New Wheat Herbicides for 2008

New Wheat Herbicides for 2008

BASF
Clearmax®

Bayer
Huskie
Dow
Cleanwave® • PowerFlex Starane ® NXT • WideMatch
Dupont
Affinity® BroadSpec • Agility® SG Ally® Extra
FMC
Aim®

March 7, 2008

Many of the herbicides recently introduced for winter wheat are mixtures of two or more herbicides, often with two or more modes of action. As herbicide resistance in weeds continues to expand, combining different modes of action can be an effective strategy to stave off further problems. Following is a brief descriptions of these new winter wheat herbicides, categorized according to manufacturer. 

Always be sure to read and follow label directions when using any of these products.

BASF

Clearmax®

Clearmax herbicide is a co-pack of imazamox (Beyond®) and MCPA ester. Imazamox is an ALS inhibitor (Group 2) and MCPA is a synthetic auxin (Group 4). Clearmax should only be used with Clearfield wheat cultivars such as Above, Infinity CL, or Bond CL. These cultivars contain the gene or genes for tolerance to imazamox. Other wheat cultivars treated with Clearmax herbicide will be seriously injured or killed.

Table 1. Effect of liquid fertilizer rate on the efficacy of Beyond and Clearmax herbicides for feral rye control.
Herbicidea
32-0-0
Timing
Crop injury
Feral rye control
Foreign material
Wheat yieldb
 
% v/v
 
%
bu/ac
Beyond
2.5
Fall
0
90
0.2
51
Clearmax
2.5
Fall
7
94
0.2
46
Beyond
25
Fall
0
83
0.8
50
Clearmax
25
Fall
3
92
0.1
53
Beyond
50
Fall
0
22
4.0
61
Clearmax
50
Fall
0
93
0.2
54
Beyond
2.5
Spring
0
73
3.4
55
Clearmax
2.5
Spring
2
88
0.8
60
Beyond
25
Spring
0
8
9.3
50
Clearmax
25
Spring
0
77
2.0
62
Beyond
50
Spring
0
0
9.6
48
Clearmax
50
Spring
0
77
2.4
58
Check
0
0
30.4
27
LSD (5%)c
 
 
2.4
8.6
6.4
15
a All herbicide treatments contained the equivalent of 5 oz/ac of Beyond herbicide + 0.5% v/v of NIS.
b Wheat yield does not contain rye grain.
c We are 95% certain that treatment means in the same column that differ by at least the given amount are indeed due to treatment effects and not the result of random or uncontrolled variation.

Due to the expense of Clearmax ($17.80-$22.25/ac), it is primarily used to control troublesome winter annual grass weeds such as jointed goatgrass, downy brome, and feral rye. Control of these weeds is generally best with fall application. Wheat should be tillering before herbicide application. Early spring applications also can be effective, but effectiveness may be somewhat inconsistent compared to fall applications, with the possible exception of feral rye, which is more difficult to control. Spring applications should be made prior to stem elongation (jointing) in the wheat. Clearmax also will provide good control of most winter annual broadleaf weeds present at the time of application; most warm season weeds will not be present at the optimum application time and will probably not be satisfactorily controlled with Clearmax.

In field studies conducted in the Nebraska Panhandle, Clearmax provided similar to slightly better control of feral rye than Beyond herbicide. Clearmax also provided slightly better control of tumble mustard in one year when it was present with the rye (data not shown). In a 2006/2007 study conducted near Sidney, liquid fertilizer (32-0-0) was used at three rates (2.5%, 25%, and 50% v/v) with Beyond and Clearmax applied in the fall and spring. Herbicide treatments were applied in 10.9 gallons/acre of spray solution. The higher rates of fertilizer reduced feral rye control with Beyond, particularly the spring applications (Table 1). However, feral rye control with Clearmax was not reduced with increasing fertilizer rates. Crop injury was slightly greater with Clearmax than with Beyond.

In western Nebraska, Clearfield wheat, Clearfield sunflower, Clearfield canola, edible legumes or soybeans may be planted any time after an application of Clearmax herbicide. Minimum recrop intervals for other common crops include: three months to alfalfa and non-Clearfield wheat; four months to rye; eight and one-half months to corn (Clearfield or non-Clearfield); nine months to barley, grain sorghum, millets, oats, and sunflowers; 18 months to barley and turnips; and 28 months to canola and sugarbeets.

Bayer CropScience

Huskie
Huskie herbicide is a premix containing pyrasulfotole and bromoxynil (Buctril®) plus a crop safener. Pyrasulfotole is the first wheat herbicide that is an HPPD inhibitor (Group 27). Balance® and Callisto® are two corn herbicides with this site of action. Bromoxynil inhibits photosynthesis at photosystem II, site B (Group 6).

