By Alan York
W eeds reduce yield and quality in small grains. An effective weed management program should include:
Weeds that most often cause problems in small grains are winter annual broadleaf weeds, such as chickweed and henbit; perennials, such as wild garlic and curly dock; and Italian ryegrass. One of the best tools for suppressing weeds in small grains is a healthy, vigorous crop. Good crop management practices that rapidly establish the wheat stand and develop the canopy will minimize effects of weeds.
2,4-D
This phenoxy herbicide is available in several formulations, and marketed under many trade names. The three basic formulations are amines, esters, and acid + ester mixtures. Ester or acid + ester formulations tend to be more effective under cooler conditions. Ester and acid + ester formulations also mix well with liquid nitrogen. Amine formulations can usually be mixed with liquid nitrogen, but the amine herbicide must first be premixed with water (one part herbicide to four parts water) and then the water-herbicide mixture added to the nitrogen with good agitation. Amines tend to give less burn on the small grain than esters when nitrogen is used as the carrier.
An amine formulation is safer to use when plants sensitive to 2,4-D are nearby. Ester and acid + ester formulations of 2,4-D can volatilize under warmer conditions and damage susceptible off-target species, such as tobacco seedlings in greenhouses.
2,4-D controls several common winter broadleaf weeds, such as buttercups, cornflower, wild mustard, and wild radish (see Table 14-1 at the end of this file). However, 2,4-D does not control chickweed, henbit, and knawel.
Timing is critical in order to avoid injury to small grains. Small grains are most tolerant to 2,4-D after they are fully tillered but before jointing (Feekes Growth Stages 4 and 5). Application before this growth stage may cause a “rat-tail” effect, whereby the leaf does not form and unfurl properly. The crop may appear stunted and delayed in maturity, and tiller development may be adversely affected. 2,4-D should not be applied after jointing as malformed seed heads may result.
2,4-D can be applied to wheat, barley, oats, and rye. Oats are less tolerant than the other small grains and should not be treated under cold, wet conditions.
Dicamba
Dicamba is a benzoic acid herbicide sold under the trade names Banvel, Banvel SGF, and Clarity. Generic brands may also be available. Banvel contains 4 pounds per gallon of acid equivalent formulated as the dimethylamine salt. Banvel SGF contains 2 pounds per gallon of acid equivalent formulated as the sodium salt. Clarity contains 4 pounds per gallon of acid equivalent formulated as the diglycolamine salt.
Dicamba is more effective than 2,4-D on chickweed, henbit, and knawel but less effective on species like buttercup, cornflower, shepherdspurse, Virginia pepperweed, wild mustard, and wild radish (see Table 14-1).
Dicamba can be applied to wheat, barley, and oats. Proper timing is crucial. Apply dicamba after the small grain is fully tillered but prior to jointing (Feekes Growth Stages 4 and 5). Extreme care should be used when applying dicamba near sensitive plants, such as tobacco seedlings in greenhouses. Minute amounts of dicamba drift can injure tobacco.
Table 14-1. Weed Response to Herbicides |
|||||||
Species |
Buctril |
2,4-D Post- emergence |
Dicamba Post- emergence |
Finesse Pre- emergence |
Harmony Extra Post- emergence |
Hoelon Post- emergence |
Osprey Post- emergence |
Buttercup |
- |
G |
F |
- |
G |
N |
E |
Common chickweed |
PF |
P |
G |
G |
G |
N |
- |
Cornflower |
E |
G |
FG |
- |
P |
N |
G |
Curly dock |
PF |
P |
F |
- |
E |
N |
PF |
Cutleaf eveningprimrose |
G |
E |
G |
- |
PG |
N |
- |
Field pennycress |
G |
G |
F |
- |
G |
N |
- |
Henbit |
F |
P |
F |
G |
G |
N |
- |
Italian ryegrass |
N |
N |
N |
F |
N |
E1 |
G |
Knawel |
P |
P |
G |
- |
G |
N |
- |
Shepherdspurse |
G |
GE |
FG |
- |
E |
N |
- |
Swinecress |
GE |
G |
G |
- |
E |
N |
- |
Vetch |
F |
FG |
E |
- |
P |
N |
- |
Virginia pepperweed |
FG |
E |
F |
- |
G |
N |
- |
Wild garlic |
P |
F |
F |
- |
E |
N |
- |
Wild mustard |
G |
GE |
F |
G |
FG |
N |
G |
Wild radish |
FG |
GE |
F |
G |
G |
N |
G |
Key: E=excellent control, 9-% or better
G=good control, 80 to 90%
F=fair control, 50 to 80%
P=poor control, 25 to 50%
N=no control, less than 25%
1Does not control Holeon-resistant ryegrass
Harmony Extra
Harmony Extra is a prepackaged mixture of the sulfonylurea herbicides thifensulfuron-methyl and tribenuron-methyl. Harmony Extra can be applied to wheat, barley, oats, and triticale.
