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THE CONNECTICUT

AGRICUITDRAL EXPERIMENT SIMIOE

NE^W HAVEN, CONN.

BULLETIN 166, NOVEMBER, 1910.

THE MANAGEMENT OF TOBACCO
SEED BEDS.

V

By W. M. HiNSON and E. H. Jenkins.

The Bulletins of this Station are mailed free to citizens of Con-
necticut who apply for them, and to others as far as the limited
editions permit.

CONNECTICUT AGRICULTURAL EIPERIIENT STATION.

BOARD OF CONTROL.
His Excellency, Frank B. Weeks, Ex officio, President.

Prof. H. W. Conn, Vice President Middletown.

, Secretary

E. H. Jenkins, Director and Treasurer New Haven.

George A. Hopson Wallingford.

Charles M. Jarvis Berlin.

Frank H. Stadtmueller Elmwood.

James H. Webb Hamden.

STATION STAFF.

Chemists.

Analytical Laboratory.

John Phillips Street, M.S., Chemist in Charge.

E. Monroe Bailey, M.S. C. B. Morrison, B.S.

R. B. Roe, A.B. . C. E. Shepard.

Laboratory for the Study of Proteids.
T. B. Osborne, Ph.D., Chemist in Charge. E. L. Ferry, Assistant.
Botanist, G. P. Clinton, S.D. Assistant, E. M. Stoddard.
Entomologist, W. E. Britton, Ph.D. Assistant, B. H. Walden.
Forester, Samuel N. Spring, M.F. Assistant, W. O. Filley.
Plant Breeding, H. K. Hayes, B.Agr.
Seed Testing, Miss M. H. Jagger.

Stenographers and Clerks. Miss V. E. Cole, Miss L. M. Brautlecht,

Miss E. B. Whittlesey, Miss Luva Francis.
In Charge of Buildings and Grounds, William Veitch.
Laboratory Helper, Hugo Lange. Sampling Agent, V. L. Churchill.

THE MANAGEMENT OF TOBACCO
SEED BEDS.

By W. M. Hinson and E. H. Jenkins.

This bulletin is a part of the cooperative experimental work done jointly
by the Bureau of Plant Industry of the United States Department of
Agriculture, represented by Mr. Hinson, and by this Station.

The object of the seed bed is to get healthy stocky plants with
compact roots ready to set in the field when the ground and air
are warm enough for them to grow rapidly and without check.
This bulletin aims to give what experiment and observation have
taught regarding this matter.

The same beds may be used for years if properly handled,
and this plan makes it worth while to build substantial wooden
frames, to hold the cloth or sash and in some cases to lay steam
or water pipes in the bed for heating in emergency. The
dangers from the accumulation of weeds, the increase of fungi
or "disease" in the soil, and the sprouting of tobacco seed pos-
sibly of a different variety sowed the previous year, are all
obviated by the sterilization of the bed with steam, to be
described later.

Fertilisers. Tobacco plants of the right size to set in the field
carry very little plant food in them and can grow to the proper
size for transplanting in a poor soil. But if they grow in either
a poor or a dry soil, they have to spread their roots widely
in it in order to get the food or water which they need. This
delays their growth above ground, the spreading, straggling
roots are damaged in transplanting and the plant, as a result,
is checked in growth.

But in a well-fertilized bed the roots, finding all the plant food
and water which they need close at hand, make a compact bunch
of roots easy to pull with slight loss to the seedling plant. To
secure this it is not necessary to use exceptionally large doses of
fertilizer.

4 CONNECTICUT EXPERIMENT STATION, BULLETIN l66.

The complete or partial failure of beds is oftener caused by
too thick seeding and want of skill or care in watering and partic-
ularly in airing the beds than by over-fertilizing or under-
fertilizing the soil. If the plants do not grow as they ought,
seek the cause in these things and in diseases which result from
insufficient ventilation before dosing the bed with fertilizers.

Horse manure is an excellent dressing, for, aside from its
fertilizing value, the vegetable matter in it makes the soil hold
and carry water better than it could without it and feeds
the bacteria which make nitrogenous manures available. If beds
are steam-sterilized, the weed seeds, which are always present
in manure, will give no trouble.

