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Which methods best limit Fusarium wilt in greenhouse cucumbers?
In five greenhouses at a Jordanian seed station where about 80% of cucumber plants had shown Fusarium wilt symptoms the season before, cucumbers grafted onto a resistant rootstock, or planted into fumigated soil, lost far fewer plants over 12 weeks than untreated rows. Deep tillage and the farm's fungicide program sat in between.
Fusarium wilt is a soil-borne disease, and once it is in a greenhouse it is hard to shift. A University of Jordan team set out to identify which Fusarium was killing greenhouse cucumbers across the country, then compared five ways of managing it, against an untreated control, under commercial greenhouse conditions in Madaba (Annuka et al., 2026).
What this means for your grow
In this trial, the two strongest options were grafting cucumbers onto Shintoza Prime rootstock and fumigating the soil with metam potassium before planting: by week 12 they had lost 3.68% and 1.12% of plants, against 43.04% in untreated rows. Both have costs the authors point out: fumigation cost about $120 per greenhouse in Jordan (the paper does not name the currency) and leaves the greenhouse empty for about 20 days, and grafting is costly and needs about 30 days in the nursery. This was one site in one season, in soil, so the authors say more trials across locations and seasons are needed before broad recommendations are made. If you grow cucumbers in soil where Fusarium wilt keeps coming back, it is a reminder that grafting onto a resistant rootstock is one of the tools worth looking into.
What did the team do?
First, they went looking for the culprit. Between 3 February and 2 October 2024 they collected 165 cucumber plants with Fusarium-type symptoms from the main growing governorates of Jordan (Amman, Mafraq, Irbid and Madaba). All of them came from greenhouse cucumbers. They grew the fungus from the plants in the lab, identified it with DNA sequencing, and sorted the Fusarium oxysporum isolates into pathogenic groups with group-specific PCR tests. In three experiments in a controlled-environment room, they then infected cucumber seedlings, and other cucurbits, with selected isolates to see which ones caused disease.
Then came the management trial, at Al-Jinan Seeds Station in Madaba, where Fusarium wilt of cucumber is common. Five greenhouses were used as blocks. In the season before, about 80% of the cucumber plants in them had shown Fusarium wilt symptoms by the end of the season. Each greenhouse had six rows, one for each treatment:
- deep tillage, to about 1.0 to 1.2 m, about a month before planting
- conventional tillage, to about 20 cm
- grafting onto Shintoza Prime, a cucurbit rootstock
- an untreated control
- the farm's usual program of soil-applied fungicides, given through the irrigation system
- soil fumigation with metam potassium, 20 days before planting
The cucumber cultivar was Global F1, which had shown Fusarium wilt symptoms on several farms and was considered susceptible locally. Seedlings went in on 25 July 2024, with 125 plants per treatment row, and the team counted dead plants and measured height every two weeks for 12 weeks.
What did they find?
- The cause: of the 50 isolates that gave usable DNA sequences, 46 were Fusarium oxysporum. Pathogenic groups 1, 3 and 4 were found, and group 1 was the most common.
- The worst group: group 1 caused the most cucumber deaths in all three inoculation experiments, killing 68.8%, 81.3% and 66.7% of plants.
- Other cucurbits: the group 1 isolate caused no deaths in squash or melon. Some watermelons died in the second experiment, but as many or more died in the uninfected control, so the authors did not put those deaths down to the fungus.
- The management trial: cumulative mortality at 12 weeks was 43.04% in the untreated rows, 34.24% with conventional tillage, 16.80% with deep tillage, 9.92% with the fungicide program, 3.68% with grafting and 1.12% with fumigation.
- What counted statistically: grafting and fumigation were not significantly different from each other, or from the fungicide program. The untreated control and conventional tillage were not significantly different from each other.
- Plant height: grafted plants averaged 350.2 cm, fumigated plants 348.2 cm and the fungicide program 337.6 cm, against 303.2 cm, 294.8 cm and 280.0 cm for conventional tillage, deep tillage and the untreated control.
What could it mean?
The authors conclude that, under the conditions of this on-farm trial, soil fumigation with metam potassium and grafting onto Shintoza Prime rootstock gave the strongest suppression of disease-associated deaths, with deep tillage and the fungicide program in between. They say no single approach should be assumed to give control everywhere, and that cost, crop rotation, soil health, pesticide stewardship and local disease pressure all matter when choosing. The fungicide program was the farm's existing mix of products, so the authors warn it should not be read as a test of any one fungicide against Fusarium. The trial was run under commercial greenhouse conditions in Jordan; it was not a test of what works in a home garden.
