Incognita Race Research Articles

Nematode resistance to tropical Meloidogyne species in Moringa oleifera

Attempts are underway to cultivate Moringa oleifera Lam. in tropical areas as a developmental crop due to its nutritional, pharmacological and industrial applications. However, the success of developmental-plant-related projects depends on the degree of nematode resistance in the introduced plants to the tropical root-knot (Meloidogyne species) nematodes. The objective of this study was to determine the degree of nematode resistance in M. oleifera seedlings to M. incognita race 2 and M. javanica under greenhouse conditions. Two parallel experiments were conducted, with seedlings in each inoculated with a series of different nematode species. At 56 days after inoculation, the M. incognita race 2 and M. javanica reproductive factor (RF) values ranged from 0–0.34 and 0.01–0.42, respectively. Nematode infection did not have any effect on plant growth variables. In conclusion, M. oleifera was resistant to population densities of tropical Moloidogyne species in South Africa.

Efficacy of Nemafric-BL phytonematicide from fresh Cucumis africanus fruit on suppression of root-knot nematodes and growth of tomato plants

Cucurbitacin-containing phytonematicides are prepared from fruits dried at 52oC in air-forced ovens, which could not be available for use by resource-poor farmers to prepare the products. The objective of this study was to determine the influence of Nemafric-BL phytonematicide prepared using fermented crude extracts of fresh fruit from wild watermelon (Cucumis africanus) on growth of tomato (Solanum lycopersicum) plants and root-knot (Meloidogyne species) nematodes. Seedlings of tomato cultivar ‘Floradade’ were inoculated with 3000 eggs and second-stage juveniles (J2) M. incognita race 2 in pot trials, with treatments comprising a series of Nemafric-BL phytonematicide concentrations. Fiftysix days after inoculation, the phytonematicide had reduced eggs and J2 in roots by 8497%, J2 in soil by 49–96% and total nematodes by 70–97%. Plant variables and log22transformed concentrations of Nemafric-BL phytonematicide exhibited quadratic relations, with the model being explained by 74–98% associations. In conclusion, fresh fruit of C. africanus could be used for the preparation of Nemafric-BL phytonematicide.

Reproduction of Meloidogyne incognita and M. graminis on Several Grain Sorghum Hybrids.

A total of 27 grain sorghum hybrids were evaluated in a series of greenhouse experiments to determine their susceptibility to Meloidogyne incognita race 3 and M. graminis. Each hybrid was inoculated with 2,000 nematode eggs/pot. Reproduction by M. incognita was numerically greater than M. graminis on 93% of the hybrids tested, indicating that grain sorghum is a better host for M. incognita than M. graminis. A wide variation in host suitability was observed on these hybrids in a second experiment as reproduction by M. incognita ranged from 395 to 3,818 eggs/g of root. Only two hybrids, Terral RV9782 and RV9823, consistently supported <20% reproduction by M. incognita compared to the most susceptible hybrid, Golden Acres 5556. Reproduction of four isolates of M. incognita was evaluated on six selected hybrids in a third greenhouse experiment. Hybrid susceptibility was similar to that observed in the previous experiment for all isolates. A difference in isolate aggressiveness was observed between two of the four isolates across all hybrids. In fields where damaging populations of M. incognita are present, most grain sorghum hybrids will likely maintain or increase the nematode population for the subsequent crop.

Host status of progenies of yellow passion fruit to Meloidogyne incognita race 2

The host status of eighteen progenies (CRP 01-12 to CRP 16-12, CRP 19-12 and CRP 20-12) and two cultivars (FB 200 Yellow Master and FB 300 Araguari) of yellow passion fruit to Meloidogyne incognita race 2 was evaluated in a greenhouse experiment. The height and the biomass of the plants, besides the numbers of galls, eggs and second-stage juveniles in roots and soil were assessed after 70 days of cultivation of the genotypes and tomato (control) in plastic pots with 2 kg of soil infested with 5,000 eggs of the nematode. The reproduction factor of the pathogen (RF = Final population/Initial population) was calculated for classifying the genotypes as immune (RF = 0), resistant (RF < 1) or susceptible (RF ≥ 1). The cultivar FB 200 is resistant to M. incognita race 2 and can be cultivated in areas infested with this nematode.

Root-Knot Nematodes (Meloidogyne spp.) Parasitizing Resistant Tobacco Cultivars in Southern Brazil.

