfitzer juniper
had been planted twelve days previously, their rate of rooting was sig-
nificantly increased (103). Vitamin B,i, in a solution of 1:5,000,000, sim-
ilarly applied to sand once a week, hastened rooting and caused cuttings
to retain leaves better in the case of about one-third of the species with
which it was used (98).

In anj^ case, or without regard to the explanation, the addition of loam
to sand has a good effect on rooting of cuttings of some species. Whether
or not the results would be even better if the loam were first sterilized
was not determined, but the risk of trouble from that quarter may be
less great than might be expected. It is interesting to note that cuttings
of woody plants sometimes root better in old sand — sand which has been
used for rooting cuttings and is probably contaminated, certainly not
clean — than they do in new, fresh sand (113), and that cuttings of azaleas
(44) and Erica (105) rooted better in a medium in which they had pre-
viously been rooted or grown than in one freshly prepared.

Insertion of Cuttings and Their Subsequent Care

Cuttings are inserted firmly in the rooting medium, usually as deeply as
possible without burying the leaves. Leafy cuttings of most woody plants
are likely to do best if inserted slantingly, not vertically, for, in the slant-
ing position, inore of the leaves are near or upon the rooting medium
where there is less danger of the air being too dry. If there is much top
growth before rooting or transplanting, cuttings so set may not have
straight stems, but that risk is slight except with the most actively grow-
ing material.

To help prevent wilting, cuttings in bench or frame are usually shaded
with cheesecloth or whitewashed glass and sprinkled with water several
times a day, a practice which is likely to give better results than heavier
and less frequent waterings. Good temperatures of the air are 70° to 80°
F. days, 60° to 65° F. nights (130). Bottom heat, 70° to 72,° F. often
hastens rooting (49). It was used here in fall, winter, and spring but,
because of high air temperatures, not in summer. Bottom heat at 70° to
75° F. gave better results than at 80° to 85° F. with cuttings of Japanese
yew and Pfitzer juniper (103), and temperatures of 75° to 80° F. are known
to be too high for best rooting of cuttings of some other species (49;).

The most effective temperatures for rooting treated cuttings are between
70° and 80° F. and root-inducing substances are without much eft'ect if
cuttings, after treatment, are given a low temperature (49, 58), 60° F. or
lower (61).

Treated cuttings need no less care than untreated, although, if treat-
ment is effective, they may not need it for so long a time.

Results with Individual Species

Abelia grandiflora. Softwood cuttings root readily, but treatments with
indolebutyric acid (10 mg./L, 24 hr., or 2 mg./gm. talc) (61) may hasten
rooting. Taken here in early August, they rooted 100 percent in 7 weeks
without treatment, in 4 weeks with treatment (12.5 mg./l., 24 hr.). Root-
ing of July cuttings was similarly hastened by treatment with Hormo-
din (102).



PROPAGATION OF TREES AND SHRUBS 13

Abeliophyllum distichum. Untreated hardwood cuttings which were taken
here in mid-March and immediately inserted in sand-peat rooted 63
percent in 10 weeks.

Abies, fir. February cuttings of Colorado fir, untreated, rooted 60 percent
in peat moss, little or not at all in sand-peat or sand (67). Sandy soil
is the English rooting medium (7). Rooting of winter cuttings of Spanish
fir and Veitch fir was improved by treatment with indolebutyric acid
40 to 80 mg./l., 24 hr., or 12 mg./gm. talc (61). Cuttings of Spanish fir
also responded to treatment with 10 to 20 mg./cc. applied by the con-
60 percent without treatment (87).

Acanthopanax Sieboldianits. Late June cuttings rooted 7Z percent in 27 days
after treatment with indolebutyric acid (20 mg./l., 24 hr.), not at all mean-
while without treatment (57). August cuttings rooted 50 percent in 55
days without treatment, 80 percent with treatment (100 mg./l., 20 hr.) (83).

Acer, maple. Hardwood, late November, cuttings of silver maple which
were buried in a cool place until February and then planted in sand at 72° F.
rooted 84 percent (52). Hardwood, late winter or early spring, cuttings of
A. barbinerve, A. caudatum, A. cissifolium, A. rufinei-ve, and A. Tschonoskii
rooted 20 to 80 percent in 4 to 9 weeks in sand at 70° to 74° F., bottom
heat (111).

