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| Herbicide | Application and Remarks |
| Grass Control | ||
| Sethoxydim Poast |
Rate: | 0.28 lb ai/A (1.5 pints/A) for most annual grasses or 0.38 lb ai/A (2 pints/A) for volunteer cereals (Section 2ee label for Poast in Idaho). |
| Time: | Apply to actively growing annual grasses at stage of grass growth indicated on label. For volunteer cereal control, apply before tillering up to 4 inches tall. | |
| Remarks: | See labels for specific rates for weed species and weed size. Always add a nonphytotoxic oil concentrate to the spray tank at 32 oz/A or methylated seed oil at 20 oz/A, or Dash HC at 16 oz/A. Sethoxydim is most effective on actively growing grasses before they reach the maximum size listed on label. Larger, more mature grasses can often be controlled, but two applications may be required. Sethoxydim will not control annual bluegrass or any of the fine fescues and is relatively weak on downy brome. | |
| Caution: | Control may be erratic on grasses stressed by
drought, temperature extremes, insect damage, herbicide injury, etc. Do
not apply if rain is expected within 1 hour after application. Do not
cultivate within 5 days before or 7 days after application. Do not apply within 30 days of harvest. BASF does not recommend use of sethoxydim tank-mixes other than those listed on label. Do not apply more than 0.94 lb ai/A Poast (5 pints/A) in one growing season. |
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| Quackgrass | ||
| EPTC Eptam |
Rate: | 4 lb ai/A (4.5 pints/A) |
| Time: | Apply and incorporate just before planting potatoes. | |
| Remarks: | Thoroughly till quackgrass infestations before application so that rhizomes are chopped into pieces 2 to 3 inches or smaller. EPTC must be incorporated immediately and thoroughly after application, either with a rotovator or by cross-disking. Use on mineral soils containing less than 10% organic matter. | |
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| rimsulfuron Matrix |
Rate: | 0.0156 to 0.023 lb ai/A (1 to 1.5 oz/A 25% DF) + nonionic surfactant at 0.125 to 0.25% v/v (1 to 2 pints/100 gal spray solution) |
| Time: | Apply postemergence to 4- to 6-inch quackgrass. | |
| Remarks: | A new Matrix label has been submitted to
EPA but was not available before this handbook went to press. Be sure to
consult the new label tor current recommendations. Also may be used as a split postemergence + postemergence application. Use 0.0156 lb to 0.023 lb ai/A (1 to 1.5 oz/A 25% DF) rimsulfuron + 0.125 to 0.25% nonionic surfactant (1 to 2 pints/100 gal spray solution) at each application; do not exceed a total of 0.039 lb ai/A (2.5 oz/A 25% DF) rimsulfuron. With split applications, the second application should be 14 to 28 days after the first. Rimsulfuron is a sulfonylurea herbicide. Biotypes of kochia, prickly lettuce, and Russian thistle resistant to sulfonylurea herbicides infest Idaho and Washington and will not be controlled by rimsulfuron applied alone. Therefore, employ resistance-management strategies when using rimsulfuron. A key strategy is to tank-mix rimsulfuron with a herbicide that has a different mode of action and is effective on the resistant species. Labeled tank-mixes are described in the Annual Grass and Broadleaf Weeds portion of this section. |
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| Caution: | Applied postemergence, rimsulfuron may
temporarily yellow potato foliage. Under environmental stress (cool, wet
weather or hot or humid weather), rimsulfuron applied postemergence also
may cause leaf malformations and stunted growth. Potatoes recover
within 7 to 10 days. To reduce potential injury, apply only if it has
been sunny for at least 3 successive days. Do not use on seed potatoes unless permitted by a supplemental label. Do not apply within 60 days of harvest. Avoid spray drift. Rimsulfuron is very active even at low dosages, and many crops including small grains, canola, sugarbeets, peas, and onions are very sensitive to rimsulfuron drift. Refer to the label for crop rotation restrictions. |
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| sethoxyim Poast |
Rate: | 0.47 lb ai/A (2.5 pints/A). Section 2ee label for Idaho, Washington, and Oregon. |
| Time: | Apply when quackgrass shoots are 6 to 8 inches tall. A second application at 0.28 lb ai/A (1.5 pints/A) may be needed if regrowth occurs. | |
