Root-knot nematodes (RKN) cause extensive damage to grapevine cultivars. RKN-resistant grapevine rootstocks remain vulnerable to biotic and abiotic stresses. This study aimed to determine the influence of composted animal manures (CAMs) [chicken manure (CM), cow manure (CowM), and sheep manure (SM)] with or without plant growth-promoting rhizobacteria (PGPR) on the population of Meloidogyne incognita, free-living nematodes (FLNs) and predaceous nematodes (PNs) residing in the soils of vineyard cultivars (Flame, Superior and Prime). The nematodes were isolated from grapevine roots and rhizosphere soils, then the absolute frequency of occurrence (FO), relative FO, prominence value (PV), and population density (PD) were assessed. The impact of CAMs and PGPR on the growth parameters, fruit output, and quality of three grapevine varieties was subsequently evaluated. Eight treatments included a control without CAMs or PGPR amendments, the CAMs alone, or CAM treatments combined with PGPR. The results showed that FLNs and PNs were more abundant in Prime than Flame or Superior cultivars when poor sandy loam soils were supplied with CAMs. Among all tested manures, CM was the best treatment as a nematicide. This was evident from the decreased numbers of M. incognita and increased numbers of FLNs and PNs in grapevine fields. Compared to the soil-applied oxamyl (a systemic nematicide), which was efficiently suppressive on M. incognita for two months, CM significantly (P < 0.05) decreased PD of the phytonematodes for five months, improved soil structure and enhanced the soil biological activities. There were significant (P < 0.05) increases in the number of leaves/vines by 79.9, 78.8, and 73.1%; and total fruit weight/vine by 76.9, 75.0, and 73.0% in Flame, Superior, and Prime varieties, respectively, compared to untreated vines. Regardless of the cultivar, soils amended with CM + PGPR achieved the lowest number of M. incognita among all other treatments, followed by SM + PGPR and CowM + PGPR. It was concluded that CAMs amendment, mainly CM, along with PGPR in poor sandy soils of temperate areas, is considered a sustainable approach for reducing parasitic nematodes and improving agricultural management.

Metal-based nanoparticles (MNPs) are gaining attention as promising components of nanopesticides, offering innovative solutions to enhance agricultural pest management while addressing environmental concerns associated with traditional pesticides. MNPs, such as silver, copper, zinc, nickel, gold, iron, aluminum, and titanium, exhibit unique nanoscale properties. These properties enable the formulation of MNPs for controlled and sustained release, thereby reducing application frequency and minimizing environmental runoff. This controlled release mechanism not only improves pest management efficacy but also reduces risks to non-target organisms and beneficial species, aligning with the principles of sustainable crop protection. This review examines nanopesticides based on their specific targets, such as nanoinsecticide, nanobactericide, nanofungicide, nanonematicide, and nanoviricide. It also explores the mechanisms of action of metal-based nanoparticles, including physical disruption, chemical interactions, and biological processes. Additionally, the review details how MNPs compromise cellular integrity through mechanisms such as membrane damage, DNA disruption, mitochondrial impairment, and protein denaturation. Despite these advantages, significant challenges remain, particularly concerning the environmental impact of MNPs, their long-term effects on soil health and ecosystem dynamics, and potential risks to human safety. Addressing these challenges is crucial for realizing the full potential of MNPs in sustainable agriculture.

Meloidogyne arenaria (peanut root-knot nematode, PRKN) is an important pest in peanut (Arachis hypogea) production in the United States, including specialty Virginia-type peanuts. Cultivars resistant to PRKN and nematicide application are two available methods for managing PRKN. The objectives of this study were to determine the impacts of resistant Virginia-type peanut cultivars (Georgia-19HP and TifJumbo) on (1) management of PRKN abundances and damage and (2) total free-living nematode soil abundances. A common susceptible cultivar (Bailey II) with or without in-furrow fluopyram nematicide was compared to the resistant cultivars without nematicide in field trials in Florida (2022 and 2023). Resistant cultivars reduced midseason PRKN abundances from roots by 92-98% and final PRKN soil abundances by 81-93% relative to the untreated susceptible cultivar. Fluopyram reduced midseason PRKN root abundances by 65-74% and final PRKN soil abundances by 42-51% relative to untreated susceptible. Although PRKN reproduced on peanuts, no damage symptoms were observed, yield did not vary by treatment in 2022, and yield was significantly greater for fluopyram than either resistant cultivar in 2023. Impacts on total free-living nematode soil abundances were inconsistent. In summary, either fluopyram or resistant cultivars are effective tools for managing PRKN abundances in Virginia-type peanuts.

