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VOLUME 36
NUMBER 3
BLUEBERRY
CULTURE
SUPPLEMENT TO
FLORIDA QUARTERLY BULLETIN OF THE
DEPARTMENT OF AGRICULTURE
JULY, 1926
NATHAN MAYO
Commissioner of Agriculture
Tallahassee, Florida
Artcraft Printers, Tallahassee. Florida
DIRECTIONS FOR BLUEBERRY CULTURE, 1921*
By FREDERICK V. COVILLE, Botanist
Bulletin 974, U. S. Dept. Agr.
EARLY EXPERIMENT WITH BLUEBERRIES
The experiments which have led to the present publica-
tion were begun in 1906. The work of the first four years
resulted in a publication entitled "Experiments in Blue-
berry Culture," issued in 1910.** This work was widely
distributed, and a copy came into the hands of Miss Eliza-
beth C. White, New Lisbon, N. J. Miss White at once
perceived the significance of the experiments and the im-
portance of testing their application to the waste lands
surrounding her father's cranberry bogs. An informal
agreement of co-operation resulted. In 1913 this was
replaced by a formal contract, the object of which was to
provide suitable conditions for a field test of the blueberry
hybrids produced in the course of the experiments at
Washington, D. C. The location of the testing plantation
is at Whitesbog, four miles east of Browns Mills, N. J., in
the sandy, peaty, acid soil of the pine barrens. Up to the
present time sixteen acres have been planted with 27,000
different hybrid seedlings. Thus far, about 18,000 of
these hybrids have been fruited and four of them have
been selected and approved as worthy of introduction
into agriculture. Propagation material from these four
hybrids has been placed in the hands of nurserymen for
commercial propagation.
Miss White has also brought together at Whitesbog a
very remarkable collection of selected wild mulberry
plants. Several of these have been used as breeding
stocks in the blueberry development work carried on by
the department.
In the present bulletin are included such results of the
experiments and experience at Washington, Whitesbog,
and other points as constitute a brief practical guide for
persons desiring to take up blueberry culture.
*Revised by the writer from "Directions for Blueberry Culture, 1916," which
was published as United States Department of Agriculture Bulletin 334.
**The publication mentioned, issued as Bulletin No. 193 of the Bureau of
Plant Industry, gave a detailed account of the principles of blueberry culture,
including the soil requirements and peculiarities of nutrition of the blueberry
plant and the details of the growing of seedlings. It contained 100 pages of
text, with 18 plates and 31 text figures. It was reissued in 1911. Both editions
are now out of print.
SPECIAL REQUIREMENTS
Success in blueberry culture rests especially on the
recognition of two peculiarities in the nutrition of these
plants: (1) Their requirement of an acid soil; (2) their
possession of a root fungus that appears to have the bene-
ficial function of supplying them with nitrogen.
If blueberries are planted in a soil with an alkaline or
neutral reaction, such as the ordinary rich garden or
fertile field, it is useless to expect their successful growth.
In such a situation they become feeble and finally die.
Blueberries require an acid soil, and they thrive best in
that particular type of acid soil which consists of a mix-
ture of sand and peat.t
Good aeration of the soil is another essential. It is
commonly but erroneously supposed that the highbush or
swamp blueberry (Vaccinium corymbosum), the species
chiefly desirable for cultivation, grows best in a perma-
nently wet soil. It is to be observed, however, that the
wild plants of the swamps occupy situations which,
though perhaps submerged in winter and spring, are ex-
posed to the air during the root-forming period of summer
and autumn; or, when growing in permanently sub-
merged places, they stand on a hammock or in a cushion
of moss which rises above the summer water level and
within which the feeding roots of 'the bush are closely
interlaced. In actual culture, moreover, it has been found
that the swamp blueberry does not thrive in a perma-
nently wet or soggy soil.
Although some species of Vaccinium, such as the com-
mon lowbush blueberry of the northeastern United States,
Vaccinium angustifolium (called V. pennsylvanicum by
some authors), grow and fruit abundantly in sandy up-
lands that are not subject to drought, the swamp blue-
berry grows best in soils naturally or artificially supplied
with adequate moisture.
These, then, are the three fundamental requirements of
successful blueberry culture: (1) An acid soil, especially
one composed of peat and sand; (2) good drainage and
thorough aeration of the surface soil; and (3) permanent
tThe degree of soil acidity best suited to blueberries is about specific acidity
100, corresponding to a hydrogen ion concentration, Ph.5. See a paper by
Edgar T. Wherry, "Soil Acidity and a Field Method for Its Measurements,"
published in the technical Journal Ecology, vol. 1, pp. 100 to 173, July, 1920,
with a colored plate. The same subject is treated more fully by Dr. Wherry
in the general appendix to the Smithsonian Report for 1920, also with a
colored plate, under the title "Soil Acidity -Its Nature, Measurement, and
Relation of Plant Distribution."
but moderate soil moisture. Under such conditions the
beneficial root fungus which is believed to be essential
to the nutrition of the plant need give the cultivator no
concern, for even if the necessary fungus were wholly
lacking in the soil of the new plantation each healthy
bush set out in it would bring its own supply of soil-
inoculation material.
Next in importance to soil conditions is a convenient
location with reference to a good market. The berries
should reach their destination without delay, preferably
early in the morning following the day of picking. To
secure the best prices they should also reach the market
before the height of the main wild blueberry season. A
situation to the south of the great areas of wild blue-
berries in northern New England, Canada, and northern
Michigan is therefore desirable. One of the most promis-
ing districts for blueberry culture is the cranberry region
of New Jersey, for there an ideal soil occurs in conjunc-
tion with an early maturing season and excellent ship-
ping facilities to the markets of Philadelphia and New
York.
Situations liable to late spring freezes, such as the
bottoms of valleys, should be avoided, for although the
blueberry plant itself is seldom permanently injured by
such a freeze, its crop of fruit may be destroyed.
It has been observed that in or around bodies of water,
such as cranberry reservoirs or cranberry bogs tempor-
arily flooded to prevent frost or insect injury, the wild
bushes often produce normal crops of blueberries in
season in which the wild crop of upland blueberries has
been destroyed by late spring freezes. Proximity to such
bodies of water is evidently advantageous.
In regions subject to very low temperatures a blanket
of snow sufficiently deep to cover the bushes often pro-
tects them completely, when twigs not covered by the
snow are winter-killed. In the very cold February of
1918 the fruiting twigs of lowbush hybrids at Whitesbog,
N. J., unprotected by snow, were killed by temperatures
of about 120 F. below zero. Both parents of these hybrids
were uninjured at Greenfield, N. H., where the tempera-
ture went down to 30 below zero, but the plants there
were covered with deep snow. Another observation made
in the same season on Crotched Mountain, N. H., merits
attention in this connection. Wild blueberry bushes 6 to
7 feet high, the tops of which projected through the snow,
bore no fruit on the exposed tops in the following summer,
while the sides and bases of the same bushes, which had
been covered with snow, yielded the usual abundance of
berries. The dead fruit buds still remained on the winter-
killed twig tips at the exposed tops of the bushes.
IMPORTANCE OF SUPERIOR VARIETIES
In the southern United States and in the Middle West
blueberries are not ordinarily distinguished from huckle-
berries, but in New England the distinction is very clearly
drawn. The name huckleberry is there restricted to
plants of the genus Gaylussacia, the berries of which con-
tain ten large seeds with bony coverings like minute
peach pits, which crackle between the teeth. The name
blueberry is applied in New England to the various
species of the genus Vaccinium, in which the seeds,
though numerous, are so small that they are barely
noticeable when the berries are eaten. It is probable
that the comparatively low estimation in which this fruit
is held in the South is largely due to the lack of a dis-
tinctive popular name and the consequent confusion of
the delicious small-seeded southern Vacciniums with the
coarse large-seeded Gaylussacias. It is the culture of the
small-seeded blueberries only, as distinguished from the
large-seeded huckleberries, that is here advocated.
