This video will show you how to mix and
load liquid pesticide
into your knapsack sprayer in the field. You will need your
container of pesticide and label; your
knapsack sprayer that has been checked
calibrated and is ready for use; clean water;
a mixing tray; a pesticide box;
your planning notes; measuring cylinders
or jugs; a spill kit of a dustpan and brush,
sand or soil and a plastic bag or appropriate container
that can be labeled and securely sealed;
and the personal protective equipment
that should be worn when mixing that product
and as directed by your pesticide label.
From the product label you will know
the amount of pesticide to be applied
and the water volume rate to use.
In this demonstration we will be spraying
at the label rate of
4 L of pesticide in 200 L of water
to be sprayed over 1 ha or 10,000 square meters of land
Although we will be spraying a much smaller area of 1200 square meters.
To spray 1200 m we will need 24 L of spray solution.
containing 0.48 L or 480 ml of pesticide.
You may find our online spray mix
calculator will help you with your own calculations.
The capacity of your knapsack sprayer's
tank is important here.
Filling your sprayer up to the top will
increase the risk of leaks from the cap and its vent.
To reduce the risk, International Standards
recommend a minimum 5% unused tank volume
so that there is a gap between the top
of the spray liquid and the tank opening.
We will allow a 10% spare volume
and so suggest filling this sprayer to
the 18 L mark at the maximum.
This means we will need one tank of 18 L containing 360 ml of pesticide in 17.64 L of water and
a part tank of 6 L containing 120 ml of pesticide in 5.88 L of water.
Choose your mixing site carefully;
make sure that you will not
have to carry a loaded knapsack sprayer very far.
If you do not have a dedicated mixing area area or need to mix your spray solution
nearer to the treatment area,
refer to your label for any advice on selecting a suitable mixing site.
Ideally it should be away from animals,
children and surface water such as streams and ponds
and not near any drinking water sources
or habitation and other sensitive areas.
The ground must be flat and your mixing tray stable.
Before you start mixing make sure that the weather
and other conditions remain suitable for spraying.
If you are not sure what to check
view our video 'Just before you spray'
for some suggestions
Position all the equipment you will need to use
to mix your pesticide so that is is convenient
and safe to use. Pesticides are more safely transported
from your pesticide store to field mixing site
in a lockable non permeable box. These
boxes will also keep your pesticide
much more secure when you are spraying.
It is best to add pesticide and water
from the side furthest from the straps
on the sprayer. Straps can absorb drops
and spills liquids so it is safer when you are pouring
from this side. We will mix the 18 L quantity first.
Remove the sprayer's lid and place this
upside down on the mixing tray.
Using clean water and with the filter basket in place
add about 9 L of water carefully and without splashes.
Pesticide quantities for knapsack spraying use are likely to be small
so make sure you use equipment that can accurately measure small amounts of product.
Sometimes graduated container caps can be used.
Measure out the exact amount of liquid
pesticide that you need for 18 L,
360 ml of this product for this use.
Use caution and take great care with all undiluted chemicals that you are handling.
PPE will help to protect you but it is much better for you and the PPE
not to come into contact with the pesticide at all.
Pour the product onto the water in the half full tank.
For safety, replace the pesticide container cap now.
Using clean water, rinse the measuring cylinder
or jug and pour the rinsing water into the tank.
Do this 3 times. Replace the lid.
Carefully agitate the pesticide with the water until it is fully dispersed by raising the sprayer
a few centimeters by its handles or its
straps and gently rocking it back and forth.
Remove the lid and taking care to avoid spills and drips
place it upside down again, on to the mixing tray.
Add the remaining water up to the tank scale's 18 L mark.
Replace the lid and agitate the spray solution now
...and again later when you are about to use it.
If any accidental spill occurs then use the sand
or sawdust in your spill kit to contain liquid and absorb it.
Do this as soon as possible and before
it spreads too far,
contaminates other surfaces or, if on the ground,
penetrates below its surfaces. Scoop up
the contaminated material
and place it in a plastic bag that has
been sealed and labeled
for safe disposal later
Return the pesticide container to its
store or secure box
and lock it.
Re-check the label to see what
additional PPE you need for the way you are
applying that product and then go spraying.
Our operator is following best practices and so will retain the use of his coveralls,
gloves,
boots and face shield for downward spraying this product.
It is very good practice to make up a
little less spray solution than is needed for
your last knapsack sprayer load.
This means you leave a small unsprayed area
which you can later spray with the water
used for cleaning your sprayer
so when you come to mix the part tank,
makes less than is needed.
In this case we had calculated to use a
further 6 L in total
so we will prepare 5.5 L of pesticide solution.
We should then have a small un-sprayed
area that will be later sprayed with the cleaning water.
In this case we need 5.5 L
so put 2.5 liters of water in to start with.
Measure and add the product needed. In this case we
will measure out 110 ml to make up 5.5 L of spray solution.
Rinse the measuring cylinder three times
and add this water to the spray liquid.
If you have emptied any pesticide
containers, also rinse them with water
and add the rinsing water into the
sprayer tank. Do this twice more.
Replace the tank lid. Agitate the
sprayer to mix the product with the water.
Add the remaining water so that there is now 5.5 L
of mixed spray solution and agitate the tank again now
and then again just before using. Check
that all pesticide container lids
have been replaced securely and place the containers
in your lockable pesticide box.
Spray out this part load and place a
cane where you now have an un-sprayed small area.
Put your clean mixing equipment away ready for the next use.
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