V- 
Vol. LXX. No. 4092. 
NEW YORK, APRIL 1, 1911. 
WEEKLY, $1.00 PER YEAR 
STEAM STERILIZING TOBACCO SEED BEDS 
Suitable for Other Plant Growing. 
HISTORY OF WRITER’S EXPERIMENTS.—In 
1906 the writer’s attention was called to a series of 
tobacco seed beds, where the plants were affected by 
some serious trouble, by the owner, James Harvey, of 
Hockanum, Conn. The writer found on investigation 
that the trouble was due to a root disease, which was 
identified by Mrs. Flora Patterson of the Bureau of 
Plant Industry of the United States Department of 
Agriculture as Thielovia bosicolo, or tobacco root-rot. 
The young plants attacked by this disease turned yel¬ 
low, and the larger plants, in addition to having yel¬ 
low or mottled appearing leaves, wilted when the beds 
became slightly dry, and where not supported by 
neighboring plants, fell over on the soil. When the 
plants were pulled up for examination, it was found 
that most if not all the roots were rotted off, and when 
the roots were examined, were found to be black in 
appearance, in many cases the small roots being en¬ 
tirely rotted away, leav¬ 
ing only blackened 
stumps at the base of the 
plants. In the diseased 
beds, the living roots 
were found to be rotted 
at the ends, black in ap¬ 
pearance, and the affect¬ 
ed plants had a stunted 
or dwarfed appearance. 
Plants from the dis¬ 
eased beds, set in the 
regular fields, grew 
slowly, and if conditions 
were favorable developed 
into imperfect poor 
plants. The leaves cured 
from these diseased 
plants produced a poor 
inferior grade of cigar 
wrappers or binders, 
without necessary elas¬ 
ticity or strength. 
In 1906 and the fol¬ 
lowing season, the 
writer began an extensive 
set of experiments with 
different methods of ster¬ 
ilizing the seed beds in 
order to prevent the dam¬ 
age from the root-rot. 
Formalin, tobacco bed 
burners, steam and other methods were tried in several 
places, but mainly at the Indian Head Plantation at 
Granby, Conn. In these experiments the writer 
found that it was possible to kill the fungus with 
formalin, but its use was not satisfactory from sev¬ 
eral standpoints. The tobacco bed burners, in which 
the soil was heaped in a large pan, and heated by a 
fire underneath, were dangerous, as where the soil 
was overheated the productive capacity of the soil 
was injured seriously from several apparent causes. 
Where the soils were burned by piling wood or other 
material on the surface and maintaining a slow fire, 
the physical condition of the soil was injured, and 
this method was abandoned as unsatisfactory. 
The writer in the course of some asparagus breed¬ 
ing work at Concord, Mass., learned of a steam ster¬ 
ilizer used by some of the growers of vegetables and 
flowers under glass, and through the Connecticut 
Agricultural Experiment Station at New Haven, se¬ 
cured two of them. Their use in tobacco beds was 
unsatisfactory in the trials made, because it was found 
impossible to bring the soil up to the desired tem¬ 
perature with the steam generators at hand. In work¬ 
ing with the sterilizers, however, the writer found 
that by covering the apparatus in the soil with 
heavy cloths more effective steaming could be done. 
This plan gave birth to the idea of using a solid pan 
for confining the steam, preparing the soil of the bed 
ready for steaming, then setting the pan over this 
loosened soil and forcing the steam into the soil under 
pressure. I made an experimental pan of this sort, 
and prepared a section of a seed bed for its trial. A 
small upright engine was used to supply steam, and 
the soil temperatures determined at different depths 
with standardized thermometers. 
Even with the small engine available for the trial 
it was found possible to heat the loosened soil under 
the pan rapidly and up to 185° F. and higher, holding 
the soil temperature at this point as long as desired. 
Several sections of seed beds were treated at different 
temperatures and at different periods of time. 
