Ampersand increases weed control at low Suppress use rates

Ampersand Suppress

One of the most difficult and expensive aspects of organic farming is weed control. Organic growers have few options and most of those options are substantially more expensive and less effective than conventional herbicides. For example, two of the most popular organic herbicides are Weed Slayer and Suppress, both of which, are non-selective herbicides.

Ampersand Results

Suppress @ 3% + Ampersand @ 0.25%


Average weed control improvement


Maximum weed control improvement when compared to Suppress alone

Suppress @ 6% + Ampersand @ 0.125%


Average improved performance against hard to control weeds


Maximum improvement against hard to control weeds when compared to Suppress alone

Weed Slayer and Suppress cost $130/gallon and $65/gallon, respectively, whereas a conventional non-selective herbicide such as Bayer/Monsanto's Roundup is $17.50/gallon (generic glyphosate products are 40% to 50% less expensive than Roundup). In addition to being more expensive on a per unit basis, these organic herbicides often have use rates that are generally higher than Roundup. Weed Slayer is labeled for use at 1% to 3% and Suppress is labeled at 3% to 9% compared to Roundup which is labeled at 1 quart per acre.

If the grower applies a spray volume of 25 gallons per acre it would require: 1 to 3 quarts of Weed Slayer, or 3 quarts to 2.25 gallons of Suppress per acre, compared to a single quart of Roundup. Consequently, Weed Slayer would cost the grower $32.50 to $97.50 per acre, Suppress would cost $48.75 to $146.25 per acre compared to $4.38 per acre for Roundup.

Attune Agriculture’s adjuvant Ampersand® was designed to increase the amount of spray volume that gets to the target plant, with ingredients that slow down droplet evaporation which increases the amount of time a pesticide can be absorbed into the plant. Ampersand has been shown to be particularly effective when it is used with systemic pesticides, those that must penetrate into the plant to be effective. Attune has conducted numerous field trials that have demonstrated that the addition of Ampersand accelerates control, can potentially reduce pesticide use rates, and/or extend residual control.

Attune Agriculture engaged Crop Inspection Service (CIS) in Valley Center, CA to conduct a trial to determine the impact of Ampersand on Suppress organic herbicide. CIS used 3 weed species, barnyard grass, annual spurge and wild mustard. A single application of Suppress alone or mixed with Ampersand was made to weeds grown in pots. Percent control was measured 2, 7 and 14 days after application (DAA).

With the lowest labeled use rate of Suppress (3%), the addition of 1 quart of Ampersand per 100 gallons of spray, increased control by an average of 79% across the species tested. With annual spurge, Ampersand increased control by 96%. With the middle use rate of Suppress (6%), the addition of 1 pint of Ampersand per 100 gallons increased the herbicide’s performance against harder to control barnyard grass and wild mustard by an average of 26%. With barnyard grass, the control was improved by 46%.

“Ampersand substantially improved the performance of Suppress herbicide. A quart of Ampersand added to 100 gallons of a 3% Suppress spray mix provided weed control comparable to a 6% Suppress use rate. A pint of Ampersand added to 100 gallons of a 6% Suppress spray mix increased weed control to levels nearing conventional herbicides.”

Buzz Uber

Owner, CIS
Since 2005, Crop Inspection Service in Valley Center, CA has been advising growers about pests and making recommendations for their control in Southern California.

The significance of this study is that growers that typically spray Suppress at 6% could achieve a similar level of control with half that amount of herbicide by adding 1 quart of Ampersand. Alternatively, if a grower continues to use Suppress at 6%, the addition of 1 pint of Ampersand would increase levels of control comparable to conventional herbicides.

Percent Weed Control With Supress @ 3%

Suppress @ 3%
+ Ampersand @ 0.25%

Percent Weed Control With Suppress @ 6%

Suppress @ 6%
+ Ampersand @ 0.125%