Not all registered pesticides are listed. The following are listed alphabetically. When choosing a pesticide, consider information relating to environmental impact, resistance management, the pesticide's properties, and application timing. Tank mixes may be necessary to achieve desired control; see the Susceptibility of Weeds to Herbicide Control for information on specific weed control. Always read the label of the product being used.
COMMENTS: Apply with a controlled applicator or with
low-pressure flat fan nozzles. For annual weed control, use 1 lb/acre in
3–10 gal water. Ammonium sulfate can also be added (1 to 2% by weight
or 8.5 to 17 lb per 100 gallon of water) to the spray solution to
significantly improve control in areas with hard water. It is important to
add the ammonium sulfate to the water before adding the herbicide. Apply to
young annuals or vigorously growing perennials in flowering stage. Some
perennials require the 3.7 lb a.e./acre rate of glyphosate for control. May
be used to kill young weeds in the planting row before planting. As a result
of the no-till effect, new weeds usually do not establish for a month or
more. Do not use more than 10.6 lb per year. Resistance to glyphosate has
been documented in certain weed species. Residual period: none.
COMMENTS: Apply to soil under trees. Do not apply on young
trees until 1 month after planting. Do not apply within 1 month of harvest.
For best results, incorporate and follow with 1/2 to 1 inch of water or an
immediate shallow cultivation. Dichlobenil can be very effective in
controlling perennial weeds around sprinkler heads. Residual period:
4–6 months.
B.
DIURON
1.6–3.2 lb a.i.
(Karmex, Direx, Diuron)
12
0
WSSA MODE OF ACTION GROUP NUMBER1: 7
COMMENTS: Apply to the soil under trees at least 3 years of
age. A single application may be made in winter or split applications between
fall and spring. Diuron is sometimes combined with other preemergence
herbicides to broaden the spectrum of weeds controlled. These combination
treatments frequently use lower rates of diuron. Adjust rates according to
soil texture. Do not use on soils with less than 1% organic matter.
Considered to be a ground water contaminant and requires a use permit within
Ground Water Protection Areas. Residual period: 8–12 months.
C.
FLUMIOXAZIN
0.188–0.376 lb
a.i.
(Chateau SW)
12
60
WSSA MODE OF ACTION GROUP NUMBER1: 14
COMMENTS: For use on dormant nonbearing and bearing trees
established for one year or more. Apply in 10 or more gal water/acre to soil
under trees when completely dormant. Do not apply on newly planted trees
unless soil is firm and there are no cracks in soil around base of trees.
Best control is achieved when irrigation or rainfall occurs within 21 days.
Can be mixed with other pre- or postemergence herbicides. It will not provide
adequate control of emerged weeds, unless mixed with a postemergence
herbicide. Use is allowed under a supplemental label. Avoid creating dust
that can move flumioxazin up into the tree canopy. Flumioxazin should not be
applied within 300 yards of actively growing (non-dormant) pears. Residual
period: 3–6 months.
D.
ISOXABEN
0.5–1.0 lb a.i.
(Gallery T&V)
12
365
WSSA MODE OF ACTION GROUP NUMBER1: 21
COMMENTS: For use on non-bearing trees only. Wait until soil
has settled around newly planted trees before applying. Controls broadleaf
weeds only with a preemergence application and will not control emerged
weeds. If weeds are emerged, lightly cultivate or add a postemergence
herbicide. Requires incorporation for activation, either by light cultivation
(1 to 2 inches) or rainfall (minimum of 0.5 inch) within 21 days after
application. Sprinkler or flood irrigation can also be used for
incorporation. Apply in at least 10 gal/acre of water. Residual period:
4–6 months.
E.
NORFLURAZON
2.0–3.9 lb a.i.
(Solicam DF)
12
60
WSSA MODE OF ACTION GROUP NUMBER1: 12
COMMENTS: Effective on annual broadleaf and grass species. Can
suppress yellow nutsedge or bermudagrass when used year after year. Apply to
soil as a directed spray from fall to early spring under trees established
for at least 2 years. If no rainfall occurs within 4 weeks, incorporate with
sprinkler or flood irrigation. Remove existing weeds with cultivation or a
postemergence herbicide, because it has no postemergence activity. Avoid
higher rates on sandy or gravelly soils to prevent injury to trees.
Considered to be a ground water contaminant and requires a use permit within
Ground Water Protection Areas. Apply in 20–100 gal water/acre. Residual
period: 6–12 months.
F.
ORYZALIN
2–6 lb a.i.
(Surflan, Oryzalin 4 A.S., etc.)
