Polysulfides Applied as Formulated Garlic Extract to Protect Tomato Plants against the Root-Knot Nematode Meloidogyne incognita

Abstract

The devastating root-knot nematode Meloidogyne incognita can cause severe damage to field and greenhouse crops. Due to high economic losses, alternative products are essential to replace banned or strictly regulated nematicides that affect human health and/or the environment. Garlic based products have been previously investigated as environmentally friendly nematicides and their active substances, diallyl polysulfides exist as formulated nematicides on the market. We tested the garlic-based nematicide NEMguard® DE as protective of tomato roots. In vitro evaluation of the lethal concentration (LC) showed strong nematicidal activity with LC50 of 0.8 mg/mL after 96 h and LC90 of 1.5 mg/mL. NEMguard® DE showed protective effect against M. incognita as a single application in small pots and a second application further reduced root galling, significantly. Large greenhouse trials were carried out in two consecutive years to test single and monthly applications of NEMguard® DE. In both years, no controlling effect could be observed on M.incognita. We assume that the silt content of the loamy sandy soil used had an effect on the polysulfides, inhibiting their nematicidal effect. We conclude that further experiments are necessary to investigate the nematicidal potential of NEMguard® DE under different soil compositions or as a different formulation.

A Review of the Potency of Plant Extracts and Compounds from Key Families as an Alternative to Synthetic Nematicides: History, Efficacy, and Current Developments

“…Garlic EOs stand out as one of the most promising botanical nematicides, and when well-prepared, its efficacy is even comparatively better than the renown synthetic carbofuran and dazomet chemicals ( Jardim et al, 2020 ). Its EOs are rich in volatile and non-volatile nematode toxic sulphur compounds, especially the organosulfur allicin, which in itself breaks down to highly toxic sulfur compounds such as diallyl sulfide, diallyl disulfide, diallyl trisulfide, ajoene, and dithiines, among others ( Eder et al, 2021 ; Jardim et al, 2020 ). Allicin is touted to be the principle active nematicidal compound in garlic.…”

Cucurbitaceae COld Peeling Extracts (CCOPEs) Protect Plants From Root-Knot Nematode Infections Through Induced Resistance and Nematicidal Effects

“…To find out whether mCOPE-triggered protection against rootknot nematodes could be agronomically relevant for rice and tomato cultivation, a comparison with commercially available nematicides or IR stimuli was performed. The garlic extract Nemguard R , marketed for the control of root-knot nematodes specifically (Ladurner et al, 2014;Eder et al, 2021), was used as reference nematicide. The IR stimuli included in this study were Actigard R , a commercial formulation of benzothiadiazole (BTH; Schurter et al, 1990) and FytoSave R , a preparation of chitooligosaccharides and oligogalacturonides (COS-OGA) complexes (van Aubel et al, 2014;Clinckemaillie et al, 2017).…”

“…Nemguard R is an example of a successfully commercialized extract of garlic (Allium sativum) that is used to control Meloidogyne spp. specifically (Ladurner et al, 2014;Eder et al, 2021). Interestingly, combined IR-triggering and direct antipathogenic effects have also been demonstrated for some (plantderived) compounds (Kagale et al, 2004;Godard et al, 2009;Hassan et al, 2009;Sangeetha et al, 2013;Krzyzaniak et al, 2018).…”

Fluorescence Probes for Reactive Sulfur Species in Agricultural Chemistry

“…For example, polysulfides can convert GSH, Cys, and protein thiols into persulfides in animal systems, thereby participating in biological processes, such as signal transduction and redox control . In plant systems, especially in Allium plants rich in sulfane sulfurs, the signal molecule that performs biological functions may be sulfane sulfurs rather than small-molecule thiols or H 2 S. , Accordingly, developing effective fluorescent probes for detecting and imaging sulfane sulfurs is very significant in the context of agricultural chemistry.…”