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Essential oils (EOs) from lavandin are known for a large spectrum of biological properties but poorly and contrastingly documented for their activity against phytoparasitic nematodes. This study investigated the toxicity of EOs from three different lavandin cultivars, Abrialis, Rinaldi Cerioni, and Sumiens, either to juveniles (J2) and eggs of the root-knot nematode Meloidogyne incognita and to infective stages of the lesion nematode Pratylenchus vulnus. The suppressive activity of treatments with EOs from the three lavandin cultivars in soil infested by M. incognita was also investigated in a greenhouse experiment on potted tomato. The compositional profiles of tested EOs were also analyzed by GC-FID and GC-MS. Linalool was the major component of all the three EOs, as accounting for about 66%, 48%, and 40% of total EO from cv Rinaldi Cerioni, Sumiens, and Abrialis, respectively. Linalool acetate was the second most abundant compound in the EOs from cv Abrialis (18.3%) and Sumiens (14.9%), while significant amounts of camphor (11.5%) and 1,8-cineole (12.1%) were detected in cv Rinaldi Cerioni and Sumiens EOs, respectively. The mortality of M. incognita&nbsp, J2 peaked 82.0%, 95.8%, and 89.8% after a 24 h treatment with 100 mg·mL−1 solutions of cv Abrialis, Rinaldi Cerioni, and Sumiens EOs, respectively. Infective specimens of P. vulnus were largely more sensitive than M. incognita&nbsp, J2, as there were peak mortality rates of 65.5%, 67.7%, and 75.7% after 4 h of exposure to Abrialis, Rinaldi Cerioni, and Sumiens EO, respectively. All three lavandin EOs significantly affected also M. incognita egg hatchability, which reduced to 43.6% after a 48 h egg mass exposure to a 100 µg·mL−1 solution of cv Rinaldi Cerioni EO. Soil treatments with the three lavandin EOs strongly reduced, according to a dose–effect relationship, density of M. incognita eggs, and J2 both on tomato roots and in soil, as well as significantly reduced gall formation on tomato roots. Finally, almost all soil treatments with the lavandin EOs also resulted in a positive impact on tomato plant growth.

In this study, the relationship between nematicidal activity and chemical composition of ten essential oils (EOs) from different plant species was investigated both in in vitro assays on juveniles (J2) and eggs of the root-knot nematode Meloidogyne incognita and in experiments on tomato in soil infested by M. incognita. Nematode J2 were exposed for 4, 8 or 24 h to 0.78&ndash, 100 &mu, g mL&minus, 1 concentrations of each EO, whereas 24, 48 or 96 h exposures to 250, 500 and 1000 &mu, 1 solutions were tested on M. incognita egg masses. Treatments with 50, 100 or 200 &mu, g kg soil rates of each EO were applied in the experiment on potted tomato. The highest nematicidal potential resulted for the C. verum EO, as highly toxic to both M. incognitaJ2 and eggs and strongly suppressive on nematode multiplication on tomato roots. The infestation of M. incognita on tomato roots was also strongly reduced by the EOs from E. citriodora and S. aromaticum, both highly toxic to M. incognitaJ2 but less active on nematode eggs. Adversely, R. graveolens EO strongly inhibited the egg hatch but was limitedly toxic to the infective J2. Chemical composition of the EOs was determined by GC-FID and GC-MS. The ten EOs showed a very different chemical composition in terms of major phytochemicals, with one or two dominant components totally amounting up to 85%. The structure&ndash, activity relationship based on the main phytochemicals identified in the assayed EOs and their nematicidal effects on M. incognita was also discussed. Results from this study confirmed that the selection of suitable EO raw materials can lead to the formulation on new effective nematicidal products.