Our study surveyed Meloidogyne spp. from tobacco cultivars in Brazil carrying the Rk gene, which confers resistance to Meloidogyne incognita races 1 and 3. Identification of Meloidogyne populations from 39 tobacco fields was based on the analysis of esterase phenotypes, perineal patterns, and 18S-internal transcribed spacer (ITS)1-5.8S ribosomal RNA sequences. Biometric characterization and differential host tests of isolates were determined as well. We detected M. incognita, M. javanica, M. enterolobii, M. arenaria, and M. inornata in 18 (46.2%), 16 (41%), 10 (25.6%), 2 (5.1%), and 1 (2.6%) samples, respectively. Mixtures of species were found in 25.6% of the samples. This is the first report of M. inornata parasitizing tobacco in Brazil's southern region. Two morphological and biochemically unusual populations had host ranges and ITS1 sequences nearly identical to M. enterolobii and M. incognita, respectively. Pathogenic and biometric intraspecific variations were observed. Based on our results and considering the limited efficiency of the Rk gene, it is indispensable not only to search for resistance sources to M. incognita virulent strains but also to consider resistance to M. enterolobii, M. inornata, M. arenaria, and M. javanica in tobacco breeding programs. Changes in integrated management procedures should be considered to avoid increased crop damage in the future.

Response of mineral malnutrition elements in African ginger pseudo-stems to nematode infection

ABSTRACTInterference of nematode infection with mineral malnutrition (MMN) elements in biofortificated cultigens could devalue the health potential of such crops for humans. A pot trial was conducted to determine the response of selected MMN elements in African ginger (Siphonochilus aethiopicus) pseudo-stems to the southern root-knot (Meloidogyne incognita) nematode. Fifty-six days after inoculation, the sensitivity of the pseudo-stems to nematode infection was confirmed, with 23–45% reduced potassium in pseudo-stem tissues, but had no effect on other MMN elements. In conclusion, population densities of M. incognita race 2 should be managed to enhance the potential uses of S. aethiopicus as a biofortification crop.

Reproduction of Meloidogyne incognita Race 3 on Flue-cured Tobacco Homozygous for Rk1 and/or Rk2 Resistance Genes.

Most commercial tobacco cultivars possess the Rk1 resistance gene to races 1 and 3 of Meloidogyne incognita and race 1 of Meloidogyne arenaria, which has caused a shift in population prevalence in Virginia tobacco fields toward other species and races. A number of cultivars now also possess the Rk2 gene for root-knot resistance. Experiments were conducted in 2013 to 2014 to examine whether possessing both Rk1 and Rk2 increases resistance to a variant of M. incognita race 3 compared to either gene alone. Greenhouse trials were arranged in a completely randomized design with Coker 371-Gold (C371G; susceptible), NC 95 and SC 72 (Rk1Rk1), T-15-1-1 (Rk2Rk2), and STNCB-2-28 and NOD 8 (Rk1Rk1 and Rk2Rk2). Each plant was inoculated with 5,000 root-knot nematode eggs; data were collected 60 d postinoculation. Percent galling and numbers of egg masses and eggs were counted, the latter being used to calculate the reproductive index on each host. Despite variability, entries with both Rk1 and Rk2 conferred greater resistance to a variant of M. incognita race 3 than plants with Rk1 or Rk2 alone. Entries with Rk1 alone were successful in reducing root galling and nematode reproduction compared to the susceptible control. Entry T-15-1-1 did not reduce galling compared to the susceptible control but often suppressed reproduction.

Action of medicinal plant extracts on juveniles ofMeloidogyne incognitarace 2

Phytonematodes are parasites that seriously affect crops worldwide, compromising agricultural production and sometimes preventing the use of many cultivated areas. The search for alternative control measures to replace conventional nematicides is a global concern, and explains research into natural substances due to their being efficient and environmentally friendly. The aim of this study was to evaluate the effect of plant extracts from the false daisy (Eclipta alba), basil (Ocimum basilicum), mugwort (Artemisia vulgaris), citronella (Cymbopogon winteranus), water willow (Justicia pectoralis), comfrey (Symphytum officinalle), cuban mint (Mentha x vilosa), pink root (Spigelia anthelmia), epazote (Chenopodium ambrosioides) and wild mint (Mentha arvensis) on motility and mortality in juveniles of Meloidogyne incognita race 2. Extracts, obtained from dried leaves under infusion or macerated in water, were diluted and spread onto Petri dishes to which were added 50 second-stage juveniles (J2). After remaining for 48 hours in the extracts, all the J2, both mobile and immobile, were counted and then transferred to water, where after 24 hours, the percentage of dead J2 was determined. Any still active J2 were inoculated into ‘Santa Clara’ tomato seedlings in a greenhouse so as to evaluate their infectivity. The macerated extracts of the medicinal plants, except for the citronella, cuban mint and wild mint, showed high nematicide activity, with over 70% of the J2 dead. Total mortality was seen with the extracts of pink root, false daisy and epazote. The absence of galls in the root system of the inoculated tomato plants confirmed the toxic effect of these extracts.

