Weed Control: Five Questions With… Michael Cunnane About Herbicides

American/Western Fruit Grower recently had a conversation with Michael Cunnane, DuPont Crop Protection’s product manager for specialty herbicides, addressing the issue of what growers look for in herbicides, the recent trends that have come about in response to resistance issues with glyphosate, and what new products growers can be on the lookout for in the future. What follows are the questions we posed to Cunnane and his responses.

Q: What are the key attributes DuPont looks for when developing herbicides for fruits and vegetables, and how do those attributes relate to grower needs?

A: First and foremost I would say in the last five to seven years the number one attribute is control of the more aggressive, resistant weed species that are showing resistance to the standard herbicides currently being used. DuPont looks to deliver a product that offers contact control of any of those species, soil residual control or, in the best possible case, both. Next we look for acceptable levels of crop safety, and the third attribute is EPA registerability.

Q: What are growers saying is most important in weed control?

A: The number one thing that growers think is important is the amount of time any given herbicide can control weeds. The next grower consideration is the ability to spray whatever herbicide they choose when there are adjacent non-labeled crops present without causing damage from drift. In addition, cost effectiveness is always in the consideration set, and a short re-entry interval is pretty important because growers have numerous field activities, and the last thing they want is to spray an herbicide that keeps their workers out of the fields for any significant amount of time.

Q: Thanks to resistance issues, what types of trends do you see regarding replacements or alternatives to Roundup?

A: A trend we have seen in the last five years is renewed uses of older chemistries. This is occurring because the effectiveness of Roundup caused a culture where quite a bit of the marketplace would plan on treating, depending on the crop, two or four times with Roundup only. That worked great for a period of time, but because it has not worked so well recently, growers have had to use some of the older soil residual chemistries like pendimethalin, diuron, or oxyfluorfen. A more recent trend includes the new contact herbicides that have been introduced for vegetables and fruits. One major piece of chemistry is glufosinate, which is Rely (Bayer CropScience), in vegetables. Another new PPO (protoporphyrinogen oxidase) burndown tool introduced recently is called Treevix (BASF) for use on crops like pome fruit and tree nuts.

Another trend that is occurring out west is the willingness of manufacturers to introduce premix herbicides into the vegetable and fruit areas. As resistance spreads in these pockets and valleys, the ability to use a premix across the board, on broader acres, has increased prior to three years ago when resistance issues were in pockets. A lot of our competitors are introducing premixes of current chemistries. I think we are seeing this trend because tolerance issues have spread continuously over a bigger area.

Q: What types of products does DuPont have coming down the pike?

A: Last year we introduced a new formulation of Matrix herbicide, which is registered on tomatoes, potatoes, grapes, tree nuts, tree fruit, and citrus. It is a soluble granular (SG) formulation. The benefit to growers with the SG formulation of Matrix is that 100% of the herbicide is getting sprayed. The previous version went into a suspension in water, which meant that a percentage of it floats in the water or sticks the tank walls and lines, so not all of herbicide was sprayed on the crop. Farther down the pike, DuPont is investing in bringing in multiple new fungicides for commercial sale in 2012 and 2013 time frames.

Q: Where do you see this segment of the crop protection industry headed in the future?

A: Producing the highest quality fruits and vegetables with the highest yield will always be the goal of the grower. From an herbicide perspective, I see limited herbicide investment by the industry in these spaces for two reasons: there are multiple, effective approaches available today to control their issues and there are very few “true” unmet needs. The reason we have resistance is that Roundup, being as effective, broad-spectrum and inexpensive as it was, took over a huge part of the market, putting significant selection pressure on nature’s most adaptable species.