This study sought to identify and characterize Heterorhabditis indica, its symbiotic bacteria, and Meloidogyne incognita, while assessing the nematicidal efficacy of silver nanoparticles synthesized using Photorhabdus luminescens supernatant (PsAgNPs). Molecular and phylogenetic analyses verified the identity of H. indica and M. incognita, revealing no nucleotide discrepancies from previously characterized species. P. luminescens exhibited entomopathogenic properties, and its supernatant enabled the biosynthesis of PsAgNPs under optimal conditions (26 +/- 2 degrees C, pH 9). Characterization of PsAgNPs indicated a UV-visible absorption peak at 430 nm, a crystalline structure with an average particle size of 22.38 nm (XRD), and a zeta potential of -41.7 +/- 0.74 mV, signifying high stability. FTIR analysis suggested that proteins and polysaccharides contributed to nanoparticle stabilization, while EDX confirmed 70.01% silver purity. SEM and TEM analyses demonstrated spherical nanoparticles with sizes ranging from 15.5 to 40 nm. In vitro bioassays revealed that PsAgNPs significantly suppressed M. incognita egg hatchability and juvenile mortality in a dose-dependent manner. At 200 mu g/mL, PsAgNPs reduced egg hatchability to 24.6% and caused 100% juvenile mortality. In contrast, the bacterial supernatant alone exhibited a lower efficacy. The LC50 values for PsAgNPs were 13.1 mu g/mL and 14 mu g/mL at 12 and 24 h, respectively, indicating potent nematicidal activity. In vivo pot experiments on tomato plants demonstrated a pronounced reduction in gall formation (95.3%) and egg mass production (93.1%) at 100 mu g/mL PsAgNPs. Soil nematode populations were significantly reduced, with the lowest density recorded in PsAgNP-treated plants (53.3 juveniles). Additionally, PsAgNPs substantially enhanced plant growth, increasing fresh and dry shoot and root biomass by 61.2% and 64.6%, respectively, compared to controls. Histopathological analysis corroborated reduced tissue damage in PsAgNP-treated plants. These results underscore the potential of PsAgNPs as a viable biocontrol agent for managing M. incognita, presenting an environmentally sustainable alternative to traditional nematicides.

The root-knot nematode, Meloidogyne incognita, poses a significant economic threat as an endoparasite for various vegetables, including cabbage. Utilizing botanicals is an essential aspect of green technology to combat root-knot nematode infection. This study investigates the efficacy of four botanicals (Oxalis corniculata, Ricinus communis, Lantana camara, and Pluchea lanceolata) as emerging phyto-nematicides against M. incognita using both in vitro experiments (J2 mortality after 24, 36 and 48 hours exposure to 3000, 2000, 1000, 500, and 0 mg/L of the four botanicals and then determination egg hatching of M. incognita after 3 and 5 days incubation with various concentrations of the selected botanicals) and pot experiments. In the in vitro study, different extracts from the leaves of botanicals were applied to the second juvenile stage (J2) of M. incognita. The highest mortality of J2 and reduction in egg hatching for O. corniculata extract (89.96 and 86.79%), while the lowest effects (9.01 and 11.50 %) were observed for P. lanceolata extract. The extract of O. corniculata caused complete damage to the morphology of J2 via rupturing the cuticle of posterior, middle, and interior portion. In the pot experiment, M. incognita adversely affected growth shoot length (51.37%), root length (55.10%), fresh head weight (63.14%), and dry head weight (61.79%) by down-regulation of biochemical and epidermal traits compared to un-inoculated plants. However, the soils amended with botanicals especially O. corniculata recorded highest retardation of M. incognita infestation in cabbage roots, hence improved the growth and yield compared to the infected plants. The most beneficial effect denoted by O. corniculata at 100 g/pot on the infected cabbage plants associated with improving carotenoids (83%), chorophyll (117%), and nitrate reductase activity (79%) compared to stressed plants only. Also, O. corniculata at 100 g/pot maximally increased the number of stomata (130%), lengths (87%), and width (141%) of stomatal pore infected cabbage plants compared to the infected plants. These findings recommended the importance of O. corniculata as an eco-friendly organic phyto-nematicide that effectively restrict the damaging impacts of M. incognita on cabbage and may be other crops.