From the market standpoint the features of superiority
in a blueberry are sweetness and excellence of flavor;
large size; light-blue color, due to the presence of a dense
bloom over the dark-purple or almost black skin; "dry-
ness," or freedom from superficial moisture, especially
the fermenting juice of broken berries; and plumpness-
that is, freedom from the withered or wrinkled appear-
ance that the berries begin to acquire several days after
picking.
Although blueberry plantations may be formed by the
transplanting of unselected wild bushes or by the grow-
ing of chance seedlings, neither of these courses is advo-
cated, because neither would result in the production of
fruit of an especially superior quality. Seedling plants,
even from the largest berried wild plants, produce small
berries as often as large ones. The cultivator should
begin with the purchase of a few plants of selected hybrid
varieties or by the transplanting of the best wild bushes,
selected when in fruit for the size, color, flavor and earli-
ness of the berry and the vigor of productiveness of the
bush. These he should propagate by layering, by division
and by cuttings. Through a combination of these methods
a valuable old plant can often be multiplied by several
hundred at one propagation, the fruit of the progeny re-
taining all the characteristics of the parent.
In making selections among wild bushes it is an excel-
lent plan to preserve for future reference about a dozen
of the largest berries in a tightly stoppered wide-mouthed
bottle containing a mixture of 1 part of formalin, or 40
per cent formaldehyde, to 15 parts of water. Each bottle
should contain berries from only a single bush, or, in the
case of a plant that spreads by the root, from a single
patch. Care should be taken not to rub the delicate
"bloom" from the berries. A small twig bearing two or
three leaves, from the same plant from which the berries
were taken, should also be placed in the bottle. The
Department of Agriculture would be glad to receive such
samples and identify them for the sender. Some of the
bushes thus located might prove to be of value in the blue-
berry breeding work of the department.
Great interest has developed recently in Florida on the
subject of blueberry culture. Extravagant and mislead-
ing statements have been published and thousands of
ordinary wild bushes have been sold at high prices, the
purchasers being led to believe that the plants were of
specially selected or adapted varieties. One company,
located near Tampa, published as the frontispiece of a
blueberry advertising pamphlet a natural-size illustration
of a quart box of one of the United States Department of
Agriculture selected hybrids, without designating it as
such. The reader of the pamphlet would naturally be-
lieve that the bushes the firm was selling would produce
such berries as were shown in the illustration. The real
success of a- single blueberry plantation near Crestview,
in northwestern Florida, set with selected plants from the
near-by woods, is chiefly responsible for the present wave
of blueberry exploitation in that State. The best advice
that can be given at present to those desiring to experi-
ment with the blueberry culture in Florida is to make
certain that any plants they buy are as represented by
the seller, to be sure that alleged improved varieties are
not in reality ordinary wild blueberries, perhaps inferior
to wild bushes that the purchaser might find in his own
neighborhood by 'careful search. The selected hybrids
described in this bulletin are of northern parentage and
probably will not thrive in Florida because Florida win-
ters are not sufficiently cold to give these plants the chill-
ing they require in winter.ff The United States Depart-
ment of Agriculture has already begun the breeding of
improved blueberries from species native in Florida, but
it greatly desires better southern breeding stock than it
now possesses. Those interested in the advancement of
blueberry culture in Florida are especially urged to make
selections among their wild blueberries in accordance
with the general directions given in the two preceding
paragraphs.
PROPAGATION
While grafting or budding is almost indispensable in
experimental work with blueberries, bushes propagated
by these methods are not suitable for permanent com-
mercial plantations, because such bushes are continually
sending up new and undesirable shoots from the stock.
Budding, however, is the best known means of producing
a large quantity of cutting wood from a valuable selected
blueberry hybrid. It is useful also in testing the quality
of a new variety, for a budded blueberry when properly
handled comes into bearing two years from the time of
budding and doubtless will continue to yield for several
years, until the budded stem becomes old and decrepit.
BUDDING
The best season for budding the blueberry is from the
middle of July to the middle of August. The ordinary
method of shield budding, with a T-shaped cut and dry
and unwaxed raffia wrapping, has proved the most suc-
cessful of all the methods tried. In selecting budwood,
attention should be paid to the following points: A bud
forms at the base of each leaf; at first the scales covering
the bud are green; when they are a little older they be-
come straw-colored, and later brown. When the buds
have reached this brown stage they are of the proper age
for use. All three stages may occur at the same time on
a single branch, and in such a case the upper part of
ttFor an account of the experiments that led to this conclusion, see "The
Influence of Cold in Stimulating the Growth of Plants," published in the
Journal of Agriculture Research for October 15, 1920, vol. 20, pp. 151 to 160,
with 16 plates.
This and other methods of budding are described in Farmers' Bulletin 157.
"The Propagation of Plants," by L. C. Corbett.
probably will not thrive in Florida because Florida win-
ters are not sufficiently cold to give these plants the chill-
ing they require in winter.ff The United States Depart-
ment of Agriculture has already begun the breeding of
improved blueberries from species native in Florida, but
it greatly desires better southern breeding stock than it
now possesses. Those interested in the advancement of
blueberry culture in Florida are especially urged to make
selections among their wild blueberries in accordance
with the general directions given in the two preceding
paragraphs.
PROPAGATION
While grafting or budding is almost indispensable in
experimental work with blueberries, bushes propagated
by these methods are not suitable for permanent com-
mercial plantations, because such bushes are continually
sending up new and undesirable shoots from the stock.
Budding, however, is the best known means of producing
a large quantity of cutting wood from a valuable selected
blueberry hybrid. It is useful also in testing the quality
of a new variety, for a budded blueberry when properly
handled comes into bearing two years from the time of
budding and doubtless will continue to yield for several
years, until the budded stem becomes old and decrepit.
BUDDING
The best season for budding the blueberry is from the
middle of July to the middle of August. The ordinary
method of shield budding, with a T-shaped cut and dry
and unwaxed raffia wrapping, has proved the most suc-
cessful of all the methods tried. In selecting budwood,
attention should be paid to the following points: A bud
forms at the base of each leaf; at first the scales covering
the bud are green; when they are a little older they be-
come straw-colored, and later brown. When the buds
have reached this brown stage they are of the proper age
for use. All three stages may occur at the same time on
a single branch, and in such a case the upper part of
ttFor an account of the experiments that led to this conclusion, see "The
Influence of Cold in Stimulating the Growth of Plants," published in the
Journal of Agriculture Research for October 15, 1920, vol. 20, pp. 151 to 160,
with 16 plates.
This and other methods of budding are described in Farmers' Bulletin 157.
"The Propagation of Plants," by L. C. Corbett.
the branch should be discarded. A bud is more easily
handled if the tiny leafstalk is left attached to it. Pro-
vision for this is easily made by cutting off the blades, but
not the stalks, of the leaves when the branches that are
to be used for budwood are removed from the parent
bush. Care should be taken to discard the large fat flow-
ering buds that occur toward the ends of the branches.
In most blueberry plants, however, these flowering buds
do not develop until after the budding season.
When blueberry buds are to be inserted the same day
on which the budwood is cut, the sticks require no other
treatment than to be kept in the shade of the folds of a
moist, clean towel. The budwood is easily ruined, how-
ever, by continued subjection to the high temperatures
prevalent at the midsummer budding season. Any bud-
wood that has been cut should therefore be kept on ice at
night or at any other time when it is not in actual use.
In carrying blueberry budwood long distances, excel-
lent results have been secured by the use of a thermos
bottle. The bottle, opened, and the budwood, in clean,
moist wrappings and with additional moist packing ma-
terial, should be kept on ice for several hours until thor-
oughly chilled. Just before the journey is to begin the
chilled budwood and packing material is placed in the
bottle and the bottle closed. Immediately on arrival at
its destination the bottle should be opened and the con-
tents kept chilled in an ice box until used. By this method
blueberry budwood has been kept in perfect condition for
more than a week, and probably that period can be much
prolonged.
The best wood on.which to bud is the lower portion of
vigorous basal shoots of the season, especially those from
plants that were cut to the stump in the preceding winter
or early spring. On such shoots the bark can be lifted
with ease much later in the season than on older stems.
