Search Results (11)

Thousands of species of parasitic weeds, such as dodder, pose significant threats to agricultural crops due to their ability to spread rapidly through seeds. When cultivated lands become infested with dodder, the quality of production declines, leading to substantial damage. The most effective way to limit the infestation of agricultural lands by parasitic weeds, particularly dodder, is to control the quality of seeds intended for sowing. To obtain seed material free of dodder seeds, special separation machines equipped with magnetic drums are used. These machines operate on the principle of magnetic fields acting on ferromagnetic particles, which helps differentiate the physical states of the seeds intended for separation. This paper presents experimental research on magnetic drum separation techniques for removing dodder seeds from alfalfa seed mixtures. The study examines variables such as magnetic drum speed, feed rate, amounts of iron powder, water, solution (water and glycerin), and the initial content of dodder seeds. The experimental results indicated that using a water–glycerin solution at optimal concentrations for moistening the seeds enhances the separation efficiency of dodder seeds from alfalfa seed mixtures, compared to using only water. Additionally, the numerical content of dodder seeds in the A and C sorts, which primarily contain the seeds of the main crop, decreases with each pass through the machine, resulting in higher quality seed material. The research found that using appropriate parameters—drum rotation speed (20 rpm), iron powder quantity (19 g/min), and seed feed rate (25.39 g/s)—achieved a “free” classification for dodder in alfalfa seeds. These findings are valuable for evaluating the performance of separation equipment with magnetic drums to obtain high-quality seed material. They are also beneficial for designers, machine-building units, and economic agents specializing in this field. Full article

Field dodder (Cuscuta campestris yuncker) is an important parasitic weed that has negative impacts on the growth and yield of alfalfa (Medicago sativa L.). Effective control of field dodder in alfalfa crops is necessary to reduce yield losses. Field studies were conducted to evaluate the efficacy of various herbicides on field dodder in a new-seeded alfalfa crop at three locations (Karaj, Jiroft, and Urmia) in Iran during 2020–2021. The herbicides evaluated were imazethapyr (100 g a.i. ha⁻¹), glyphosate (six doses ranging from 143 to 348 g a.i. ha⁻¹ + ammonium sulfate at 8 kg ha⁻¹), and propyzamide (1250, 1500, and 1750 g a.i. ha⁻¹). The results demonstrated that propyzamide at 1750 g a.i. ha⁻¹ provided complete control of field dodder in terms of percentage change in biomass at first (100%) and second (99%) cuttings of alfalfa in Urmia. The imazethapyr at 100 g a.i. ha⁻¹ provided 96 and 87% control at the first and second cuttings, respectively, whereas propyzamide at 1750 g a.i. ha⁻¹ showed the best efficacy in increasing alfalfa biomass at the first (up to 82%) and the second cuttings (up to 81%), depending on the location. Glyphosate provided reasonable control of the field dodder at the first (73%) and the second cutting (82%). However, at higher rates (307 and 348 g a.i. ha⁻¹), it caused significant reductions in alfalfa biomass due to crop injury, especially at the first cutting. The use of propyzamide at 1750 g a.i. ha⁻¹ is recommended for highly effective control of field dodder in alfalfa crops without compromising the crop yield. Full article

Dodder (Cuscuta spp.) is a dangerous parasitic plant that causes serious damage to crop production and is challenging to eliminate. Herbicide application is a common strategy to control dodder in the field, but it is costly, ineffective, and further results in hazardous outcomes. Therefore, our study aims to identify the potential pathogens in naturally occurring dodder infections which may provide efficient biocontrol options. In this regard, the pathogens were isolated from the infected plants, their pathogenicity was validated through inoculation, and the optimal culture conditions for their growth were identified by determining the pathogenicity difference. The pathogenicity range was determined in vitro using the leaves of common horticultural plants and crops. Furthermore, a small range of horticultural plants parasitized by Cuscuta reflexa in the field were inoculated with the pathogen to determine their biosafety and biocontrol potential, and the pathogens were identified by morphological and molecular characterization. We found 7 strains that were isolated after pathogen enrichment culture. Among them, Cbp6 and Cbp7 showed the highest pathogenicity against C. reflexa. After testing the inoculation of more than 50 species of plants, only 9 species showed varying degrees of lesions on leaves, which proved the high biosafety for common plants. Field spraying of these pathogens showed a good control effect on C. reflexa after 21 days; the disease severityreached 66.0%, while its host plant did not display obvious symptoms. In conclusion, the pathogens Cbp6 and Cbp7 were identified as Alternaria alternata, and the results of this study provide a theoretical basis for the biological control of dodder. Full article

