COMMENTS: Fumigants such as 1,3-dichloropropene are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone.
B.
CARFENTRAZONE
(Shark EW)
Label rates
12
15
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: For weeds with hard seed coats that escaped fumigation.
C.
METAM SODIUM*
(Vapam)
Label rates
See label
NA
COMMENTS: For spot treatment of certain perennials.
. . . or . . .
METAM POTASSIUM*
(K-Pam HL)
Label rates
See label
NA
Postemergence
A.
CARFENTRAZONE
(Shark EW)
Label rates
12
15
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Apply when weeds are small.
B.
GLYPHOSATE
(Roundup PowerMax)
Label rates
See label
14
. . . or . . .
(Touchdown HiTech)
Label rates
See label
14
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Apply in controlled droplet application or with low-pressure flat fan nozzles. For annual weed control use 10–40 gal water/acre with 1 lb/acre. Apply to young annuals or vigorously growing perennials in the early flowering stage or to nutsedge when it has 5–6 leaves. Some perennials require the maximum rate for control. Adding sprayable ammonium sulfate at 5 to 10 lb/100 gal of spray solution before the glyphosate is added can often improve control.
POSTPLANT
Preemergence
A.
CARFENTRAZONE
(Shark EW)
Label rates
12
15
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: For weeds with hard seed coats that escaped fumigation. Not recommended for blackberries or young raspberries. Apply to base of canes; do not contact foliage.
B.
DIURON*
1.6–2.4 lb a.i.
(Karmex DF)
2–3 lb
12
0
(Direx 4L)
1.6–2.4 qt
12
0
WSSA MODE-OF-ACTION GROUP NUMBER1: 7
COMMENTS: Direct spray to the soil under canes at least 3 years of age. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Pay special attention to soil texture and rate adjustments; do not use on soils with less than 1% organic matter. Residual period: 8–12 months. For best results, apply during the winter months when weeds are less than 2 inches. See label for rainfall concerns.
C.
NAPROPAMIDE
4 lb a.i.
(Devrinol 50DF)
8 lb
24
0
WSSA MODE-OF-ACTION GROUP NUMBER1: 15
COMMENTS: Apply in 20–60 gal water/acre. Must be incorporated within 4 to 7 days of application or sprinkler irrigated. Can be combined with a postemergence if weeds have emerged.
D.
ORYZALIN
2–4 lb a.i.
(Surflan AS)
2–4 qt
24
0
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: Apply in 20–60 gal water/acre. If rain does not occur within 21 days, sprinkle irrigate with 1/2 to 2 inches water. May be combined with postemergence if weeds have emerged. Most applications are with the 4 lb a.i./acre rate to give maximum residual.
Postemergence
A.
CARFENTRAZONE
(Shark EW)
Label rates
12
15
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Apply when weeds are small. Not recommended for blackberries or young raspberries. Apply to base of canes; do not contact foliage.
B.
GLYPHOSATE
0.4–3.7 lb a.e.
(Roundup)
11 fl oz– 3.3 qt
See label
See label
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Recently, Conyza spp. (horseweed and fleabane) have shown resistance or tolerance to both glyphosate and paraquat: If these herbicides fail to control these weeds under expected circumstances, use alternative control methods.
C
PARAQUAT*
0.64–1 lb a.i
(Gramoxone SL)
2–4 pt
24
0
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: Apply in 30–60 gal water/acre to young plants. Thorough wetting of the weed foliage is essential for control. Use a 0.5% nonionic surfactant. Repeat treatment as new growth occurs. Do not treat more than 3 times per year. Recently, Conyza spp. (horseweed and fleabane) have shown resistance or tolerance to both glyphosate and paraquat: If these herbicides fail to control these weeds under expected circumstances, use alternative control methods.
D.
SETHOXYDIM
0.28–0.47 lb a.i.
(Poast)
1.5–2.5 pt
12
45
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: Apply to young annual or perennial grasses. Repeat applications will be required for the control of perennial grasses. Add 2 pt crop oil concentrate to the spray solution. Do not apply to grass that is stressed or poor control may result. Residual period: less than 1 month.
HERBICIDE COMBINATIONS
For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i.
A.
GLYPHOSATE
0.4–3.7 lb a.e.
(Roundup PowerMax)
11 fl oz–3.3 qt
See label
14
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
. . . PLUS . . .
ORYZALIN
4 lb a.i.
(Surflan AS)
4 qt
24
0
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
. . . or . . .
NAPROPAMIDE
4 lb a.i.
(Devrinol 50DF)
8 lb
24
0
WSSA MODE-OF-ACTION GROUP NUMBER1: 15
COMMENTS: Combines post- and preemergence activity to control existing weeds, leaving residual control of most annual weeds up to 6 months. Combination choice depends on weed spectrum and how rapidly the application can be incorporated. Be sure to follow restrictions on labels of both products in a tank mix; the most restrictive limits must be followed.
*
Permit required from county agricultural commissioner for purchase or use.
‡
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 until the orchard can be harvested. In some cases the REI exceeds the PHI The longer of these two intervals is the minimum time that must elapse before harvest may take place.
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.