Background There are relatively few scientific works on the use of homeopathy to manage plant pathogens, particularly nematodes. A handful of studies focused on Meloidogyne spp. parasitizing vegetables have brought contradictory results on nematode control and enhancement of plant tolerance to parasitism. Objective Our goal was to assess the effect of Cina—a well-known anti-nematode ingredient—on Meloidogyne enterolobii parasitizing lettuce. Methods Cina was applied daily on nematode-inoculated plants, from the seedling stage until harvest. We tested an evenly spaced range of Hahnemannian concentrations (c), which were applied though irrigation with a constant dose of the ingredient. Several absolute and relative controls were employed to allow the assessment of the effect of Cina on nematode reproduction and lettuce growth. Results Cina affected growth of non-parasitized plants, both positively and negatively; this effect was modulated by the c applied and the thermal stress suffered by the plants in one of the assays. The effect of Cina on the growth of nematode-parasitized plants was neutral or negative. Cina reduced nematode reproduction by 25–36%. Conclusion Based on the moderate negative effect of Cina on M. enterolobii reproduction, it seems this ingredient may be useful as a complementary strategy for Meloidogyne control. But Cina did not enhance the tolerance of lettuce to Meloidogyne spp.
For decades there have been anecdotal claims of synergistic interactions between plant-parasitic nematodes and soil-borne fungi causing decline of productivity of passion fruit (Passiflora edulis) orchards. An empirical confirmation of these disease complexes would impact disease management and plant breeding for resistance. To test those claims, we subjected passion fruit plants to single or concomitant parasitism by Meloidogyne javanica or M. incognita and Fusarium nirenbergiae or Neocosmospora sp. under controlled conditions. Non-inoculated plants served as control for the assays. The severity of shoot symptoms and variables related to plant growth, the extent of fungal lesions, and nematode reproduction were assessed to characterize the interactions. The shoot symptoms and effect on plant growth induced by the pathogens varied, but no synergy between the pathogens was observed. Moreover, the volume of tissue lesioned by the fungi was not affected by co-parasitism of the nematodes. Conversely, plant resistance to the nematodes was not affected by co-parasitism of the fungi. The interactions M. incognita-F. nirenbergiae, M. incognita-Neocosmospora sp., M. javanica-F. nirenbergiae, and M. javanica-Neocosmospora sp. were not synergistic as previously claimed, but instead neutral.
Background Nosodes are homeopathic preparations (HPs) obtained from tissues or substances associated with the targeted disease or from culture of the pathogenic agent. Nosodes are thought to modulate host resistance, easing symptoms or promoting cure. A few studies have been published about control of plant-parasitic nematodes with HPs, but none with nosodes. Conceptually, nosodes prepared from nematode infective stages might interact with the plant's pathogen-recognition system and initiate or modulate plant resistance to nematodes. Objective Our goal was to investigate whether nosodes prepared from second-stage juveniles (J2) of Meloidogyne enterolobii can affect the moderate resistance already existing in the lettuce cultivar ‘Elisa’. Methods Nosodes at the Hahnemannian concentrations (cH) 6, 18, 30 and 42 were applied on lettuce plants through irrigation, with a constant daily dosage. The nosode treatment started at the seedling stage, before nematode inoculation with 3,000 eggs + J2 per plant. A series of absolute and relative controls, and 10 replicates per treatment, were employed. At harvest, variables related to plant growth and nematode reproduction were assessed. Results The nosode at 6, 18, and 30cH reduced (p <0.05) the nematode reproduction factor and root density. The nosode effect was cH-dependent since nematode reproduction was favored by treatment with 42cH. The nosode also affected (p <0.05) lettuce roots, which presented higher or lower fresh weight and volume depending on the cH applied and the condition—parasitized or not. Conclusion Nosodes obtained from Meloidogyne J2 may affect plant parasitism by nematodes, possibly by interfering with plant resistance. The nature—positive or negative—and intensity of the nosode effect depends on the cH applied to the plants. Further studies are necessary to identify which cH values are more effective in reducing nematode reproduction without causing negative side effects on plant growth.
No abstract
Humulus lupulus (Cannabaceae) is a climbing herbaceous plant with perennial production, intended mainly for the brewing industry. H. lupulus is widely cultivated in temperate regions; hop cultivars have shown good adaptation in regions of Brazil. In a hop-growing area in São Mateus, the state of Espírito Santo, leaf wilting and galling of the root system was observed. Soil and root samples were taken to the laboratory and processed, and the nematodes extracted from the Meloidogyne genus were identified by morphology, morphometry, and biochemical analysis. According to the results, the species identified in the hop roots was Meloidogyne morocciensis. This is the first report of H. lupulus as host of M. morocciensis.
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