In taking the bud from the stick of budwood the cut is
made just deep enough to leave a thin layer of wood
attached to the middle of the bud slice. The raffia should
be tied rather tightly, so that the juice almost begins to
be squeezed from the soft bark. Special care should be
taken that the raffia wrapping does not become wet and
fermentation ensue between the raw surfaces of bud and
stock. Plants budded in a greenhouse should therefore
be watered on the surface of the ground, not on the
foliage. In the case of outdoor plants liable to be wet by
the rain the bud wrappings can be effectually protected
by the use of a piece of strong paraffined paper about six
inches square made into a little cone about the stem just
above the bud wrappings and securely tied there with
raffia, the lower part of the cone hanging down around
the stem like a little skirt, keeping the rain away from
the bud and its wrappings.
Union of the bud with the stock should take place in
two to three weeks. As soon as the budded stem has
increased in diameter sufficiently to cause pronounced
choking by the raffia, all the wrappings should be re-
moved. Otherwise the choked stem may be broken off
by the wind. If choking does not occur the wrapping
may be allowed to remain until spring.
Before growth begins in the following spring the stem
is cut off above the inserted bud, which is still dormant.
Only the inserted bud should be allowed to grow, all
other growth from the stock being promptly rubbed off
as soon as it starts. Under this treatment the shoot from
the inserted bud is very succulent and heavy, and a wind
easily breaks it from the stock. To prevent this, the
growing shoot, beginning at a length of 6 to 8 inches,
should be tied at intervals to a strong stake.
In greenhouse experiments a growth of more than 8
feet has been obtained in the first season from an inserted
bud on a vigorous plant, and when the shoot has been
made to branches repeatedly by removing the growing
tips, as many as 70 cuttings have been produced the first
year from a single valuable bud. In field practice at
Whitesbog about 10 cuttings on the average are produced
the first year from a single inserted bud, and in individual
cases as many as 30 have been produced.
STUMPING
The easiest way to propagate the swamp blueberry is
by a special process of layering called "stumping." The
directions are as follows:
(1) In late fall, winter, or spring, preferably in early
spring before the buds have begun to push, cut off at the
surface of the ground either the whole of the plant or as
many of the stems as it is desired to devote to this method
of propagation. The stems that are cut off are discarded,
or they may be used for cuttings, as described under
"Tubering" or "winter cuttings."
(2) Cover the stumps to the depth of 2 to 3 inches
with a mixture of clean sand and sifted peat, two to four
parts of sand to one of peat by bulk. A rough box or
frame may be built on the ground to keep the sand bed
in place.
(3) Care must be taken that the sand bed be not al-
lowed to become dry except at the surface during the
summer.
(4) The new growth from the stumps, which without
the sand would consist of stems merely, is transformed in
working its way through the sand bed into scaly, erect or
nearly erect rootstocks which on reaching the surface of
the sand continue their development into leafy shoots.
Although roots are formed only sparingly on the covered
bases of stems, they develop abundantly during spring
and early summer on these artificially produced root-
stocks, and by the end of autumn all the shoots should be
well rooted at the base. They should remain in place in
the sand bed till winter or early spring, undisturbed and
exposed to outdoor freezing temperatures; but the sand
should be mulched with leaves, preferably those of red
oaks, to prevent heaving in freezing weather and to main-
tain an acid condition of the soil.
(5) Early in the following spring, before the buds have
begun to push, open the bed and sever each well-rooted
shoot carefully from the stump. Discard the upper por-
tion of the shoot, making the cut at such a point as to
leave on the basal portion about three buds above the
former level of the sand bed. If the cut at the basal end
of the rooted shoot is not smooth or the wood is cracked,
recut the surface with a sharp thin-bladed knife. The
discarded upper portion of the shoot may be used for
winter cuttings.
(6) Set the rooted shoots in a cold frame or a cool
greenhouse in a soil mixture consisting of two parts, by
bulk, of rotted upland peat and one part of clean sand.
The plants may be set in individual pots if the propagator
prefers, the pots being bedded to the rim in the sand.
(7) Cover the frame with muslin or other white shade
suspended above the glass, giving the plants plenty of
light but little or no direct sunlight, and for the first two
or three months keep the temperature at not to exceed
65 F. if practicable. When subjected to high tempera-
tures the newly cut shoots are liable to die and rot from
the base upward.
(8) Watering should be as infrequent as practicable,
only sufficient to keep the soil moist but well aerated, not
soggy.
(9) The frame should receive ventilation, but not
enough to cause the new twigs to droop. These are most
susceptible to over-ventilation and to over-heating when
they have nearly completed their growth.
(10) After the new twigs have stopped growing and
their wood becomes hard, new root growth takes place.
Then secondary twig growth follows, either from the
apex of the new twigs or from another bud lower down
on the old wood of the original rooted shoot. Until this
secondary twig growth takes place the life of the plant is
not assured.
SOIL MIXTURES FOR BLUEBERRIES
A very successful potting mixture or nursery-bed mix-
ture for blueberry plants consists of one part, by measure,
of clean or washed sand, nine parts of rotted upland peat,
either chopped or rubbed through a seive, and three parts
of clean, broken crocks-that is, pieces of ordinary un-
glazed, porous, earthenware flower pots. No loam, and
especially no lime, should be used. Manure is not neces-
sary, and in the present state of our knowledge may be
regarded as dangerous, although in small quantities it
serves to stimulate the plants, at least temporarily. The
danger from manure apparently lies in its tendency to
injure the beneficial root fungus of the blueberry plant.
The use of broken crocks in the potting mixture is based
on the fact that the rootlets seek them and form around
them the same kind of mats that they form at the wall of
the pot, thus increasing the effective root surface and the
vigor of growth. If crocks are not available, the soil
mixture should consist of two to four parts of peat to one
part of sand.
The peat most successfully used for potting blueberry
plants is an upland peat procured in kalmia, or laurel,
thickets. In a sandy soil in which the leaves of these
bushes and of the oak trees with which they- usually grow
have accumulated and rotted for many years, untouched
by fire, a mass of rich leaf peat is formed, interlaced by
the superficial rootlets of the oak and laurel into tough
mats or turfs, commonly two to four inches in thickness.
The turfs, ripped from the ground and rotted from two
to six months in a moist but well-aerated stack, make an
ideal blueberry peat. A good substitute is found in sim-
ilar turfs formed in sandy oak woods having an under-
brush of ericaceous plants other than laurel. The tufts
of lowbush blueberries serve the same purpose admir-
ably. Oak leaves raked, stacked and rotted for about
eighteen months without lime or manure are also good.
The leaves of some trees, such as maples, rot so rapidly
that within a year they may have passed from the acid
condition necessary for the formation of good peat to the
alkaline stage of decomposition, which is fatal to blue-
berry plants. Even oak leaves rotted for several years
become alkaline if they are protected from the addition
of new leaves bearing fresh charges of acidity. The
much decomposed peat in the submerged lower layers of
deep bogs, such as is used for fuel in Europe, is not suit-
able for blueberry-soil mixtures.
TUBERING
By ordinary methods cuttings of the swamp blueberry
could at first be rooted only in occasional instances. Suc-
cessful special methods, however, were afterwards de-
vised for these plants. The most novel of the methods
devised, but the one easiest of operation, is that of tuber-
ing. This method involves the same principle as that
employed in stumping, namely, the forcing of new shoots
in such a manner that their basal portions are morpho-
logically scaly rootstocks, with a strong rooting tendency.
The directions for tubering as applied to the swamp blue-
berry are as follows:
(1) Make stem cuttings from outdoor plants between
midwinter and early spring, before the buds have begun
to make their spring growth, and preferably on a warm
day when the twigs are not frozen. A still better plan is
to make the cuttings in autumn after the leaves have
fallen, and store them for about two months in moist
sphagnum moss or clean basswood sawdust on ice at a
temperature just above freezing.
For a fuller discussion of the conditions under which leaves decompose
into leaf peat as distinguished from leaf mold, and the fundamentally different
effect of the two on the growth of plants, consult "The Formation of Leaf-
mold," Smithsonian Report for 1913, pp. 333 to 343 (also separately printed).
