Home Industry News Hazelnuts Oregon Department of Ag Approves New Herbicide Use for Young Hazelnut Orchards

Oregon Department of Ag Approves New Herbicide Use for Young Hazelnut Orchards

The Oregon Department of Agriculture (ODA) has approved SLN No. OR-200011, a Special Local Need registration under FIFRA Section 24(c), to allow use of the Albaugh, LLC product Quinstar® 4L, EPA Reg. No. 42750-169, for control of field bindweed and other weeds in hazelnuts (non-bearing only) grown in Oregon. The label and completed EPA Form 8570-25 for this SLN are enclosed.

Oregon produces more than 99% of the total U.S. hazelnut crop. In a letter of support for this SLN registration, Michelle Armstrong of the Oregon Hazelnut Commission states that there are now more than 89,000 acres of hazelnuts planted in the state. The acreage in production has more than doubled in the last 10-15 years, as new varieties that are resistant to eastern filbert blight (EFB) have become commercially available. As the industry has been rapidly expanding during recent years and older EFB-infected trees are replaced, several thousands of acres of new orchards are being planted each year. It typically takes about four (4) years or more after an orchard is planted before it is bearing a harvestable crop.

According to the Hazelnut Commission and Dr. Marcelo Moretti, Oregon State University (OSU) Extension Weed Management professor, the management of perennial weeds such as field bindweed is one of the most challenging problems faced in orchard crops. If left uncontrolled, field bindweed can quickly overgrow young plants, such as newly planted hazelnut trees. Selective and systemic herbicides are the most effective tools for managing perennial weeds such as bindweed, but hazelnut growers have limited options available. Essentially, their options are limited to 2,4-D and glyphosate products.

Glyphosate use is restricted in hazelnut orchards during the season because of crop injury concerns; spot-spraying is widely practiced, but is time-consuming and not very effective and may only be used to treat weeds away from the trees to avoid crop injury. Efficacy of 2,4-D against bindweed is also limited, and concerns with volatilization and drift may also restrict its use to only short periods during the season. Meanwhile, contact herbicides registered for use on hazelnuts, such as glufosinate, carfentrazone, saflufenacil, and paraquat, provide only transient removal of the treated foliage, with negligible impact on survival of the weed plants.

Albaugh, LLC applied for this SLN registration for use of Quinstar® 4L on hazelnuts to address the growers’ special local need for an effective product for controlling field bindweed and other weeds growing on the orchard floor and in close proximity to the newly planted and young hazelnut trees during the growing season, without crop injury concerns. 

Dr. Moretti has been evaluating quinclorac and other herbicides in long-term field trials conducted in several different young/non-bearing orchards and across multiple hazelnut varieties and trees ranging from one to four years old. The results of these studies thus far (two years in) strongly indicate that the young hazelnut trees are very tolerant of quinclorac. No crop injury or negative impacts to the trees has been observed from quinclorac applied at rates up to 1.5 lb. active ingredient per acre. By comparison, Dr. Moretti’s studies in other crops in this growing region demonstrate excellent control of field bindweed at rates of 0.375 lb. a.i. per acre (12.6 fl. oz. Quinstar® 4L per acre), which is the application rate provided by this SLN registration.

No residue tolerances have been established to support food-use applications of quinclorac on hazelnuts (Dr. Moretti currently is pursuing quinclorac/hazelnut [Crop Group 14-12, Tree Nut Group] residue studies with the IR-4 Project). Therefore, use under this SLN registration is limited to non-bearing hazelnuts only.

David L. Priebe
State Registration Specialist Pesticides Program
Oregon Department of Agriculture Phone: (503)986-4656

Email: dpriebe@oda.state.or.us

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