Final report for LNE22-449R
Project Information
This project evaluated foliar nickel (Ni) application, using nickel sulfate (NiSO₄·6H₂O), as a micronutrient amendment with potential supplementary fungal‑control benefits for cranberry production. Previous research demonstrated that nickel nutrition can enhance urea nitrogen utilization, improve yield, reduce heat stress, and contribute to suppression of leaf and fruit rot in several crop systems. The project hypothesized that supplemental Ni could similarly improve cranberry productivity while reducing fungal‑control resistance pressures.
Project objectives included assessing Ni phytotoxicity, evaluating Ni’s role in suppressing leaf blight and fruit rot, quantifying its effects on crop nutrition and abiotic stress tolerance, and developing best‑practice recommendations for growers. Greenhouse and field trials were conducted to measure cranberry growth response, nickel uptake, and disease outcomes. Potted cranberry plants grown in sand–peat media were used to evaluate controlled nutrient uptake and phytotoxic thresholds, followed by field trials that examined fruit rot incidence and overall plant performance under commercial bog conditions. Leaf‑blight fungal species were isolated and cultivated to perform inoculation studies assessing whether Ni‑treated plants exhibited reduced susceptibility.
Cranberry growers in the Northeast Atlantic region, representing roughly 40% of U.S. cranberry acreage, have faced increasing heat stress and rising fungicide demand. Based on conservative projections from similar nickel studies, potential yield gains of 0–5%, up to 10% reductions in post‑harvest fruit rot, and modest (<10%) reductions in fungicide use were anticipated.
Preliminary soil and tissue analyses from New Jersey cranberry bogs showed low natural Ni availability and low plant Ni levels. Early phytotoxicity trials indicated that low‑dose foliar Ni improved plant size and leaf coloration without causing visible toxicity, suggesting potential agronomic benefit. Engagement with growers and collaboration with the Marucci Cranberry and Blueberry Research Center informed treatment design, field implementation, and interpretation of results.
Pot trials showed that cranberry exhibited toxicity responses to nickel similar to other crops, with reduced growth and chlorosis occurring at doses above ~100 mg Ni per plant. In greenhouse experiments, foliar applications resulted in lower nickel intake than soil applications, as seen in the milder toxicity response. Field trials demonstrated that foliar Ni applied at rates up to 20 lb Ni per acre did not increase yield or reduce fruit rot. These findings indicated that Ni alone was insufficient for fruit‑rot control and functioned more effectively as a supplemental rather than primary intervention. Limited plant uptake in bog settings suggested that applied Ni may have been rapidly leached due to irrigation, rainfall, and acidic soil conditions (pH 4.5–5).
In conclusion, while Ni has strong physiological effects in many crops, its impact on cranberry under bog conditions was limited. Future research exploring surfactant‑enhanced foliar delivery or slow‑release soil formulations may improve Ni uptake and strengthen its potential benefits for cranberry production.
1. Conducted research will evaluate foliar nickel application for cranberry, including:
a. assessment of nickel phytotoxicity, and practices for minimizing environmental impact.
b. foliar nickel contribution to leaf and fruit pathogen suppression for supplementary fungal.
c. crop nutrition: improved urea nitrogen conversion by plants, increased yield, and abiotic stress tolerance.
2. Best practice to apply nickel for increased crop yield and reducing fungicide applications.
3. Novel approach: adopting foliar nickel as part of a nutrition management plan. Incorporating foliar nickel application
by cranberry growers using best management plan recommendations from this research and be supported by outreach
activities.
Cooperators
Research
Scope:
Cranberry plants from two varieties—Mullica Queen and Crimson Queen—were evaluated for their response to nickel (Ni). The study determined the Ni phytotoxicity threshold, assessed how competing cation transport affected Ni intake, and examined the effect of Ni application on leaf rot and fruit rot development.
Plants:
Cranberries were grown from transplants in 2×2‑inch pots under controlled greenhouse conditions during the 2022 growing season (May–October), and were then transferred outdoors to allow natural dormancy. Field trials were conducted at the Rutgers cranberry research bogs, where 5×5‑foot plots with 1‑foot buffer hems were flagged within established 2–3‑year‑old bogs.
Nickel Delivery:
Nickel was applied either as the commercially available Nickel Plus (5–0–0; 5.7% Ni) or as nickel sulfate (NiSO₄·6H₂O), with application rates ranging from 0–500 mg Ni per plant. Delivery methods included soil application and foliar spraying. To evaluate synergistic interactions between Ni uptake and competing cations, nickel was applied in 1:0, 1:1, and 1:3 mg plant⁻¹ ratios with zinc and iron.
Plant Response:
Plant response to nickel was evaluated qualitatively using visual indices for leaf color (1–10), dead leaf percentage (0–100%), and overall growth rating (1–10). Quantitative assessments included leaf chlorophyll measurements using a SPAD 502 meter (Spectrum Technologies) and canopy normalized difference vegetation index (NDVI) readings using a CM1000 instrument (Spectrum Technologies).