Meloidogyne enterolobii is an emerging global threat and is damaging to sweetpotato (Ipomoea batatas) production in the southeast United States. Nematicide application is one of the few management strategies currently available against this nematode, and field testing is urgently needed. The objective of this study was to assess common nematicides for management of M. enterolobii and nontarget effects on free-living nematodes in sweetpotato field production. Treatments were (i) untreated control, (ii) fumigation using 1,3-dichloropropene, or at-transplant drench of fluorinated nematicides (iii) fluazaindolizine, (iv) fluopyram, or (v, vi) fluensulfone at 2 or 4 kg a.i./ha. In 2022, a field trial was conducted under severe M. enterolobii pressure and was repeated in 2023 in the same location without treatment rerandomization. Fumigation using 1,3-dichloropropene (1,3-D) was the only consistently effective nematicide at improving marketable yield relative to control and also consistently reduced most storage root galling measurements and midseason Meloidogyne soil abundances. Fluensulfone at 4 kg a.i./ha consistently improved total yield but not marketable yield, whereas fluensulfone at 2 kg a.i./ha, fluazaindolizine, and fluopyram did not improve yield. Each fluorinated nematicide treatment reduced at least one nematode symptom or nematode soil abundances relative to control, but none provided consistent benefits across years. Even with 1,3-D fumigation, yield was poor, and none of the nematicide treatments provided a significant return on investment relative to forgoing nematicide application. There were minimal effects on free-living nematodes. In summary, 1,3-D is an effective nematicide for M. enterolobii management, but additional management will be needed under severe M. enterolobii pressure.

Although plant damages caused by phytoparasitic nematodes has been known at world level since the second half of the 19th century, the most effective methods for their management were discovered only in the past century. At first, plant parasitic nematodes (PPN) were controlled by the same products used against insect pests (carbon disulfide, chloropicrin, methyl bromide), but since 1940, with the discovery of the nematicide activity of the soil fumigant DD (dichlopropane-dichloropropene), chemical nematicides played a pivotal role in increasing the yield of many agricultural crops. In the second half of the past century and especially during its last two decades, the high demand from the farmers for chemical products having immediate nematicidial activity stimulated the interest of many chemical companies in patenting and marketing an increasing number of new chemical products. They were both fumigants (methyl bromide, chloropicrin, dibromoethane, bromochloropropane, dichloroethane, dichloropropane, dichloropropene, dazomet, metam sodium, metam potassium, methyl isothiocyanate, dimethyldisulfide) and non-fumigants (aldicarb, abamectin, benfuracarb, cadusaphos, carbosulfan, carbofuran, benfuracarb, fosthiazate, fluopyram, fenamiphos, ethoprophos, oxamyl, iprodione, thionazin). In the meantime, awareness increased about the negative impact of plant protection products were having on the environment and the need to regulate their approval and use in the European Union (EU). This resulted in a number of EU decrees adopted by all member States to restrict the marketing and use of these products. This led to a drastic reduction in p.a. nematicides on the market, which are already in limited numbers compared to fungicides and insecticides. In this phase of transition towards eco-sustainable agriculture, as alternative products are not yet available for all crops and for all the different species of parasitic nematodes, agricultural operators are having considerable difficulties. The future of the market for synthetic nematicides is not promising. Today, only a handful of active ingredients (dazomet, metam sodium, metam potassiium fenamiphos, fosthiazate, fluopyran, abamectin) are registered in EU. However, studies are underway to search for less polluting products, such as plant extracts, volatile organic compounds, and nano-formulations. The use of these products should be integrated with the implementation of appropriate crop systems, the use of cover crops, soil amendments, rigorous sanitation practices, and resistant planting material, obtained both by conventional and modern technique, for a sustainable control of PPN.