Usually it is best to prepare the beds and work in manure in
the late fall, thus leaving less to be done in the rush of spring
work. A thick cover of leaves on the bed prevents deep freez-
ing and makes the beds workable somewhat earlier in the spring.

A moderate amount of chemical fertilizers should be put on
in spring, worked in with the rake, and the bed cleaned of all
trash and smoothed ready for seeding.

Object of Sterilizing the Beds. To this matter we wish to
call special attention. The sterilization of beds used for forcing
greenhouse crops has been practiced by successful growers for
years. The results of our experiments in sterilizing tobacco beds
have led some successful growers to adopt this practice, which
has thus been abundantly tested and has proved to be practicable
and profitable. The practice, which will be described in detail
later, consists either in steaming the soil sufficiently to kill all
seeds and microbes in it to the depth of two inches or more, or
in treating the beds with formalin to largely accomplish the same
thing. Beds which have been properly sterilized by steam will
need no weeding, as only an occasional weed will show itself
before the seedling tobacco plants are pulled. This saving of
labor alone pays the cost of sterilizing when the apparatus for it
is at hand. The root rot will also be killed and the tobacco thus
saved from its attacks. Whether "calico" is lessened by the
treatment has not been determined, although our observation
this year, to which we refer later, suggested that this might be
the case.

STERILIZATION OF BEDS. 5

It is a matter of common observation, both in greenhouses and
in tobacco beds, that the plants in steriHzed soil start quicker
and grow faster than in untreated soil. This may be in part
explained by the warming of the soil, partly by a possible solvent
action of the steam or heated moisture on the plant food in the
soil, but is no doubt in large part due to a change in the microbe
life of the soil effected by the treatment, which may utterly
destroy certain kinds of microbes, repress others and yet leave
conditions favorable for the rapid growth later of those species
which make available the nitrogen of the soil or otherwise favor
the growth of the tobacco plant.

The root rot and some other fungous troubles appear to be
completely destroyed by steam sterilization and largely by the
formalin treatment.

Apparatus for Steam Sterilizing. There are required a port-
able steam boiler — six to eight horse power — which will maintain
a pressure of from 75 to 100 pounds, and steam hose which will
stand that pressure, with the necessary connections. The steam-
ing apparatus found most convenient was devised by Mr. A. D.
Shamel and is shown in the plate.

It is a pan six by ten feet square and six inches deep, made
of i8-gauge galvanized iron and having a handle bar at each end.
It is reinforced with strap iron to make it more rigid and is fitted
with a nipple for the hose connection. The one in use at East
Hartford cost $40.00 and should last ten years.

If a sterilizing pan cannot be got readily, experience has shown
that a tight wooden box of about the same measurement is equally
effective and being a poor conductor of heat probably needs less
steam to do the same work.

The Operation of Steam Sterilizing. The bed, having been
fertilized, is raked smooth and made ready for sowing. The
pan is inverted over one end of the bed and its edges pressed well
into the soil. Steam is turned on and kept at a pressure of at
least 70 pounds for thirty minutes. Some experimenters recom-
mend an hour, but in our work this year thirty minutes was
sufficient to kill all seeds.

The pan is then moved on, and it is recommended to cover
the steamed soil with burlap to hold the heat as long as may be.

6 CONNECTICUT EXPERIMENT STATION, BULLETIN l66.

Where the beds are many and long, much time can be saved
by putting the boiler midway of the bed and using two sterilizers,
one at each end of the bed. The steam is turned into the second
when the first has been steamed for thirty minutes, and the pan
remains there to hold the heat for twenty-five minutes and is
then moved on.

To sterilize i8o square yards of seed beds this year at W. K.
Ackley's in East Hartford cost the labor of two men for two
days, $6.00. No weeding was needed on these beds.

To weed 90 square yards of unsterilized beds till the seedlings
were pulled, cost in labor $12.00.

The beds were sterilized April nth and 12th. Seed was sown
on the 15th. The covers were taken off the beds May 15th and
the seedlings were ready to set on June 2d, all of them healthy.

The plants on unsterilized and hand-watered beds were one
week later.

As to the effect on prevalence of "calico," we do not yet attach
great importance to our observations because of the freaky way
in which this trouble appears. Part of the field was set with
plants from the sterilized bed and part from an adjoining one
which was not sterilized. We counted all the plants in two rows
on both parts and also the number of "mongrels" or "calico"
plants. Only 2.V1 per cent, of the plants from sterilized beds
showed the trouble, but from the unsterilized bed 30 per cent.
But on a neighbor's field, where the same experiment was made,
the difference was not great, though still quite evidently in favor
of the plants from sterilized soil.