Nickel Accumulation:
Cranberry leaf and fruit samples were analyzed for major and trace elements. Dried samples were digested using nitric and hydrochloric acids (HNO₃, HCl) and analyzed via inductively coupled plasma spectroscopy (ICP‑OES/MS).
Leaf and Fruit Rot:
The effects of Ni on leaf and fruit rot were evaluated by comparing infection severity between Ni‑free controls and Ni‑treated plants. Leaf rot was assessed in greenhouse trials, where potted plants were inoculated with locally collected rot strains whose taxonomy had been confirmed using RNA‑based PCR. Following inoculation, leaf rot progression was monitored and recorded.
Fruit rot evaluation was conducted exclusively in field plots due to its complexity. A representative 1×1‑foot subplot was marked in each bog plot near harvest (September–October), and fruit were harvested and sorted to determine rot incidence. Additional multispectral imaging analyses were used to quantify fruit coverage and assess disease development in harvested samples.
Ongoing research work throughout the first year of nickel trials evaluated the delivery of nickel (foliar/soil application), the effect of competing cations, and toxicity response in preliminary greenhouse and field cranberry bog trials. The cranberry varieties selected for trial were crimson queen (CQ) and mullica queen (MQ), which were transplanted into 2x2 pots for greenhouse trials and grown in experimental research bogs for field trials at The Philip E. Marucci Center for Blueberry and Cranberry Research and Extension (Chatsworth, NJ).
a. cranberry model plant trials in a controlled environment greenhouse:
2022 Season:
Results from the mixed urea-Ni application (Nickel plus, NIPAN) to potted cranberry plants in the greenhouse are outlined in Figure 1. Cranberry plants from both varieties (CQ, MQ) showed high sensitivity to soil urea application resulting in burnout of all plants. In contrast, foliar urea application resulted in more vegetative growth than plants that did not receive foliar urea, with multiple new shoots observed for each growth stem. While results for urea application did not show a significant difference between Ni-urea and urea treatment, the finding regarding the foliar urea response and the sensitivity to soil urea application is of interest for further study in the following season. Comparison of chlorophyll content (SPAD) and growth index values (growth, color, dead leaf) showed no significant difference between varieties (MQ, CQ) and nickel application rate (0-20 mg). This is in contrast to the expected results since 20 mg nickel plant-1 is the suggested application rate for small vegetable and fruit plants. one possible reason for the lack of nickel response is the nickel loss through leaching in the model plants. A revised model plant setting will address this issue by modifying the growth system setting to limit wash-off with drip irrigation and collect leachate from selected pots for mass balance of nutrient.
Experiments on the role of competing cations in nickel intake were evaluated using chlorophyll content (SPAD) and growth evaluation (growth, color, dead leaf), as shown in Figure 2. The result showed limited growth response to treatments, with similar color, size, and chlorophyll content between varieties and competing cations application rates. A repeat application to plants will apply higher nutrient rates and re-evaluate the growth response.
An additional study looks into Ni toxicity response applied 0-100 mg Ni plant-1 as NiSO4 (aq) (Figure 3). Results show that higher Ni application rates (40, 100 g) for both cranberry varieties (CQ, MQ) had the least successful growth average, but results were not significantly different between 5-100 mg Ni. Additional studies will evaluate Ni toxicity under an improved model plant irrigation system, as mentioned above. The average MQ variety growth was slightly improved compared to CQ when Ni was applied to the soil. A reverse trend was observed for the foliar application Ni where the CQ variety grew better. However, the results were fairly similar, with most growth parameters not significantly different. A follow-up study will re-apply Ni at 0-1000 mg plant-1 under an improved model plant setting with drip irrigation to prevent leaching off Ni.
2023 Season
Following the 2022 season result that showed no variety effect on Ni, the application trial continued using a single variety. Trays of "Haines" cranberry pugs were obtained from a local supplier and transplanted in 2-inch x 2-inch pots. Cranberry was treated with Ni only or with competing Zn, Fe, delivered by soil or foliar application. Following Ni application, plants were grouped in randomized treatment blocks, placed in 11-inch x 11-inch x 1.5-inch trays, and irrigation was done via roots only to prevent washoff of treatments.
Results from Ni application (Figure 4) established the phytotoxicity levels of Ni to young cranberry plants at 100-500 mg/plant and 50-100 mg/plant for toxicity response. Competition of other Me2+ Cataions Zn and Fe had little effect on plants' physiological response (Figure 5).
At the end of the growth season, plants were winterized in the nonheated greenhouse for continued trials in the following 2024 season.
b. Field trials at cranberry bogs.