The molecular mechanisms underlying insect gall formation remain unclear. A major reason for the inability to identify the responsible genes is that only a few systems can be experimentally validated in the laboratory. To overcome these problems, we established a new galling insect model, Smicronyx madaranus. Our manipulation experiments using nail polish sealing and insecticide treatment revealed an age-dependent change in gall formation by S. madaranus; adult females and larvae are responsible for gall induction and enlargement, respectively. Furthermore, it has been suggested that substances released during oviposition and larval feeding are involved in each process. Phylogenetic analysis showed that gall-forming weevils, including S. madaranus, belong to two distinct lineages that utilize different host plants. This may indicate that gall-forming traits evolved independently in these Smicronyx lineages. The efficacy of RNA interference (RNAi) in S. madaranus was confirmed by targeting the multicopper oxidase 2 gene. It is expected that the mechanisms of gall formation will be elucidated by a comprehensive functional analysis of candidate genes using RNAi and the S. madaranus galling system in the near future. Full article

Cuscuta campestris Yunck. is a parasitic weed responsible for severe yield losses in crops worldwide. The selective control of this weed is scarce due to the difficult application of methods that kill the parasite without negatively affecting the infected crop. trans-Cinnamic acid is secreted by plant roots naturally into the rhizosphere, playing allelopathic roles in plant–plant communities, although its activity in C. campestris has never been investigated. In the search for natural molecules with phytotoxic activity against parasitic weeds, this work hypothesized that trans-cinnamic acid could be active in inhibiting C. campestris growth and that a study of a series of analogs could reveal key structural features for its growth inhibition activity. In the present structure–activity relationship (SAR) study, we determined in vitro the inhibitory activity of trans-cinnamic acid and 24 analogs. The results showed that trans-cinnamic acid’s growth inhibition of C. campestris seedlings is enhanced in eight of its derivatives, namely hydrocinnamic acid, 3-phenylpropionaldehyde, trans-cinnamaldehyde, trans-4-(trifluoromethyl)cinnamic acid, trans-3-chlorocinnamic acid, trans-4-chlorocinnamic acid, trans-4-bromocinnamic acid, and methyl trans-cinnamate. Among the derivatives studied, the methyl ester derivative of trans-cinnamic acid was the most active compound. The findings of this SAR study provide knowledge for the design of herbicidal treatments with enhanced activity against parasitic weeds. Full article

Cuscuta campestris is a parasitic weed species that inflicts worldwide noxious effects in many broadleaf crops due to its capacity to withdraw nutrients and water directly from the crop vascular system using haustorial connections. Cuscuta campestris control in the majority of crops affected is non-existent, and thus, research for the development of control methods is needed. Hydrocinnamic acid occurs naturally in the rhizosphere, playing regulatory roles in plant–plant and plant–microbe communities. The toxicity of hydrocinnamic acid against C. campestris was recently identified. In the present work, a structure–activity relationship study of 21 hydrocinnamic acid analogues was performed to identify key structural features needed for its allelopathic action against the seedling growth of this parasitic plant. The findings of this study provide the first step for the design of herbicides with enhanced activity for the control of C. campestris infection. Full article

Cuscuta campestris is a parasitic weed species with noxious effects in broadleaf crops worldwide. The control of Cuscuta in the majority of crops affected is limited or non-existing. We tested, for the first time, the effect of eighteen metabolites in in vitro-grown Cuscuta seedlings. We found that 2-benzoxazolinone, hydrocinnamic acid and pisatin caused the strongest inhibition of seedling growth. In addition to seedling growth, pisatin caused necrosis of the Cuscuta seedling, occurring mostly at the seedling shoot. Scopoletin and sesamol treatments caused toxicity, observed as a black staining, only at the Cuscuta root apices, while caffeic acid, ferulic acid and vanillic acid caused toxicity, observed as brown staining, in the root apices. The structure–activity relationships in four structural derivatives of 2-benzoxazolinone, and five structural derivatives of hydrocinnamic acid, were also studied. The identification of new herbicidal modes of action against Cuscuta is the first step in creating new alternatives to sustainable chemical control of parasitic weeds. Full article

Dodder (Cuscuta campestris Yunck.) is one of the most devastating parasitic plants, which reduces quantity and quality of crops. The inhibitory effect of catnip (Nepeta meyeri Benth.) extracts on germination and some seedling characteristics of the C. campestris were investigated in three phases in a laboratory and greenhouse. Aqueous extracts from different organs of N. meyeri were used in bioassays. The N. meyeri extracts reduced germination percent, root and shoot growth, and dry weight of C. campestris seedlings. Moreover, results showed an inhibitory effect of the N. meyeri extracts on the activity of alpha-amylase, protease, and beta-1,3-glucanase enzymes in C. campestris germinating seeds. Under greenhouse conditions, C. campestris seeds were planted with 30-day-old alfalfa plants and irrigated with N. meyeri extracts. The application of extracts from different organs of N. meyeri reduced emergence percent and length of stem and hampered C. campestris attachment to alfalfa. N. meyeri extracts also inhibited the activity of antioxidant enzymes and increased the accumulation of hydrogen peroxide and the malondialdehyde in C. campestris seedlings. The strongest inhibitory effects were observed from flower, leaf, and stem extracts of N. meyeri, respectively. However, after C. campestris attachment to alfalfa plants, treatment by N. meyeri extracts did not exhibit any effect on infestation efficiency and C. campestris growth traits. According to these findings, N. meyeri extract, especially from flower and leaf, may be recommended as a potent bio-control agent to control germination and early stage development of C. campestris. Full article

