Technology
continually changes the way chemicals are applied to crops. Decreasing spray
drift and increasing application effectiveness are two important goals when
making spray application decisions. The type of application and the chemical
being used will determine which type of nozzle to use and which droplet size
will be needed.
According to
Tom Reed, regional manager from TeeJet, the trend in spraying is moving towards
using larger droplets to decrease the amount of drift. In reality, it is much
easier to control droplets in the medium to extremely coarse ranges.
Soil Incorporated Applications
Looking at
soil-incorporated applications, larger droplets are more desirable. In this
type of application, larger droplets are used since they will reduce drift
potential. Beyond this, coverage is less of a concern because soil moisture or
tillage will distribute the output. Since the full cone nozzle generally
produces larger droplets, it is a good nozzle tip to use for soil-incorporated
applications.
Pre-Emergence Applications
Much like
soil-incorporated applications, larger droplets will provide sufficient
coverage with pre-emergence applications. Flood nozzles create large droplets
and work well for pre-emergence applications.
Post-Emergence Contact Applications
Moving
along, post-emergence contact applications require complete coverage of the
plants to ensure application effectiveness. In this application type, the
chemical is only active at the site of contact. The twin orifice nozzle tip is
often associated with this application because the two directions of the output
combined with the smaller droplets improves coverage and penetration of the
canopy. The hollow cone nozzle is also equipped to handle post-emergence
contact applications. It is designed to produce smaller droplets ensuring
better coverage.
Post-Emergence Systemic Applications
On the other
hand, in post-emergence systemic applications complete coverage is not
essential for application effectiveness since the chemical will translocate
throughout the plant. In this instance, it is not necessary to use smaller
droplets. In many systemic applications, due to the chemicals used, drift can
cause a great deal of damage, so air induction nozzle tips or extended range
flat-fans are recommended due to their larger droplet outputs.
After
sorting through the types of applications and determining the type to be used,
it is also essential to factor in the spraying process that will be used.
Broadcast spraying varies a great deal from banded or direct spraying and
requires different types of nozzles.
Band Spraying
In band
spraying, only a certain portion of the land will receive the chemical
application leaving untouched areas. This type of application requires the
spray nozzles to produce a uniform amount of spray over the entire sprayed
area, or band. In this case, even-flow fans are more desirable for their
ability to produce the uniform spray pattern. Hollow cones and twin even-flat
fans are also appropriate choices for band or direct spraying applications
depending on the type of application that will be applied. The nozzle tips do
not require overlap to produce a uniform spray output making them useful for
applying pesticides to specific areas.
Because of
the different spray patterns produced by even flat-fans, it is essential not to
confuse the even flat-fan tips with other flat-fan nozzles which are primarily
used for broadcast applications.
Broadcast Spraying
To achieve
uniform distribution in broadcast applications, overlap the outer edges of
individual spray patterns. The recommended amount of overlap will depend on the
nozzle tip design. For many broadcast applications, using a full cone nozzle or
a flood nozzle will produce the desired results. Additionally, consider the
special feature nozzle tips such as the extended range or the drift reducing
nozzles for their ability to produce complete coverage during broadcast
spraying.
It is important to evaluate the
application goals and make changes accordingly. Customizing your application
with the best nozzle to use and the recommended droplet size will cut down on
spray drift and increase your application efficiency.
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