Cross-spectrum herbicides combine convenience with simple decision-making for control of both grass and broadleaf weeds. Their popularity has been increasing over the past decade as growers look for convenient ways to control weeds that typically affect crops in their soil zone, without having to sift through herbicide guides and product labels.
“Over the past half a dozen years, cross-spectrum products have gone from about 22 per cent of grass herbicide use to over 35 per cent of usage on cereal acres in Western Canada,” says Kelly Bennett, Western Canada herbicides category leader with Corteva Agriscience. “It comes down to both simplicity and efficacy to a farmer, and cross-spectrum products offer both.”
Cross-spectrum products are combined so that the two products work well together, combat problem weeds in a given area and are physically compatible in a sprayer tank. Generally designed for the widest possible weed spectrum coverage, overlapping control and tested for compatibility, cross-spectrum products are packaged at optimum mixing rates for peak convenience and effectiveness.
There are currently about 126 different herbicide products on the market for cereal growers in Western Canada. Of those products, 35 are specifically registered for grassy weed control, and more than 70 for only broadleaf weed control. Bennett says it can be daunting to determine a combination that best suits an individual farmer’s crops, weed profile and rotational needs.
“Of all of those herbicide possibilities there are now 22 cross-spectrum products,” he says. “So that narrows things down significantly. Next, when a grower looks at their specific soil zone, there are about 10 options per soil zone. When you think of all the combinations that were possible before, taking a close look at your weed profile and choosing from 10 products is a much simpler decision-making process.”
Bennett says that the needs of each operation are different, but an advantage of cross-spectrum products is that they come “pre-measured,” which simplifies sprayer filling when compared to tank mixes. One box or one drum, or a drum plus a case component, will treat a set number of acres. This keeps it simple for the spray crew at a very busy time — allowing for quicker refills, reducing time and the potential for error.
Corteva’s cross-spectrum solutions
Corteva has two products for the brown soil zone and two for the black zone. Avenza and Tridem are formulated for use for growers in the brown soil zones, while Rexade and Rezuvant XL are for those in the black soil zone.
“Farmers asked for perennial and annual broadleaf control with no carryover into the new year for recropping into lentils and chickpeas,” says Bennett. Avenza and Tridem were our response to that demand — offering control without any recropping restrictions.”
Tridem is a Group 2 grass herbicide plus a Group 2/4 combination broadleaf component for use by wheat growers with the flexibility to add either 2,4-D or MCPA to customize the weeds targeted. Avenza is a Group 1 grass herbicide plus the same broadleaf component for use on both wheat and barley and which requires an add-in of MCPA to expand the weed list. Both have multiple modes of action on a significant number of broadleaf weeds and are excellent resistance management tools.
For black soil zone growers, Corteva offers Rexade and Rezuvant XL. Both offer control of a wide range of tough-to-control broadleaf weeds such as cleavers, chickweed, fleabane, hemp nettle and lamb’s quarters. Rexade, a Group 2 grass herbicide for wheat growers combined with two Group 4 broadleaf weed actives, is an all-in-one-box, complete solution. It requires no extras and no adjuvants, which makes it unique even among cross-spectrum products, and simple and easy to use. Rexade also has the surprising attribute of a wide spray window starting at the two-leaf stage, despite having 2,4-D in the mix. This advantage is due to the combination of actives and safener in the product, and was discovered by Corteva’s research scientists in Western Canada.
Rezuvant XL is a Group 1 grass control, cross-spectrum product for use on both wheat and barley and is formulated with two Group 4 broadleaf components for convenience in handling. It requires the add-in of MCPA to round out the weed control, giving it a long list of weeds controlled to a very high level.
“With all four of these products we have tried to make them as convenient as possible for larger farmers,” says Bennett. “Some might ask why these products are not just formulated in a single jug or drum? Well, sometimes that doesn’t work from a chemical formulation perspective or it may be too costly to develop and register. But also it may be more effective and convenient to have the flexibility to customize with a choice of add-ins, such as MCPA or 2,4-D, at the sprayer.”
Both Avenza and Tridem are available in a co-pack in two difference sizes. Rexade is an all-in-one box that covers 40 acres. Rezuvant XL — whose new formulation is just being launched this year, is currently available in 240 acre drums but will be available in both cases and drums by next spring.
“One of the great things about all of these products is that they are fantastic rotational tools,” says Bennett. “These cross-spectrum products as a group were designed with complete weed management in mind, giving growers both Group 1 and Group 2 grass control options, and all will work well for broadleaf herbicide rotations.”
So how does a farmer choose which cross-spectrum product is right for them? “There are really a few simple things to consider,” says Bennett. “First — their soil zone. Next, do they want a Group 1 or Group 2 grass weed control. Third — are they planning for wheat or barley? And finally they can consider how important convenience is to them? Is it a priority that their herbicide is in a single container or do they want the flexibility to customize with an add-in product? These are all easy questions to answer and using a cross-spectrum product is all about worry free performance and simplifying weed control.”