Efficient approaches aimed at restricting Cuscuta campestris distribution can be based on the control of seed germination. Thus, data on effects of environmental factors, seed age, seed longevity and viability, and hosts on C. campestris seed germination and emergence would provide valuable information in that context. Seeds of 26 populations of C. campestris were collected from different locations in Serbia during the field season August–October between 2005 and 2019. Seeds were collected in three major agronomic regions in Serbia: Banat (13 populations), Srem (11 populations), and Macva (2 populations). The objectives of this study were to investigate the effects of different temperatures and light on seed germination and seedling growth of populations of C. campestris, determine possible correlations between seed age or hosts and total germination and seedling growth, and survey the morphological diversity and genetic variability of seeds of this parasitic plant. Large variability of germination patterns was observed within each agronomic region, and the high variance of seed germination patterns within regions reflects the ability of C. campestris to adapt to local agricultural management practices. For practical purposes, populations that start and complete their emergence earlier are considered harder to control. Thus, farmers should implement effective mechanical and chemical management measures for early-germinating populations. Full article

The dodders (Cuscuta spp.) are parasitic plants that feed on the stems of their host plants. Cuscuta campestris is one of the most damaging parasitic plants for the worldwide agricultural production of broad-leaved crops. Its control is limited or non-existent, therefore resistance breeding is the best alternative both economically and environmentally. Common vetch (Vicia sativa) and bitter vetch (Vicia ervilia) are highly susceptible to C. campestris, but no resistant genotypes have been identified. Thus, the aim of this study was to identify in V. sativa and V.ervilia germplasm collections genotypes resistant to C. campestris infection for use in combating this parasitic plant. Three greenhouse screening were conducted to: (1) identify resistant responses in a collection of 154 accessions of bitter vetch and a collection of 135 accessions of common vetch genotypes against infection of C. campestris; (2) confirm the resistant response identified in common vetch accessions; and (3) characterize the effect of C. campestris infection on biomass of V. sativa resistant and susceptible accessions. Most common vetch and bitter vetch genotypes tested were susceptible to C. campestris. However, the V. sativa genotype Vs.1 exhibited high resistance. The resistant phenotype was characterized by a delay in the development of C. campestris posthaustorial growth and a darkening resembling a hypersensitive-like response at the penetration site. The resistant mechanism was effective in limiting the growth of C. campestris as the ratio of parasite/host shoot dry biomass was more significantly reduced than the rest of the accessions. To the best or our knowledge, this is the first identification of Cuscuta resistance in V. sativa genotypes. Full article

Peppermint (Mentha piperita L.) and chamomile (Chamomilla recutita (L.) Rausch.) are aromatic plants with considerable economic value. These plants and their essential oils are used in medicine, cosmetics, and the food industry. One of the main limiting factors in peppermint and chamomile commercial cultivation is weed competition since weeds are able to decrease both oil amount and biomass yield. The purpose of the present study was to determine the effect of parasitism by field dodder (Cuscuta campestris Yunck.) on peppermint and chamomile dry weight and their essential oil yield and composition. Essential oils from both noninfested and infested peppermint and chamomile plants were obtained by hydrodistillation and characterized chemically by gas chromatography (GC) coupled with mass spectrometry (MS). The amount of dry matter accumulated by peppermint and chamomile plants infested by field dodder was lower (25% and 63%, respectively) compared to noninfested plants. Essential oil yield increased for peppermint (3.87% (v/w) and 3.63% (v/w)), but decreased for chamomile (0.2% (v/w) and 0.5% (v/w)) both from infested and noninfested plants, respectively. The oil composition profile significantly differed in terms of content. In peppermint plants, field dodder infestation increased menthone content by 23%, and decreased the content of both menthol by 11% and pulegone by 67%. Furthermore, δ-cadinene was detected only in oil extracted from infested peppermint plants. Compared to peppermint, chamomile plants were significantly more affected by field dodder in terms of essential oil yield, as well as oil composition and plant dry weight. In chamomile plants, (E)-dendrolasin was detected in the oil of noninfested plants, and 1,4-dimethyl-7-(1-methylethyl)-azulen-2-ol was detected only in the oil of infested plants. Full article