•••
T RA D E N E W S
AUBREY KRUGER
FUMIGATION
of grain
Renier Vermaak, Head of
Fumigation at Senwes in Klerksdorp.
SENWES SCENARIO HAD
A CHAT TO THE CHIEF
FUMIGATOR IN KLERKSDORP, RENIER VERMAAK,
TO LEARN MORE ABOUT
THE FUMIGATION OF
GRAIN.
WHAT DOES THE FUMIGATION OF GRAIN INVOLVE?
Fumigation is the safe and effective
combating of grain storage insects
in stored grain in such a manner
that the grain will be safe for the
end user and free of insects.
HOW DOES IT WORK?
Fumigation involves the application of formulations which release
phosphine and which fills the area
around the grain kernel with a
toxic gas. It is important to understand that the grain is not fumigated, but the space around it. Due
to this there will be no phosphine
residue on the grain. When grain
is sprayed, the substance used will
break down to an acceptable residue level, which is safe for the end
consumer, after 21 days.
INTEGRATED PEST
MANAGEMENT
A program where you do everything to eliminate insects and fumigation is the last way out. In the
industry we talk about store hy-
14
giene. It goes hand-in-hand with
cleaning actions in and around silo
complexes, the preparation of storage structures / silo bins, sealing of
structures and regular monitoring.
It is like a kitchen. You do not put
food on a dirty plate - the plate has
to be clean. The same applies with
store hygiene.
The poison breaks down after
approximately 21 days, after which
the grain will be exposed to insects
once again. Store hygiene is the
most important point of departure
in the elimination of re-infestations.
SUBSTANCES USED
Phosphine, methyl bromide and
certain other products are used to
combat insects. At this stage we
use phosphine. Phosphine reacts
with the atmosphere (moisture,
heat and oxygen) to release a gas.
Spraying substances work well, but
due to residue levels, many buyers
prefer not to buy sprayed grain.
Methyl bromide is very expensive
and is being phased out because it
is an ozone depleting substance.
TYPES OF FUMIGATION
Mass fumigation - silo bins, silo
bags and storage dams where
grain is stored in large quantities.
Tablets, pills or circulation fumigation are used. Tablets and pills are
worked into the grain and a gas is
released.
Circulation - a formula is added
to the bin and the air (gas) circulates inside the bin, which kills the
insects.
Bag fumigation – When bagged
products are fumigated. It is la-
Feb/Mar 2016 • SENWES Scenario
bour-intensive and safety is even
more important here.
HOW LONG IS THE
FUMIGATION PROCESS?
You require a minimum exposure
period of 120 hours and the structure has to be airtight. The KT-value has to be reached, which is the
exposure measured against the gas
concentration over time. A low
concentration will require a longer
exposure time.
KILLS ALL STAGES IN THE
LIFE CYCLE OF AN INSECT
Fumigation must kill all stages in
the life cycle of an insect - insects,
larvae, pupae and eggs. Insects
and larvae are the most active they inhale the poison and die
first - within 24 hours! Pupae and
eggs take longer to absorb poison.
Pupae and eggs are sometimes exposed, but not long enough to kill
them. As a result the next generation will build up a resistance.
INSPECTIONS
We look at store hygiene, correct
fumigation and preparatory procedures. Legislation relating to
safety and the use of registered
substances at the correct dosages is
complied with at all times.
EQUIPMENT
A full-face mask with filter must
be worn. Every type of poison
has its own filter can, inorganic
gasses and organic vapour. Act
85 of 1993, Occupational Safety
and Health, regulates a safe work
environment. Regular monitoring
must be done to prevent exposure