What were the limitations?
The management trial was one site in one season, and the authors call for more trials over more locations and seasons. Some grafted plants died in the first two weeks, which the authors think was probably graft union failure or early sensitivity, and aphids were drawn to the grafted plants. Deep tillage left the soil poorer in nutrients, which the authors say weakened the plants. Of the 165 plants collected, 96 cultures were kept (some were lost to contamination, including mites in the incubator), and only 50 gave usable DNA sequences. Twenty-five F. oxysporum isolates did not fit any of the pathogenic groups tested. The discussion says grafted plants gave higher yields than non-grafted plants, but the paper reports no yield figures. The rootstock is called Shintoza supreme in the treatment table and Shintoza Prime elsewhere in the methods and results; this post uses Shintoza Prime.
Trial details
- Where: survey samples from 50 fields in Amman, Mafraq, Irbid and Madaba governorates, Jordan, all from greenhouse cucumbers, processed at the Plant Pathology Laboratory, School of Agriculture, The University of Jordan. Inoculation experiments in a controlled-environment room. Management trial at Al-Jinan Seeds Station, Madaba, near King's Academy, in five greenhouses.
- Who: Department of Plant Protection, School of Agriculture, The University of Jordan, Amman.
- Crop: cucumber (Cucumis sativus), cultivar Global F1 in the management trial; grafted plants on Shintoza Prime cucurbit rootstock. Inoculation experiments also used squash, watermelon, grafted watermelon and melon.
- How long: survey from 3 February to 2 October 2024. Management trial: sown in a nursery on 5 July 2024 (grafted plants sown 50 days before transplanting), transplanted on 25 July 2024, followed for 12 weeks. The second inoculation experiment ran for about seven weeks.
- System: greenhouse soil. Fumigation with metam potassium at about 10 L per treatment row, 20 days before planting. The fungicide program, applied through the irrigation system, was hymexazol 30% (week 1), azoxystrobin 32.2% plus metalaxyl-M 12.5% (week 2), Fostyl-Aluminium 80% (week 4; the paper's spelling), cyazofamid 40% (week 6), captan 80% (week 8) and hymexazol plus Fostyl-Aluminium (week 10). All rows got the same irrigation, fertiliser and routine applications, including algae-based products, plus fluopyram twice and oxamyl once as preventive nematode control, although the site had no record of nematodes. The third inoculation experiment used sterilised peat moss.
- Lighting and climate: the controlled-environment room ran at 26 °C with 12 hours of light and 12 hours of dark.
- Design: survey of 165 symptomatic plants; 96 cultures kept; DNA sequencing (RPB2) of 96 isolates, 50 usable; pathogenic-group PCR on the 96 isolates. Inoculation experiments with 16 plants per treatment (first and second) and 24 per main treatment (third), each with uninoculated controls. Management trial: randomised complete block design, six treatments, five greenhouse blocks, 125 plants per treatment row, deaths and height recorded at 2, 4, 6, 8, 10 and 12 weeks; ANOVA with Tukey's HSD at P ≤ 0.05.
- Results: cumulative mortality at 12 weeks (mean ± SE): untreated 43.04 ± 4.00%, conventional tillage 34.24 ± 5.40%, deep tillage 16.80 ± 1.66%, fungicides 9.92 ± 2.61%, Shintoza Prime 3.68 ± 0.78%, fumigant 1.12 ± 0.32%. Plant height: 280.0, 303.2, 294.8, 337.6, 350.2 and 348.2 cm in the same order. Treatment effects P < 0.0001 for every end-of-season measure.
- Funding and conflicts: the Deanship of Scientific Research, The University of Jordan (grants 1121 and 2281). The acknowledgements thank Eng. Ibrahim Annuka for funding the field experiment at the Jinan Agricultural Company station. The authors declare no commercial or financial conflicts of interest.
- Publication: Frontiers in Agronomy 8:1961835, published 4 November 2026, https://doi.org/10.3389/fagro.2026.1961835. Licence: CC BY 4.0.
- Not reported in the paper: greenhouse temperature, humidity and lighting during the management trial, soil type, fertiliser rates and yield.
Links
References
- Annuka, M. I., Alananbeh, K. M., & Al-Amir, F. M. (2026). Survey, characterization, host specificity and evaluation of some control methods of Fusarium species associated with wilt disease on cucumber in Jordan. Frontiers in Agronomy, 8, 1961835. https://doi.org/10.3389/fagro.2026.1961835