Harmony Extra controls most of the common winter annual broadleaf weeds (see Table 14-1). Cornflower is the major exception. Wild radish must be small (less than 6 inches in diameter) for adequate control by Harmony Extra. 2,4-D at 0.25 to 0.375 pounds active ingredient per acre may be mixed with Harmony Extra for improved wild radish control and for control of cornflower. Harmony Extra is very effective on curly dock and wild garlic (see section on wild garlic).
A nonionic surfactant at the rate of 1 quart per 100 gallons of spray solution is recommended when Harmony Extra is applied in water. Harmony Extra may be applied using liquid nitrogen as the carrier. In this case, premix the herbicide in water and add the mixture to the nitrogen with agitation. Since adding surfactant to nitrogen may increase burn on the small grain foliage, reduce the surfactant rate to 0.5 to 1.0 pint per 100 gallons of spray solution. For easy-to-control weeds, consider eliminating the surfactant when nitrogen is the carrier. However, do not eliminate surfactant when treating wild garlic. Do not use surfactant when mixtures of Harmony Extra and 2,4-D are applied in nitrogen.
An advantage of Harmony Extra compared with 2,4-D or dicamba is the wide window of application. Harmony Extra can be applied to wheat, barley, oats, or triticale after the two-leaf stage but before the flag leaf is visible. Application no later than the fully tillered stage is recommended for better spray coverage on weeds.
Buctril
Buctril, active ingredient bromoxynil, is a contact herbicide that controls several broadleaf weeds if applied when weeds are small (see Table 14-1). Buctril has a limited fit on small grains in North Carolina because it does not control species like chickweed and henbit, and because timing of application is so critical.
Buctril can be applied to wheat, barley, oats, rye, and triticale from crop emergence until the boot stage.
Timing of application is critical. Susceptible weeds should not exceed four leaves, 2 inches in height, or 1 inch in diameter.
Italian ryegrass is a widespread problem in small grains in North Carolina. Research has shown that wheat yields are reduced 0.4 percent for every ryegrass plant per square yard. Heavy infestations, if uncontrolled, can reduce yields by 75 percent or more.
There are currently no control programs for Italian ryegrass in oats, rye, or triticale. These crops should not be planted in ryegrass-infested fields unless significant yield reduction is acceptable.
As discussed below, the herbicide Hoelon generally is highly effective on Italian ryegrass. Unfortunately, much of the ryegrass in North Carolina has become resistant to Hoelon. At least 60 percent of the ryegrass in the piedmont is resistant to Hoelon, and isolated infestations of Hoelon-resistant ryegrass can be found in the coastal plain.
Control of Hoelon-Susceptible Italian Ryegrass
Hoelon, containing the active ingredient diclofopmethyl, can be applied to wheat and barley to control Italian ryegrass. Hoelon applied to rye often causes unacceptable injury, and Hoelon will kill oats. North Carolina research has shown that triticale tolerates Hoelon. However, Hoelon is not registered for use on triticale. Hoelon does not control broadleaf weeds, wild garlic, or annual bluegrass.
Hoelon is an aryloxyphenoxy propionate herbicide. Herbicides of this type work slowly. It is not unusual for 2 to 3 weeks to pass before Hoelon symptoms appear, and up to 8 weeks before the ryegrass is dead.
Hoelon can be applied postemergence to any variety of wheat anytime before the first node, or joint, develops (up to Feekes Growth Stage 6). Hoelon can be applied postemergence to specific varieties of barley after tiller initiation (Feekes Growth Stage 3) but prior to jointing. The Hoelon label specifies application only to specific varieties of barley; see label for details. While wheat tolerance of Hoelon is typically very good, barley is less tolerant. Cold temperatures (less than 40°F) or prolonged wet conditions can increase barley sensitivity to Hoelon.
Timely application of Hoelon is essential for good control. Best control is obtained when treating one- to three-leaf ryegrass (about 2 to 3 inches tall; see Table 14-2). Higher rates are required for larger ryegrass (Table 14-3), and even then control decreases.
Table 14-2. Postemergence Hoelon Effectiveness |
|
Ryegrass Height |
Percent Control |
2 |
100 |
4 |
70 |
6 |
40 |
| Table 14-3. Postemergence Hoelon Rates for Ryegrass | |
Ryegrass Growth Stage |
Hoelon Rate (pints per acre) |
1 to 3 leaves |
1.33 |
3 to 4 leaves |
1.33 to 2.0 |
5 leaves to 2 tillers |
2.0 to 2.67 |
It is typically best to apply Hoelon postemergence from mid-November to mid-December. The weather during this period is generally more favorable for herbicide activity and field operations than the weather after Christmas.
Temperature has a significant impact on Hoelon activity on ryegrass. Better activity is obtained under warmer temperatures. Nighttime temperatures should be above 35ºF for 3 days before and 3 days after application.
The Hoelon label allows for addition of crop oil concentrate. A crop oil is usually not necessary, and it may increase the risk of crop injury under stressful conditions. However, a crop oil can improve control under dry conditions or when treating large ryegrass. Do not add crop oil when treating barley.