(2) The cuttings are to be made from vigorous plants
grown in well-lighted situations and with stems therefore
well stored with starch. Use unbranched portions of the
old and hardened branches and stems, about a quarter of
an inch to an inch, or even more in diameter. From 3 to
4 inches is a suitable and convenient length. Make the
cuts with pruning shears or a fine-toothed saw and re-
move the bruised wood at the cut ends with a sharp knife.
Be careful not to injure the bark or split or strain the
wood.
(3) Lay the cuttings horizontally in a box about eight
inches deep in a bed of pure clean sand and cover them
to the depth of about three-quarters of an inch with a
mixture of sifted rotted peat (two parts) and clean sand
(one part). Or the whole bed may be composed of sand
mixture with about an equal bulk of peat. Or the bed
may consist of a mixture of basswood sawdust and peat,
described under "Winter Cuttings." Moisten the bed
well with rain water, bog water, or other pure water (free
from lime) from a springling pot, and see that the bed is
closely and firmly packed about the cuttings. Cover the
box or cutting bed with a pane or panes of glass, the top
of the box being flat, so that the glass fits it rather snugly.
The box should be so prepared that any surplus water
will drain away beneath through holes in the bottom cov-
ered with clean broken crocks and sphagnum moss.
(4) Keep the box at a temperature of 550 to 650 F., or
as near those limits as practicable. A temperature of 700
or above is likely to ruin the cuttings.
(5) To avoid excessive temperatures, do not allow
direct sunlight upon the glass, either keeping the box by
north light or keeping it shaded, as by a white cloth or
paper cover suspended several inches above the glass, or
in a shaded greenhouse.
(6) Keep the air over the bed saturated with moisture.
This condition will be evidenced by the condensation of
the moisture on the under side of the glass during the
cooler part of the day or whenever a cold wind blows
against the glass.
(7) Watering should be as frequent as practicable,
only sufficient to keep the cutting bed moist but well
aerated and the atmosphere above it saturated. If the
glass fits tightly, a second watering may not be needed
for several weeks.
(8) Within a few weeks new growth will begin to
appear above the soil. When the shoots have reached
a length proportionate to their vigor, commonly 1 to 3
inches, their further growth is self-terminated by the
death of the tip. After the leaves have reached their full
size and acquired the dark green color of maturity, the
time has come for the development of roots.
(9) The new growth, which if it had originated above
the bed would be like an ordinary shoot, was transformed
in working its way through the soil and become a scaly,
erect rootstock, which on reaching the surface of the bed
continued its development into a leafy shoot. During the
spring and early summer roots form in abundance on the
lower or rootstock portion of these shoots.
(10) After a shoot is well rooted it commonly, though
not invariably, makes secondary twig growth the same
season, usually from a bud in the axil of the uppermost
leaf. If the rooting of the shoot has not already been
ascertained by direct examination, the making of such
secondary growth is good evidence that rooting has actu-
ally taken place.
(11) When a shoot is well rooted, with 1 to 2 inches
in length, it is ready to be potted. If the shoot has not
already disconnected itself from the dead cutting it
should be carefully severed with a sharp knife. In the
process of tubering the behavior of the cuttings is essen-
tially identical with that of real tubers, like those of the
potato. The original cutting dies, but the sprouts that
arose from it root at the base and form independent
plants.
(12) The rooted shoots should be potted in clean
2-inch earthenware pots in the standard blueberry-soil
mixture already described.
(13) The pots should be bedded in moist sand up to
the rim in a glass-covered frame or box, well lighted, but
protected from direct sunlight and slightly ventilated,
but with a saturated or nearly saturated atmosphere.
(14) To obtain rapid growth, gradually accustom the
rooted plants to a well-ventilated atmosphere and then to
half sunlight, this adjustment extending over a period of
about three or four weeks.
(15) If preferred, the rooted shoots may remain in the
original cutting bed until the following spring, the cutting
bed being exposed during the winter to freezing tempera-
tures, but mulched with oak leaves, and the plants may
then be transferred, with their whole root mat intact, to
a peat and sand nursery bed at a spacing of about a foot
each way.
Where propagating is to be done on a sufficiently large
scale, outdoor coldframes may be used instead of cutting
boxes. At Whitesbog the process of tubering has been
carried on with great success in muslin-shaded cold-
frames, and the handling of the cuttings, both before and
after rooting, has been much simplified. The cuttings are
made in the fall, packed in boxes in loose, moist, clean
sphagnum moss or basswood sawdust, and stored during
the winter in a cool cranberry house at a temperature of
about 400 F. As soon as the frost is out of the ground
beds of clean sand are laid down in the coldframes, and
the cuttings are pressed into the sand until the upper side
is level with the surface. The whole is then covered with
an inch layer of sifted peat (about two parts) and sand
(one part). At first the frames were completely shaded
by clean white muslin on a framework about 7 feet above
the ground. They are given a small amount of ventilation.
In 1919 and 1920 an experiment was tried at Whites-
bog, on the recommendation of Mr. V. A. Vanicek, an
expert plant propagator of Newport, R. 1., in the use of
lath instead of muslin shades. The shades are so con-
structed that the lath is about 4 inches above the sash of
the coldframe, and the distance between the laths is the
thickness of a lath, about a quarter of an inch. This con-
struction allows each cutting to receive direct sunlight,
but for only a few minutes at a time. The proportion of
cuttings that rooted under these lath shades was a little
better than that under the muslin shades. It is to be
hoped that further experience with lath shades will es-
tablish their apparent superiority over muslin shades, for
they are less expensive and more easily handled.
The shades and sash are removed in early October, and
in late autumn, after most of their leaves have fallen, the
rooted plants are taken out of the frames, so that these
can be made ready for a new lot of cuttings very early
the next spring. The strongest of the rooted plants taken
out of the frames are sometimes set at once in their per-
manent places in the field plantation. The others are
placed in nursery beds at a spacing of about 10 inches
each way, where they remain during the winter and the
following growing season.
The cutting bed should be watered often enough to
keep it from drying at the surface.
WINTER CUTTINGS
The rooting of leafy cuttings of the bluebrry in summer
is difficult, because in a temperature above 700 F. the
cuttings usually blacken and die. With the aid of a
shaded greenhouse, winter cuttings can be started early
enough to make roots before warm weather comes on.
Similar results can be obtained in coldframes so located,
sheltered and manipulated as to prolong their low tem-
perature as late as possible in the season.
The essentials of a successful coldframe for blueberry
propagation are as follows: (1) It should be located on
the cool, shaded north side of a building or in some other
situation where it will not receive reflected heat from
neighboring structures. (2) The cuttings should receive
an abundance of light, but little or no direct sunlight, a
condition best obtained in the case of isolated frames by
the use of muslin or slat shades. Frames on the north
side of a building will also require shade in early morn-
ing and late afternoon from March to September. On
sunless days all shade should be removed so that the cut-
tings will receive as much light as possible. (3) There
should be ample space for the circulation of cool air be-
tween the frames and the shade. (4) The frames should
be kept closed or nearly closed, with a little ventilation
at night to refill the frame with cool air, until the cuttings
are rooted. The closing not only keeps the air saturated
with moisture and prevents the drying of the cuttings,
but it also tends to maintain a cool ground temperature
within the frame.
The use of a greenhouse in which to start the cuttings,
followed by the transfer of the cuttings boxes to cold-
frames at the beginning of warm weather, permits an
even more prolonged protection of the cuttings than can
be obtained in either greenhouse or coldframes alone and
increases the percentage of rooted plants. The direc-
tions for rooting winter cuttings of the blueberry by this
method are as follows:
(1) Make the cuttings in late autumn, removing any
leaves that have not already fallen.
(2) Make the cuttings from wood of the preceding
summer's growth, rejecting such portions as bear the
large fat flowering buds. The cuttings are to be made
from well-matured unbranched twigs or shoots grown in
well-lighted situations, and therefore well stored with
starch.
