About herbicide application techniques

1. HERBICIDE APPLICATION
TECHNIQUES

2. For effective weed management
we must have
 Knowledge of weed problem
 Knowledge of herbicide
 Knowledge of formulations
 Knowledge of techniques and equipment

3.  There are several herbicides application techniques that
can be used to control herbaceous weeds, trees and
bushes of various sizes.
 Applications can be soil (PPI or Pre; fumigation)
fumigation) or foliar.
 Foliage application can be broadcast (uniform on the entire
area) or directed (target individual plants).
 Can be applied as concentrated sprays or granular
formulations may be broadcasted, diluted with water or
diesel, and applied with sand/soil.

4. Herbicides can be applied by a variety
of means including
 Boom sprayers
 Aerial spraying
 Misters
 Blanket wipers
 Rope wick applicators
 Weed seekers
 Back-pack sprayers.

5. Boom sprayer on crop
 Most common type of apparatus for applying herbicides in
broadscale farming.
 A sprayer has many components, the most important being
the nozzles, which split the herbicide into many small
droplets that are projected through the air to the target.
 The nozzle determines the effectiveness of spraying.
 All other components are necessary to position the nozzles
and provide them with a continuous supply of herbicide at
the correct pressure

7. Aerial spraying
 Aerial herbicide application is the quickest, most economical and highly
efficient delivery system to control brush acres on a utility right-of-way
over a given lifetime.
 Most Economical Technique
 Quickest Application
 4acres in 7 minutes
 Chemical Side Trimming
 Easily Covers Inaccessible
 Areas/Rough Terrain

9. On the basis of volume of spray-mix the
technique of spraying is classified as:
 1. High volume spraying (300-500 l/ha)
 2. Low volume spraying (50
 -150 l/ha)
 3. Ultra low volume spraying (<5 l/ha)
 The range of volume of spray mix in each of the
above
 case is arbitrary

10. Misters
 Misters are a useful but imprecise way of applying herbicides
to large areas quickly.
 They rely on wind to drift the herbicide. If the wind is too light
or the spraying speed too high, the swath width will decrease,
possibly causing overdosing and wasted chemical.
 If the wind is too strong or gusty, it increases the swath width,
which will reduce the chemical application rate and increase
the risk of damage from spray drift.

12. Blanket wipers
 Blanket wipers are made of a vertical strip of material
attached to a horizontal frame.
 The vertical strip, or blanket, acts as the wiping surface
making direct contact with the target weed.
 This equipment has been developed as an alternative to
rope wick applicators.
 A non- selective herbicide is generally used with
successful weed control dependent on the height
differential between crop and weed.
 Wipers are used in broadacre application to control radish
or mustard in lupins or chickpeas or to 'top' grasses in
pasture.

13.  Units have been designed to fit all terrain bikes and hand
held equipment has been developed for back yard and
environmental use to treat weeds such as cape tulip,
Paterson’s curse, Guildford grass, arum lily, and bracken
fern.
 Herbicide can be selectively applied to these plants without
damaging pasture legumes or native seedlings in revegetation
areas.
 The best time to wipe weeds in crops is September to early
October when the weeds are flowering and are 20–30cm taller
than crop or pasture plants

15. Rope wick applicators
 Rope wick applicators consist of a series of ropes impregnated with a
non-selective herbicide, usually glyphosate.
 They are not widely used, but they can be useful for the control of tall
weeds in a crop or pasture.
 Normal spraying with a non -selective herbicide would not be possible
in this situation, however a rope wick applicator can be moved above
the crop or pasture and wipe the herbicide only onto the taller weeds,
hence selective control is obtained.
 This technique has been partially successful for controlling cape tulip,
docks, rushes, thistles and bracken in pasture.
 Because they can only operate at slow speeds and the ropes are very
expensive, rope wick applicators have not gained wide acceptance

17. Detect sprayer
 Detection technology (for example, Weedseeker and
Weedit) uses infrared and near infrared light to detect green
weeds and sprays only green plants in paddocks.
 In action, light-emitting diodes (LEDs) point two different
light sources, infrared and near infrared, towards the
ground.
 Green weeds have a different reflective signature to
stubble or soil.
 The system can operate at speeds up to 20 kilometres per
hour (km/h), requiring a stable boom to aid operational
efficiency

19. Spot spraying v/s wick wiping
 This method is a quicker alternative to hand roguing and can
be used to sterilize weed seed.
 Spot spraying usually involves the application of a non-
selective herbicide to individual weeds using a sprayer in a
back-pack or mounted on an all terrain vehicle (ATV).
 The sprayer should have a single nozzle on a wand attached
to a flexible hose.
 A boom sprayer fitted with weed detector units may also be
used for applying non-selective herbicides to low-density
infestations in fallows.

20.  Wick wiping performed with a hand-held rope-wick
wiper is an alternative to spot spraying when there
is the possibility of herbicide drift onto sensitive
adjacent plants.
 It is particularly useful if the weed is taller than the
crop canopy.
 There are multiple 'wiper technologies' available,
including wick wipers, rope wipers, carpet wipers
and weed wipers.

22. Nozzles for spraying herbicides
 The main types of applicators available are:
 Hydraulic nozzles
 Twin fluid nozzles
 Controlled droplet applicators
 Air induction nozzles
 Air assisted nozzles.
 Changing the nozzle type, size, height and pressure will
change the amount and effectiveness of herbicide reaching
the target area.