Weeds Pages
| Common name | Amount per acre | REI‡ | PHI‡ | |
|---|---|---|---|---|
| (Example trade name) | (hours) | (days) | ||
| Not all registered pesticides are listed. The following are listed alphabetically. When choosing a pesticide, consider information relating to environmental impact, resistance management (PDF), the pesticide's properties, and application timing. Tank mixes may be necessary to achieve desired control; see Susceptibility of Winter Weeds and Susceptibility of Spring and Summer Weeds to Herbicide Control for information on specific weed control. Always read the label of the product being used. | ||||
| PREPLANT | ||||
| Before weeds emerge | ||||
| A. | METAM SODIUM* | |||
| (Vapam HL) | Label rates | See label | NA | |
| COMMENTS: For spot treatment of certain perennial weeds. | ||||
| After weeds emerge | ||||
| A. | GLYPHOSATE | 0.38–3.7 lb a.e. | 4 | NA |
| (Roundup WeatherMax)
(Roundup PowerMax) |
0.675–6.57 pt
0.55–5.38 pt |
|||
| 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 to 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 to 6 leaves. Some perennial weeds require the 3.7 lb a.e/acre 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 | ||||
| Before weeds emerge | ||||
| A. | ISOXABEN | 0.5–1.0 lb a.i. | 12 | 365 |
| (Trellis) | 0.66–1.33 lb | |||
| WSSAMODE-OF-ACTION GROUP NUMBER1: 21 | ||||
| COMMENTS: For use in nonbearing vineyards only. Apply in 20 to 60 gal water/acre. Requires rainfall or irrigation within 21 days of herbicide application to activate. May be combined with postemergence herbicides if seedlings have emerged. Combine with oryzalin if annual grasses are expected. | ||||
| B. | NAPROPAMIDE | 4 lb a.i. | 24 | 35 |
| (Devrinol 50DF) | 8 lb | |||
| WSSAMODE-OF-ACTION GROUP NUMBER1: 15 | ||||
| COMMENTS: Apply in 20 to 60 gal water/acre. Must be incorporated within 4 to 7 days of application or sprinkler irrigated. Can be combined with a postemergence herbicide if weeds have emerged. | ||||
| C. | ORYZALIN | 2–4 lb a.i. | 24 | 0 |
| (Surflan A.S.) | 2–4 qt | |||
| WSSA MODE-OF-ACTION GROUP NUMBER1: 3 | ||||
| COMMENTS: Apply in 20 to 60 gal water/acre. If rain does not occur within 21 days, sprinkle irrigate with 0.5 to 2 inches water. May be combined with postemergence herbicide if weeds have emerged. Most applications are with the 4 lb a.i./acre rate to give maximum residual. | ||||
| D. | OXYFLUORFEN | 1.25–2 lb a.i. | 24 | 0 |
| (Goal 2XL) | 5–8 pt | |||
| WSSA MODE-OF-ACTION GROUP NUMBER1: 14 | ||||
| COMMENTS: Apply in 20 to 60 gal water/acre on firm soil. Must not be mechanically disturbed or poor weed control will result. May be used preemergence or early postemergence. Often is combined with oryzalin or glyphosate. The 1 lb a.i./acre rate gives minimal residual control but is combined with glyphosate to increase spectrum of annual weeds controlled. For use during the dormant season only (before February 15). Do not apply to kiwifruit established less than three years unless vines are on a trellis wire a minimum of 3 ft above the soil surface. | ||||
| After weeds emerge | ||||
| A. | GLYPHOSATE | 0.38–3.7 lb a.e. | 4 | 14 |
| (Roundup WeatherMax)
(Roundup PowerMax) |
0.675–6.57 pt
0.55–5.38 pt |
|||
| 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 to 40 gal water/acre with 1 lb a.e./acre. Apply to young annuals or vigorously growing perennials in the early flowering stage or to nutsedge when it has 5 to 6 leaves. Some perennial weeds require the 3.7 lb a.e./acre rate for control. | ||||
| B. | PARAQUAT* | 0.64–1 lb a.i | 12 or 24 | 14 |
| (Gramoxone SL 2.0) | 2.5–4.0 pt | (See comments) | ||
| WSSA MODE-OF-ACTION GROUP NUMBER1: 22 | ||||
| COMMENTS: Apply in 30 to 60 gal water/acre to young plants. Thorough wetting of the weed foliage is essential for control. Use a 0.5% nonionic surfactant. Repeat herbicide application as new growth occurs. Do not apply this herbicide more than three times per year. Note: 12 hour REI is for dormant applications only, all other uses require a 24 hour REI | ||||
| 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. | ||||
| * | 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 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. |
| NA | Not applicable |