(3) About four inches is a suitable length for finished
cuttings. A sharp thin-bladed knife should be used. In
the finished cutting, the upper end of the diagonal cut at
the base of the cutting should come just below a sound
bud, and the cut at the upper end of the cutting should
be about an eighth of an inch above a sound bud. If the
cuts are first made with pruning shears, remove with the
knife the bruised wood at the cut ends. The diagonal
knife cuts should be as short as is practicable without
bruising the bark or splitting or straining the wood. To
avoid infection of the cuttings, the knife must be kept
clean. This may be done conveniently by dipping the
blade in alcohol and wiping it on a clean towel. The cut-
tings must not be allowed to become dry. This is easily
prevented by laying them in the fold of a clean, moist
towel.
(4) The cutting box should be made of sound, clean
wood, about eight inches deep inside and of any con-
venient size, with drainage holes in the bottom. The cut-
ting bed should be laid down over a groundwork of clean
broken crocks, gravel or other material that will provide
good drainage. On this place about 31/2 inches of rather
coarse basswood sawdust mixed with about one-fourth of
its bulk of peat, the whole bed, including the drainage
material, being four inches or a little more in thickness.
Wet the bed thoroughly with clean rain water or other
pure water (free from lime) from a sprinkling pot.
(5) With a newly whittled stick or other clean imple-
ment punch holes about three inches deep in the cutting
bed at a spacing of two to three inches each way, accord-
ing to the thickness of the cuttings. In setting the cutting
in the hole be sure to press it down far enough and firmly
enough to make sure that the cut surface at the base is in
contact with the sawdust, but be careful not to injure the
delicate new tissue at the base of the cutting by pushing
it forcibly into the cutting bed. With the stick tamp the
sawdust firmly about the cutting. Cover the box with a
pane or panes of glass.
(6) To prevent injury of the cuttings by overheating,
allow little or no direct sunlight on the boxes. Shade
them with muslin or paper or slats so hung as to permit
ample circulation of cool air between the shade and the
glass.
(7) Keep the air inside the box saturated or nearly
saturated with moisture. This condition will be shown by
the condensation of the moisture on the under side of the
glass at night or at other cool portions of the day.
(8) Watering should be as infrequent as practicable,
only sufficient to keep the cutting bed moist but well
aerated and the atmosphere in the box saturated. If the
glass fits tightly, the period between necessary waterings
may extend over several weeks.
(9) Place the box for a month in a temperature of 550
to 600 or 650 F., in either darkness or indirect sunlight.
At the end of a month the new healing-over growth,
called a callus, should have been formed at the base of
each cutting.
(10) After the cuttings are callused the temperature
in the cutting house should be allowed to run down each
night to a temperature of 350 F. or as near that point as
the weather permits, but the cuttings should not be al-
lowed to freeze. The day temperature should approach
but not exceed 600. Shade the boxes from direct sun-
light, but give them all the indirect light practicable.
(11) After two months of this alternate chilling and
moderate warming the buds on many of the cuttings
should have begun to push. It is then time to raise the
night temperature to 550, keeping the day temperature at
about 600 F.
(12) After new twigs have developed from the upper
buds and their growth has been terminated by the brown-
ing and shedding of the tips, and the new leaves have
reached their full size and acquire the dark-green color
of maturity, the formation of roots is about to begin.
(13) When all or most of the cuttings in the frame
have begun to root, ventilation of the box should be be-
gun. The best superficial evidence that a cutting has
rooted is the development of secondary twig growth,
either from the apex of one of the first set of new twigs
or from another bud lower down on the old wood of the
cutting. If secondary growth does not take place, the
development of a plump but dormant bud at the apex of
one of the leafy twigs is also good evidence that cutting
has begun to root. Cuttings that are healthy but not yet
rooted at the time ventilation begins usually die from
excessive transpiration.
(14) Ventilation should be only slight at first and
should be increased very gradually, the transition to full
ventilation extending over a period of several weeks. If
any of the sensitive secondary growth begins to wilt, re-
duce the ventilation immediately until the wilting ceases.
Be especially careful not to give too much ventilation on
windy days. By the time the tips of the secondary shoots
are browned and shed and their leaves are mature in size
and color, the cuttings have developed sufficient root
growth to warrant full ventilation.
(15) All cuttings that are dying should be removed
from the bed at once. Those injured by high temperature
usually turn brown at the base first, the dead area ex-
tending upward until the new growth collapses. Those
otherwise sound but suffering from excessive ventilation
before they are rooted usually indicate their bad condi-
tion by the marginal yellowing of their leaves before they
drop and the stems become withered.
(16) The plants are best left in the cutting bed all
winter, either indoors at a temperature slightly above
freezing, or outdoors mulched with leaves, preferably oak
leaves. In early spring, before the buds have begun to
push, they should be very carefully lifted and moved,
with the whole root mat and adhering soil intact, to a
peat and sand nursery bed at a spacing of about a foot
each way or potted in the standard blueberry-soil mix-
ture.
ROOT CUTTINGS
The early experiments with root cuttings gave such a
small percentage of rooted plants that further experi-
ments in the greenhouse were abandoned. At Whitesbog,
N. J., however, in order that the underground parts as
well as the tops of selected wild plants might be utilized,
cuttings of these parts were made, about three to four
inches long and of all sizes down to a little less than an
eighth of an inch in diameter. These were given the same
treatment as tubered cuttings in coldframes. A good per-
centage of unusually vigorous rooted sprouts resulted. It
was found later, however, that most of the pieces that
rooted were not true root cuttings, but were from under-
ground portions of stems, properly stem-base cuttings.
MOUND LAYERING
Wild blueberry plants, and hybrids also, vary greatly
in their response to the different methods of propagation
here described. Cuttings of the common lowbush blue-
berry (Vaccinium angustifolium) usually do not yield a
large percentage of rooted plants. The same is true of
hybrids between this species and the swamp blueberry.
For these plants the old-fashioned method of mound lay-
ering has been found satisfactory. The procedure is
simply to cover up the bases of the stems to the depth of
two to four inches with peat and sand soil in which the
plants are growing. If this is done in spring, soon after
flowering, the stems are usually well rooted by the end
of the season, and each one is ready to be taken off as a
separate plant.
TREATMENT OF YOUNG PLANTS
When blueberry plants, either large or small, are
grown in porous pots, the surface of the pot should never
be allowed to become dry, for the rootlets which grow
through the soil to the wall of the pot for air are ex-
tremely fine and easily killed by drying, to the great in-
jury of the plant. This danger may be eliminated by
bedding the pots to the rim in a well-drained bed of sand
or by setting the pot in another pot of two to four inches
greater diameter, with a packing of moist sphagnum moss
between and broken crocks at the bottom.
A burning of the young leaves and growing tips of
twigs is often produced by the hot sun from the middle
of June to the middle of September. Plants in pots or
nursery beds are easily protected from such injury and
forced to their maximum growth by a half-shade covering
of slats, the slats and the spaces between being of the
same width. On cloudy days the shade should be re-
moved. It should not be used in the fall or spring.
During the winter blueberry plants should be kept
outdoors, exposed to freezing temperatures, their soil
inches long and of all sizes down to a little less than an
eighth of an inch in diameter. These were given the same
treatment as tubered cuttings in coldframes. A good per-
centage of unusually vigorous rooted sprouts resulted. It
was found later, however, that most of the pieces that
rooted were not true root cuttings, but were from under-
ground portions of stems, properly stem-base cuttings.
MOUND LAYERING
Wild blueberry plants, and hybrids also, vary greatly
in their response to the different methods of propagation
here described. Cuttings of the common lowbush blue-
berry (Vaccinium angustifolium) usually do not yield a
large percentage of rooted plants. The same is true of
hybrids between this species and the swamp blueberry.
For these plants the old-fashioned method of mound lay-
ering has been found satisfactory. The procedure is
simply to cover up the bases of the stems to the depth of
two to four inches with peat and sand soil in which the
plants are growing. If this is done in spring, soon after
flowering, the stems are usually well rooted by the end
of the season, and each one is ready to be taken off as a
separate plant.
TREATMENT OF YOUNG PLANTS
When blueberry plants, either large or small, are
grown in porous pots, the surface of the pot should never
be allowed to become dry, for the rootlets which grow
through the soil to the wall of the pot for air are ex-
tremely fine and easily killed by drying, to the great in-
jury of the plant. This danger may be eliminated by
bedding the pots to the rim in a well-drained bed of sand
or by setting the pot in another pot of two to four inches
greater diameter, with a packing of moist sphagnum moss
between and broken crocks at the bottom.
