Source: OREGON STATE UNIVERSITY submitted to NRP
ELECTRICAL WEED CONTROL IN HAZELNUT - ADVANCING THE TECHNOLOGY, QUANTIFYING THE BENEFITS, AND DEVELOPING A NOVEL APPLICATION METHOD
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
ACTIVE
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
1030992
Grant No.
2023-70006-40609
Cumulative Award Amt.
$324,892.00
Proposal No.
2023-02984
Multistate No.
(N/A)
Project Start Date
Sep 1, 2023
Project End Date
Aug 31, 2026
Grant Year
2023
Program Code
[ARDP]- Applied Research and Development Program
Recipient Organization
OREGON STATE UNIVERSITY
(N/A)
CORVALLIS,OR 97331
Performing Department
(N/A)
Non Technical Summary
This is an ARDP single-function research project focused on Plant Protection Tools and Tactics. This project will consider the performance, safety, and economic sustainability of electric weed control (EWC) as an herbicide resistance-management strategy in hazelnut orchards. Herbicide resistance is the greatest weed management challenge identified in multiple commodities. In Oregon hazelnut orchards, there are confirmed cases of resistance and multiple resistances to postemergence and more recently preemergence herbicides, jeopardizing herbicide mixtures and rotations as management tools. EWC can fundamentally change weed management in hazelnut and mitigate herbicide resistances. EWC is the only effective non-chemical weed control tool because tillage is limited in hazelnut, and mowing is ineffective. Our approach includes field research in collaboration with growers and on university farms. We have established four objectives to advance the integration of EWC in hazelnut orchards. (i) Development of weed-specific recommendations for EWC in short-term studies in commercial fields. (ii) Quantification of the effect of foliar-applied electrical weed control (EWC) on weed densities, herbicide use, and gross returns under different weed management approaches in hazelnuts. (iii) Continued evaluation of the effects of EWC applied over multiple years on hazelnut growth and yield. (iv) Develop soil-applied EWC recommendations to manage preemergent weeds In partnership with the private sector. Expected outcomes include reducing reliance on herbicides, mitigating herbicide resistance management costs, and reducing human exposure to chemicals. Our findings will apply to a wide range of perennial crops.
Animal Health Component
100%
Research Effort Categories
Basic
0%
Applied
100%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
21612101140100%
Knowledge Area
216 - Integrated Pest Management Systems;

Subject Of Investigation
1210 - Filbert;

