New Soil Adjuvant Helps in Resistance Weed Control

Fresno, California — In the face of continuing herbicide resistance, weed specialists are urging growers to apply one and, in some cases, two pre-emergent herbicide treatments to reduce the dependence on post-emergent sprays. To help in this effort, ORO®-RZ, a new soil adjuvant, has been introduced by Oro Agri Inc. ORO-RZ has shown encouraging results in boosting pre-emergent herbicide control of tough broadleaf weeds.

In two consecutive years of university research field trials, the addition of ORO-RZ to popular, pre-emergent herbicide treatments significantly reduced the infestation of certified Roundup-resistant marestail in soybeans. ORO-RZ was added to a premium marestail pre-emergent treatment that was fall-applied preceding spring planting of soybeans. In both years, the ORO-RZ plus premium treatment provided a higher level of marestail control compared to the premium herbicide application alone. In Year 1, at 320 DAT, the ORO-RZ plot had 93% control versus 70% for the herbicide alone. Likewise, in Year 2 the ORO-RZ application returned 87% control versus 72% control for the premium treatment alone at 296 DAT.  

According to Riley Reynolds, Oro Agri Director of Sales and Marketing, the explanation behind the improved performance of soil-applied pesticides is fairly simple. ORO-RZ, with its great spreading and penetrating ability, helps the pre-emergent herbicide lay down a uniform blanket of protection to control germinating weed seedlings. It distributes the herbicide application evenly within the soil profile, even in hydrophobic soils. Adding ORO-RZ to the tank helps eliminate gaps in herbicide protection that allow weed emergence.”

For more in-depth information, including field trial results, go to

Please contact your local Oro Agri area sales manager for your closest ORO-RZ retailer.

ORO-RZ is not currently registered for use in California.