The best time to take softwood cuttings of maples is probably late spring
and early summer. Cuttings of Acetr argiituin, A. barbino've, box-elder, and
Japanese maple which were taken, with a heel, when oldest leaves were
no more than half grown rooted 35 to 100 percent in sand in 18 to 60
days (111). Such cuttings responded to treatments with indolebutyric
acid. Equivalent concentrations for June cuttings of Japanese maple are
2 to 5 mg./gm. talc or 10 to 40 mg./l., 24 hr. (49). Early July cuttings
of red maple rooted 60 percent after treatment (20 mg./l., 24 hr.), not
at all without it (1). June cuttings of silver maple rooted 85 percent
after treatment (50 mg./l., 32 hr.), not at all without it (65). June cut-
tings from very young Norway maples responded slightly to treatment
with indoleacetic acid (100 mg./l., 24 hr.) (109). Cuttings of sugar maple,
taken in early summer, rooted 100 percent in sand-peat in 40 days after
treatment with indoleacetic acid (10 mg./l., 48 hr.), 33 percent without
ireatment (87). Snow (92) took cuttings of sugar maple from young
trees, made them four inches long with all leaves but the upper removed,
and set them deeply in sand-peat in an outdoor propagating frame. By
the end of summer, the cuttings which he took in mid-June had rooted
25 to 36 percent without treatment and about 66 percent after treatment
with indolebutyric acid (50 mg./l., 3 hr. ). Results were decidedly less
good with cuttings taken in July.

Actinidia. Cuttings are taken in summer and fall. September cuttings of
A. arguta, in sand, rooted 86 percent in one month after treatment with indole-
butyric acid (5 mg./l., 24 hr.), 42 percent without it (96). Equivalent con-
centrations for treatment of December cuttings are 20 to 40 mg./l., 24 hr. ;
4 to 10 mg./gm. talc; or, by the concentrated solution-dip method, 1 to 4
mg./cc. (49). July cuttings of A. chinensis, in sand-peat, rooted 100 per-
cent in 40 days after treatment with indoleacetic acid (100 mg./l., 48 hr.),
60 percent without treatment (87).

Ahius, alder. Cuttings, which do not root very readily, are taken in autumn
as soon as the leaves fall and inserted in sandy soil (7).



14 MASS. EXPERIMENT STATION BULLETIN 382

Amelanchier, shadbush, is not easily propagated by cuttings (51). Soft-
wood, summer cuttings of one species rooted 25 percent after treatment with
indoleacetic acid (50 mg./I., 24 hr.), 8 percent without it (65). There is
some evidence that A. canadensis can be propagated by hardwood cuttings
taken in April and set in a solar frame (85).

Amorpha fruticosa. Softwood, July cuttings, made with the basal cut at
a node and planted untreated in sand, rooted 100 percent (116).

Andromeda, bog-rosemary. Untreated cuttings of A. glaucophylla and
A. Polifolia which were taken here in January rooted 100 percent in 8 weeks
in sand-peat, less well in sand, and treatments with root-inducing sub-
stances were without effect.

Airctostaphylos Uva-ursi, bearberry. Untreated cuttings taken here in Jan-
uary rooted 86 percent in sand in 12 weeks. February cuttings rooted
best, about 90 percent in 74 days, wlien multiple terminal cuttings (those
having three or more shoots on one branch) were treated and inserted in
sand-peat with bottom heat at 76° F. (22). Treated October cuttings
rooted better if made of basal parts of shoots rather than of their tips (48).
Effective concentrations of indolebutyric acid are 40 mg./l., 24 hr., or
12 mg./gm. talc (61).

Aristolochia. September cuttings of one species, untreated, rooted 75 per-
cent in sand in 26 days (98). Dutchman's pipe is more readily propagated
by softwood, summer, than by hardwood cuttings (80).

Aronia, chokeberry. Softwood, summer cuttings of red chokeberry root in
good percen*^ages (42). Cuttings of that species and of black chokeberry
gave best results when the basal cut was made a half inch below a
node (14).

Berberis, barberry. Cuttings are taken in summer or fall. August cuttings
of B. Thunbcrgii (44), the basal cut a half-inch above the base of the current
season's growth (46), root readily in sand-peat. Cuttings of evergreen species
may well be taken later than those of the deciduous (105). There was 100
percent rooting of untreated cuttings of B. candidida and B. triacanthophora
which were taken here in late November and inserted in sandy soil, the
medium used for barberry cuttings in England (7, 105). December cuttings
of B. verruculosa rooted well in sand (67). Rooting of July cuttings of that
species was at least hastened by indolebutyric acid (83). Cuttings of B.
Sargentiana rooted 80 percent in 51 days after treatment with indolebutyric
acid (50 mg./l., 24 hr.), 60 percent without it (72). Hormodin No. 2 im-
proved rooting of cuttings of B. Julianae (102).