It was found that when the pan was removed from 
the soil the soil was left in perfect condition for seed¬ 
ing, and the warm moist soil was in ideal shape for 
sowing seed. The soil was not wet, but just moist 
enough for sowing. The seed was sown and lightly 
raked in. It was found that the steaming had not 
only killed the fungus, but had also killed all weed 
seeds, other fungus diseases such as the “damping off” 
fungus, and left the soil so that it was much easier 
to water and keep in condition than unsteamed soils. 
Extensive practical trials of this apparatus, which 
has been called the Shamel steam sterilizer, were 
made by the writer at Suffield, Hockanum, Conn., 
and other points, with perfect success in every trial. 
Later these results were confirmed by others in other 
sections in experimental trials and practical use. 
There is no doubt of the value and importance of the 
use of this method for sterilizing diseased or healthy 
tobacco bed soils, or other soils where seedlings are 
raised as in the case of tobacco. 
DESCRIPTION OF PAN.—The Shamel steam 
sterilizer pan is made of galvanized steel or galvanized 
iron, of such size as to fit the seed beds to be steril¬ 
ized. The original sterilizers were made six feet wide 
by 10 feet long, and six inches deep. The edges of 
the pan were supported by angle iron so as to pro¬ 
tect them, and in the middle of the bottom of the pan 
r. one-inch iron tube was soldered to the pan so as to 
attach onto the steam hose at one end and admit the 
steam into the pan at the other end when it was set 
in place ready for work. A steam hose 50 feet long 
was used to convey the steam from the engine or 
generator to the pan, and to admit of moving the pan 
the length of a 100-foot bed, without moving the en¬ 
gine or steam generator. This pan and steam hose 
were bought at a price of less than $50 per outfit, and 
two sets have been in yearly use for four years with¬ 
out apparent serious depreciation in value. With pro¬ 
per cafe they ought to last many years more. 
SOLRCE OF STEAM.—The first trials of this 
method were conducted with a small upright steam 
engine of about three horse-power as steam generator. 
In later trials similar engines, to be found in every 
neighborhood, have been 
used with success. It is 
necessary when steriliz¬ 
ing soils to have enough 
fuel on hand, and desir¬ 
able to have one man de¬ 
vote most of his time to 
keeping up a hot con¬ 
tinuous fire. Wood is a 
very satisfactory fuel, 
although oil and coal 
have both been used. 
PROPER TIME FOR 
STERILIZING. — The 
time to sterilize the seed 
beds depends on several 
conditions, but on the 
whole the ideal time is 
just before the seed is 
ready to be sown. When 
a' neighborhood uses an 
apparatus in common 
(a method to be recom¬ 
mended), it may some¬ 
times be necessary to 
sterilize some time be¬ 
fore the beds are ready 
for sowing. The seed 
can be sown as soon as 
the beds are sterilised 
with beneficial results. 
STERILIZING THE 
SOIL.—The beds should be fertilized and prepared 
ready for sowing. The better the tilth of the soil the 
more efficient the sterilizing. Set the pan in the pre¬ 
pared bed, turn in the steam, and if any escapes about 
the pan heap up a little loose soil about the edges of 
the pan so as to confine all of the steam in the pan. 
The best results in the writer’s experiments were se¬ 
cured by supplying a full head of steam, or as nearly 
a full head as possible, maintaining a' pressure in the 
boiler of from 50 to 75 pounds of steam, and con¬ 
tinuing this process for one hour. The length of time 
necessary to apply the steam will vary with the con¬ 
dition of the soil, outside temperature and other 
causes. One-half hour in many cases gave good re¬ 
sults, but as a rule one hour was preferable. When 
the steaming of one section is finished the fireman 
and one other man can move the pan to the next sec¬ 
tion, and so on until the bed is finished, when it 
should be sown with the seed. If desirable it would 
be interesting for the grower to use different lengths 
of time in different sections of the beds, and note the 
THE SHAMEL STEAM STERILIZER AS USED IN. PLANT BEDS. Fig. 140 . 
