The following is a brief description of new herbicide products or significant label changes. Failure to mention specific products is not intentional and does not imply that Iowa State University (ISU) does not recommend these products.
Accent Gold (DuPont) Label granted
Accent Gold is a four-active-ingredient (a.i.) product, containing nicosulfuron, rimsulfuron, flumetsulam, and clopyralid. The rates of nicosulfuron and rimsulfuron are the same as found in Basis Gold, but flumetsulam and clopyralid (the same active ingredients and ratio as found in Hornet) have been substituted for atrazine. The product is targeted for producers who like the concept of Basis Gold, but do not want to use atrazine. The use rate is 2.9 oz/acre on corn up to 12 inches in height or with 6 collars. Accent Gold should be applied prior to foxtails reaching 6 inches in height. The injury potential to corn will increase if environmental conditions or cultural practices place the crop under stress. Accent may be applied following Accent Gold if grasses are not adequately controlled by the residual activity.
Atrazine Label change
Restrictions on application of atrazine in the vicinity of tile-outletted terraces were changed in March, 1997. The original restrictions prohibited application of atrazine within 66 feet of terrace standpipes with tile outlets. The label changes allow the use of atrazine near standpipes if the product is mechanically incorporated to a depth of 2 to 3 inches in the entire field, or if the field is maintained under a no-till system with high crop residue management. High crop residue management is described as a system where little or no crop residue is removed from the field during and after crop harvest.
Authority First/Synchrony STS (DuPont), Authority First/Classic: Registration pending
These products are copacks with a preemergence component (Authority) and a postemergence component (Synchrony or Classic). The first component is a 75% a.i. sulfentrazone product (Authority First) applied at 4-5.3 oz/acre. The post component is either 0.5 oz/acre of Synchrony or 0.67 oz/acre of Classic.
Balance (Rhone-Poulenc): Registration pending
This product will be labeled for preplant incorporated (PPI) or preemergence use in corn. Balance represents a new herbicide family and a new mode of action. It interferes with the synthesis of plant pigments, thus resulting in a bleaching of susceptible plants. The herbicide provides broad-spectrum control of broadleaf weeds. It is particularly strong on most small-seeded broadleaves and velvetleaf. Weaknesses include cocklebur and wild buckwheat. Of particular note is Balance's activity on woolly cupgrass. Balance has provided more consistent control of woolly cupgrass than currently available preemergence herbicides (metolachlor, acetochlor, etc.); however, Balance may need supplemental strategies (post herbicides, cultivation) to provide full-season woolly cupgrass control. Occasional corn injury has been observed in ISU field trials. Due to the mode of action, injury is easily observed and may be a concern with some growers. In ISU trials, corn has regained color quickly with no evidence of lasting impact on crop development. Balance will usually be used in combination with a reduced rate of an amide herbicide to improve consistency of foxtail control.
Bladex/Extrazine (DuPont): Label change
Under the phased withdrawal of cyanazine from the market, the maximum use rate for 1998 will be 3.0 lb a.i./acre (equivalent to 3.3 lb of Bladex 90DF or 4.4 lb of Extrazine 90DF).
Exceed (Novartis) Label change
Further restrictions have been placed on the Exceed label to reduce carryover problems. There is now an 18-month restriction for planting normal soybeans following Exceed for all of Iowa. South of I-80, STS soybeans can be planted 10 months after application.
First Rate (DowElanco): Label granted
Cloransulam-methyl is from the same chemical family as flumetsulam (Broadstrike). Like Broadstrike, it is an ALS-inhibitor that is active on broadleaf weeds. First-Rate is cleared for PPI, preemergence, and postemergence applications in soybeans. The strength of First-Rate is its activity on weeds in the composite family, including cocklebur, common and giant ragweed, and sunflower. It is one of the more consistent products for these species. First-Rate is used at 0.6 oz/acre for soil applications and 0.3 oz/acre for postemergence applications. The label states that soil-applied First-Rate may increase the severity of iron chlorosis symptoms.
Python (DowElanco): Label granted
Python is a new product in the Broadstrike family, but includes only flumetsulam (active ingredient of Broadstrike). It is cleared for preemergence use in both corn and soybeans, but DowElanco will be emphasizing the soybean market. Python has activity on many small-seeded broadleaves and velvetleaf, but it is weak on cocklebur and other members of the composite family. Use rates are from 0.8 to 1.0 oz/acre. Python at 1.0 oz/acre is equivalent to 0.05 lb a.i. of flumetsulam, whereas 2.5 pt/acre of Broadstrike + Dual is equivalent to 0.063 lb a.i. of flumetsulam. Corn injury by flumetsulam has occurred with preemergence applications under conditions that stress the crop.
Raptor (American Cyanamid): Label granted
Raptor is a new herbicide in the imidazolinone family (Scepter, Pursuit, etc.). It is cleared for postemergence use in soybeans. The main differences between Pursuit and Raptor are Raptor's shorter residual activity and its greater activity on grasses and lambsquarter than Pursuit. The label recommends that Raptor be applied at 5 oz/acre if applied alone or at 4 oz/acre if used as a sequential treatment with a soil-applied grass herbicide.
Reliance STS (DuPont): Label change
The Reliance STS label now allows the product to be applied to soybean varieties not designated STS. Use rate is 0.5 oz/acre. The label states that a temporary crop response may occur following application. The use rate of Reliance is equivalent to 0.18 oz/acre of Pinnacle and 0.32 oz/acre of Classic.
Spirit (Novartis): Label granted
Spirit is a combination of primisulfuron (Beacon) and prosulfuron, the two active ingredients in Exceed. Spirit is a 3:1 ratio of primisulfuron: prosulfuron, whereas Exceed is a 1:1 ratio. The use rate of Spirit is 1 oz/acre. There will be a 10-month rotation restriction for soybeans south of I-80 and an 18-month restriction north of I-80. Application window is from 4- to 24-inch corn. Drop nozzles should be used when corn is greater than 20 inches in height.
This article originally appeared on pages 15-17 of the IC-480 (2) -- February 16, 1998 issue.