24
0
WSSA MODE OF ACTION GROUP NUMBER1: 3
COMMENTS: Preemergence selective herbicide primarily for
annual grass control. Apply to the soil surface in 20–40 gal
water/acre. If rain does not occur within 21 days, sprinkle irrigate with
0.5–2 inches of water. May be combined with a postemergence herbicide
if weeds are present. Most effect on annual grasses and numerous broadleaf
annuals. Very safe for young or newly planted trees and on sandy or sandy
loam soils. Used to maintain control in strips down the row. The higher rates
give the longest soil residual. Usually used at 4 lb a.i./acre. If Surflan
was used previously in the field with regularity, stunting of newly planted
trees has been observed. Residual period: 4–10 months.
G.
OXYFLUORFEN
0.5–2 lb a.i.
(GoalTender)
24
0
WSSA MODE OF ACTION GROUP NUMBER1: 14
COMMENTS: Apply in 40–100 gal water/acre on firm soil.
Must not be mechanically disturbed or poor weed control will result. Often
combined with oryzalin. Check label for use period. Do not use after February
15 to avoid phytotoxicity to foliage and fruit. Residual period: 2–6
months.
H.
PENDIMETHALIN
1.9–3.8 lb a.i.
(Prowl H20, etc.)
24
60
WSSA MODE OF ACTION GROUP NUMBER1: 3
COMMENTS: Apply in 10 or more gal water/acre to soil under
trees. Do not apply on newly planted trees unless soil is firm and there are
no cracks in soil around base of trees. Best control is achieved when
irrigation or rainfall occurs within 7 days. Will not control emerged weeds.
Residual period: 4–10 months.
I.
PRONAMIDE*
1–4 lb a.i.
(Kerb)
24
0
WSSA MODE OF ACTION GROUP NUMBER1: 3
COMMENTS: Do not apply to trees less than 1 year old.
Selective herbicide for control of winter annual and perennial grasses. Apply
in fall after fruit harvest. Apply in 40–50 gal water/acre to the soil
at the base of the trees. Must be applied before weed emergence because it
will not control emerged weeds. Rainfall or irrigation is essential after
application for effective weed control. Residual period: 4-8 months.
J.
RIMSULFURON
0.03 lb a.i.
(Matrix FNV)
4
7
WSSA MODE OF ACTION GROUP NUMBER1: 2
COMMENTS: Apply in 10 or more gal water/acre to soil under
trees. Apply only to trees that have been established for one full growing
season. Best control is achieved when irrigation or rainfall occurs within 2
weeks after application. When band applications are made and 50% or less of
an orchard is treated, a second application can be made. Will not control
emerged weeds. Residual period: 4–10 months.
K.
SIMAZINE
1–2 lb a.i.
(Princep Caliber 90)
12
0
WSSA MODE OF ACTION GROUP NUMBER1: 5
COMMENTS: Apply to the soil under trees older than 3 years.
Make only one application per year. Use the high rate for heavy soils.
Simazine is frequently used in combination with other preemergence
herbicides. On light soils, simazine is often used at rates of 0.5–1 lb
a.i./acre. Do not use on gravel, sand, or loamy sand soils. If irrigating
immediately after application, limit water to 0.5 inch. Considered to be a
ground water contaminant and requires a use permit within Ground Water
Protection Areas. Residual period: 8–12 months.
Postemergence
A.
2,4–D*
0.95–1.4 lb a.e.
(Orchard Master, etc.)
48
14
WSSA MODE OF ACTION GROUP NUMBER1: 4
COMMENTS: For use on established trees one year or older.
Effective on most broadleaf annual weeds. Provides partial control of field
bindweed. Apply as a directed spray to weeds, using low-pressure flooding
nozzles between the tree rows. Best results are obtained when applied a few
days after an irrigation. Do not allow drift or crop injury may result. No
more than two applications allowed during the growing season. Residual
period: none.
B.
CARFENTRAZONE
0.008–0.03 lb
a.i.
(Shark)
12
3
WSSA MODE OF ACTION GROUP NUMBER1: 14
COMMENTS: Postemergence contact herbicide used for quick top
kill of many broadleaf weed species. Apply anytime during the season, but if fruit is present, avoid use or apply with extreme care to avoid drift. Also
used for sucker control. Apply in a minimum of 20 gal water/acre to weeds
less than 6 inches tall. Repeat treatments as new growth occurs, but at least
14 days apart. Do not use more than 2 oz a.i./acre per season. Use 0.25%
nonionic surfactant, 1.0% of a crop oil concentrate, or a silicone or MSO
surfactant. Residual period: none.
C.
CLETHODIM
0.07–0.12 lb a.i.