Hoelon should not be applied postmergence in nitrogen nor tank mixed with other herbicides. Either of these situations can reduce ryegrass control. Additionally, to avoid reduced ryegrass control, do not apply 2,4-D or dicamba within 5 days of applying Hoelon. Hoelon may be tank mixed with fungicides, but fungicides are typically applied in the spring, after the optimum timing of Hoelon application.
Hoelon may be applied preemergence to wheat. Do not apply preemergence to barley. Applied preemergence, Hoelon can be very effective if adequate rainfall for activation is received prior to ryegrass emergence. However, Hoelon is consistently more effective when applied postemergence.
Achieve, containing the active ingredient tralkoxydim, is a cyclohexadione herbicide that has the same mechanism of action as Hoelon. Achieve can be applied postemergence to wheat or barley. Ryegrass should be no larger than the three-leaf stage when treated. Achieve and Hoelon are similarly effective on one- to two-leaf ryegrass; Hoelon is more effective on larger ryegrass. The adjuvant Supercharger at 2 quarts per 100 gallon of spray solution is recommended. Do not apply Achieve in liquid nitrogen nor tank mix with other herbicides. Achieve does not control broadleaf weeds or annual bluegrass.
Osprey herbicide, discussed below under Control of Hoelon-Resistant Italian Ryegrass, provides excellent control of Hoelon-susceptible and Hoelon-resistant ryegrass.
Control of Hoelon-Resistant Italian Ryegrass
Much of the ryegrass in the piedmont of North Carolina is resistant to Hoelon. Isolated areas of Hoelon-resistant ryegrass can also be found in the coastal plain.
Achieve will not control Hoelon-resistant ryegrass.
The herbicide Finesse (active ingredients chlorsulfuron plus metsulfuron methyl) can be used to manage Hoelon-resistant ryegrass. Finesse can be applied preemergence or postemergence to wheat and barley. Only preemergence application is suggested for ryegrass control. Ryegrass control by Finesse has been variable in North Carolina research. Timely rainfall after application is required. Control has ranged from very good to very poor, with late-season control averaging 50 to 60 percent. Some stunting of wheat has been observed on very sandy soils.
If soybeans are to be planted following wheat or barley treated with Finesse, use only an STS variety of soybean. Finesse has a long soil residual, and injury to non-STS soybeans can occur. Corn, cotton, grain sorghum, or non-STS soybeans can be planted the year following the STS soybeans.
Osprey herbicide (active ingredient mesosulfuron plus a safener) was registered for use on wheat in the spring of 2004. In extensive research in North Carolina, this herbicide has controlled both Hoelonresistant and Hoelon-susceptible ryegrass extremely well. Osprey kills ryegrass slowly; it often takes 4 to 6 weeks for ryegrass to die.
Osprey is a sulfonylurea herbicide. As a group, there are many cases of weeds becoming resistant to sulfonylurea herbicides. Hence, growers who have Hoelon-susceptible ryegrass are encouraged to rotate use of Hoelon and Osprey rather than relying solely on Osprey to control ryegrass in every wheat crop. Rotating these herbicides will slow the development of resistance and extend the useful life of both products.
Osprey has a wide application window for wheat; the herbicide can be applied postemergence to wheat any time from emergence up to the jointing stage. However, the size of the ryegrass is important. For best results, ryegrass should be in the one-leaf to two-tiller stage. Osprey applied during this stage of ryegrass growth has consistently given nearly complete control. Osprey is less consistently effective on larger ryegrass. While excellent control of ryegrass with six or more tillers has been obtained in some studies, inadequate control was obtained in other studies.
An adjuvant is required with Osprey. The label recommends a methylated seed oil at 1.5 pints per acre or a “basic blend” adjuvant (defined as an adjuvant containing nonionic surfactant plus nitrogen or methylated seed oil plus nitrogen) at 0.8 to 1.6 pints per acre. In addition to methylated seed oil, but not as areplacement, one can also add 1 to 2 quarts per acre of nitrogen solution. The nitrogen may improve control of larger ryegrass or ryegrass under adverse conditions. In North Carolina research, methylated seed oil has generally been the most consistently effective adjuvant although good results have also been obtained with nonionic surfactant plus nitrogen.
In addition to ryegrass, Osprey controls small annual bluegrass, wild mustard, wild radish, common chickweed, and henbit. For best results, these broadleaf weeds need to be 2 inches or less. Osprey may be mixed with Harmony Extra to broaden the spectrum of control. Use nonionic surfactant plus nitrogen as the adjuvant when mixing Osprey and Harmony Extra.
The Osprey label cautions the user to not apply topdress nitrogen within 21 days after Osprey application. Additionally, one should not use liquid nitrogen as the carrier for Osprey. Ryegrass control has been excellent with Osprey applied in liquid nitrogen, but there is concern over wheat injury and possible yield reductions. Wheat tolerance of Osprey applied in water is excellent.
Double-cropped soybeans can be planted 90 days after Osprey application. In case of a wheat crop failure, cotton or peanuts also can be planted 90 days after Osprey application. There is a 12-month rotational restriction for corn.
Wild garlic does not compete with small grains, but aerial bulblets harvested with the grain gives a garlicky flavor to flour made from infested wheat. Off-flavor milk products result when dairy cows are fed infested small grains. Growers receive a substantial discount for garlicky wheat.