Effectiveness of salicylic acid, Pseudomonas fluorescens CHA0 and Trichoderma viride to control Meloidogyne incognita race 2 on different tomato cultivars

Summary The effects of salicylic acid (SA), Trichoderma viride and Pseudomonas fluorescens CHA0 were studied on the root-knot nematode Meloidogyne incognita race 2 in resistant and susceptible tomato cultivars (Gina VF, Falat CH, Falat 111, Karoon) during 2012-2013. Four-leaf tomato seedlings were used, grown in pots containing 1000 g of sterilized soil; each seedling receiving 20 ml of T. viride suspension containing 1×106 spores, 30 ml of P. fluorescens CHA0 with 109 cfu/ml, 5mM of salicylic acid and 2000 second stage nematode juveniles. Parameters relevant to nematode population and plant growth were evaluated. The biocontrol agents and salicylic acid were effective in nematode control in combined and single treatments. High reductions in root galling and egg mass indices were observed with combination of SA and biocontrol agents. The greatest increase in plant growth was obtained when cv. Falat CH was treated with SA followed by P. fluorescens CHA0 and T. viride. The highest number of galls was recorded in cv. Karoon, followed by cvs. Falat 111, Gina VF and Falat CH. Pseudomonas fluorescens CHA0 provoked the highest increase in fresh and dry root weight, fresh and dry shoot weight and plant length in all free nematode treatments. The results indicated that chemical inducer (salicylic acid), in combination with biocontrol agents (T. viride and P. fluorescens CHA0), stimulated and eventually increased plant growth.

Herança de resistência ao Meloidogyne incognita raça 2 em pepino

Root knot nematodes are among main problems in cucumber production, mainly in protected cultivation. The utilization of resistant cultivars is the most efficient and cheapest method of control. The objective of this research was to study the genetic inheritance of resistance to Meloidogyne incognita in cucumber. A cross between a inbred line obtained from Tsuyataro hybrid (L1), moderately resistant, and another from the Yoshinari hybrid (L2), susceptible to M. incognita race 2 was done. Population F1 (L1 x L2) between these two lines, generations F2 and F1BC1 were obtained for both lines (F1BC1L1 and F1BC1L2). Six treatments (two parental lines, generations F1, F2, F1BC1L1 and F1BC1L2) were evaluated in a complete block design with five replications. Plants were inoculated with the nematode (5,000 eggs per plant) after transplantation. At 60 days after inoculation gall and eggs mass index in root and reproduction factor (FR) were determined. Statistical-genetics analyses were performed according to the segregation obtained in generations F1, F2 and backcrossings to estimate the resistance of inheritance observed. The FR observed for line L2 (Yoshinari) was 7.21, more than twice of the observed for line L1 (Tsuyataro) that was 3.28. The partial resistance to M. incognita race 2 in ‘Tsuyataro’ cucumber is quantitative, with predominance of additive effects, with three main genes conditioning it.

Controle alternativo de nematoide das galhas (Meloidogyne incognita) raça 2, com óleos essenciais em solo

A ação de produtos naturais sobre fitopatógenos tem sido investigada visando-se avaliar sua eficácia no controle alternativo de doenças, principalmente na agricultura orgânica. O objetivo desse trabalho foi avaliar o efeito dos óleos essenciais de alecrim pimenta (Lippia sidoides) e capim citronela (Cymbopogonwinterianus) no controle de Meloidogyne incognita raça 2, em tomate (Solanumlycopersicum) e celósia (Celosia plicata). Para tanto, conduziu-se ensaio em esquema fatorial 6 x 2, com cinco repetições. O ensaio foi realizado em casa de vegetação do Setor de Fitossanidade do Departamento de Fitotecnia/CCA/UFC, no período de abril a junho de 2007. As mudas utilizadas neste ensaio foram transplantadas para vasos plástico contendo 2 kg de solo estéril, nos quais, 24 horas após o transplantio, foram inoculados com 4.000 ovos/J2 de M. incognita, raça 2, exceto as testemunhas negativas. Em 50% do número de vasos, aplicou-se, logo em seguida, 100 ml das soluções de cada óleo essencial em cada vaso na concentração de 2,5 ml L-1. Esperaram-se mais 48 horas para aplicação da mesma quantidade nos vasos restantes. Este volume corresponde a 60% da capacidade de campo desse substrato, que foi previamente calculada. A avaliação final do ensaio deu-se aos 45 dias após a inoculação. Analisou-se em relação ao nematoide: número de galhas (NG), número de ovos (NO), índice de massas de ovos (IMO), fator de reprodução (FR), redução no fator de reprodução (RFR). Quanto ao desenvolvimento das plantas mensurou-se: altura da planta, massa fresca e seca da parte aérea e massa fresca do sistema radicular. Verificou-se que a reprodução do nematoide, mostrou-se menos eficiente em tomate. Os óleos essenciais empregados reduziram a taxa reprodutiva do nematoide em 83 e 29%, em tomate e celósia, respectivamente. As épocas de aplicação dos óleos essenciais diferiram quanto à reprodução do nematoide, para número de galhas e fator de reprodução.