Field Of Science
1140 - Weed science;
Goals / Objectives
Objective 1: Develop weed-specific recommendations for EWC. Determine the effectiveness of EWC technologies over weed species in short-term studies.Objective 2: Quantify the effect of EWC on weed densities, herbicide use, and gross return under different weed management approaches. (research-oriented)Objective 3: Monitor the long-term effect of EWC on hazelnut growth and yield.Objective 4: Develop a soil-applied EWC method to manage weeds in preemergence.
Project Methods
Objective 1: Develop weed-specific recommendations for EWC. EWC depends on its efficacy and operation costs. To develop a cost-effective EWC tactic, we must identify optimal performance under various environmental and operational conditions. We anticipate conducting six replicated studies annually, lasting nine weeks each. These will be initiated in fall-winter, spring, and summer. Each study will include three operation speeds (one to six km h-1) and one to three operations performed at three weeks intervals. The experiment will be organized as a two-factor factorial organized as a randomized complete block design. A nontreated check and grower's standard weed control (e.g., glufosinate) will be included for comparison. We will record data describing operation parameters (speed, voltage, amperage), soil type, temperature, gravimetric soil moisture, and weed density by species, size, and coverage following methods proposed previously. Weed response to electrical damage will be visually quantified on a rating scale ranging from 0% (no injury) to 100% (weed death) every seven days. Above-ground weed biomass will be collected, separated into reproductive and non-reproductive structures, and weighted.Objective 2: Quantify the effect of EWC on weed densities, herbicide use, and gross return under different weed management approaches.A long-term field study will be initiated at the OSU Lewis Brown Research Farm in Corvallis, OR. The orchard will be planted with a commercial cultivar at 3 by 6 m spacing, irrigated, and trained as a single-trunk tree following standard production practices. The following treatments will be compared: 1) weedy check, 2) weed-free check, 3) standard practices (pre-and post-emergence herbicides) plus mowing, 4) electrical weed control, and 5) standard practice plus electrical weed control. Treatments will be applied in winter, spring, summer, and fall. Retreatment will be performed as needed to minimize weed seed production. Treatments will be arranged in a randomized complete block design with five replicates. Trunk cross-sectional area and canopy volume will be estimated by measuring plant height and diameter Yield will be recorded when trees reach bearing age. Weeds will be identified at the species level. Weed control per species will be assessed monthly with visual estimates. Weed cover and weed presence will be recorded at three sampling times per year, including late winter, mid-summer, and early fall. A grid with 25 intersecting points will be mounted on a 0.25 m-2 quadrat and measured four times per plot per sampling time in a regular distribution pattern (Nkoa et al. 2015). All expenses for purchased materials will be recorded. The labor required for all activities will be recorded to the nearest second and differentiated between the machine operator and hand labor. We will calculate machinery costs using an online tool.using a mixed model. Contrasts will be used to compare EWC to the standard method.Objective 3: Monitoring the long-term effect of EWC on hazelnut growth and yield.This objective continues a study initiated in 2021 with the previous NIFA CPPM grant award 2020-70006-32982. The current work aims to monitor the EWC effect on hazelnut growth and yield when applied to hazelnut suckers. The orchard was planted with two cultivars of economic importance in Oregon, 'Yamhill' and 'Wepster,' with drip irrigation. The treatments include (1) nontreated weed-free check, (2) power harrow as a reference, (3) EWC at a high rate (0.4 km h-1) without suckers; (4) EWC at a low rate (1.25 km h-1) without suckers, (5) EWC at a high rate (0.4 km h-1) with suckers, and (6) EWC at a low rate (1.25 km h-1) with suckers. Treatments will be applied to the same plots four times a year. The field is weed-free with moving, hand weeding, and spot treatments. We will monitor tree trunk growth, sucker shoot elongation, canopy volume, yield, and leaf nutrient analysis to monitor the long-term effects like methods described in objective 2. The experimental design is a two-factor randomized complete block with six replicates. Hazelnut cultivar and the treatments are the second factors.Objective 4: Develop a soil-applied EWC method of managing weeds in preemergence. (research-oriented)In this objective, we will use a commercially available unit to apply a pulse electric field (PEF) to the soil to kill weed seeds before they emerge. PEF has been shown to reduce the germination of yellow nutsedge by 75% after a 40 s treatment at 14 kV. The Direct Energy System (DES, Lisi Global, Inc.) unit delivers energy via pins or electrodes inserted into the soil (Figure 6). Pin spacing and length are adjusted according to the volume of soil to be treated. The DES unit is autonomous, battery-powered, and capable of delivering electricity while stationary or moving up to 8 km h-1. The application apparatus uses pins 1.27 cm wide mounted on a 1.2 m long bar. Electric pulses are delivered at the soil surface and up to a maximum depth of 25 cm. A field study will compare PEF effects against naturally occurring weed species and newly planted hazelnut. The orchard will be planted in a Malabon silt loam soil at the OSU Corvallis Research Farm. The electric pulse will be applied to a depth of 2 cm. PEF treatments will include three levels of electric field strength designated as low (20 kV.mm-1), medium (50 kV.mm-1), or high energy (200 kV.mm-1). Pulse frequency, width, and duration of treatment (travel speed) will be manipulated to achieve three energy inputs ranging from as low as 20 J.cm-3 to as high as 150 J.cm-3. A non-treated control and a weed-free treatment will be included as references. Treatments will be applied twice yearly to the same plots in early spring and early fall for two years. The number and width of pulses will be recorded. These data will inform the energy required to provide adequate weed control without disrupting hazelnut growth.

Progress 09/01/24 to 08/31/25

Outputs
Target Audience: Hazelnut growers Oregon Hazelnut Commission Organic producers Small fruit producers Hop growers Stone and pome fruit growers Vegetable growers Changes/Problems:The greatest challenge in 2025 was advancing Obj 4. After several delays and repeated attempts, the study was resumed in the summer of 2025. However, tree vigor had been compromised due to the extreme heat and weed competition experienced in the previous year, which affected overall plant health and limited the availability of robust experimental material. What opportunities for training and professional development has the project provided?A Ph.D. student is leading this project, with support from two undergraduate research assistants. The research has generated strong interest among growers and industry stakeholders. Results have been shared through two extension presentations and a field day held at the Lewis Brown Research Farm. The field day drew over 60 participants, including growers, industry representatives, and extension professionals, providing an opportunity for direct engagement and discussion of practical implications for weed management in hazelnuts. How have the results been disseminated to communities of interest?Project findings have been disseminated to academic peers through presentations at both national and regional Weed Science Society meetings. Local outreach efforts have focused on direct engagement with growers, primarily through in-person events such as field days, workshops, and extension presentations. These activities have facilitated the transfer of research outcomes to end-users and fostered dialogue on practical implementation strategies. What do you plan to do during the next reporting period to accomplish the goals?We plan to expand our efforts under Obj 1 in 2025 and 2026. The additional data that will support the development of a predictive model describing how electricity interacts with different weed species. This model will enable simulation of various treatment scenarios to optimize electrical weed control strategies, with the goal of reducing weed density and mitigating the spread of herbicide resistance. Concurrently, we will continue work on the remaining objectives to ensure comprehensive progress across all areas of the project.

