New Herbicides
for Corn and Soybeans 2001
Tim Trower* and Chris
Boerboom
Define
Define is a new 60% DF formulation
of the active ingredient flufenacet from Aventis. Flufenacet is
not a new active ingredient as it is currently a component in
Epic, Domain, Axiom, and Axiom AT herbicides. Define may be applied preplant (up to 14 days), preplant
incorporated (mix into the top 1-2 inches), or preemergence to
field corn, white corn, or field corn grown for seed; it is not
currently labeled for use in popcorn or sweet corn. The label cautions growers to check with the local seed
corn company prior to applying Define to inbred lines as
unacceptable crop injury may occur. Like most soil-applied herbicides, the use rate is
dependant on the soil type and organic matter. A rate of 14-20 oz product per acre will be required for
most Wisconsin soils. Do
not exceed a maximum use rate of 21 oz product/A per growing
season. Define may
be applied using water or sprayable fluid fertilizer as the
carrier at a minimum of 10 GPA, or impregnated onto dry bulk
fertilizer. Adequate
soil moisture is required for maximum weed control and a rotary
hoeing 5-7 days after application will help activate the
herbicide in the absence of rainfall.
Define will not provide
broad-spectrum, season-long weed control without a tankmix
partner, planned sequential application, or mechanical
cultivation. Annual
grasses that are listed on the label as controlled included the
foxtail species, crabgrass species, barnyardgrass, and fall
panicum. Most of the important broadleaf species are only listed as
suppressed or partially controlled. The label has a long list of approved tankmix partners
and sequential herbicide treatments that will improve and expand
the weed control spectrum.
Corn and soybeans may be replanted
immediately after an application of Define, potato can be
planted after 1 month, cabbage and other leafy vegetables can be
planted after 4 months, and alfalfa, most small grains, and
popcorn can be planted after 12 months.
Harmony GT
DuPont is replacing Pinnacle with
a new formulation of thifensulfuron-methyl for postemergence use
on soybeans. Harmony
GT is a more concentrated formulation, containing 75%
active ingredient compared to 25% active ingredient for
Pinnacle. Since
Harmony GT is more concentrated than Pinnacle, the use rate is
considerably lower at 1/12 oz. product per acre. A non-ionic surfactant at a rate of 1-2 pts/100 gal spray
solution is required; the higher rate may cause temporary crop
injury during periods of hot, humid weather. A crop oil concentrate at 0.5% v/v may be used instead of
a non-ionic surfactant under periods of dry or cool weather.
The label also states that ammonium sulfate or 28% UAN is
recommended in addition to non-ionic surfactant or crop oil
concentrate when velvetleaf is present. Harmony GT may be applied postemergence to soybeans anytime
after the first trifoliate has fully expanded to 60 days prior
to harvest. Harmony
GT will provide the same weed control as Pinnacle.
Steadfast
Steadfast is a new premix
from DuPont for postemergence weed control in field corn. Formulated as a 75% WDG (water-dispersible granule),
Steadfast contains 50% nicosulfuron (the active ingredient in
Accent) and 25% rimsulfuron (the active ingredient in Matrix).
The labeled use rate is ¾ oz product per acre and the
final spray solution must contain either a crop oil concentrate
at 1% v/v or a non-ionic surfactant at 0.25-0.5% v/v. The addition of either 28% UAN at 2 qt/A or ammonium
sulfate at 2 lbs/A is recommended with either adjuvant. Steadfast may be applied to corn that is up to twelve
inches tall or has six leaf collars, whichever is the most
restrictive. Rainfall within 5 to 7 days after application will
aid with residual activity. The final spray solution must not be allowed to set in
the tank more than 24 hours after mixing or after four hours if
tankmixed with Hornet to avoid product degradation and loss of
efficacy. Do not
tankmix Steadfast with any of the following tankmix partners due
to potential crop injury or weed control antagonism: Bladex,
Basagran, Laddok, 2,4-D containing herbicides, foliar
organophosphate insecticides, and other ALS containing
herbicides. Make
sure to check for label restrictions when applying Steadfast to
corn treated with soil insecticides as unacceptable crop injury
may occur. The
label states that Steadfast has not been evaluated on all corn
varieties and limits applications to field corn, including food
grade (yellow, dent, hard endosperm) and DuPont Optimum High-Oil
with relative maturities of 88 days or greater. Applications to corn varieties not listed above may
result in crop injury and growers should consult their seed
supplier or local DuPont representative for further labeling.
Steadfast is labeled to control
many emerged annual grasses including foxtails, woolly cupgrass,
wild proso millet, and fall panicum as well as quackgrass and a
few broadleaf weeds such as redroot pigweed, Pennsylvania
smartweed, jimsonweed, and wild mustard. Other key broadleaf weeds are listed as suppression only and
require a tankmix partner or mechanical cultivation to achieve
acceptable control. Steadfast
provides the best control when applied to small, actively
growing weeds and does provide some residual activity. Steadfast is not effective on large or smooth crabgrass
and growers should consider using a soil-applied grass herbicide
prior to Steadfast if crabgrass is a problem.