A combination of adequate nitrogen fertilization and herbicide application is needed to control wild garlic. Application to wheat of 2 pints per acre of an ester formulation of 2,4-D will reduce aerial bulblet formation and bend over the tops of wild garlic plants so that a combine header can be set high enough to pass over most of the aerial bulblets. Control by 2,4-D, however, can be inconsistent. Additionally, 2,4-D at 2 pints per acre can injure wheat.
Harmony Extra at 0.5 to 0.6 ounce per acre is very effective on wild garlic. Wild garlic should be less than 12 inches tall and should have 2 to 4 inches of new growth (if treated in the spring) when Harmony Extra is applied. Temperatures of 50ºF or higher will enhance control. Add nonionic surfactant according to the label.
Peak, containing the active ingredient prosulfuron, will also control wild garlic very well. It is at least as effective on wild garlic as Harmony Extra, but it is less effective on several broadleaf weeds. Peak can be applied to wheat, barley, oats, rye, and triticale from the three-leaf stage until just before the second node is visible. Add a nonionic surfactant or crop oil according to label directions.
There are no rotational restrictions following the use of Harmony Extra. There is a 10-month rotational restriction for soybeans, cotton, peanuts, and tobacco following application of Peak. Soybeans should not be double-cropped behind small grains treated with Peak.
Winter annual weeds, such as chickweed, henbit, annual bluegrass, and Italian ryegrass, are often emerged at the time of planting. Unless killed at time of planting, these weeds will have a head start on the crop and will be very competitive.
Emerged weeds can be killed at planting with glyphosate or paraquat. See comments in Table 14-4.
A burndown herbicide is recommended in nearly every case. If few to no weeds are present at planting, one might consider eliminating the burn down and plan to apply Harmony Extra after the small grain reaches the two-leaf stage. Timing is critical as small winter annuals emerged at planting can quickly become too large for good control. Without a burndown herbicide, it may also be necessary to treat sooner than normal for ryegrass.
A major concern with eliminating the burn down in no-till is annual bluegrass. This winter annual grass can be a significant problem. Fortunately, it can e controlled when Osprey is properly applied.
Other weed management practices for no-till small grains are the same as previously discussed.
Table 14-4. Chemical Weed Control in Wheat, Barley, Oats, Rye, and Triticale |
|||||
Crop |
Weed |
Herbicide and Formulation |
Amount of Formulation Per Acre |
Pounds Active Ingredient Per Acre |
Precautions and Remarks |
Wheat Preplant No-Till |
Emerged annual broadleaf and grass weeds, top-kill of perennials |
paraquat (Gramoxone Max) 3 SL |
1.33 to 2.7 pt |
0.5 to 1 |
Rate depends upon weed size; see label. Apply before crop emerges. Add nonionic surfactant at 1 pt per 100 gal spray solution or crop oil concentrate at 1 gal per 100 gal spray solution. See application directions on label. May be tank mixed with Hoelon. |
Emerged annual broadleaf and grass weeds, control or suppression of perennial weeds |
glyphosate diammonium salt (Touchdown) 3.57 SL (3 lb a.e.) |
1 to 3 pt |
0.38 to 1.13 |
Rate depends upon weed species and size; see label. Apply before crop emergence. Adjuvant recommendations vary by glyphosate brand; see label of brand used for details. |
|
Wheat Preemergence |
Annual ryegrass |
chlorsulfuron + metsulfuron methyl (Finesse) 75 WDG |
0.5 oz |
0.0195 + 0.0039 |
Ryegrass control is variable; expect only suppression. May stunt wheat on sandy soils. Suggested primarily for fields with Hoelon-resistant ryegrass. Also controls most annual broadleaf weeds. Plant only STS soybeans following wheat harvest. May cause severe injury in non-STS soybeans. |
diclofop-methyl (Hoelon) 3 EC |
2 to 2.67 pt |
0.75 to 1 |
Apply immediately after planting. Use 2 pt per acre on coarse-textured soils with less than 2% organic matter. Use 2.67 pt per acre on fine-textured soils, soils with greater than 2% organic matter, or in fields with known heavy ryegrass infestations. Do not make more than one application of Hoelon per season. Biotypes of ryegrass resistant to Hoelon are becoming more common within the state. Hoelon should not be applied to fields where resistance is suspected. |
||
diclofop-methyl (Hoelon) 3 EC |
1.33 to 2.67 pt |
0.5 to 1 |
Apply when ryegrass is in the one- to five-leaf stage. See label for specific rates depending upon weed size. Application to smaller ryegrass is more effective. Make only one application per season. Do not tank mix with broadleaf herbicides or use liquid nitrogen as the carrier. Apply before the first wheat node (joint) develops. May add 1 to 2 pt per acre of crop oil concentrate under dry conditions or when ryegrass is large. In most cases, crop oil is not necessary. See precautions on label concerning temperatures. Biotypes of ryegrass resistant to Hoelon are becoming more common within the state. Hoelon should not be applied to fields where resistance is suspected. |