Impacts
What was accomplished under these goals? Obj 1: Four new studies were initiated to evaluate strategies for controlling wild carrot, horsetail, quackgrass, and other problematic weed species. The primary objective is to identify approaches that reduce the cost of electrical weed control while minimizing reliance on herbicides. We are assessing the effectiveness of different application speeds, both following mowing and as a standalone treatment with electricity. These studies are being conducted off-campus in areas with naturally occurring, difficult-to-control weed infestations. Obj 2: The study, initiated in 2025, evaluates the effects of six weed management strategies on crop growth, weed populations, and production costs. Preliminary results show that treatments involving electricity or integrated weed management (electricity combined with herbicides and mowing) reduced weed densities by over 90% compared to mowing alone or untreated controls. Ongoing assessments are measuring leaf water potential to determine the impact of weed competition on crop water availability. Obj 3: This study evaluates the impact of electrical weed control on hazelnut tree performance under commercial production conditions. Key physiological and agronomic parameters, including stomatal conductance, vegetative growth, leaf nutrient content, and nut yield, have been monitored annually to assess potential stress or negative effects resulting from repeated applications of electrical weed control. After five consecutive seasons, results consistently show that electrical weed control does not negatively affect tree health, nutrient levels, or productivity. These findings provide strong evidence supporting the safety and sustainability of this technology as a non-chemical weed management tool in perennial cropping systems such as hazelnuts. Obj 4: This study was initiated in 2024; We are repeating it in 2025, but tree mortality has been an issue, likely a result of heat stress and weed competition.

Publications


    Progress 09/01/23 to 08/31/24

    Outputs
    Target Audience: Hazelnut growers Oregon Hazelnut Commission Organic producers Small fruit producers Hop growers Stone and pome fruit growers Vegetable growers Changes/Problems:The biggest challenge for 2024 was recruiting a graduate student to participate in the project. After several interviews, we selected a student who graduated in the summer of 2024 and initiated the work in September with OSU. That has delayed some advancements in Objective 1, but we plan to expand in 2025. What opportunities for training and professional development has the project provided?A PhD student is currently working on the project, and two undergraduate students assist. Multiple growers and members of the industry have seen the results of our work at two extension presentations and one field day at the Lewis Brown Research Farm. The field day event attracted the over 60 farmers. How have the results been disseminated to communities of interest?Dissemination to academic peers was done at the National Weed Science Society meeting and at the American Society of Horticultural Sciences. Dissemination to local growers was done primarily through face-to-face events. Oregon hazelnut growers are a well-defined audience, and readily attracted to outreach events. What do you plan to do during the next reporting period to accomplish the goals?We plan to expand our work in 2025 on objective 1: collect data that can be used for creating a model that predicts electricity interactions with weeds test different scenarios on how best to use electricity to reduce weed density and mitigate resistance spread. We will continue the other objectives.

    Impacts
    What was accomplished under these goals? Objective 1: Develop weed-specific recommendations for EWC. Determine the effectiveness of EWC technologies over weed species in short-term studies. We conducted two studies in 2024 in a commercial field infested with Canada thistle. The results indicated that two applications of electricity at 1.5 mph were superiror to one application of the herbicide clopyralid in reducing weed biomass, shoot number, and flower density. Objective 2: Quantify the effect of EWC on weed densities, herbicide use, and gross return under different weed management approaches. The orchard that will be used for this study was planted in 2024, and the treatments will initiated in 2025. Objective 3: Monitor the long-term effect of EWC on hazelnut growth and yield. This study was successfully conducted for one more year. We monitored stomatal conductance, growth, leaf nutrient content, and yield. We are now processing the samples to evaluate hazelnut quality. Objective 4: Develop a soil-applied EWC method to manage weeds in preemergence. This study was initiated in 2024; we planted the orchard and applied the first treatments. We are not monitoring tree growth and weed control and are preparing for additional treatments in 2025.

    Publications