Corn may be replanted immediately
after an application of Steadfast. The rotational intervals for
the following crops are listed: popcorn, sweet corn, seed corn (10 days), soybean (15
days), winter cereals (4 months), spring cereals (8 months), dry
beans, peas, snap beans (10 months), alfalfa (12 months). Refer to the label for a complete list of rotational
guidelines.
Amplify
Amplify is Monsanto’s
formulation of cloransulam-methyl, which is the same active
ingredient as in FirstRate, for use in soybeans. Amplify is formulated as an 84% WDG and is applied at the
same rates as FirstRate.
Gauntlet
Gauntlet is FMC’s co-pack
of sulfentrazone and cloransulam-methyl, the same active
ingredients in Authority and FirstRate, for use in soybeans.
Gauntlet may be applied preplant incorporated into the
top 1-3 inches of soil and no more than 30 days prior to
planting, preplant surface applied no more than 30 days prior to
planting, or preemergence; do not apply if the soybeans are
emerging (cracking stage) as crop injury may occur. Each co-pack of Gauntlet consist of two water soluble
packets, an outer packet containing 26.5 ounces of sulfentrazone
and an inner packet containing 3 ounces of cloransulam-methyl.
The co-pack will not dissolve in fluid fertilizers so
dissolve in water before adding if a fluid fertilizer is used as
the carrier. Each packet must be used together and will treat four to five
acres depending soil organic matter. One package will treat 5
acres on soils with 3% or less organic matter, delivering 0.25
lb ai/A of sulfentrazone and 0.031 lb ai/A of cloransulam-methyl,
or 4 acres on soils with greater than 3% organic matter,
delivering 0.31 lb ai/A of sulfentrazone and 0.039 lb ai/A of
cloransulam-methyl. Gauntlet
is labeled for the control of a wide range of annual grasses and
broadleaves, including foxtails, large and smooth crabgrass,
fall panicum, jimsonweed, common lambsquarters, nightshades,
pigweeds, common and giant ragweed, Pennsylvania smartweed,
velvetleaf, waterhemp, and the sedges.
Soybeans
may be planted anytime after a Gauntlet application. The
rotational intervals for the following crops are listed: wheat
(4 months), popcorn (9 months), field and seed corn (10 months),
other cereal grains and alfalfa (12 months), and sweet corn (18
months). Please
refer to the label for a complete list of rotation.
Valor
Valor is a new
active ingredient from Valent that has just received EPA
registration for use on soybeans. Valor is a member of the
N-phenyl-phatalimide herbicide
family and works by inhibiting the PPO enzyme in the plant.
Valor is formulated as a 51% WDG and may be used as a
burndown or preemergence (do not incorporate) application to
soybeans, applying after soybean emergence will result in severe
injury. The label cautions that crop injury may increase when Valor
is applied on poorly drained soils or when applied under wet,
cool conditions. Planting
soybean seed at least 1.5 inches will minimize the risk of crop
injury under normal growing conditions. Do not tank mix with or apply Valor in the same field
where the following herbicides are applied: flufenacet (Axiom, Domain, Define), alachlor (Lasso,
Micro-Tech), metolachlor (Dual II Magnum, Boundary), or
dimethenamid (Frontier, Outlook).
Like most
soil-applied herbicides, the use rate is dependant on the soil
type and organic matter. A
rate of 2 to 2.5 oz/a will be adequate for most Wisconsin soils.
Do not exceed a maximum use rate of 3 oz/a per growing
season. Valor
should be applied using water as the carrier at a minimum of 10
GPA for preemergence applications or 15 GPA for burndown
applications. Do not apply Valor by air or through any type of irrigation.
Adequate soil moisture is required for maximum weed
control and a rotary hoeing 5-7 days after application will help
activate the herbicide in the absence of rainfall.
Valor is
primarily a broadleaf herbicide that provides some annual grass
suppression; it will not provide broad-spectrum, season-long
weed control without a tankmix partner, planned sequential
application, or mechanical cultivation. Broadleaves that are listed on the label as controlled at
2 oz/a include seedling dandelion, common lambsquarters,
marestail/horseweed, eastern black nightshade, pigweeds, and
shepherd’s-purse. The
2.5 oz/a rate is labeled for control of common ragweed and
waterhemp. Weeds
that are suppressed at 2.5 to 3 oz/a include giant
ragweed, smartweeds, velvetleaf, large crabgrass, barnyardgrass,
giant foxtail, and fall panicum. Check the label for the list of approved tankmix partners to
expand the weed control spectrum. Valor may fit into many weed control programs, from one
component in a total preemergence program to providing early
season weed control and extending the postemergence application
window in Roundup Ready or conventional soybeans.
Valor
application rates will determine the rotational restrictions.
The following rotational restrictions apply when Valor is
applied up to 2 oz/a or less: field corn, sorghum, sunflower,
tobacco and wheat can be planted 30 days after application;
barley, dry bean, rye and sweet corn can be planted after 4
months; and all other crops can be planted after 12 months.
If the Valor rates are above 2 oz/a, the rotational
interval for field corn, sorghum, sunflower, tobacco and wheat
increase to 2 months, but the other intervals remain the same.
Finally, do not graze treated fields or feed treated
forage or hay to livestock.
February 2001 |