||
mesosulfuron (Osprey) 4.5 WDG |
4.75 oz |
0.013 |
Controls Hoelon-resistant ryegrass. Apply when ryegrass is in one-leaf to two-tiller stage. Add methylated seed oil or basic blend adjuvant as directed on label. May be mixed with Harmony Extra; in this case, use nonionic surfactant plus nitrogen as directed on label. Do not apply using liquid nitrogen as the carrier. Do not topdress wheat within 21 days after Osprey application. |
||
WIld garlic, curly dock, and most winter annual broadleaf weeds except cornflower and vetch |
thifensulfuron-methyl + tribenuron-methyl (Harmony Extra) 75 WDG |
0.3 to 0.6 oz |
0.0094 to 0.0188 + 0.0047 to 0.0094 |
Apply after the two-leaf stage of wheat but before flag leaf is visible. Use 0.3 to 0.4 oz for most winter annual weeds. Use 0.5 to 0.6 oz for wild garlic and wild radish. Wild garlic should be less than 12 in. tall and should have 2 to 4 in. of new growth. Control is enhanced when application is made during warm temperatures (50ºF or more) to actively growing garlic plants. Add 1 qt of nonionic surfactant per 100 gal of spray solution. Liquid nitrogen may be used as the carrier. May tank mix Harmony Extra with 0.125 to 0.375 lb active ingredient of 2,4-D for improved control of wild radish. Follow mixing instructions on the label when using nitrogen as the carrier or when mixing with 2,4-D. Reduce surfactant rate according to label instructions when using nitrogen as the carrier or when mixing with 2,4-D. Do not tank mix with Hoelon. |
|
Wheat Post-emergence (continued) |
Wild garlic and annual broadleaf weeds |
prosulfuron (Peak) 57 WDG |
0.38 to 0.5 oz |
0.0135 to 0.0178 |
May be applied from three-leaf stage until just before second node is detectable in stem elongation. For wild garlic only, use 0.25 to 0.5 oz. Add nonionic surfactant at 1 qt per 100 gal or crop oil concentrate at 1 gal per 100 gal spray solution. Can use liquid nitrogen as the carrier, but use only nonionic surfactant in this case. Peak controls wild garlic, wild mustard, wild radish, field pennycress, shepherds-purse, and cutleaf evening primrose. Does not control henbit; chickweed control may not be adequate. Can tank mix with Banvel or 2,4-D; see respective labels for details, including mixing instructions. See precautions on label concerning cold, wet weather. Note the 10month rotational restriction for soybeans, cotton, peanuts, and tobacco. Do not double-crop soybeans behind wheat treated with Peak. |
Most winter annual broadleaf weeds except chickweed, henbit, and knawel |
2,4-D amine (various brands) 3.8 SL |
1 pt 0.67 pt |
0.48 0.48 0.35 |
Apply after wheat is fully tillered (usually 4 to 8 in. tall; stages 4 and 5 on Feekes scale) but before jointing. Spraying wheat too young or after jointing can cause deformed heads, reduced yields, and uneven ripening. Better results are obtained when daytime temperatures are above 50°F. Increase the rate of 2,4-D by 50% to control corn cockle. Liquid nitrogen may be used as the carrier for 2,4-D. Ester formulations can be added directly to the nitrogen. If using amine formulation, premix in water (1 part 2,4-D to 4 parts water) and add mixture to nitrogen with strong agitation. Amine formulations give less burn than ester formulations in nitrogen. |
|
Most winter annual broadleaf weeds |
dicamba |
|
0.125 |
Apply after wheat is fully tillered but before jointing. Better results will be obtained if applied when daytime temperatures are above 50°F. Liquid nitrogen may be used as the carrier. |
|
Wheat Preharvest |
Most winter annual broadleaf weeds (continued) |
dicamba |
|
0.125 |
Apply after wheat is fully tillered (usually 4 to 8 in. tall; stages 4 and 5 on Feekes scale) but before jointing. Compared to dicamba alone, tank mixture is more effective on buttercup, cornflower, field pennycress, Virginia pepperweed, shepherdspurse, wild mustard, and wild radish. Use this tank mix only if both herbicides are necessary for weed control. Tank mix may injure wheat. |
Annual broadleaf and grass weeds, suppression of perennial weeds |
glyphosate diammonium salt (Touchdown) 3.57 SL (3 lb a.e.) |
1 to 2 pt |
0.38 to 0.75 0.39 to 0.74 |
Apply after hard dough stage of grain (30% or less grain moisture) and at least 7 days before harvest. Do not apply to wheat grown for seed. |
|
Annual broadleaf weeds |
2,4-D amine (various brands) 3.8 SL |
1 to 2 pt |
|
Apply when grain is in hard dough stage or later. Do not allow drift to sensitive crops (be especially careful with ester formulations). Amine formulations strongly encouraged if sensitive crops are nearby, especially cotton and tobacco. |
|
Barley Preplant No-Till |
Emerged annual broadleaf and grass weeds, top-kill of perennials |
