Commodities: Fieldcrops: Peanuts
2009 Peanut Update
2009 PEANUT WEED CONTROL UPDATE
Eric P. Prostko
1) Tips for Managing Palmer Amaranth in Peanuts
1) Deep turn (plow) or use extreme cover crops
2) Do everything possible to start off with a clean seedbed at planting
3) Use a residual herbicide (i.e. Valor or Dual Magnum/Generics)
4) Apply POST herbicides when pigweed is 3” or less in height
5) Remove escaped weeds by hand, flail mower, or with a rope-wick applicator prior to seed production
2) Suggested Herbicide Programs for Managing ALS-Resistant Palmer Amaranth in Peanut. 1
|
Preplant Incorporated |
Preemergence2 |
Cracking or early postemergence3 (Palmer < 2 in.) |
Postemergence4 (Palmer < 3 in.) |
Prowl5 or Sonalan |
Valor6,7 |
Cobra7 or Ultra Blazer7,8 |
|
Prowl5 or Sonalan |
Valor6,7 + Dual Magnum9 |
Cobra7 or Ultra Blazer7,8 |
|
Prowl5 or Sonalan |
Paraquat + Storm + Dual Magnum9 |
Cobra7 or Ultra Blazer7 + Dual Magnum9 |
1ALS-resistant Palmer amaranth is a very serious concern. An aggressive management program is necessary to slow spread of the resistant biotypes and to reduce selection pressure in areas currently not infested with resistant biotypes. A combination of soil residual and postemergence herbicides will be required for optimum control.
2Strongarm is not included in this table because it is an ALS-inhibiting herbicide. However, it can be used for the control of other broadleaf weeds. If Strongarm is used preemergence, Cadre or Pursuit should NOT be applied postemergence.
3Apply cracking or early postemergence treatment only if weeds have emerged.
4Cadre or Pursuit may be tank-mixed with Cobra or Ultra Blazer if needed for control of other weed species. Cadre and Pursuit are ALS- inhibitors. Because of concerns with weed resistance to ALS-inhibitors, a mixture of Cobra or Ultra Blazer with Cadre or Pursuit would be preferred over Cadre or Pursuit alone. When using Cadre or Pursuit, follow all labeled crop rotation restrictions.
5Generic brands of Prowl (pendimethalin) are available and perform similarly. Prowl or Sonalan can be used preemergence if 0.5-0.75" of water can be applied within 48 hours of application. They can be tank-mixed with Valor in this situation.
6If Valor is properly activated with 0.5-0.75" of rainfall or irrigation within 7 days of application, it is unlikely that an “at-cracking” treatment will be required. However, if control with Valor is unacceptable, an “at-cracking” treatment of paraquat + Storm + Dual Magnum should be applied.
7Valor, Cobra, Storm, and Ultra Blazer have the same mode of action (PPO inhibitor). Consequently, no more than 2 applications of these herbicides should be used in a season.
8Dual Magnum can be tank-mixed with Cobra or Ultra Blazer if additional residual control is needed in these programs.
9Generic brands of metolachlor are available (Stalwart, Parallel PCS, Me-Too-Lachlor). However, these generic brands have not provided the same length of residual control as Dual Magnum (S-metolachlor) in some UGA field trials. When tank-mixing paraquat, Cobra or Ultra Blazer with Dual Magnum/generics, additional spray adjuvants (NIS, COC) are not needed and will likely increase peanut injury.
3) Suggested Management Programs For The Control Of Tropical Spiderwort (Benghal Dayflower) In Peanut:
Tropical spiderwort (a.k.a. Benghal dayflower) is a plant that does not tolerate either tillage or shade. Consequently, herbicide control programs will likely be more effective with conventional tillage systems and twin-row planting patterns.
Herbicide Program 1
a) PRE Immediately After Planting: Valor @ 3 oz/A + Dual Magnum or generic metolachlor (Stalwart, Parallel PCS, Me-Too-Lachlor) @ 1 pt/A and
b) POST when spiderwort is 1-2" tall: Cadre/Impose 2L @ 4 oz/A or Strongarm @ 0.45 oz/A + Dual Magnum or generic metolachlor (Stalwart, Parallel PCS, Me-Too-Lachlor) @ 1 pt/A.
Herbicide Program 2
a) AT-CRACK (before 28 days after peanut cracking): Apply Gramoxone Inteon @ 12 oz/A or Gramoxone Max/Firestorm/Parazone @ 8 oz/A + Basagran @ 8 oz/A + Dual Magnum or generic metolachlor (Stalwart, Parallel PCS, Me-Too-Lachlor) @ 1 pt/A and
b) POST (2-3 weeks after at-crack spray): Apply Cadre/Impose 2L @ 4 oz/A or Strongarm @ 0.45 oz/A + Dual Magnum or generic metolachlor (Stalwart, Parallel PCS, Me-Too-Lachlor) @ 1 pt/A.
*When using Dual Magnum or generic metolachlor POST in combination with Cadre/Impose, Gramoxone/Firestorm, or Strongarm, additional spray adjuvants (NIS, COC) are not necessary. The maximum amount/A/year of Dual Magnum that can be applied is 2.8 pts. The maximum amount/A/year of Stalwart, Parallel PCS, or Me-To-Lachlor that can be applied is 2.66 pts.