(SelectMax)
24
365
WSSA MODE OF ACTION GROUP NUMBER1: 1
COMMENTS: Use on nonbearing trees only. Apply to young perennial
grasses. Repeat applications will be required for control of perennial
grasses. Apply in 10 to 40 gal water/acre. Add 0.25% nonionic surfactant to
the spray solution. Spray pressure should be between 30 and 60 PSI, with
higher pressures used when weed density is high and directed at the grasses
(avoid applying over the tops of young trees). Do not apply a broadleaf
herbicide within one day following application or reduced grass control may
occur. Residual period: none.
D.
FLUAZIFOP-P-BUTYL
0.25–0.375 lb
a.i.
(Fusilade DX)
12
365
WSSA MODE OF ACTION GROUP NUMBER1: 1
COMMENTS: Use on nonbearing trees only. Apply in 20 to
40 gal water/acre and add 0.5% nonionic surfactant. Do not apply to
water-stressed grasses or poor control may result. Repeat applications may be
required for johnsongrass and bermudagrass. Residual period: none.
E.
GLYPHOSATE
0.82–3.3 lb a.e.
(Roundup WeatherMax, etc.)
4
1
WSSA MODE OF ACTION GROUP NUMBER1: 9
COMMENTS: Apply with controlled droplet application or with
low-pressure, flat-fan nozzles. For annual weed control, use 1 lb a.i./acre
in 3–10 gal water. Ammonium sulfate can also be added (1 to 2% by
weight or 8.5 to 17 lb per 100 gallon of water) to the spray solution to
improve control in areas with hard water. It is important to add the ammonium
sulfate to the water before adding the herbicide. For chemical mowing,
consult label for exact timing and rates, depending on weed size and species.
Apply to young annuals or vigorously growing perennials. Some perennials
require the 4 lb a.i./acre rate of glyphosate for control. A good herbicide
for perennial weeds, but doesn't eradicate field bindweed or nutsedge. Not
effective on some broadleaf weeds at older stages of growth (little mallow
and filaree). Avoid drift onto green bark or foliage of tree or injury will
result. It is important to monitor treated areas for escaped weeds, as
glyphosate resistant weeds have been observed in orchards where the herbicide
has been used repeatedly for several years. Residual period: none.
F.
OXYFLUORFEN
0.5–2 lb a.i.
(GoalTender)
24
0
WSSA MODE OF ACTION GROUP NUMBER1: 14
COMMENTS: Apply in 40–100 gal water/acre on firm soil.
Must not be mechanically disturbed or poor weed control will result. Often
combined with oryzalin. Check label for use period. Do not use after February
15 to avoid phytotoxicity to foliage and fruit. Residual period: 2–6
months.
G.
PARAQUAT*
0.625–1.0 lb a.i.
(Gramoxone Inteon)
12
0
WSSA MODE OF ACTION GROUP NUMBER1: 22
COMMENTS: Nonselective postemergence contact herbicide used
for quick top kill of most weed species. Less effective against perennials
that will regrow (bermudagrass, dallisgrass, johnsongrass and field
bindweed). Most effective when used in late winter or early spring on small
annual grass species in combination with preemergence herbicides. Apply in 10–60
gal water/acre to young weeds. Use 0.25% nonionic surfactant or 1.0% volume
per volume of a crop oil concentrate. Repeat treatment as new growth occurs.
Do not exceed 3 applications per season. Residual period: none.
H.
SETHOXYDIM
0.19–0.47 lb a.i.
(Poast)
12
14
WSSA MODE OF ACTION GROUP NUMBER1: 1
COMMENTS: Apply to young perennial grasses. Repeat
applications will be required for the control of perennial grasses. Add 2
pt/acre of a nonphytotoxic crop oil concentrate to the spray solution.
Residual period: none.
**
Herbicide rates are expressed in lb a.i./acre. Always
verify the concentration of the formulated herbicide product to ensure
accurate and effective rates are used.
‡
Restricted entry interval (REI) is the number of hours
(unless otherwise noted) from treatment until the treated area can be safely
entered without protective clothing. Preharvest interval (PHI) is the
number of days from treatment to harvest. In some cases the REI exceeds the
PHI. The longer of two intervals is the minimum time that must elapse before
harvest.
1
Group numbers are assigned by the Weed Science Society of
America (WSSA) according to different modes of action. Although weeds may
exhibit multiple resistance across many groups, mode of action numbers are
useful in planning mixtures or rotations of herbicides with different modes
of action. For more information, see www.hracglobal.com.
*
Permit required from county agricultural commissioner for
purchase or use.
NA
Not applicable.
Text Updated: 11/12
Treatment Table Updated: 11/12