paraquat (Gramoxone Max) 3 SL |
1.33 to 2.7 pt |
0.5 to 1 |
Rate depends upon weed size; see label. Apply before crop emerges. Add nonionic surfactant at 1 pt per 100 gal spray solution or crop oil concentrate at 1 gal per 100 gal spray solution. See application directions on label. |
Barley Post-emergence |
Emerged annual broadleaf and grass weeds, control or suppression of perennial weeds |
glyphosate diammonium salt (Touchdown) 3.57 SL (3 lb a.e.) |
1 to 3 pt OR |
0.38 to 1.13 OR |
Rate depends upon weed species and size; see labels. Apply before crop emergence. Adjuvant recommendations vary by glyphosate brand; see label of brand used for details. |
Annual ryegrass |
diclofop-methyl (Hoelon) 3 EC |
1.33 to 2.67 pt |
0.5 to 1 |
Apply when ryegrass is in the one- to four-leaf stage and after tiller initiation but prior to jointing of barley. Make only one application per year. Do not tank mix with broadleaf herbicides or use liquid nitrogen as the carrier. Do not add crop oil. Apply only to the following varieties of barley: Anson, Boone, Henry, Milton, Molly Bloom, Mulligan, Nomini, Pennco, Starling, Sussex, and Wysor. Cold (lower than 40°F) and/or prolonged wet conditions increase barley sensitivity to Hoelon. Biotypes of ryegrass resistant to Hoelon are becoming more common within the state. Hoelon should not be applied to fields where resistance is suspected. |
|
Wild garlic, curly dock, and most winter annual broadleaf weeds except cornflower and vetch |
thifensulfuron-methyl |
0.3 to 0.6 oz |
0.0094 to 0.0188 0.0047 to 0.0094 |
Apply after the two-leaf stage of barley but before flag leaf is visible. Use 0.3 to 0.4 oz for most winter annual weeds. Use 0.5 to 0.6 oz for wild garlic and wild radish. Wild garlic should be less than 12 in. tall and should have 2 to 4 in. of new growth. Control is enhanced when application is made during warm temperatures (50ºF or more) to actively growing garlic plants. Add 1 qt of nonionic surfactant per 100 gal of spray solution. Liquid nitrogen may be used as the carrier. May tank mix Harmony Extra with 0.125 to 0.375 lb a.i. of 2,4-D for improved control of wild radish. Follow mixing instructions on the label when using nitrogen as the carrier or when mixing with 2,4-D. Reduce surfactant rate according to label instructions when using nitrogen as the carrier or when mixing with 2,4-D. Do not tank mix with Hoelon. |
|
Wild garlic and annual broadleaf weeds |
prosulfuron (Peak) 57 WDG |
0.38 to 0.5 oz |
0.0135 to 0.0178 |
May be applied from three-leaf stage until just before second node is detectable in stem elongation. For wild garlic only, use 0.25 to 0.5 oz. Add nonionic surfactant at 1 qt per 100 gal or crop oil concentrate at 1 gal per 100 gal spray solution. Can use liquid nitrogen as the carrier, but use only nonionic surfactant in this case. Peak controls wild garlic, wild mustard, wild radish, field pennycress, shepherdspurse, and cutleaf eveningprimrose. Does not control henbit; chickweed control may not be adequate. Can tank mix with Banvel or 2,4-D; see respective labels for details, including mixing instructions. See precautions on label concerning cold, wet weather. Note the 10-month rotational restriction for soybeans, cotton, peanuts, and tobacco. Do not double-crop soybeans behind barley treated with Peak. |
|
Most winter annual broadleaf weeds except chickweed, henbit, and knawel |
2,4-D amine (various brands) 3.8 SL |
|
0.48 0.48 0.35 |
Apply after barley is fully tillered but before jointing. Spraying barley too young or after jointing can cause deformed heads, reduced yields, and uneven ripening. Better results are obtained when daytime temperatures are above 50°F. Increase the rate of 2,4-D by 50% to control corn cockle. Liquid nitrogen may be used as the carrier for 2,4-D. Ester formulations can be added directly to the nitrogen. If using amine formulation, premix in water (1 part 2,4-D to 4 parts water) and add mixture to nitrogen with strong agitation. Amine formulations give less burn than ester formulations in nitrogen. |
|
Barley Preharvest Oats Preplant No-Till |
Most winter annual broadleaf weeds |
dicamba |
|
0.125 |
Apply before jointing stage of growth. Risk of crop injury is least if applied after winter dormancy and before grain begins to joint. Better results will be obtained if applied when daytime temperatures are above 50°F. Liquid nitrogen may be used as the carrier. |
dicamba |
|
0.125 0.24 |
Apply after barley is fully tillered but before jointing. Compared to dicamba alone, tank mixture is more effective on buttercup, cornflower, field pennycress, Virginia pepperweed, shepherdspurse, and wild mustard. Use this tank mix only if both herbicides are necessary for weed control. Tank mix may injure barley. |
||
Annual broadleaf weeds |
2,4-D amine (various brands) 3.8 SL |
1 to 2 pt |
0.48 to 0.95 0.48 to 0.95 |
