Weed Control with CBI Herbicides

There are only a few weed control products on the U.S. lawn care market that use cellulose biosynthesis inhibitors (CBIs), including Dow’s Gallery pre-emergent herbicide for most tolerant cool- and warm-season turfgrasses, and BASF’s Drive XLR8 post-emergent herbicide for established cool- and warm-season turf. In October 2010, Bayer Environmental Science entered this arena when it introduced Specticle, a pre-emergent herbicide for warm-season turf. Quali-Pro is also offering a new product called Isoxaben 75WG, a wettable pre-emergent herbicide.

Laurence Mudge, technical services coordinator for Bayer Environmental Science, says that a CBI’s mode of action, which is what a chemical does to kill or control a weed, is not understood very well—for good reason.

“With some classes of chemistry, like the triazine herbicides or the sulfonylurea herbicides, we know exactly how they work and what they affect,” Mudge says. “In the case of CBIs, it’s a little bit of a mystery.”

What CBIs Do. What we do know is that cellulose biosynthesis inhibitors affect the assembly of cellulose. Therefore, while CBIs do not prevent seeds from germinating, they do stop weed growth by inhibiting the development of root cells when the seedlings come into contact with the CBI.

“Plants produce cellulose to make cell walls that give the plants structure,” Mudge reiterates, adding that cellulose is to a plant what bones are to a human.

Are CBIs More Effective? While Mudge is not certain that cellulose biosynthesis inhibitors are more effective than other modes of action, he does believe this: Most contractors do not know what CBIs are or how they work, because up until now they’ve had no real reason to take an interest. With respect to herbicides, “Modes of action usually aren’t a factor for contractors until there’s a problem,” Mudge says. Potentially, that time is now.

“ALS inhibitors represent one herbicide class where we now have a lot of resistance issues,” Mudge points out. “They’ve been used over and over for so long that the mode of action doesn’t work well anymore.” If a contractor has been using an ALS-inhibiting herbicide and is not getting results, simply switching to another ALS-inhibiting herbicide will not solve his or her problem.

“Typically, active ingredients are developed first for production agriculture and are later considered for use on turf and ornamentals,” says Matt Bradley, marketing manager for Specticle. “Specticle (Indaziflam), however, was designed specifically for the turf market. This is going to make it more effective for turf managers to tackle those unique challenges offering a broad spectrum weed control with residual that performs unlike any other pre-emerge available in the market today.”

Visit Herbicides for a look at some of the products available today.