Research Project: Advancing Weed Control Solutions in Cranberry

Location: Horticultural Crops Production and Genetic Improvement Research Unit

Project Number: 2072-30500-001-026-A
Project Type: Cooperative Agreement

Start Date: Sep 1, 2026
End Date: Dec 31, 2029

Objective:
Objective 1. Develop chemical management tools and recommendations for controlling perennial weeds, such as slough sedge and three-squared rush, while supporting the registration of new active ingredients. • Conduct greenhouse and field research to identify herbicides and application strategies that effectively control the most problematic perennial weeds in cranberry systems. • Evaluate how different herbicide chemistries, application timings, and treatment combinations affect weed suppression, crop safety, and cranberry growth and yield. • Integrate greenhouse findings with field trials to generate practical recommendations that align with cranberry phenology and grower management windows. Objective 2. Evaluate and integrate spot treatment methods with electrical weed control to manage perennial weeds in cranberry cultivation. • Test the performance of electric weed control (EWC) technologies under commercial cranberry field conditions. • Compare EWC efficacy and crop impacts to conventional spot treatment methods such as glyphosate wick wiping, including single and sequential applications. • Evaluate the feasibility, consistency, and crop safety of EWC over multiple years and locations to determine whether it can serve as a reliable, commercially viable weed management option. Objective 3. Quantify the economic and operational costs of proposed weed control methods through development of economic return-on-investment. • Compare the costs and operational requirements of herbicide based treatments and electric weed control. • Quantify labor, equipment, material, and fuel inputs to estimate per acre treatment costs. • Calculate economic return on investment by linking treatment costs to differences in cranberry yield and market value. • Use economic metrics to determine which weed management strategies are most cost effective and under what conditions they offer the greatest benefit to growers.

Approach:
Objective 1: Cooperator will develop recommendations for postemergence control of these weeds in greenhouse and field studies. Greenhouse studies: seeds of these weed species were collected from cranberry bogs in 2025, and will be germinated in the greenhouse, with individual seedlings transplanted to 2L pots. Plants will be treated with a variety of registered or unregistered herbicides. Each herbicide will be applied at the highest label rate allowed; selected treatment combinations will be included. Plants will be treated at the 5 to 8 inches height (vegetative growth) and pre-flowering stage. These phenological stages roughly coincide with cranberry phenology and opportunities for treatment in the field. Visual estimate of weed control, weed height, seed production, above ground biomass, and regrowth will be assessed. Experiments will be conducted at the Cooperator greenhouses in Corvallis. The experiment will be a random complete block design with six replicates and will be repeated in time. Each species will be treated as an independent experiment. Field studies will also be conducted. Objective 2: Efficacy and crop tolerance of electric weed control (EWC) by hand-held applicator will be evaluated in two field experiments conducted in commercial cranberry fields in Oregon. Electricity will be generated by an Cooperator-owned commercial EWC unit. EWC systems generate a high-voltage current applied directly to the target plant via foliage contact and conducted downward through the roots. As the current passes through the plant, electrical resistance generates heat. Cellular water vaporizes, the cell membrane ruptures and plant death ensues1, 2. The performance of EWC will be compared to spot wick-wiping of glyphosate. We will also evaluate the two applications of EWC, glyphosate-wiping or EWC followed by glyphosate. The experimental design will be a randomized block design with four replicates. The experiment will be conducted for two years at the exact locations. We plan to perform the study at two locations. Objective 3: A partial cost analysis of EWC versus herbicide spot treatment will record cost of material, equipment, and fuel use on a per-acre basis. We will record operation efficiency (hours/acre)3. Economic return on investment (EROI) will be calculated using the equation EROI = [treated yield-nontreated yield] * [cranberry price– cost of treatment]. EROI will be applied to all treatments.