2023 season
Foliar Nickel (as NiSO4) was applied to cranberry bog plots (5 ft x 5 ft, with 2 ft borders, n=10; N=60) at 0-25 lb/acre spraying rates. Bog plots were sprayed mid-June 2023, and fruit was collected by late Aug 2023 for fruit rot analysis. Growth observation and NDVI chlorophyll imaging did not show treatment effect or damage to treated plots from applied Ni (Figure 6). Evaluation of Fruit rot showed that increasing Ni application slightly decreased fruit rot from 40±34% to 25±16% (Figure 7). The work plan for the 2024 season intends to evaluate the long-term effect of the Ni application following the foliar application.
2024 season
The experiment in established research plots continued for a second season, and foliar nickel was re-applied to half of the replicates ( N=5). Following the application, samples were periodically evaluated for color index, and fruit leaf and soil samples were collected at the conclusion of the growing season.
In addition, a new study of cranberry plots trial was established, treated with 0-10 lb/acre (n=6) of foliar Ni delivered in three applications over the duration of the growing season. These plots were evaluated for color index and yield in a similar manner to the two-season experiment that was described in detail. Evaluation of foliar nickel effect on fruit rot (Figure 8), yield (Figure 9), fruit size (Figure 10), and color index (Figure 11) shows limited effect of Ni application.
The application of nickel in the form of nickel sulfate (NiSO₄) demonstrated limited to no measurable effect on cranberry yield or plant disease suppression across both potted‑plant experiments and field‑scale bog trials. Elevated nickel doses in potted systems—exceeding 100 mg Ni per plant—caused clear toxicity symptoms and increased plant mortality. In contrast, even substantially higher soil application rates in field settings (exceeding 5 lb Ni per acre) did not produce comparable mortality, indicating that nickel is less toxic under commercial bog hydrological conditions.
The contrasting outcomes between the potted and field systems appear to result primarily from differences in water movement and nickel mobility. Potted cranberries placed in deep trays experienced reduced drainage and prolonged exposure to elevated nickel concentrations, amplifying toxic effects. In production bogs, however, rapid water exchange, frequent washing and flood cycles, and the naturally elevated water table likely facilitated dilution and leaching of applied nickel, thereby reducing both toxicity and treatment efficacy.
Despite the known antimicrobial properties of nickel, foliar applications ranging from 0–20 lb Ni per acre did not reduce fruit rot incidence in field trials. This outcome suggests that nickel uptake and residence time were insufficient under field conditions. Tissue analyses corroborated this finding, indicating minimal nickel accumulation in plant tissues. These results point to the need for reconsidering surfactants, delivery methods, and formulation strategies if foliar nickel treatments are to be effective. Another contributing factor may be the thick cranberry leaf cuticle, which likely restricts foliar penetration and promotes rain‑ and irrigation‑induced nickel wash‑off.
Finally, the sandy, low–cation‑exchange‑capacity soils typical of cranberry bogs, combined with their acidic pH (4.0–5.5), create conditions that promote high nickel leaching. This further limits the persistence and agronomic impact of nickel sulfate under field conditions.
Overall, while potted trials indicate potential phytotoxicity at high localized nickel concentrations, field results demonstrate that the hydrological and soil characteristics of cranberry bogs significantly reduce both the risks and the potential benefits of nickel sulfate applications.
Education & outreach activities and participation summary
Educational activities:
Participation summary:
- Newsletter: https://njaes.rutgers.edu/soil-profile/pdfs/sp-v27.pdf
- Presentation for fruit growers about Nickel Nutrition: Mineral Nutrition and Plant Health. New Jersey Agricultural Convention and Trade Show. 40 participants. Feb 2024
- Mineral Nutrition and Plant Health, Northeast Regional Committee on Soil Testing. Milford, PA. 20 participants. October 2023
- Mineral Nutrition and Plant Health, Mid-Atlantic Soil Test & Plant Analysis Work Group. Raleigh, NC. 50 participants. October 2023
- Urea Nitrogen Fertilizer and Nickel Nutrition for Orchard Health. South Jersey Tree Fruit Twilight Meeting, Clayton, NJ. 30 participants. June 2023
- Nickel Plant Nutrition. Northeast Regional Committee on Soil Testing. Milford, PA. 20 participants. October 2022
- Mineral, Plant, Animal, and Human Connections to Soil Health. Rutgers NJAES Soil Health Initiative. Cook Campus. 40 participants. March 2022
Learning Outcomes
Based on research experience with Nickel nutrition of cranberry, Rutgers Cooperative Extension is examining the need for this micronutrient in a wide range of horticultural crops grown across New Jersey. Thus, although this SARE project focuses on cranberry, we expect the findings to have broader implications for many horticultural and agronomic crops.
Project Outcomes
Northeast Soil Test Working Group held October 2022 meeting in Milford, PA. At that meeting Heckman and Rabinovich presented an overview of the SARE-funded Nickel Nutrition Project, and discussed the potential implications for university soil test laboratories to have a role in nickel plant and soil analysis. At this meeting, this SARE project was acknowledged.
Grower's interest in this project is evident by the invitation to speak about Nickel Nutrition Research at New Jersey Fruit Grower meeting March 2023. At this meeting, there will be an acknowledgment of the connection to this SARE project.