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IMPORTANT PRECAUTIONS
- PASTURE /RANGELAND
• Injury to or loss of desirable trees or other plants may result if
VELPAR L is applied or if equipment is drained or flushed on
or near desirable trees or other plants, on areas where their
roots may extend, or in locations where the chemical may be
washed or moved into contact with their roots.
• Poor weed and brush control may result from the following:
–Use on poorly drained sites
–Applications made when the soil is saturated with water and
rain is imminent within 24 hours
–Applications to soils high in organic matter (greater
than 5%)
• Following mechanical cutting or clearing, allow stumps and
injured trees sufficient time to adequately resprout before
applying VELPAR L.
• Do not use VELPAR L on frozen soils.
• Weed and brush control results depend on sufficient moisture
to activate VELPAR L.
• When VELPAR L is applied as a basal soil treatment, there is
no restriction on grazing by domestic animals nor on cutting
surrounding vegetation for forage or hay.
• For broadcast pasture applications of VELPAR L, do not cut
treated vegetation for forage or hay nor graze domestic
animals on treated areas for 60 days.
SPRAY DRIFT MANAGEMENT
The interaction of many equipment- and weather-related factors
determines the potential for spray drift. The applicator is
responsible for considering all these factors when making
application decisions. Avoiding spray drift is the responsibility
of the applicator.
IMPORTANCE OF DROPLET SIZE
The most effective way to reduce drift potential is to apply large
droplets (greater than 150–200 microns). The best drift
management strategy is to apply the largest droplets that provide
sufficient coverage and control. The presence of sensitive
species nearby, the environmental conditions, and pest pressure
may affect how an applicator balances drift control and
coverage. Applying larger droplets reduces drift potential, but
will not prevent drift if applications are made improperly or
under unfavorable environmental conditions! See the Wind,
Temperature and Humidity, and Temperature Inversions sections
below.
CONTROLLING DROPLET SIZE
- GENERAL TECHNIQUES
• Volume - Use high flow rate nozzles to apply the highest
practical spray volume. Nozzles with higher rated flows
produce larger droplets.
• Pressure - Use the lower spray pressures recommended for the
nozzle. Higher pressure reduces droplet size and does not
improve canopy penetration. When higher flow rates are
needed, use a higher-capacity nozzle instead of increasing
pressure.
• Nozzle Type - Use a nozzle type that is designed for the
intended application. With most nozzle types, narrower spray
angles produce larger droplets. Consider using low-drift
nozzles.
CONTROLLING DROPLET SIZE - AIRCRAFT
• Number of Nozzles - Use the minimum number of nozzles
with the highest flow rate that provide uniform coverage.
• Nozzle Orientation - Orienting nozzles so that the spray is
emitted backwards, parallel to the airstream will produce
larger droplets than other orientations.
• Nozzle Type - Solid stream nozzles (such as disc and core
with swirl plate removed) oriented straight back produce
larger droplets than other nozzle types.
BOOM LENGTH AND HEIGHT
• Boom Length (aircraft) - The boom length should not
exceed 3/4 of the wing length, using shorter booms decreases
drift potential. For helicopters use a boom length and position
that prevents droplets from entering the rotor vortices.
• Boom Height (aircraft) - Application more than 10 ft above
the canopy increases the potential for spray drift.
• Boom Height (ground) Setting the boom at the lowest
labeled height (if specified) which provides uniform coverage
reduces the exposure of droplets to evaporation and wind.
The boom should remain level with the crop and have
minimal bounce.
WIND
Drift potential increases at wind speeds of less than 3 mph
(due to variable direction and inversion potential) or more
than 10 mph. However, many factors, including droplet size
and equipment type determine drift potential at any given
wind speed. AVOID GUSTY OR WINDLESS
CONDITIONS.
Note: Local terrain can influence wind patterns. Every
applicator should be familiar with local wind patterns and
how they effect spray drift.
TEMPERATURE AND HUMIDITY
When making applications in hot and dry conditions, set up
equipment to produce larger droplets to reduce effects of
evaporation.
SURFACE TEMPERATURE INVERSIONS
Drift potential is high during a surface temperature inversion.
Surface inversions restrict vertical air mixing, which causes
small suspended droplets to remain close to the ground and
move laterally in a concentrated cloud. Surface inversions are
characterized by increasing temperature with altitude and are
common on nights with limited cloud cover and light to no
wind. They begin to form as the sun sets and often continue
into the morning. Their presence can be indicated by ground
fog; however, if fog is not present, inversions can also be
identified by the movement of smoke from a ground source or
an aircraft smoke generator. Smoke that layers and moves
laterally in a concentrated cloud (under low wind conditions)
indicates a surface inversion, while smoke that moves upward
and rapidly dissipates indicates good vertical air mixing.
SHIELDED SPRAYERS
Shielding the boom or individual nozzles can reduce the
effects of wind. However, it is the responsibility of the
applicator to verify that the shields are preventing drift, and
not interfering with uniform deposition of the product.
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