Betula. Birches are not easy to propagate by cuttings (73), but treated
softwood cuttings will root to some extent. Summer cuttings of European
birch rooted 25 percent after treatment with indoleacetic acid (50 mg./l.,
32 hr.), not at all without it (65). Cuttings of gray birch taken in July,
with the tenninal buds and all but one or two square inches of leaf area
removed, rooted 30 percent after treatment with indolebutyric acid (50
mg./l., 6 hr.); and cuttings of canoe birch rooted 50 percent after treat-
ment with indolebutyric acid (20 mg./l., 24 hr.) (1).

Buddleia, butterfly bush, is easy to propagate by cuttings. Taken here in
late June or early July and inserted untreated in sand, cuttings of B. alterni-
folia rooted 83 percent and cuttings of B. Davidi rooted 100 percent. Treat-
ment with indolebutyric acid (33 mg./l.. 24 hr.) hastened the rooting of June
cuttings of B. alt ernif alia (114).



PROPAGATION OF TREES AND SHRUBS 15

Buxus, box. Untreated summer (67), fall (44, 125). or winter cuttings of
B. sempervirens root very readily in sand (105, 125) or sandy soil (127).
Rooting of July (57), October (125), and February cuttings of B. sempervirens
was hastened by treatment but not otlierwise affected. Optimum concentra-
tions of indolebutyric acid are 40 mg./l., 24 hr., for that species and 20 mg./l,
24 hr., for B. microphylla, or 12 mg./gm. talc fcur either (61).

Callicarpa is easy to propagate by both softwood and hardwood cuttings.
Hardwood cuttings of C. dichotoma taken here in early January rooted 100
percent in sandy soil in two months without treatment and in one month after
treatment with indolebutyric acid (40 mg./l., 18 hr.). Untreated summer
cuttings of that species root in high percentages in sand (44, 125), but root-
ing of August cuttings was hastened by treatment with indolebutyric acid
either in talc or 5 mg./l., 24 hr. (96). Late June cuttings of C. Bodinieri
rooted 100 percent in 20 days after treatment (5 or 10 mg./l, 24 hr.) (57).
Tips of shoots of C. japonica gave better results (59) and responded better to
low concentrations than did cuttings made of basal parts (48).

Calluna vidgaris, heather. Summer, fall, and winter cuttings root well with-
out treatment. Untreated cuttings taken here in September, November,
and January rooted 90 to 100 percent in sand-peat in 6 to 8 weeks, more
slowly or less well in sand or sandy soil. Optimum concentrations of
indolebutyric acid are 20 to 40 mg./l., 24 hr., or 12 mg./gm. talc (61).

Camellia japonica is not very difficult to propagate by cuttings taken in July,
or when new growth is only moderately hard, and planted in sand-peat
(30). Cuttings of the variety alba plena are less easy to root, but cuttings
of some other varieties root readily enough after treatment (49) with
indolebutyric acid 40 to 80 mg. /L, 24 hr., 12 mg./gm. talc (61), or 4 to 10
mg./cc. b\- the concentrated solution-dip method (49). July cuttings
rooted 100 percent in 10 weeks after treatment (100 mg./l., 24 hr.) (114).
Stevens* got equally good rooting of cuttings made of somewhat harder
wood following treatment with indolebutyric acid (60 mg,/l., 24 hr.). He
got better rooting in sand-peat than in sand, better rooting with bottom
heat at 70° to 75° than at 60° F.

Caragana. Late July cuttings of pea-tree, treated or not, rooted more than
80 percent in sand (102). Equivalent concentrations of indolebutyric acid for
May cuttings of C. Boisii are 10 mg./l., 24 hr., or 4 mg./cc. bj- the concen-
trated solution-dip method, or 2 to 5 mg./gm. talc (49).

Ca-rya Pecan, pecan. Hardwood, early April, cuttings of the variety Posey,
made of wood two to four years old, were allowed to callus in moist
sphagnum at 68° to 78° F. for about three weeks, then treated with in-
dolebutyric acid (100 mg./l., 24 hr.) and set in sand at 70° F. bottom
heat, where large cuttings, a half inch in diameter, rooted 63 percent (95).
Smaller cuttings rooted less well and there was no rooting of the un-
treated. Equivalent concentrations for treatment of such cuttings are
40 mg./l., 24 hr., or 2 to 12 mg./gm. talc (49).

Catalpa. These can be propagated by softwood, summer cuttings in sand



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