Huskie may be applied at rates ranging from 11 to 15 oz/ac; however, effective control of many common broadleaf weeds found in winter wheat can be achieved with 11 to 13 oz/ac plus 2,4-D or MCPA ester. The cost of Huskie herbicide ($7.50-$10.20/ac) will probably limit its use to situations where ALS-resistant weeds are a concern. Good coverage is essential to good control, so apply Huskie in at least 10 gallons of water/ac. Add ammonium sulfate at 0.5 to 1.0 lb/ac and NIS at 0.25 to 0.5% v/v.

Table 2. Kochia and Russian thistle control with Huskie herbicide.
   
Weed control

Treatment

Rate

Kochia

Russian thistle

 
oz product/ac
%
Huskie

11

72
95
NIS
0.5% v/v
 
 
AMS
8
 
 
Huskie
15
83
97
NIS
0.5% v/v
 
 
AMS
8
 
 
Huskie
11
92
97
MCPA ester
12
 
 
NIS
0.5% v/v
 
 
32-0-0
64
 
 
Ally
0.1
43
67
2,4-D ester (6 lb)
5.3
 
 
NIS
0.5% v/v
 
 
Check
 
0
0
LSD (5%)
 
16
32
a We are 95% certain that treatment means in the same column that differ by at least the given amount are indeed due to treatment effects and not the result of random or uncontrolled variation.
In a 2007 study conducted near Sidney, Huskie used alone at the 15 oz/ac rate, or at the 11 oz/ac rate with MCPA, provided good to excellent control of kochia and Russian thistle (Table 2). Both weed species contained a significant population of ALS-resistant plants, as evidenced by the poor control provided by the Ally + 2,4-D ester treatment.

Recrop intervals include: seven days to wheat, barley, oats, rye, and triticale; four months to grain sorghum, millet, and soybean; and nine months to alfalfa, canola, chickpeas, corn, dry beans, field peas, lentils, potatoes, safflower, sunflowers, and sugarbeets.

Dow

Cleanwave®
Cleanwave herbicide is a premix of aminopyralid (Milestone® and fluroxypyr (Starane®). Aminopyralid and fluroxypyr are both synthetic auxins (Group 4). Apply Cleanwave at the rate of 14 oz/ac. For best control, apply in at least 10 gallons of water/ac.

Although fluroxypyr is very safe for wheat, aminopyralid can cause injury similar to dicamba or 2,4-D if applied after wheat stem elongation (jointing) or under adverse climate conditions. The aminopyralid in Cleanwave broadens the range of weeds controlled by fluroxypyr alone. In field studies conducted in 2006 near Sidney, Cleanwave provided very good control of wild buckwheat. Cleanwave may be best suited for fields where kochia and/or wild buckwheat are the main weeds of concern. It is very effective on ALS- and dicamba-resistant kochia. Cleanwave is weak on mustard species, pigweed species, and Russian thistle and should be tank mixed with 2,4-D or a sulfonylurea herbicide such as Ally or Express to help with the control of these weeds.

Recrop intervals include: anytime to grasses and wheat; four months to barley, corn, millet, oats, rye, or triticale; nine months to canola (rapeseed); and 18 months to alfalfa, chickpea, dry bean, field pea, lentil, potato, safflower, soybean, sugarbeet, or sunflower.

PowerFlex
PowerFlex™ herbicide received EPA registration for use in winter wheat on Feb. 29, 2008. PowerFlex contains pyroxsulam and a crop safener. Pyroxsulam is a new sulfonamide herbicide that inhibits the ALS enzyme (Group 2) and will be used to control common grass and broadleaf weeds in winter wheat. Other herbicides in this class include Maverick®, Olympus®, and Olympus Flex®. In studies conducted in Colorado and Kansas, PowerFlex has provided good control of Bromus species (downy brome, Japanese brome, and cheat) as well as many of the common winter annual broadleaf weeds. PowerFlex has a shorter soil residual than Maverick, Olympus, or Olympus Flex, which will allow greater rotational flexibility. Expected rotational intervals are nine months or less to most crops of interest to Nebraska growers.

Starane® NXT
Starane NXT herbicide is a premix of fluroxypyr (Starane) plus bromoxynil (Buctril®). Fluroxypyr is a synthetic auxin (Group 4) and bromoxynil inhibits photosynthesis at photosystem II, site B (Group 6).

Starane NXT poses little risk for crop injury and the window of application extends from three-leaf wheat to flag leaf emergence. Starane NXT provides excellent control of kochia, including ALS- and dicamba-resistant kochia. It also works very well on puncturevine and common purslane. Good plant coverage is essential for best control, so use with at least 10 gallons of water/ac. Best control is achieved with small weeds up to 4 inches tall or with a 2-inch rosette. Apply Starane NXT at a rate of 14 to 21 oz/ac. Recrop intervals include: 30 days to wheat, barley, and oats and 120 days to all other crops.

