Abstract
BACKGROUND: Organic vegetable growers face significant challenges in managing plant-parasitic nematodes, particularly root-knot nematodes (RKN; Meloidogyne spp.), because of restrictions on the use of synthetic chemicals. This study evaluated the efficacy of seven commercially available Organic Materials Review Institute-certified bionematicides against Meloidogyne incognita under greenhouse and field conditions. A cucumber plasticulture field study was also conducted to compare the efficacy of four best-performing bionematicides, including azadirachtin, cold-pressed neem oil, thyme oil and saponins of Quillaja saponaria, identified in the greenhouse study and a chemical nematicde (oxamyl) using two application regimes: calendar-based (following the product label) and nematode life-cycle-based (following the M. incognita life cycle using degree-days assessment). RESULTS: In the greenhouse study with tomato, azadirachtin and thyme oil significantly reduced M. incognita root galling and reproduction factor (final nematode population/initial nematode population) compared with a positive control. In the field trial with cucumber, the nematode life cycle was completed in 23 days during the spring season and 24 days during the fall season, accumulating 380 and 398 degree-days, respectively, above a base temperature of 10 °C. For calendar-based applications, only azadirachtin significantly reduced nematode density, whereas for life-cycle-based applications, all treatments except saponins of Q. saponaria were effective. Oxamyl was more effective when applied according to the nematode life cycle than on a calendar-based regime. Life-cycle-based applications generally outperformed calendar-based applications based on numerical values, even in cases in which the differences were not significant. For the galling index, calendar-based applications of azadirachtin and cold-pressed neem oil reduced the galling index more than life-cycle-based applications at mid-season. At the end of the season, only azadirachtin under the calendar-based application differed significantly from the control, while all other treatments (except saponins of Q. saponaria) had lower root galling indices than the calendar-based applications. CONCLUSION: These findings indicate that both application regimes can be used to manage M. incognita in organic farming systems. Of particular significance is the novel life-cycle-based approach developed in this study, which may confer enhanced sustainability benefits by optimizing nematicide application timing and reducing treatment frequency, ultimately leading to a decline in soil nematode population densities. © 2025 Society of Chemical Industry.
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Claims 12
Claim · model-written summary
Azadirachtin reduced tomato root galling and nematode reproduction factor in the greenhouse.
- Taxon
- tomato
Solanum lycopersicume0 - Treatment
- azadirachtine0
- Interactor
- M. incognita
_penetrates_a_tomato_root_-_USDA-ARS.jpg?width=60)
Meloidogyne incognitae0pathogen - Outcome
- M. incognita root galling and reproduction factore0
- Direction
- reducede0
- Comparator
- positive controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_penetrates_a_tomato_root_-_USDA-ARS.jpg?width=500)
Verbatim
e0“In the greenhouse study with tomato, azadirachtin and thyme oil significantly reduced M. incognita root galling and reproduction factor (final nematode population/initial nematode population) compared with a positive control”
Claim · model-written summary
Thyme oil reduced tomato root galling and nematode reproduction factor in the greenhouse.
- Taxon
- tomatoSolanum lycopersicume0
- Treatment
- thyme oile0
- Interactor
- M. incognitaMeloidogyne incognitae0pathogen
- Outcome
- M. incognita root galling and reproduction factore0
- Direction
- reducede0
- Comparator
- positive controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the greenhouse study with tomato, azadirachtin and thyme oil significantly reduced M. incognita root galling and reproduction factor (final nematode population/initial nematode population) compared with a positive control”
Claim · model-written summary
The cucumber-field nematode life cycle lasted 23 days and accumulated 380 degree-days in spring.
- Taxon
- cucumber
Cucumis sativuse7 - Outcome
- nematode life cyclee0
- Value
- 23 dayse0
- Qualifier
- 380e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the nematode life cycle was completed in 23 days during the spring season and 24 days during the fall season, accumulating 380 and 398 degree-days, respectively, above a base temperature of 10 °C”
e7“A cucumber plasticulture field study”
Claim · model-written summary
The cucumber-field nematode life cycle lasted 24 days and accumulated 398 degree-days in fall.