Previous in vitro investigation of the nematotoxic effect of Artemisia annua and its main phytochemicals have indicated that this plant can be a potential source of nematicidal products. Following this previous study, the objective of this work was to assess the nematicidal activity of soil treatments with meal and water extract from dry biomass of Artemisia annua on the root-knot nematodes Meloidogyne incognita and M. hapla and on the cyst nematode Globodera rostochiensis in experiments on potted tomato and potato, respectively. Meal was applied at 5, 10, 20 or 40 g kg −1 soil rates, whereas soil treatments with 25, 50, 100 and 250 g L −1 water solutions of the extract were applied either in a single application or splitted into four treatments. Gall formation and multiplication of both M. incognita and M. hapla on tomato roots were significantly reduced by all soil treatments with A. annua meals. Both single and splitted application of A. annua water extract effectively reduced M. incognita population on tomato roots and in the soil. In the experiment on potato, almost all rates of A. annua meal and extract significantly reduced soil population density of G. rostochiensis , without any statistical difference among the two applications. The nematicidal activity of A. annua products on root-knot nematodes resulted not statistically different or even higher than that of the nematicide fenamiphos. A significant increase of growth was always recorded on tomato and potato plants as a side effect of treatments with meal or water extract. Data from these experiments seem to indicate that products from A. annua can be potential candidates for the formulation of new nematicides suitable for a sustainable nematode management, though field trials are still needed for an effective demonstration of a commercial exploitation.

This study was aimed to investigate the activity of the Asteraceae species Taraxacum officinale against the root-knot nematode Meloidogyne incognita. Leaf and root extracts of T. officinale were tested in vitro at a range of 62.5-1000 and 250-1000 ?g mL-1 concentrations on nematode juveniles and eggs, respectively, whereas treatments with 10-40 g kg-1 soil rates of dry leaf and root T. officinale biomass were applied to soil infested by M. incognita in greenhouse experiments on potted tomato. Peak 36 and 50% juvenile mortality and 14.8 and 23.8% egg hatchability reduction were recorded at the maximum concentration of leaf and root extracts, respectively. Soil treatments with T. officinale leaf and root material strongly suppressed nematode multiplication and gall formation on tomato roots and significantly increased plant growth. Chicoric acid and 3-O- and 3,5-di-O-caffeoylquinic acid were found to be the main components of leaf and root extract, respectively, and proved, as the total hydroalcoholic extracts from T. officinale leaf and root material, for an antioxidant activity. Data from this study indicate the suitability of plant materials from T. officinale for a potential formulation of nematicidal products to include in sustainable nematode management strategies.

Nematotoxic effect of an aqueous extract of Artemisia annua and its components caffeic acid, chlorogenic acid (5-caffeoylquinic acid, 5-CQA), artemisinin and the related semi-synthetic artesunate, was investigated on the root-knot nematode Meloidogyne incognita and the potato cyst nematode Globodera rostochiensis and on the virus-vector dagger nematode Xiphinema index. Juveniles of M. incognita and G. rostochiensis and females of X. index were exposed to 500, 250 and 125 mu l ml-1 solutions of the A. annua aqueous extract, caffeic acid, chlorogenic acid and artesunate and to 50 mu l ml-1 solution of artemisinin for 2, 4, 8 and 24 h. Egg masses of M. incognita and cysts of G. rostochiensis were exposed for 24, 48, 96 h and 1 or 2 weeks only to the extract solutions. Aqueous extract was highly effective on G. rostochiensis juveniles, whereas M. incognita juveniles were affected only at long exposure times. Adversely, egg hatch inhibition was strong on M. incognita and poor or minimal on G. rostochiensis. Females of X. index were sensitive only to long exposures to the highest extract concentration. Both caffeic and chlorogenic acid did not affect juveniles of M. incognita but were highly active on G. rostochiensis juveniles and X. index females even at the lowest concentration. Artesunate toxicity was almost zero on M. incognita and low on X. index females, but high on G. rostochiensis juveniles. Artemisinin solution was lethal to more than 50 % of G. rostochiensis juveniles within 24 h, but did not affect M. incognita juveniles and X. index females. Results suggest different roles of the tested compounds in the biocidal activity on each target nematode species. The extract of A. annua and its main phytochemicals seem to have a potential to be developed into new nematicidal formulates, though their activity should be validated in the soil.