WideMatch®
WideMatch herbicide is a premix of clopyralid (Stinger®) and fluroxypyr (Starane). Both herbicides are synthetic auxins (Group 4). The primary use of WideMatch in winter wheat is the control of Canada thistle. The window of application for WideMatch is greater than that for Curtail® (clopyralid plus 2,4-D amine). WideMatch can be applied to winter wheat from three-leaf wheat to flag leaf emergence, while Curtail should be applied from the time of wheat tillering up to wheat stem elongation (jointing). Not all Canada thistle plants may have emerged before wheat starts to joint so WideMatch may be a better fit for Canada thistle control in winter wheat grown in western Nebraska. Curtail will control a wider range of broadleaf weeds than WideMatch, but if Canada thistle is the main weed of interest, WideMatch is often the better choice. Apply WideMatch at the rate of 1.33 pt/ac.

Recrop intervals include: anytime to barley, grass, field corn, oats, sweet corn, and wheat; 120 days to canola, sugarbeets, and turnips; 10.5 months to alfalfa, dry beans, field peas, grain sorghum, safflower, sunflower, and soybeans; and 18 months to chickpeas, lentils, and potatoes.

DuPont

Affinity® BroadSpec
Affinity BroadSpec herbicide is a premix of thifensulfuron (Harmony®) and tribenuron (Express®). Both are inhibitors of the ALS enzyme (Group 2). Affinity BroadSpec has equal parts of both chemicals, while Harmony Extra® has twice as much thifensulfuron as tribenuron. Like Harmony Extra and Express, Affinity BroadSpec will primarily be used for situations where a grower wants to leave crop rotation options open, for example, in irrigated production. Recrop intervals include: anytime to wheat and barley; 45 days to any other crop other than sugarbeets, winter rape, or canola. These more sensitive crops can be planted after 60 days.

Apply Affinity BroadSpec to wheat from the two-leaf stage to before flag leaf emergence at the rate of 0.4 to 1.0 oz/ac. Add another labeled herbicide, such as 2,4-D, if using between 0.4 and 0.6 oz/ac. Add NIS at a rate of 0.06 to 0.5% v/v.

Agility® SG
Agility SG herbicide is a premix of three sulfonylurea herbicides [thifensulfuron (Harmony), tribenuron (Express), and metsulfuron (Ally®)] plus dicamba (Banvel®). The sulfonylurea herbicides are all inhibitors of the ALS enzyme (Group 2) and dicamba is a synthetic auxin (Group 4). Apply Agility SG herbicide at a rate of 2.4 to 3.2 oz/ac from the two-leaf stage of wheat to before wheat stem elongation (jointing). Add 2,4-D to broaden the range of weeds controlled, including mustards, kochia, and Russian thistle. Add NIS at a rate of 0.125 to 0.5% v/v. The metsulfuron in Agility SG herbicide provides up to five weeks of residual control of susceptible weeds and the dicamba provides control of sulfonylurea-resistant weeds such as kochia, prickly lettuce, and Russian thistle.

Recrop intervals include: one month to wheat and triticale; four months to STS soybeans, IR corn, proso millet, and grain sorghum; 10 months to barley or oats; 12 months to corn east of the Panhandle; and 22 months to soybeans.

Ally® Extra
Ally Extra herbicide is a premix of thifensulfuron (Harmony), tribenuron (Express), and metsulfuron (Ally XP). All three are inhibitors of the ALS enzyme (Group 2). Apply Ally Extra at a rate of 0.2 to 0.4 oz/ac. Ally Extra provides weed control similar to Ally XP, but it has a shorter soil residual, which allows for shorter recrop intervals. This is most relevant for proso millet and grain sorghum, which can be planted four months after application of Ally Extra compared to 10 months after Ally XP. Ally Extra fits the niche for those who want a little more soil residual than Express or Affinity BroadSpec can provide, but not as much as Ally provides. Ally Extra can be applied from the two-leaf stage of wheat until the flag leaf appears. Add NIS at a rate of 0.125 to 0.5% v/v.

Recrop intervals include: one month to wheat and triticale; four months to STS soybean, IR corn, proso millet, and grain sorghum; 10 months to barley and oats; 12 months to corn grown east of the Panhandle; and 22 months to soybean grown east of the Panhandle and safflower.

FMC

Aim®
The active ingredient in Aim herbicide is carfentrazone. Carfentrazone is a protox inhibitor (Group 14). It is the only wheat herbicide with this mode of action. Aim herbicide may be applied to wheat from prior to planting up to leaf stem elongation (jointing). It can be applied at rates from 0.5 to 2.0 oz/ac. It is best used at rates from 0.5 to 1.0 oz/ac with 2,4-D. Aim will cause leaf spotting on emerged leaves, but plants quickly outgrow the injury. Adding Aim herbicide to 2,4-D improves control of weeds like lambsquarters, mustards, kochia, Russian thistle, and wild buckwheat. Aim is a contact herbicide so good plant coverage is essential to good weed control. Apply in at least 10 gallons of water/ac.

There are no crop rotation restrictions following the use of Aim herbicide.

Drew Lyon
Extension Dryland Cropping Systems Specialist
Panhandle REC, Scottsbluff

Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the University of Nebraska-Lincoln Extension is implied. Always consult product labels for specific use recommendations and requirements.