A burning of the young leaves and growing tips of
twigs is often produced by the hot sun from the middle
of June to the middle of September. Plants in pots or
nursery beds are easily protected from such injury and
forced to their maximum growth by a half-shade covering
of slats, the slats and the spaces between being of the
same width. On cloudy days the shade should be re-
moved. It should not be used in the fall or spring.
During the winter blueberry plants should be kept
outdoors, exposed to freezing temperatures, their soil
mulched with leaves, preferably oak leaves. When kept
in a warm greenhouse during the winter they make no
growth before spring. Even then their growth is late,
abnormal, often feeble, sometimes deferred for even a
whole year.
FIELD PLANTING
Plants from cuttings or rooted shoots are ready for per-
manent field planting when they are 1 or 2 years old and
6 to 18 inches high.
It is a curious fact that these plants send out no new
roots in spring until they are in full leaf, when their
flowering is nearly or quite finished and their principal
twig growth has ceased. It is important, therefore, in
taking up either a wild or cultivated plant from the open
ground that as much as possible of the old root mat be
carefully lifted with the plant, for upon these old roots
the plants depend for moisture until their new rootlets
are formed, about two months after the first signs of
growth in spring.
In the case of mature wild bushes with very large root
systems, when it is practicable to secure but a fraction of
the root mat, say a disk only 3 or 4 feet in diameter, it is
the best procedure to cut all the stems at the time of
transplanting to stumps a few inches high. The bush will
then produce a new and symmetrical top of a size suited
to the capacity of the roots. The wood that is removed
may be used for cuttings if the plant is sufficiently val-
uable.
The stems that make up a bush usually develop fibrous
roots on their basal portions beneath the surface of the
soil and above the root crown, at which the several stems
unite. Such plants can be divided into several when
taken up for transplanting. As many as 30 plants, each
cut to a stump and with its own small but sufficient por-
tion of the root mat, have been obtained in this way from
a large wild plant. By utilizing the various methods of
propagation described in this bulletin, as many as 600
cuttings of roots, stems and twigs have been made from
a single very large wild bush.
In resetting plants from which the tops have been re-
nioved, the stumps should be made to project about an
inch above the surface of the ground. New shoots are
formed in spring from such exposed stumps much earlier
than from stumps covered with soil and not receiving the
warmth of the sun's direct rays. If the plant when reset
is made to occupy a moderate depression in the ground,
the old stump and the bases of the new stems can after-
ward be covered with soil, and a new root system will
finally develop from the new wood.
When blueberry plants are set out in early spring, be-
fore the buds have begun to push, they usually make ex-
cellent growth, and for all plants that are pruned to the
stump early spring is the best season for transplanting.
Conditions with unpruned plants, however, are differ-
ent. Since blueberry plants make no new root growth
until late spring it often happens that a period of hot
days intervenes between planting and rooting, and many
plants are injured by an excessive loss of water before
they have had time to make connection with the water
supply of the surrounding soil through the development
of new roots. The danger of such injury is greatest in
the case of plants transplanted from pots. The old root
ball sends up most of its water to the leaves, and in con-
sequence, being at first as a rule in imperfect capillary
contact with the new outside soil, the root ball commonly
contracts slightly. The contraction is often sufficient to
put the roots at the sides and bottom of the root ball
permanently out of contact with the surrounding soil, and
the plant may continue to suffer severely from drought,
although the soil outside the root ball contains plenty of
moisture.
An early autumn field planting has furnished a re-
markably successful means of avoiding this trouble with
potted plants. At this season the excessive heat of sum-
mer is over, the plants are full of leaves and vigorous,
and, being taken from pots, carry their whole root system
with them. The formation of new roots begins at once
and proceeds with great activity until the leaves are shed,
at the approach of winter. In the spring, when new leaf
growth begins, the plants are already well rooted in the
soil. They pass through the early hot period without in-
jury and develop remarkable size and vigor by autumn.
In preparing for a field plantation one precaution of
special importance must not be overlooked. For the pro-
duction of a crop of fruit under field conditions, insects
are required to carry pollen from one flower to another.
The honeybee works little on blueberry flowers. Her
tongue is so short that she can not easily reach the nectar.
The flowers are pollinated chiefly by bumblebees, whose
tongues are long, and by some of the solitary wild bees
that are small enough to crawl through the narrow open-
ing of the corolla. When blueberry flowers are pollinated
with pollen from their own bush the berries are fewer,
smaller, and later in maturing than when the pollen
comes from another bush. Some bushes are almost com-
pletely sterile to their own pollen. The pollen of a plant
grown from a cutting is likewise unsatisfactory for the
pollination of the parent plant or of other plants grown
from its cuttings. It is important, therefore, that a plan-
tation should not be made up wholly from cuttings from
one bush. Two stocks should be used, a row of plants
from one stock being followed by a row from the other.
In the permanent field plantation bushes of the wild
swamp blueberry or its hybrids should be spaced 8 feet
apart each way. When they reach mature size they will
nearly or quite cover the intervening spaces. When first
planted, however, the bushes are preferably set 4 feet
apart in the row, with the rows 8 feet apart. This spacing
permits machine cultivation in one direction. When the
bushes begin to crowd each other, every second plant in
the row will need to be removed. If the plants are set
originally at 4 by 4 feet, machine cultivation will be im-
practicable after the first year or two, and the branches
of the bushes are likely to begin to interlock after five or
six years.
For lowbush hybrids it seems probable, from the ex-
perience at Whitesbog, that a spacing of 6 by 3 feet will
give the bushes adequate room for many years. If the
bushes ultimately begin to interlace in the rows the re-
moval of every second bush would then leave them at
intervals of 6 by 6 feet.
This removal of filler bushes will furnish a large quan-
tity of propagation material, which can be rooted by the
various methods described in this bulletin and used by
the extension of the plantation.
When blueberry culture is to be tried in a sandy or
gravelly soil deficient in peat or peat-like matter, the
plants should be set in separate holes or trenches about
12 inches deep in a mixture of two to four parts of peat
or half-rotted oak leaves to one part of clean sand. The
excavations should be wide enough to provide ample
space for new growth of the roots, not less than a foot
each way from the old root ball. In small plantings, if
the materials for the mixture are easily available in quan-
tity, an 8-inch bed of it may be laid down over the whole
surface of the ground, and if a planting is to be tried on
a soil wholly unsuited to the blueberry, especially a rich
garden soil or a heavy soil affording poor drainage, the
area may first be covered with a 2-inch layer of soft-coal
cinders to keep earthworms from bringing up the under-
lying soil; next a 6-inch layer of sand, for drainage, and
finally the 8-inch bed of peat and sand mixture. When-
ever used, the peat and sand mixture should be thorough-
ly manipulated, so as to give it a uniform texture, before
the plants are set out in it, for in a soil in which layers of
peat alternate with layers of sand the capillary connec-
tion of the two is usually imperfect, and. a plant rooted in
the peat may suffer severely from drought, although the
neighboring sand still has water to spare. For a similar
reason it is important that when the plant is first set out
the peat and sand mixture shall be very tightly pressed
and packed about all sides of the old root ball.
To insure full vigor of growth the ground between the
bushes must be kept free from all other vegetation. On
rocky uplands or in situations deficient in peat a con-
tinuous mulch of oak leaves, when it is practicable to
procure them, will help toward this end, as well as keep
the soil in the necessary acid condition. It is more eco-
nomical, however, to choose such a location for the plan-
tation as will permit the use of horse-drawn machinery
and will make mulching unnecessary.
The most favorable location for blueberry culture is a
moist area with a peat covering and sand subsoil, the peat
preferably of such a thickness that deep plowing will
turn up some of the underlying sand.
The land should be so ditched or tiled that the water
level can be kept at least a foot below the surface of the
ground during the growing season.
