Fall Weed Control in Small Grains

Dwight Lingenfelter, Penn State Extension

Small grain establishment and growth can be hindered by weeds. Below are some herbicide options to consider for problem weed species.

Weeds germinating in seedling wheat. Photo: D. Lingenfelter

Dense populations of winter annual weeds can compete with wheat, barley, and other small grains in late fall and early spring and slow the rate of crop development potentially reducing yield. If winter annual weeds like common chickweed, henbit, marestail, winter annual grasses, and others emerge with the small grain and are left unchecked, the potential impact on yield could be great. In these situations, it may make sense to kill these weeds in the fall rather than early spring. Harmony Extra is the most broad-spectrum herbicide for broadleaf control, but resistant populations of common chickweed are evident in parts of the state.

In addition, there are several herbicides labeled for grass control in wheat and fall is typically the best time to make an application. Herbicides for downy brome control include, Anthem Flex/Zidua, Finesse, Osprey, and PowerFlex; annual ryegrass is controlled by Anthem Flex/Zidua, Axiom, Axial, Finesse, Osprey, Prowl, and PowerFlex; herbicides active on annual bluegrass include, Axiom, Anthem Flex/Zidua, Dimetric, Finesse, and Osprey; and roughstalk bluegrass is controlled by Osprey and PowerFlex. Make sure to include the necessary spray adjuvants. Remember that cool (less than 50°F) cloudy days can reduce herbicide activity. Also, if you plan to frost-seed or drill a companion crop such as red clover in early spring it may be best to make a fall herbicide application to avoid certain issues with herbicide residuals affecting their establishment. However, even if products such as PowerFlex, Osprey, Dimetric, and others are applied in the fall, their recrop restrictions still prevent seeding of certain crops next spring.

Burndown herbicides for no-till small grains include dicamba, Gramoxone, glyphosate, Harmony Extra, and Sharpen. Refer to the specific product label for more application information. The legitimate use of 2,4-D for burndown in wheat and other small grains is uncertain. None of the 2,4-D ester or amine labels specify application just prior to small grain seeding or emergence. Some research suggests a minimum delay of 7-10 days after application at rates up to 1 pint/A 2,4-D ester. Since 2,4-D burndown in small grains is ambiguous at best, if injury occurs liability rests with the consultant or applicator. The following table summarizes some fall herbicide options for small grains. Check a current herbicide label for the latest use information

Common Fall Herbicide Options for Small Grains

Herbicide Crops Strengths Growth stage Remarks, if any
2,4-D Wheat, barley, rye, triticale, oats Marestail, mustards, dandelion 3–6 Best to apply when small grain is 4 to 8 inches tall
Aim Wheat, barley, rye, triticale, oats Star-of-Bethlehem, pennycress 1–5
Anthem Flex Wheat Annual grasses and broadleaves delayed pre to early post (1-3) Does not control emerged weeds; suppression only of chickweed and marestail
Axial XL/ Star / Bold Wheat, barley Annual/Italian ryegrass 2–8 No control of ACCase-resistant species
Axiom wheat, triticale Certain annual grasses and several broadleaves spike-1 (2-leaf)
Clarity / dicamba Wheat, barley, rye, triticale, oats Marestail, thistles 3–6
Dimetric EXT and Metricor Wheat, barley ALS-resistant chickweed 1–5 Controls other winter annual broadleaves; wheat safety is best with early spring application (at greenup)
Finesse Cereal and Fallow Wheat, barley, triticale Most broadleaves; speedwell, and some grasses pre to 8 Pre-wheat only; watch recrop restrictions
Harmony Extra / Express Wheat, barley, triticale, oats Most broadleaves, garlic; wild carrot suppression 1–7 Will not control ALS-resistant chickweed
Huskie Wheat, barley, rye, triticale Most broadleaves 1–7 Has good activity on marestail
Maestro Wheat, barley, rye, triticale, oats Mustards, wild buckwheat 1–9 Apply when weeds are
MCPA Wheat, barley, rye, oats Same as 2,4-D 3–6
Osprey Wheat, triticale Annual/Italian ryegrass, annual bluegrass 1–5 Controls some broadleaves
Peak Wheat, barley, rye, triticale, oats Mustards, garlic; wild carrot suppression 2–6 Watch recrop restrictions
PowerFlex HL Wheat, triticale Downy brome, cheat, annual/Italian ryegrass 3-leaf to 6 Controls some broadleaves, speedwell; will not control ALS-resistant chickweed
Prowl H20 Wheat, triticale Annual ryegrass, some annual broadleaves 1–7 Apply after small grain emergence but before weeds have emerged
Quelex Wheat, barley, triticale Marestail, some annual broadleaves 2–8 Slow acting on weeds; watch recrop restrictions
Sharpen Wheat, barley, rye, triticale, oats Marestail, some annual broadleaves before crop emergence Controls existing marestail at burndown
Starane Ultra/Flex Wheat, barley, rye, triticale, oats Chickweed (including ALS-resistant) 2–9
Stinger Wheat, barley, oats Thistles and marestail 2–9 Watch recrop restrictions
Talinor Wheat, barley Some annual broadleaves 2–9 Watch recrop restrictions
Valor SX or EZ Wheat Some annual broadleaves 7-days early preplant Improves marestail control; plant wheat at least 1″ deep
Zidua Wheat Annual grasses and broadleaves 1–3; delayed pre to early post (4 tillers) Does not control emerged weeds; suppression only of chickweed and marestail

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