Fumigation of vetch seed to control the vetch bruchid

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Material Information

Title:
Fumigation of vetch seed to control the vetch bruchid
Physical Description:
2 p. : 26 cm.
Language:
English
Creator:
Hawkins, Lon A ( Lon Adrian ), b. 1880
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Dept. of Agriculture, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Vetch -- Seeds -- Fumigation   ( lcsh )
Vetch bruchid -- Control   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

General Note:
Caption title.
General Note:
"E-492 ; September 1939."
Statement of Responsibility:
by Lon. A. Hawkins.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030269641
oclc - 778703798
System ID:
AA00022983:00001

Full Text

-~ A U


E-492 September 1939


United States Department of Agriculture
Bureau of Entomology and, Plant Quarantine

FUMIGATIONII OF VETCH SEED TO CONTROL THE VETCH BRUCHID

By Lon. A. Hawkins, Division of Control Investigations


In experimental work on fumigation of vetch seed- for the vetch
bruchid, Bruchus brachialis, .carried on in 1936 and 1937 by A. C. Johnson,
J. S. Pirnckney, J. W. Bulger, and A. M. Phillips, three methods of fumiga-
tion were developed which gave complete mortality of the insects in in-
fested seed. Certain of these methods have been used quite extensively
under commercial conditions with excellent results. The three methods
are-

(1) 3Fumigation with hydrocyanic acid at atmospheric pressures
with a dosage of 4 pounds of hydrocyanic acid per 1,000 cubic feet and an
exposure of 24 hours at a temperature of 70' T. or above, and a lead not
more than 15,000 pounds per 1,000 cubic feet.

(2) Vacuum fumigation, fumigation under a pressure reduced to the-
equivalent of 2 inches of mercury or a 28-inch vacuum under normal atmos-
pheric pressure at sea level, with a dosage of 7 ounces of hyrocyanic acid
per 100 cubic feet of chamber siace at a temperature not lower than 70 F.
for a period of 2 hours, with a load not more than 15,000 pounds per 1,000
cubic feet.

(3) Carbon disulphide fumigation, fumi<;ation at normal atmospheric
pressures with a dosage of 20 pounds of carbon disulphide per 1,000 cubic
feet of chamber space for a period of 24 hours, at a temperature not lower
than 70 F., the load being not more than 12,000 poundrn. er 1,000 cubic
fee t.

Under all threo methods of fumigation the sacks of vetch seed should
be separated so that the fumigant is in contact with as much of the surface
as possible.

These investigations have been continued, and it has been shown
that both methyl bromid-e and chloropicrin can be used for fumigation of
vetch seed with assurance of complete kill of any bruchids present.

The dosage of chloropicrin four.d to be effective was 1-1/2 pounds
per 1,000 cubic feet of space, the chloropicrin being volatilized into
the chamber and mixed thoroughly with the air by means of a fan. The
fan should be operated throughout the f zigation period. Stirring the
air was found to ba essential, as in cases i.h-Are the f-nmigant was not
stirred considerable survivr.l occurred. In four experiments at temp-
eratures ranging from 61c to 76c no sirvivaj occurred in an estimated






3 1262 09224 6825
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population of 6,292. In one test iU which the air was not agitated,
with an estimated population of 1,792, there wore nine survivals. In
one test in which 150-pound sacks were used, with an estimated population
of 1,472, there was one survival. These experiments indicate that a
treatment at 70 i'F., with a dosage of 1-1/2 pounds of chloropicrin per
1,000 cubic feet and a load of 12,900 :pounds per 1,000 cubic feet, ap,
pro::imately the same as in carload shipments, in a tight chamber, such
as a refrigerator car, the air-gas mixture being circulated throughout
the period of 24 hours, would kill any vetch bruchids which might be
present in the seed in 100-pound sacks separated so that the gas could
come in contact with all sides of the sack.

In nine tests with vetch fo-d fumtigated at a dosage of 1 to 1-1/2
pounds of chloropicrin for a period of 24 hours, the germination of the
treated seed was 91.7 percent and of the untreated seed 93.1 percent,
indic&Ating that there was no appreciable injury to the seed from
fumigation.

With methyl bromide in six tests with a dosage of 3 pounds per
1,000 cubic feet and a period of exposure of 4 hours, at temperatures
ranging from 67 to 710, there was complete mortality in all cases in
an estimated population of 3,044 insects. Thrre wrs one survival when
the dosr;.ge of 3 pounds for 2 hours was used with an estimated population
of 1,634. From these data it is indicated that complete mortality of
the vetch bruchid in seed can be obtained when the seed is fumigated
with methyl bromide at a dosage of 3 pounds per 1,000 cubic feet for a
period of 4 hours, at a temperature of 70c F. The load in these tests
was 12,900 pounds per 1,000 cubic feet or at the rate of 30,000
pounds to the carload.

Germination tests of 12 sn.moles of treated and untreated seed from
the same lots gave average gir:ination of 80.5 percent for the treated
seed and 89.7 percornt for the untrc;ted seed, indicating that there was
apparently no appr.-ciabli lowering of the viability of the seed by this
treatment.

It should be emphasized that the air-gas mixture must be stirred by
means of a fan during the fumigation period and that tha fumigation chamber
must be tight. A refrigerator car with the drips plugged and the hatch
plugs firmly mtd. akes an excellent fumigation chamber.