Apply when grain is in hard dough stage or later. Do not allow drift to sensitive crops (be especially careful with ester formulations). Amine formulations strongly encouraged if sensitive crops are nearby, especially cotton or tobacco. |
|
Emerged annual broadleaf and grass weeds, control or suppression of perennial weeds |
glyphosate diammonium salt (Touchdown) 3.57 SL (3 lb a.e.) |
|
|
Rate depends upon weed species and size; see labels. Apply before crop emergence. Adjuvant recommendations vary by glyphosate brand; see label of brand used for details. |
|
Oats Post-emergence |
Wild garlic, curly dock, and most winter annual broadleaf weeds except cornflower and vetch |
thifensulfuron-methyl |
0.3 to 0.4 oz |
0.0094 to 0.0125 + |
Apply after the two-leaf stage of oats but before flag leaf is visible. Wild garlic should be less than 12 in. tall and should have 2 to 4 in. of new growth. Control is enhanced when application is made during warm temperatures (50ºF or more) to actively growing garlic plants. Add 1 qt of nonionic surfactant per 100 gal of spray solution. Liquid nitrogen may be used as the carrier. May tank mix Harmony Extra with 0.125 to 0.375 lb a.i. of 2,4-D for improved control of wild radish. Follow mixing instructions on the label when using nitrogen as the carrier or when mixing with 2,4-D. Reduce surfactant rate according to label instructions when using nitrogen as the carrier or when mixing with 2,4-D. Oats are more sensitive to 2,4-D than wheat. |
Wild garlic and annual broadleaf weeds |
prosulfuron (Peak) 57 WDG |
0.38 to 0.5 oz |
0.0135 to 0.0178 |
May be applied from three-leaf stage until just before second node is detectable in stem elongation. For wild garlic only, use 0.25 to 0.5 oz. Add nonionic surfactant at 1 qt per 100 gal or crop oil concentrate at 1 gal per 100 gal spray solution. Can use liquid nitrogen as the carrier, but use only nonionic surfactant in this case. Peak controls wild garlic, wild mustard, wild radish, field pennycress, shepherdspurse, and cutleaf eveningprimrose. Does not control henbit; chickweed control may not be adequate. Can tank mix with Banvel or 2,4-D; see respective labels for details, including mixing instructions. See precautions on label concerning cold, wet weather. Note the 10-month rotational restriction for soybeans, cotton, peanuts, and tobacco. |
|
Most winter annual broadleaf weeds except chickweed, henbit, and knawel |
2,4-D amine (various brands) 3.8 SL |
1 pt |
0.48 |
Apply after oats are fully tillered but before jointing. Spraying oats too young or after jointing can cause deformed heads, reduced yields, and uneven ripening. Also, oats are less tolerant of 2,4-D than wheat. Better results are obtained when daytime temperatures are above 50°F. Liquid nitrogen may be used as the carrier for 2,4-D. Premix in water (1 part 2,4-D to 4 parts water) and add mixture to nitrogen with strong agitation. |
|
Most winter annual broadleaf weeds |
dicamba |
|
0.125 |
Apply before jointing stage of growth. Risk of crop injury is least if applied after winter dormancy and before grain begins to joint. Better results will be obtained if applied when daytime temperatures are above 50°F. Liquid nitrogen may be used as the carrier. |
|
Oats Preharvest |
Annual broadleaf weeds |
2,4-D amine (various brands) 3.8 SL |
1 to 2 pt |
0.48 to 0.95 |
Apply when grain is in hard dough stage or later. Do not allow drift to sensitive crops, especially cotton and tobacco. |
Rye Preplant No-Till |
Emerged annual broadleaf and grass weeds, control or suppression of perennial weeds |
glyphosate diammonium salt (Touchdown) 3.57 SL (3 lb a.e.) |
|
|
Rate depends upon weed species and size; see labels. Apply before crop emergence. Adjuvant recommendations vary by glyphosate brand; see label of brand used for details. |
Rye Post-emergence |
Wild garlic and annual broadleaf weeds |
prosulfuron (Peak) 57 WDG |
0.38 to 0.5 oz |
0.0135 to 0.0178 |
May be applied from three-leaf stage until just before second node is detectable in stem elongation. For wild garlic only, use 0.25 to 0.5 oz. Add nonionic surfactant at 1 qt per 100 gal or crop oil concentrate at 1 gal per 100 gal spray solution. Can use liquid nitrogen as the carrier, but use only nonionic surfactant in this case. Peak controls wild garlic, wild mustard, wild radish, field pennycress, shepherds-purse, and cutleaf eveningprimrose. Does not control henbit; chickweed control may not be adequate. Can tank mix with Banvel or 2,4-D; see respective labels for details, including mixing instructions. See precautions on label concerning cold, wet weather. Note the 10-month rotational restriction for soybeans, cotton, peanuts, and tobacco. |
Most winter annual broadleaf weeds except chickweed, henbit, and knawel |
2,4-D amine (various brands) 3.8 SL |
1 pt 0.67 pt |
0.48 0.48 |
