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Safety - page 25 • First aid - page 33 • Resistance management - page 41
Herbicides
conservation tillage: reduced tillage, minimum
tillage, no-tillage or zero tillage, direct drilling
and chemical fallow.
Herbicides for conservation tillage are listed
below. Rates of application, weeds controlled and
other pertinent information can be found by referring
to each herbicide in this guide.
• 2,4-
D or MCPA – To control winter annuals
such as flixweed, shepherd’s-purse and stinkweed.
Application should be made to emerged weeds
prior to freeze-up.
•
Glyphosate Formulation – Apply any
glyphosate formulation mixed with a non-ionic
surfactant (if required) to actively growing
weeds. Can be tank mixed with Banvel; 2,4-D
amine; Pardner.
•
Rustler – Controls annual grasses, broadleaf
weeds and volunteer cereals. Can be tank mixed
with 2,4-D.
Nitrate poisoning of livestock
Nitrate accumulations may be caused by leaf damage
from frost, hail or herbicide action. Symptoms of
nitrate poisoning include reduced milk production
and growth rate, abortions and in severe cases, death
by suffocation. A veterinarian should be called
immediately if livestock show unusual symptoms
when they are fed forages that may contain nitrates.
After severe frost, hail or herbicide damage, the
nutrient value of the crop will decrease rapidly. In
terms of nutrition, it is important to harvest as soon
as practical; however, in the case of herbicide treated
crops, there may be a waiting period specified on the
herbicide label. Especially in the case of high risk
crops, such as oats or corn, a delay may be advisable
to permit nitrate levels to decrease. If there is a
possibility of high nitrates in feed, have the feed
analyzed at a feed testing laboratory.
Weed control in forage crops
Make sure all forages, as well as any companion
crops, present in the stand are listed for the intended
use on the herbicide label. Follow the label directions
on the herbicide container closely, especially for stage
of crop and weed development, water volume,
grazing and feeding restrictions.
Herbicide performance ratings
Herbicide performance ratings (numbers in brackets
after the names of crops or weeds) are based on data
from the Expert Committee on Weeds (Western
Section) Research Reports. These numbers are not
absolute and, therefore, not a guarantee of expected
performance. They are meant to be used as a guide
when selecting a herbicide. When a number is not
included, there is not sufficient data to provide a rating.
Tolerance of crop to herbicides
The number appearing in brackets following the
crop on which each herbicide is registered represents
the expected tolerance of the crop to that herbicide.
Due to variations in variety, weather, timing and
application techniques, this number is only
approximate. 0 = complete kill of the crop and
9
= no measurable injury to the crop.
Level of weed control with each herbicide
The number appearing in brackets after each weed
represents the average level of weed control expected
with the herbicide. Due to variation in weather,
growth stage, time of day, application technique, etc.,
this number is only approximate.
0
= no control of the weed and 9.0 = complete kill
of the weed. A weed control rating of 7.0 or greater
is considered commercially acceptable.
Water Used for Spray Application
The quality of water used can affect the efficacy of
some herbicides. Water quality includes the
cleanliness (silt, organic matter and soil), the
hardness or softness of the water and the water pH.
Some herbicides, including glyphosate containing
herbicides, adsorb to silt and organic matter, become
inactivated. This causes a decrease in herbicidal
activity. Suspended soils and organic matter in water is
usually a problem where surface water is being used.
Other herbicides, including 2,4-D amine and several
Group 1 herbicides have reduced efficacy when
applied in mineralized water. Minerals include both
calcium and magnesium sulfates, which result in
‘
hard’ water, and excessive sodium bicarbonate,
which results in ‘soft’ water. Mineralized water is
most commonly a problem when well-water is used.
When efficacy decreases, it is most apparent on
hard to control weeds and is easily confused with
late application, poor growing conditions or reduced
herbicides rates.