The ground should be plowed to the depth of 8 to 10
inches and repeatedly harrowed or otherwise tilled dur-
ing the season preceding the planting, in order to kill the
wild vegetation. The best time for such plowing is in
late spring, after the principal vegetation has used up its
winter store of starch in completing its early growth and
before the leaves have matured and the roots have begun
the new storage of starch by means of which they could
send up new sprouts.
The tillage of the plantation after the young bushes
have been set out should be sufficiently thorough to keep
down all competing vegetation. This is best done by
horse cultivation with a disk harrow, supplemented by
careful hoeing and hand weeding close about the plants.
As the bushes grow older and their roots extend into the
spaces between the rows, they develop over these root
mats close beneath the surface of the soil. The tillage
over these root mats should be very shallow, not more
than 2 or 3 inches. This is probably best accomplished
by the use of a small, light springtooth cultivator with the
teeth set closer together than usual.
In case of drought, the drainage ditches may be used
to bring the water for subirrigation. But unless the sur-
face of the ground is very level, subirrigation is likely to
result in the injury of plants in the lower spots by excess
of water. In uneven areas, therefore, surface or overhead
irrigation, if accompanied by good drainage, is preferable
to subirrigation and should be used if practicable.
Fertilizer experiments have shown that the application
of lime or of wood ashes is positively injurious to blue-
berry plants, and that stable manure, while producing a
temporary stimulation of vegetative growth, is likely to
cause serious injury later.
In greenhouse experiments at Washington it has been
found that blueberry plants are greatly stimulated by the
application of small quantities of soy-bean meal, either
mixed with the soil or applied as a mulch. This material
is acid, it has a high nitrogen content, and its nitrogen is
in organic form. Blueberry plants to which it is applied
in spring, as compared with plants not fertilized, make
more stocky growth and lay down many more fruit buds
for the succeeding year.
On an area at Whitesbog in which the proportion of
peat to sand was too small to bring about the most vigor-
ous growth of the bushes, an experiment was made in the
application, at the rate of 600 pounds per acre, or one-
eighth of a pound per square yard, of a special fertilizer
which is in successful use in cranberry culture as the
result of a series of experiments by the New Jersey State
Agricultural Experiment Station. Important characteris-
tics of this fertilizer are its acidity and its comparative
freedom from residues of sulphur. The blueberry bushes
to which this fertilizer was applied made conspicuously
better growth than those that were not fertilized, but
they neither grew better nor fruited better than bushes
mulched with 1 to 2 inches of rotted peat.
In 1919 and 1920 Mr. Charles S. Beckwith, of the
New Jersey Agricultural Experiment Station, conducted
a series of fertilizer experiments with blueberries at
Whitesbog. The most successful results were obtained
with a fertilizer applied in the spring of 1919, made up
as follows:
Pounds
N itrate of soda.................................. ........ .. 170
D ried blood ... .......................................... 23
Steam ed bone ................................ ............. 340
Phosphate rock............................. ............ 340
Potash ............. ......................................... 170
The yield in 1920 from bushes thus fertilized was more
than three times as great as from unfertilized bushes in
the same very sandy soil. On the basis of this experiment
Mr. Beckwith has recommended the application of this
fertilizer at the rate of 600 pounds per acre, or an eighth
of a pound per square yard.0
As a result of these preliminary fertilizer experiments
and in view of the fact that the swamp blueberry fruits
abundantly and continuously in soils containing the
proper proportion and quality of peat and sand, the use
of manure or any chemical fertilizer in such plantations
is not at present advocated. But if the proportion of peat
to sand is so low that the bushes appear to be suffering
for nourishment, a mulch of rotted surface peat or half-
rotted oak leaves should be applied, or a chemical fer-
tilizer similar in character to the one described above, or
some organic nitrogenous substance, such as soy-bean
meal or cottonseed meal.
The swamp blueberry does not require a yearly prun-
ing. When one of the stems of a bush becomes unpro-
ductive from injury or old age it should, of course, be cut
out. If a large part of a bush needs removal it is better
to cut all the stems to the ground and let the plant send
up new shoots, all of the same age, to form a wholly new
and systematical top. With lowbush hybrids it has been
found desirable at Whitesbog to remove each year, in
late July or early August, immediately after the picking
season, all the stems more than 1 year old which have not
made vigorous new twig growth during the season. Under
such treatment the bushes yield a good crop of berries
every year. Farther north, where the growing season is
shorter, such pruning should be done in late autumn or
very early spring.
oFor the details of this experiment, see "The Effect of Fertilizers on Blue-
berries," published in Soil Science, v. 10, pp. 309 to 312, with plate, October,
1920.
It has long been known that the occasional burning of
lowbush blueberry areas increases the yield of fruit. In
the blueberry canning district of Maine this has led to
the development of a system of burning the blueberry
barrens once in three years. In the summer following
the burning the plants do not fruit, but they send up
from the ground an enormous number of vigorous un-
branched big-leaved stems. Late in the season fruit buds
are formed in abundance on the upper part of these
stems, and in the second summer after the burning the
plants fruit heavily. They are likely also to yield fairly
well the third summer, but after that they usually be-
come unproductive. The burning should be done in the
dormant season when the plants have dropped their
leaves and the roots are fully stored with starch and
other reserve foods. From these stored materials are
formed the vigorous sprouts of the following spring. If
an area is burned in late spring or in summer, after the
stored food materials have been used up and before the
storage for the following year has taken place, the plants
will be seriously weakened. The best time for burning is
in early spring, before the buds have begun to push. A
day should be selected when the upper layers of dead
leaves are dry enough to carry a fire and the underlying
turf of upland peat is still wet. For if the fire burns so
deeply as to consume the layer of peat, from which the
plants derive the principal part of their nourishment,
their later growth and their fruiting vigor will be serious-
ly impaired. The beneficial effect of burning a blueberry
area has lead to the idea that wood ashes are a good fer-
tilizer for blueberries. Experiments have shown, how-
ever, that one of the most effective ways to kill a blue-
berry plant is to give the soil an application of wood
ashes sufficient to neutralize its acidity. When a blue-
berry area is properly burned the layer of ashes is very
thin, quite insufficient to neutralize the acidity of the
underlying peat turf, and therefore harmless, probably
indeed under these conditions beneficial. The chief bene-
fits from burning are two, both quite distinct, however,
from the fertilizing effect. Burning tends to keep down
tree growth and other competing vegetation, and it
prunes the blueberry bushes. Burning is by far the least
expensive and most effective method known for pruning
lowbush blueberries. The procedure is especially adapted
to the management of wild uncultivated areas of the two
common lowbush species of the northern United States-
Vaccinium angustifolium and V. canadense. Since the
highbush blueberry, Vaccinium corymbosum, however,
requires drastic pruning only at intervals of many years,
and even then at different times for different bushes,
burning is not a good method of pruning this species.
This is especially true of cultivated plantations, where
competing vegetation is kept down by other means.
YIELD
By proper manipulation in the greenhouse, seedling
blueberry plants can often be made to ripen a few berries
when they are 1 year old, but they do not come into com-
mercial bearing in field plantations until they are about
4 years old, when the plants are 1 to 3 feet high. They
then increase slowly to full size and full bearing. Wild
bushes of the swamp blueberry live to great age, often 50
to 100 years, still bearing heavily, and they often attain
a height of 6 to 8 feet when growing in full sunlight;
still more when shaded. Individual stems may remain
productive from 10 to 25 years. When dead they are re-
placed by new and vigorous shoots from the root.
The great promise of blueberry growing as an agricul-
tural industry, in just the right soil and under good busi-
ness management, is indicated by the yields from the
oldest of the hybrid plantings at Whitesbog. This plant-
ing consists of about a third of an acre, the plants 7 years
old in 1919. They yielded in that year at the rate of 96
bushels per acre. The berries sold at a little over $10 a
bushel, in addition to express charges and commissions,
the receipts being at the rate of $966 per acre. In 1920
this planting yielded at the rate of 117 bushels per acre,
with receipts at the rate of $1,280 per acre. These plants
were set at 3 by 5 feet and consequently yielded about
twice as much per acre at this age as they would if they
had been spaced as now advocated, at 4 by 8 feet.