The subject of "calico" is further discussed in the last para-
graph of this bulletin.

Sterilisation with Formalin or Formaldehyde. Steam steril-
ization is the more convenient where a boiler is near at hand and
effective in killing weed seeds, but for small beds and places
where the other apparatus cannot be got, the formalin treatment
can be substituted. It is best applied in the fall and when the
soil is comparatively dry. The following method was success-
fully used by Dr. Clinton of this Station in 1907 :

A solution of one part of formalin — 40 per cent, strength, —
in one hundred parts of water, that is, a pint of good commercial
formaldehyde, also called "formalin," in twelve and one-half
gallons of water, was gradually sprinkled over the bed at the

RATE OF SEEDING. 7

rate of one gallon per square foot, taking care not to puddle the
soil. The bed -was then covered with burlap or sash to hold in
the fumes.

Spring treatment leaves the bed wet and cold and it should
not be sown for a week after treatment, lest the formalin still
in the soil should kill the sprouting seed. Stirring the soil will
facilitate the evaporation of the formalin and excessive moisture.

Rate of Seeding. Assuming that clean heavy seed is used,* we
wish to call attention to the rate of seeding. The practice of
different good growers varies greatly. Four successful growers,
each raising a large acreage, gave us their rates of seeding which,
calculated to a common basis, are respectively :

I tablespoonful, or i oz. to 150 sq. feet.

I " "I " " 450 " "

Now one ounce of seed contains approximately 300,000 seeds,
of which, assuming a germination of only 75 per cent., 225,000
will sprout and grow.

5
plants

3
plants

1

less than

3
plants

Let the reader imagine the number of seedling plants given
above standing in the inch squares and he will see exactly what
the above figures mean and understand how thickly the plants
will stand on each square inch of his beds, providing 75 per cent,
of his seed "comes."

With ten seedlings on a square inch, or even half that number,
it is clear that large numbers must die from lack of light, damp-

*The advantage of heavy seed and the method of separating chaff and
light seed from it have been explained in the Report of this Station, 1905,
P- 334) and in Bull. 96 of the Bureau of Plant Industry.

8 CONNECTICUT EXPERIMENT STATION^ BULLETIN l66.

ing off, etc., or remain stunted, at least till the overtopping ones
are pulled. Such thick crowding, we believe, weakens all the
plants, makes them spindling and very hard to pull properly for
setting in the field.

An ounce of dry seed is enough to sow on 900 square feet of
bed, and this will give a stand of not more than two plants to
the square inch.

Sprouted or Dry Seed? It is a very common practice to mix
the seed with damp apple-tree "punk," or other suitable material,
and leave it in a jar in a warm place until the seed has "cracked"
and the sprout appears and then sow the mixture. If a hard, cold
storm comes at the time, the grower naturally waits for a better
day. Then the sprouts have grown too long and are likely to
be broken in sowing, or if not broken they must twist or turn
to go down into the soil, thus deforming the root, or a new
main root must be formed.

The aim of sprouting the seed is to get a somewhat earlier
start for the plant. But it is not likely that an early start of the
seed at room temperature helps it much in the end if the tender
seedling must be put into the cold soil of the bed. It looks more
likely that the plant will have a better chance if the seed germin-
ates at somewhere near the temperature it is to have during its
early growth.

Certain it is that young plants taken from a warm to a cool
place are set back in growth and often never fully recover.

All tobacco growers know that "hardening off" the plants
before setting has to be done. very carefully to avoid injury.

It would seem that vastly more injury was likely when seeds,
sprouted behind a kitchen stove, are put into soil with a temper-
ature of 40°-50° F., where the exquisitely tender root fiber must
"harden off" before it grows further.

The injury is not considered because it cannot be readily seen.

Even if we grant that the preliminary sprouting will give some
earlier plants than dry seeding, we believe it is done at the
expense of the general thriftiness of the bed, and that to get the
crop set in the field very early is rather a doubtful advantage.
Cold storms or clear,^ very cold nights are likely to come and
set back the growing crop if it does not kill it.

