Some notes on the occurrence of plant parasitic nematodes of fruit trees in Slovakia

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Nematicidal Activity of Essential Oils from Lamiaceae

The Lamiaceae family contains important aromatic plants used in traditional and modern medicine and in food and pharmaceutical industries. Plants belonging to this family are mostly exploited for the extraction of essential oils (EOs). The genus Monarda L. includes about eighteen species of herbaceous, annual or perennial plants endemic of North America. Several biological activities have been reported for plant EOs and their main components, including a biocidal activity against plant soilborne pathogens and pests, which also includes plant-parasitic nematodes [1]. The EOs can play an important role in crop protection and have been propose as an environmentally alternative to synthetic pesticides. In this study, the EOs from two Italian species of Monarda (M. dydima and M. fistulosa) were evaluated for their in vitro activity on infective stages of plant-parasitic nematodes Melodoigyne incognita. EOs from both Monarda species were strongly active on M. incognita juveniles showing a LC50 value of 1 µL mL-1 after 24 h exposure. The main constituents of EOs, carvacrol, γ-terpinene, o-cymene and thymol were also evaluated for their in vitro activity. Among them, carvacrol showed higher nematicidal activity also at low concentrations and at short exposure time [2]

Greenhouse soil solarization: effect on weeds, nematodes and yield of tomato and melon

Phase-out of methyl bromide and health concerns related to the use of pesticides are increasing the interest in alternative control strategies. Soil solarization is an effective, safe and cheap technique for the control of soil-borne pathogens and weeds. However, knowledge of the long-term effects of solarization, as well as of repeated solarization cycles, is scarce. Such knowledge should in particular help to minimize the number of solarization treatments. Therefore, we tested the residual effect of a single solarization treatment and the effects of two or three solarization cycles on root-knot nematodes, weeds and crop yield for three years on greenhouse-grown tomato and melon. Soil solarization was applied for either one, two or three consecutive years on a soil infested by the root-knot nematode Meloidogyne javanica and many annual and perennial weed species. An untreated soil was used as a control. At the end of each crop cycle yield parameters were recorded, weeds were identified and counted, and nematode infestation was evaluated. Our results show that a single solarization treatment significantly increased yields by +116%, and strongly reduced nematode infestation of $-99$% of infested plants and of $-98$% of the root gall index in the following melon crop. It also suppressed annual weed emergence three years later. Plant yields from two- and three-year solarized soil were always higher than nonsolarized control: +284% and +263%, respectively, for tomato, and +162% and +368%, respectively, for melon. Further, two- and three-year solarization treatments almost completely suppressed the infestation of the M. javanica nematode in tomato, and reduced the nematode effect in melon by $-86$% and $-79$%, respectively. Repeated solarization treatments also resulted in a high reduction of emergence of most weed species in all crop cycles. A single soil solarization treatment was shown to be effective for a long-term sustainable management of weeds, whereas the time-limited effectiveness against root-knot nematodes can be enhanced through two- or three-year repeated treatments

Evaluation of nematicidal properties of saponins from Medicago spp

The nematicidal activity of saponins from Medicago arborea (tops), M. arabica (tops and roots) and M. sativa (tops and roots) against the plant-parasitic nematode Xiphinema index was investigated. Nematicidal activity of related prosapogenins and sapogenins on X. index is also described. Saponins from Medicago spp. at different concentrations were all nematicidal, those from M. arborea tops being the less effective. In general, saponins induced 100% mortality at 500 mu g ml(-1) between 8 and 48 h, while prosapogenins resulted in toxicity starting at 125 mu g ml(-1). Differences in the effects on X. index induced by prosapogenins and sapogenins were less pronounced, although prosapogenins displayed a larger range of activity. Assays with purified sapogenins demonstrated the relationship of the observed nematicidal activity of M. sativa and M. arborea to the content of the main aglycones (medicagenic acid and hederagenin, respectively) in the saponin extracts. Hederagenin displayed the highest bioactivity, giving 38% mortality after 1 h at 125 mu g ml(-1)

Chemical Identification of Specialized Metabolites from Sulla (Hedysarum coronarium L.) Collected in Southern Italy

Sulla (Hedysarum coronarium L.) is a biennal forage legume originated from the Mediterranean basin and used for animal feeding due to its high forage quality and palatability. Several species of Hedysarum have been considered for their nutritional, pharmaceutical, and biological properties, and different applications have been reported, both for human consumption and animal nutrition. Although a systematic investigation of the chemical constituents of Hedysarum spp. has been performed in order to provide chemotaxonomic evidences for the genus and to support the pharmacological application of several species within the genus, few data are available on the chemical constituents of H. coronarium, and only the content of condensed tannins and flavonoids in leaves has been previously reported. In the present paper, results from a detailed chemical analysis of the extracts from the leaves and flowers of H. coronarium grown wild in southern Italy are presented. Identification of the main specialized metabolites within the chemical classes of flavonoids, proanthocyanidins and saponins, is described, including considerations on their content in the two plant organs. Information acquired from this study expands the knowledge on H. coronarium as a source of valuable phytochemicals for different applications in human and animal health and nutrition

Antibiotic and Nematocidal Metabolites from Two Lichen Species Collected on the Island of Lampedusa (Sicily)

The antibiotic and nematocidal activities of extracts from two coastal lichen species collected on Lampedusa Island (Sicily), Ramalina implexa Nyl. and Roccella phycopsis Ach., were tested. Methyl orsellinate, orcinol, (+)-montagnetol, and for the first time 4-chlororcinol were isolated from Roccella phycopsis. (+)-Usnic acid was obtained from Ramalina implexa. The crude organic extract of both lichen species showed strong antibiotic activity against some bacterial species and nematocidal activity. Among all the pure metabolites tested against the infective juveniles (J2) of the root-knot nematode (RKN) Meloydogine incognita, (+)-usnic acid, orcinol, and (+)-montagnetol had significant nematocidal activity, comparable with that of the commercial nematocide Velum® Prime, and thus they showed potential application in agriculture as a biopesticide. On the contrary, methyl orsellinate and 4-chlororcinol had no nematocidal effect. These results suggest that the substituent pattern at ortho-para-position in respect to both hydroxyl groups of resorcine moiety, which is present in all metabolites, seems very important for nematocidal activity. The organic extracts of both lichens were also tested against some Gram-positive and Gram-negative bacteria. Both extracts were active against Gram-positive species. The extract of Ramalina implexa showed, among Gram-negative species, activity against Escherichia coli and Acinetobacter baumannii, while that from Roccella phycopsis was effective towards all test strains, with the exception of Pseudomonas aeruginosa. The antimicrobial activity of (+)-usnic acid, methyl orsellinate, and (+)-montagnetol is already known, so tests were focused on orcinol and 4-chlororcinol. The former showed antibacterial activity against all Gram positive and Gram-negative test strains, with the exception of A. baumannii and K. pneumoniae, while the latter exhibited a potent antibacterial activity against Gram-positive test strains and among Gram-negative strains, was effective against A. baumannii and K. pneumonia. These results suggest, for orcinol and 4-chlororcinol, an interesting antibiotic potential against both Gram-positive and Gram-negative bacterial strains