The yields from this planting, from the beginning, are
shown in Table I.
Table 1.-Yield and Receipts from a Planting of Hybrid Blueberries
at Whitesbog, N. J., 1915 to 1920, Inclusive
I W *li 0 0-a P 11
a e.a r -,Ia a Vo.,-;a ...0 V ,4
Bushels Cents Bushels Cents
1915........... 6.6 18 $ 37 1918............ t46.9 30 $ 449
1916........... 29.7 22 209 1919........... 95.8 32 966
1917............ 58.3 24 448 1920............ 117:3 34 1,280
tYield reduced by late spring frosts.
With beginners in blueberry culture every graduation
in accomplishment may be expected, from the great suc-
cess indicated above to complete failure, because of
wrong soil, bad location, or poor management.
The heaviest charge against the industry is the cost of
producing rooted plants of selected varieties. At the
present time plants of the best varieties can not be pur-
chased in acre quantities. The grower must do his own
propagating from a few plants. The propagation is suf-
ficiently difficult to demand unusual skill, and it requires
constant and painstaking attention.
If the land to be used bears timber and brush, the clear-
ing is expensive.
After a plantation is established, its maintenance is
relatively inexpensive. The cost of cultivation is rather
less than that of the staple cultivated crops. The prin-
cipal charge is for the picking of the berries. At Whites-
bog 6 cents a quart has been paid for the last few years.
A good picker in an ordinary day picks about a bushel.
An exceptionally skillful picker, with unusually favorable
bushes, has picked 100 quarts, or more than 3 bushels,
in a day. For shipment to the market in crates, culti-
vated blueberries should be picked by hand, never with
a "rake" or "scoop," such as is used when blueberries are
carted direct to commercial canneries.
HYBRID BLUEBERRIES
Blueberry breeding has now been carried on for 10
years, with the result that instead of berries the size of
peas, like the ordinary wild blueberry, we now have
hybrids producing berries the size of Concord grapes. A
few plants out of the 18,000 hybrids that have been
fruited at Whitesbog are three-fourths of an inch in
diameter. A very few have borne berries even larger, a
little more than four-fifths of an inch in diameter, and in
the greenhouse a diameter of seven-eighths of an inch
has been reached. In the great majority of the hybrids,
however, the berries are intermediate in size between
ordinary wild ones and the selected hybrids. All such
small and intermediate hybrids are rejected. Propaga-
tion material placed in the hands of nurserymen for com-
mercial propagation is taken from the selected hybrids
only.
The unselected hybrid berries vary in color from light
blue to dark blue and sometimes shining black, and an
occasional bush bears red berries, or even white ones.
The variation of the blueberry hybrids in other respects
is also very marked, the plants offering an almost endless
opportunity for selection with reference to acidity, sweet-
ness, flavor, juiciness, firmness, productivity, hardiness,
season of ripening, resistance to fungous diseases, and
many other less important characteristics. In making the
selections, special consideration has been given to the
form of the bush and its possession of a foliage surface
adequate to the nourishment of a large crop of berries.
CONCLUSION
The introduction of the blueberry into agriculture has
a much more profound significance than the mere addi-
tion of one more agricultural industry to those already
in existence. Blueberries thrive best in soils so acid as to
be considered worthless for ordinary agricultural pur-
poses. Blueberry cultivation, therefore, not only promises
to add to the general welfare through the utilization of
land almost valueless otherwise, but it offers a profitable
industry to individual landowners in certain districts in
which general agricultural conditions are especially hard
and unpromising, and it suggests the possibility of the
further utilization of such lands by means of other crops
adapted to acid conditions.00
ooFor a discussion of the principles of acid-soil agriculture in districts in
which the cost of lime is prohibitory, consult "The Agricultural Utilization of
Acid Lands by Means of Acid-Tolerant Crops," United States Department of
Agriculture Bulletin No. 6, 1913.
$300 TO $600 AN ACRE PROFIT FROM YOUR
BLUEBERRY ORCHARD
HARRISON AND McCASKILL, DEFUNIAK SPRINGS
Unlike other fruit trees, which, in order to expand,
must be planted from 25 to 30 feet apart, thus limiting
their number to 70 to 90 trees per acre, blueberries thrive
best when planted comparatively close together. We
plant them 12 feet apart, which permits approximately
300 trees to the acre.
As stated, the first commercial crop gathered the third
year after planting, is usually light-about 6 quarts per
tree. The fourth year sees an increase to about 8 quarts
per tree. From then on the average increase is about 2
quarts per tree, per year.
A very conservative estimate, covering a period of eight
years, beginning with the first commercial crop at three
years and from then on until the trees are 10 years old, is
as follows:
Total Yield
No. Trees Yield Per Acre
Age of Trees Per Acre Per Tree (300 Trees)
3rd year ................... 300 6 qts. 1,800 qts.
4th year .................... 300 8 qts. 2,400 qts.
5th year .................... 300 10 qts. 3,000 qts.
6th year .................... 300 12 qts. 3,600 qts.
7th year .................... 300 14 qts. 4,200 qts.
8th year ................... 300 16 qts. 4,800 qts.
9th year .................... 300 18 qts. 5,400 qts.
10th year ........... 300 20 qts. 6,400 qts.
Last season blueberries sold for 17 cents per quart
f. o. b. shipping point. Owing to the constantly increas-
ing demand and the ever-widening market, it is not likely
that the price will drop below that figure any time within
the next ten years or more. On the contrary, it is more
than likely that the price will go up. But to be safely on
the side of conservatism, let us figure the price at only 10
cents per quart for the next ten years. Even at this low
price and figuring on the basis of the above conservative
estimate of yield, a blueberry orchard will bring the
owner an income of from $300 to $600 an acre, beginning
with the fifth year's crop, while the third and fourth
year's crop yield incomes of $180.00 and $240.00 per acre,
respectively. And it should be remembered that, after
the sixth or seventh year, many trees in a blueberry
orchard will very likely yield far above the estimates
given.
West Florida is a center of the blueberry industry in
the State. There are perhaps not more than two thou-
sand acres of bearing trees in the State, including the
wild ones. Commercializing the blueberry is of such
recent date that very few have undertaken it on a scien-
tific basis.
Many thousands of trees have been set out from wild
stock and with little regard to the requirements of the
plant as set forth in this bulletin. As a consequence many
failures will result. Florida has hundreds of thousands
of peaty lands that doubtless would produce this fruit if
properly handled.
The most popular variety of blueberry in Florida is
known as the "Rabbit Eye." The only protection the
novice has in undertaking this industry, or even in
selecting for home use, is the intelligence and honesty
of the nurseryman from whom he secures his plants. A
great deal of promiscuous experimenting will doubtless
be done before the business of handling stock for this fruit
will be standardized as has been done with the great
staple fruits of the day.
"There are three kinds of wild berries that grow in this, Okaloosa County.
One is a very dark blue, if blue it may be called. It is almost black. It is
not as large as the one we are cultivating and has more and larger seeds. It
is called, locally, The May Berry. It ripens early in May.
Another is a jet black, small berry, very hard and ripens in January and
February, but we have not considered it of a marketable value yet.
Our commercial berry is what we call, locally, The Rabbit Eye. I do not
know how the appellation came about, but it is a rather deep, but not dark,
blue color, is from half to three-quarters of an inch in diameter, when ripe
(about twice the size of the May berry and thrice the size of the little black
one), has a peculiar rough blossom end, bears in clusters, similar to grapes,
and has such small seeds that in eating them one will hardly detect the seed.
Only this one is cultivated. It is very solid, so much so it will keep a week,
after picked when ripe, without wilting or any sign of spoiling. They possess
a larger percentage of jelly than any fruit extant. One lady in this town,
during the past summer measured out 12 pints of the berries and made them
into jelly, securing eleven full pints of jelly and about a tablespoonful over.
Fine solid jelly.
Uses-They are eaten in natural state; pies, etc.;
They can as easily and as well as any fruit that grows;
They preserve like other fruits;
They are wonderful for jelly and make most delicious wine."
S. Rice, Crestview, Florida, Oct. 13, 1923.
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