| Remarks: | Always add a nonphytotoxic oil concentrate to
the spray tank at 2 pints/A. Sethoxydim provides suppression, not eradication, of quackgrass. |
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| Wild Oat | ||
| paraquat Gramoxone Extra or glyphosate Roundup |
Rate: | 0.47 lb ai/A paraquat + a nonionic surfactant
at 16 to 32 oz/A or 0.38 lb ae/A glyphosate |
| Time: | Apply before potatoes emerge. | |
| Remarks: | These materials will control only wild oats emerged at the time of application. Later-emerging wild oats will not be controlled. Some glyphosate formulations require use of nonionic surfactant; see label for details on additive use. | |
| Caution: | Paraquat is a restricted-use herbicide. Do
not apply either paraquat or glyphosate if potatoes have emerged, or crop injury may occur. |
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| EPTC Eptam |
Rate: | 3 to 6 lb ai/A (3.5 to 7 pints/A) |
| Time: | Apply and immediately incorporate into the soil before planting potatoes or after clean cultivation. | |
| Remarks: | If applied preplant, thoroughly incorporate into the soil immediately after application 2 to 3 inches deep by cross-disking 4 to 6 inches deep or by tilling with a power-driven rotary tiller cutting 2 to 3 inches deep. If applied after planting, incorporate either mechanically into the top 2 to 3 inches of soil or by sprinkler irrigation. | |
| Caution: | Refer to previous discussions of EPTC in this section. | |
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| rimsulfuron Matrix |
Rate: | 0.0156 to 0.023 lb ai/A (1 to 1.5 oz/A 25% DF) rimsulfuron + nonionic surfactant at 0.125 to 0.25% v/v (1 to 2 pints/100 gal spray solution) if weeds are emerged. |
| Time: | May be applied preemergence after hilling or drag-off but before potatoes and wild oats emerge; or postemergence to wild oats in the two- to four-leaf stage (3 to 5 inches tall). | |
| Remarks: | A new Matrix label has been submitted to
EPA but was not available before this handbook went to press. Be sure to consult the new label for current recommendations. Rimsulfuron is a sulfonylurea herbicide. Biotypes of kochia, prickly lettuce, and Russian thistle resistant to sulfonylurea herbicides infest Idaho and Washington and will not be controlled by rimsulfuron alone. Therefore, use resistance- management strategies when using rimsulfuron. A key strategy is to tank-mix rimsulfuron with a herbicide that has a different mode of action and is effective on resistant species. Labeled tank-mixes are listed in Annual Grass and Broadleaf Weeds in this section. |
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| Caution: | Applied postemergence, rimsulfuron may
temporarily yellow potato foliage. Under environmental stress (cool, wet
weather or hot or humid weather), rimsulfuron applied postemergence also
may cause leaf malformations and stunted growth. Potatoes recover
within 7 to 10 days. To reduce potential injury, apply only if it has
been sunny for at least 3 successive days.
Do not use on seed potatoes unless permitted by a supplemental label. Do not apply within 60 days of harvest. Avoid spray drift. Rimsulfuron is very active even at low dosages; many crops including small grains, canola, sugarbeets, peas, and onions are very sensitive to rimsulfuron drift. Refer to the label for crop rotation restrictions. |
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| sethoxydim Poast |
Rate: | 0.28 lb ai/A (1.5 pints/A) |
| Time: | Apply to actively growing wild oats up to 4 inches tall. | |
| Remarks: | Always add a nonphytotoxic oil concentrate to the spray tank at 2 pints/A, or methylated seed oil at 20 oz/A, or Dash HC at 16 oz/A. | |
| Caution: | Control may be erratic on grasses stressed due to drought, temperature extremes, insect damage, herbicide injury, etc. Do not apply if rain is expected within 1 hour after application. Do not cultivate within 5 days before or 7 days after application. Do not apply within 30 days of harvest. BASF does not recommend use of sethoxydim tank-mixes other than those listed on the label. Do not apply more than 0.94 lb ai/A Poast (5 pints/A) in one growing season. | |
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Malheur Experiment Station
595 Onion Avenue
Ontario, OR 97914
(541) 889-2174
FAX (541) 889-7831