- Taxon
- cucumberCucumis sativuse7
- Outcome
- nematode life cyclee0
- Value
- 24 dayse0
- Qualifier
- 398 degree-dayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the nematode life cycle was completed in 23 days during the spring season and 24 days during the fall season, accumulating 380 and 398 degree-days, respectively, above a base temperature of 10 °C”
e7“A cucumber plasticulture field study”
Claim · model-written summary
Only calendar-applied azadirachtin significantly reduced cucumber-field nematode density.
- Taxon
- cucumberCucumis sativuse7
- Treatment
- azadirachtine0
- Outcome
- nematode densitye0
- Direction
- reducede0
- Qualifier
- calendar-based applicationse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For calendar-based applications, only azadirachtin significantly reduced nematode density”
e7“A cucumber plasticulture field study”
Claim · model-written summary
Life-cycle applications were effective for all treatments other than Quillaja saponaria saponins.
- Taxon
- cucumberCucumis sativuse7
- Treatment
- life-cycle-based applicationse0
- Outcome
- effectivee0
- Qualifier
- except saponins of Q. saponariae0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for life-cycle-based applications, all treatments except saponins of Q. saponaria were effective”
e7“A cucumber plasticulture field study”
Claim · model-written summary
Oxamyl worked better with life-cycle timing than calendar timing.
- Taxon
- cucumberCucumis sativuse7
- Treatment
- Oxamyle0
- Outcome
- more effectivee0
- Direction
- more effectivee0
- Comparator
- calendar-based regimee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxamyl was more effective when applied according to the nematode life cycle than on a calendar-based regime”
e7“A cucumber plasticulture field study”
Claim · model-written summary
Life-cycle applications generally numerically outperformed calendar applications, though some differences were not significant.
- Taxon
- cucumberCucumis sativuse7
- Treatment
- Life-cycle-based applicationse0
- Outcome
- outperformede0
- Direction
- outperformede0
- Comparator
- calendar-based applicationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Life-cycle-based applications generally outperformed calendar-based applications based on numerical values, even in cases in which the differences were not significant”
e7“A cucumber plasticulture field study”
Claim · model-written summary
At mid-season calendar-applied azadirachtin reduced galling index more than life-cycle application.
- Taxon
- cucumberCucumis sativuse7
- Treatment
- azadirachtine0
- Outcome
- galling indexe0
- Direction
- reducede0
- Comparator
- life-cycle-based applicationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“calendar-based applications of azadirachtin and cold-pressed neem oil reduced the galling index more than life-cycle-based applications at mid-season”
e7“A cucumber plasticulture field study”
Claim · model-written summary
At mid-season calendar-applied neem oil reduced galling index more than life-cycle application.
- Taxon
- cucumberCucumis sativuse7
- Treatment
- cold-pressed neem oile0
- Outcome
- galling indexe0
- Direction
- reducede0
- Comparator
- life-cycle-based applicationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“calendar-based applications of azadirachtin and cold-pressed neem oil reduced the galling index more than life-cycle-based applications at mid-season”
e7“A cucumber plasticulture field study”
Claim · model-written summary
At season end only calendar-applied azadirachtin differed significantly from control.
- Taxon
- cucumberCucumis sativuse7
- Treatment
- azadirachtine0
- Outcome
- differed significantlye0
- Comparator
- controle0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“only azadirachtin under the calendar-based application differed significantly from the control”
e7“A cucumber plasticulture field study”
Claim · model-written summary
At season end other treatments except Quillaja saponaria saponins had lower galling indices than calendar applications.
- Taxon
- cucumberCucumis sativuse7
- Treatment
- all other treatmentse0
- Outcome
- root galling indicese0
- Direction
- lowere0
- Comparator
- calendar-based applicationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“all other treatments (except saponins of Q. saponaria) had lower root galling indices than the calendar-based applications”
e7“A cucumber plasticulture field study”
The same questions in other papers
azadirachtin · pest · Cucumis sativus (cucumber)Results agree
1 paper in the same direction as this paper
- positive
cold · pest · Cucumis sativus (cucumber)Positive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- negative
- negative
- positive
botanical · pest · Cucumis sativus (cucumber)Positive and negative results
17 papers in the same direction as this paper · 1 reporting no difference from an alternative
- positive
- no effect
- positive
15 papers more in this group
See all 19 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.