Northarvest 2001 Research Report
April 15, 2002
Richard Zollinger, Extension Weed Specialist, North Dakota State University, Fargo, ND
Raptor + adjuvants
A study was conducted to observe weed control and dry bean injury from Raptor applied with several experimental adjuvants compared to standard products available today. No dry bean injury was observed with any treatment but weed control was variable. Raptor + Sub 4+3 adjuvant usually gave lower weed control rating than Raptor with other adjuvants.
Soil-applied herbicides in dry bean
Several herbicides were applied to both pinto and navy dry bean varieties. Valor at 2 to 3 oz/A preplant incorporated (PPI) or Spartan at 3 to 4 oz/A PPI or preemergence (PRE) controlled most broadleaf weeds except common ragweed but caused no dry bean injury. Valor applied PRE at any rate tested caused unacceptable dry bean injury. Prowl applied PPI followed by Pursuit + Result at labeled rates gave complete grass and broadleaf weed control with no dry bean injury. Prowl (PPI) + Pursuit Plus caused significant injury to both pinto and navy varieties and injury lasted the entire season.
Postemergence herbicides in dry beans
Several treatments were applied to pinto and navy varieties in a weed free environment. Raptor and Pursuit were applied in combination with Basagran or Rezult with different adjuvant systems. Dry beans showed excellent tolerance to all treatments applied.
Future developments in herbicide registration in dry bean
Possibly prior to planting in 2002, Pursuit may be registered for use as a preplant incorporated treatment. The labeled rate is 2 fl oz/A of the liquid formulation or 0.72 oz/A of the DG formulation. Some benefits of this application is adequate soil residual to control many broadleaf weeds for the entire season. One weed of most importance is nightshade. Nightshade thrives in low light condition in the crop canopy and emerges several times throughout the growing season. An important reason why nightshade is becoming an important weed in North Dakota and Minnesota is lack effective herbicides with adequate residual control. Nightshades are very sensitive to Pursuit which allows excellent control at lower rates. Nightshade biotypes resistant to Pursuit and Raptor have been documented throughout western Minnesota and eastern North Dakota. Field histories have shown the resistant biotypes can occur after eight to ten applications. Use other modes of action in rotation crops to help reduce the incidence of ALS resistant nightshade.
Pursuit Plus contains Pursuit and Prowl herbicides. BASF may continue toward registration of Pursuit Plus on dry bean but the registration may not be approved by EPA until 2003.
Reflex may be available through Section 18 registration in 2002. Syngenta is continuing toward full federal registration which may not occur until 2003 or 2004.
Reflex provides excellent control of nightshade, kochia, pigweed species, wild mustard, common ragweed, common cocklebur, and others. It will control weeds resistant to ALS herbicides.
Several years of research on dry bean tolerance to Spartan has looked promising and the major manufacturer is progressing toward registration. Soil-applied Spartan will offer an additional mode of action to help control many small-seeded broadleaf weeds, including kochia, nightshade, pigweed, and others. Federal registration may not occur for two to three years.