ISSUE 4 May 26, 2005
ERRATUM FOR MCPA USE IN FIELD PEA
A few years ago MCPA labels were revised to restrict use in field pea to ONLY the Pacific NW U.S. No MCPA product at this time has been found to be registered for use in ND.
An important point is that even though the labeling for any particular product in question may not contain geographic restrictions, use of any product in North Dakota would not be legal unless the product is registered in the state. There is no MCPA product registered in North Dakota for use on pea. The NDDOA is willing to register an MCPA product in North Dakota for use on peas, or to receive supplemental labeling for an existing MCPA product that allows use on peas. However, nothing can be done until a registration application or supplemental labeling is received.
WILD OATS CONTROL IN WHEAT AND BARLEY
Recent rains and cool weather have resulted in the emergence of a large flush of wild oats. The following paragraphs are helpful reminders with the small grain wild oat herbicides.
Labeled on wheat, durum, 6-row and 2-row barley. Do not tank-mix 2,4-D amine or 2,4-D ester with Puma at anytime.
Do not apply to barley after jointing begins. This is very important for barley will reach the jointing stage by the 5 leaf stage. The 2-row barley varieties, especially Conlon, are considerably earlier in maturity than the 6-row types. Conlon typically begins to joint by the 4 ½ leaf stage. Do not tank-mix Bronate Advanced with Puma on 2-row barley. For additional safening of Puma on barley, mix Harmony GT + MCPA ester or Harmony GT + Starane. If temperatures are expected to drop below 40°F 2 days before or 3 days after application, do not apply Puma to barley. Window of application is emergence to 60 days before harvest. Puma has provided more consistent wild oat control under cool, damp conditions compared to warm, dry conditions.
Labeled on wheat, durum and barley from 2 leaf to boot. An excellent option for barley that has already reached the jointing stage. There is less barley response when applied in the 5 to 6 leaf stage compared to the 3 to 4 leaf stage. Achieve can be tank-mixed with MCPA ester, bromoxynil, bromoxynil + MCPA, 2,4-D ester, Curtail M, Harmony GT and Starane. Tank-mixing other herbicides, especially dicamba (clarity, others) or SU herbicides will result in reduced wild oat control. Add AMS at 7.5 to 15 lb/100 gal water. Achieve is more active under cool, damp conditions. Add Supercharge and Achieve conditioner according to label directions.
Labeled in wheat, durum, and winter wheat only, from the 2 leaf to 4th tiller stage. Discover at 3.2 fl oz/acre plus DSV adjuvant at 10.2 fl oz/A or Discover NG at 12.8 oz/A will control wild oat. For ground applications use 5 - 10 gallons of water per acre. Use 10 gallons of water per acre if conditions are dry or with dense weed populations. Avoid applications when temperatures may fall below 40°F within 48 hours prior to or after application. The addition of a MSO can enhance weed control under dry conditions. Wheat has excellent tolerance to Discover; do NOT apply to barley. Discover will control wild oats consistently over a wide range of environmental conditions. Discover is antagonized much less than other wild oat herbicides when tank-mixed with other pesticides. See label for all approved tank-mix options.
Labeled in wheat, durum and winter wheat from the 1 leaf to 4 leaf stage (prior to jointing). Apply 0.3 oz/A for green foxtail, 0.4 to 0.6 oz/A for wild oat, cheat, and yellow foxtail. Use the higher rates for yellow foxtail and for high grass weed densities. Everest at 0.6 oz/A will control wild oat up to the 4 leaf stage. Apply with basic blend adjuvants at 1% v/v or NIS at 0.25% v/v except when adding an emulsifiable concentrate (EC) or ester formulated broadleaf herbicide as a tank-mix pardner. Do NOT apply to barley.
Always apply Everest with a broadleaf herbicide. Dicamba or 2,4-D is required for safening when tank-mixing with SU herbicides (Express, Harmony Extra, Harmony GT, others). Everest is more active under cool, moist conditions. Consult label for rotation restrictions. Everest is the only POST grass product labeled on spring wheat with activity on downy brome.
Labeled in spring wheat and durum only. Can be applied from emergence to prior to jointing. Silverado at 1.75 oz/A will control wild oat from the 1 leaf to 2-tiller stage. Apply with a Bayer approved adjuvant. Refer to label for tank-mix information and crop rotation restrictions. Do not use 2,4-D with Silverado.
Labeled in wheat, durum, and barley from the 2 leaf to jointing stage. Assert will control 1 to 4 leaf wild oat. Consult label for rotation restrictions. Assert has provided more consistent wild oat control in hot, droughty conditions than other POST wild oat herbicides. Apply with a MSO oil for more consistent control. Do NOT tank-mix Assert with Stampede, dicamba (Clarity), MCPA amine or 2,4-D amine.
Hard (high pH) water can cause the Assert to thicken resulting in the herbicide to come out of solution. To reverse this or lower the pH, Muriatic acid (10% HCL to 100%HCL) can be added to the spray tank. Add only enough to change the solution to a liquid state which is usually less than 1 gal/100 gallons if for a 10% HCL conc.
VOLUNTEER BARLEY CONTROL
Everest and Discover are not labeled on barley due to severe injury potential to the barley. This has lead to the question; how good will they control volunteer barley in wheat?
Research conducted in 2001 (Page 9, green section of 2001 ND Weed Control Research), where Everest and Discover were applied at the full labeled rate on barley showed they both caused 65% injury in the form of stunting and yellowing which lasted most of the season. The barley eventually produce seed but there was no crop to compete with the barley.
Discover was applied to barley in 2000 at the NC Research and Extension Center in Minot. Barley was severely stunted but also produced seed. The barley was stunted and combined with crop competition from the wheat, would have been below the combine or swather header.
In summary, Everest and Discover will suppress volunteer barley in wheat. If the volunteer barley population is low and the wheat crop is dense and growing well, perhaps greater barley control might occur.
NDSU Extension Weed Specialist