WATERING TOBACCO BEDS. 9

Certain it is that the crop will not grow in such cold weather,
and when it starts it must grow continuously and fast to give a
crop of good quality.

We urge, therefore, that growers make a comparison them-
selves next spring, sowing sprouted seed and dry seed at the
same rate in different parts of the same bed and noting carefully
the dates when these beds respectively are ready to "pull" and
the comparative vigor of the two.

Watering the Beds. A very successful test of watering the
soil from below, subirrigation, was also carried out at
Mr. Ackley's.

A line of three-inch glazed tiHng was laid from three to five
inches deep lengthwise through the middle of the bed. The line
had little or no dip and at one end came above the surface outside
the bed with an elbow. The tile for 90 square yards of bed cost
about $8.00. Every other day about forty gallons of water were
run into this pipe from a garden hose. No other watering was
done except on the surface at the time the seed was sown.

To water an equal area of bed in the usual way while the
plants were growing cost $10.00 in labor. The cost of subirri-
gating after the pipe was laid was inconsiderable, say ten
minutes' time every other day.

A part of this bed was sterilized with formalin. Here the
plants were all healthy. There was some disease in the other
part, but the plants grew very rapidly when not diseased and fully
as well as in the bed which was watered on the surface by hand.

Where a grower has several beds, we urge the trial of this
way of watering on a single bed. If it is as successful generally
as it has been with us, it will save labor and expense.

The Use of Tobacco Water on Seed Beds. A decoction of
tobacco stems is sometimes used on the seedlings as a fertilizer
and also as an insecticide and destroyer of worms in the soil.
This should never be done. Dr. Clinton of this Station has
proved that the calico disease can be carried in the stems of
leaves infected with it, and that tobacco water prepared from such
stems may easily infect the plants which are watered with it. He
has no evidence to show that this infection passes from stems
plowed into the soil to the young plants. He has been only

lO CONNECTICUT EXPERIMENT STATION, BULLETIN IDD.

able to induce the trouble by infection through the leaf or the
growing part of the stalk.

Ventilation of the Beds. Proper airing of the beds is essen-
tial to protect the seedlings from "damping off" and other
fungous diseases. It is an art which cannot be taught except by
experience with the bed itself. When the air of the bed is nearly
saturated and warm, trouble is at hand, just as when the air of
the barn full of curing tobacco gets into the same state. And
the remedy is the same in both cases, viz., circulation of air to
carry off the moisture, even if this causes a loss of heat from the
soil, the bed or the barn.

"Calico." The experiments of the Station botanist, Dr.
Clinton, so far indicate that most of the "calico" on leaves of
commercial value in the field traces back to the seed bed or to
infection of the seedlings at the time of transplanting. To
explain this more clearly, it should be stated that "calico" is a
disease that is very easily transmitted by handling a healthy
plant after handling a "calicoed" plant, especially if any of the
juices from the "calicoed" plant are on the hands. This juice is
only effective on the immature or growing leaves. That is, one
can touch with it a fully grown leaf at the base of a tobacco
plant and it will not "calico," but the young leaves above will
become "cahcoed" though not even touched at this time. From
this it can be seen that if there are any "calicoed" plants in the
seed bed the handling of these while transplanting is likely to
greatly spread the "calico" to otherwise healthy plants. This
explains why sometimes in the field one finds every other plant
"calicoed" for quite a distance in the row. The man who set
these either got the juice from a "calicoed" plant on his hands
or else got a bunch of plants which had come in contact with
"calicoed" plants, while the man who set the alternate sound
plants had not these conditions.

Unfortunately "calico" cannot usually be recognized in the
plants while in the seed bed. Occasionally before the final setting
such plants are found. Whenever they are found, they and the
surrounding plants should be pulled out, and the other plants
should not be touched until the hands have been washed
thoroughly with soap and water.

CALICO OF TOBACCO. II

So far, the only known methods of lessening "caHco" in the
seed bed are avoiding the use of tobacco water, as noted before,
and the probable good resulting from steam sterilization. Some
growers have beheved that the careless use of fertiHzers on the
growing seedlings produced "calico," but if so, this has not yet
been proved by experimentation.

The subject of "calico" will be further discussed in the forth-
coming report of the Station botanist.

SOIL STERILIZER READY FOR STEAMING.

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Connecticut

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