Apply after rye is fully tillered but before jointing. Spraying rye too young or after jointing can cause deformed heads, reduced yields, and uneven ripening. Better results are obtained when daytime temperatures are above 50ºF. Increase the rate of 2,4-D by 50% to control corn cockle. Liquid nitrogen may be used as the carrier for 2,4-D. Ester formulations can be added directly to the nitrogen. If using amine formulation, premix in water (1 part 2,4-D to 4 parts water) and add mixture to nitrogen with strong agitation. Amine formulations give less burn than ester formulations in nitrogen. |
|
Rye Preharvest |
Annual broadleaf weeds |
2,4-D ester (various brands) 3.8 SL |
1 to 2 pt |
0.48 to 0.95 |
Apply when grain is in hard dough stage or later. Do not allow drift to sensitive crops, especially cotton and tobacco. |
Triticale Preplant No-Till |
Emerged annual broadleaf and grass weeds, control or suppression of perennial weeds |
2,4-D ester (various brands) 5.7 SL glyphosate diammonium salt (Touchdown) 3.57 SL (3 lb a.e.) glyphosate isopropylamine salt (numerous brands) glyphosate potassium salt (Roundup WeatherMax) 5.5 SL (4.5 lb a.e.) |
1 to 3 pt 11 to 32 fl oz |
0.38 to 1.13 OR 0.39 to 1.13 |
Rate depends upon weed species and size; see labels. Apply before crop emergence. Adjuvant recommendations vary by glyphosate brand; see label of brand used for details. |
Triticale Post-emergence |
Wild garlic and annual broadleaf weeds |
prosulfuron (Peak) 57 WDG |
0.38 to 0.5 oz |
0.0135 to 0.0178 |
May be applied from three-leaf stage until just before second node is detectable in stem elongation. For wild garlic only, use 0.25 to 0.5 oz. Add nonionic surfactant at 1 qt per 100 gal or crop oil concentrate at 1 gal per 100 gal spray solution. Can use liquid nitrogen as the carrier, but use only nonionic surfactant in this case. Peak controls wild garlic, wild mustard, wild radish, field pennycress, shepherds-purse, and cutleaf eveningprimrose. Does not control henbit; chickweed control may not be adequate. Can tank mix with Banvel or 2,4-D; see respective labels for details, including mixing instructions. See precautions on label concerning cold, wet weather. Note the 10-month rotational restriction for soybeans, cotton, peanuts, and tobacco. |
thifensulfuron-methyl + tribenuron-methyl (Harmony Extra) 75 WDG |
0.3 to 0.6 oz |
0.0094 to 0.0188 + 0.0047 to 0.0094 |
Apply after two-leaf stage of triticale but before flag leaf is visible. See comments for Harmony Extra under Wheat-Postemergence. |
||
Annual broadleaf weeds Annual broadleaf weeds and ryegrass suppression |
bromoxynil |
2 pt 1 pt |
0.5 |
Can be applied from triticale emergence until boot stage. Controls wild mustard, wild radish, swinecress, shepherdspurse, field pennycress, Virginia pepperweed, and knawel. Does not control wild garlic, chickweed, or henbit. Weeds must be small. Treat before weeds exceed 1 to 2 in. or two to four leaves or before rosettes exceed 1.5 in. across. This usually means a fall application. |
|
chlorsulfuron + metsulfuron methyl (Finesse) 75 WDG |
0.2 to 0.4 oz |
0.008 to 0.0016 + 0.016 to 0.0031 |
Can be applied after the two-to three-leaf stage but before flag leaf is visible. See label for weeds controlled, application rates, use of surfactant, and rotational restrictions. Early application necessary for ryegrass suppression. |
||
Table 14-4 is also available in Chapter 8 of the North Carolina Agricultural Chemicals Manual, which is updated annually and placed on the Web at http://ipm.ncsu.edu/agchem/chptr8.html. |
Table 14-5. Forage, Feed, and Grazing Restrictions for Small Grain Herbicides |
|
Product |
Restrictions |
Banvel, Banvel SGF, Clarity |
Do not graze lactating animals for 7 days after application. There are no grazing restrictions for nonlactating animals. Do not harvest for hay for 37 days after treatment. Labels for Banvel and Banvel SGF also state that animals cannot be removed from treated areas for slaughter prior to 30 days after application. |
Buctril |
Do not graze within 45 days following application. |
2,4-D |
Do not feed forage within 14 days following application. Do not feed straw to livestock if applied as a preharvest treatment. |
Finesse |
No grazing restrictions. |
Glyphosate |
No retrictions. |
Gramoxone Max |
No restrictions when used for burndown. |
Harmony Extra |
Do not graze treated fields. Do not feed forage or hay to livestock. Harvested straw may be fed or used for bedding. |
Hoelon |
Do not graze. Do not harvest forage, hay, or straw prior to grain harvest. |
Peak |
Do not graze or feed forage for 30 days after application. Do not harvest for silage for 40 days after application. |
This file is a chapter from Small Grains Production Guide, 2004-05. Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the NC Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county Cooperative Extension Center.
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Published by
North Carolina Cooperative Extension Service
Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
9/04—3M—JMG (Revised) AG-580
EO4-43980
Last Revised Sept. 2004