Resistance of sweet potato clones to meloidogyne incognita races 1 and 3

The objective of this study was to evaluate sweet potato clones for resistance to root-knot nematode, Meloidogyne incognita races 1 and 3. For each nematode physiological race, a greenhouse experiment was set up in a randomized block experimental design with three replications and six plants per plot. Fifty-eight sweet potato clones from the UFVJM germplasm bank were evaluated, plus five commercial cultivars (Brazlândia Rosada, Brazlândia Branca, Palmas, Princesa and Coquinho), plus the cv. Santa Clara tomato (susceptible to Meloidogyne spp.). Stems were planted in 72-cell expanded polystyrene trays, filled with commercial substrate and inoculated with the pathogen thirty days after planting. Forty-five days after inoculation, the eggs were extracted, counted, and later evaluated. Resistance level classification was performed based on reproduction factor (RF) and reproduction index (RI). Among the 63 analyzed clones, a percentage of 78% were classified as resistant to M. incognita race 1.79% to race 3 and 67% showed multiple resistance to both M. incognita races.

The Multi-Resistant Reaction of Drought-Tolerant Coffee 'Conilon Clone 14' to Meloidogyne spp. and Late Hypersensitive-Like Response in Coffea canephora.

Root-knot nematodes (RKN), Meloidogyne spp., have major economic impact on coffee production in Central and South America. Genetic control of RKN constitutes an essential part for integrated pest management strategy. The objective of this study was to evaluate the resistance of Coffea canephora genotypes (clones) to Meloidogyne spp. Sensitive and drought-tolerant coffee genotypes were used to infer their resistance using nematode reproduction factor and histopathology. Eight clonal genotypes were highly resistant to M. paranaensis. 'Clone 14' (drought-tolerant) and 'ESN2010-04' were the only genotypes highly resistant and moderately resistant, respectively, to both M. incognita races 3 and 1. Several clones were highly resistant to both avirulent and virulent M. exigua. Clone 14 and ESN2010-04 showed multiple resistance to major RKNs tested. Roots of 'clone 14' (resistant) and 'clone 22' (susceptible) were histologically studied against infection by M. incognita race 3 and M. paranaensis. Reduction of juvenile (J2) penetration in clone 14 was first seen at 2 to 6 days after inoculation (DAI). Apparent early hypersensitive reaction (HR) was seen in root cortex between 4 and 6 DAI, which led to cell death and prevention of some nematode development. At 12 to 20 DAI, giant cells formed in the vascular cylinder, besides normal development into J3/J4. From 32 to 45 DAI, giant cells were completely degenerated. Late, intense HR and cell death were frequently observed around young females and giant cells reported for the first time in coffee pathosystem. These results provide rational bases for future studies, including prospection, characterization, and expression profiling of genomic loci involved in both drought tolerance and resistance to multiple RKN species.

A CC-NBS-LRR type gene GHNTR1 confers resistance to southern root-knot nematode in Nicotiana.benthamiana and Nicotiana.tabacum

Root-knot nematodes are obligate parasites that invade the roots of agricultural plants and induce the formation of specialized feeding structures, especially races 3 and 4 of the southern root-knot nematode. However, not much is known about the defense mechanisms of plants against the invasion of M. incognita race 1. In this study, we characterized and performed functional analysis of the CC-NBS-LRR domain gene, GHNTR1. Using the GHNTR1 promoter to drive the GUS marker gene, we found that GUS expression was high in the roots and shoots of seedlings, four leaves stages, and mature stages. When GHNTR1 was transiently expressed in Nicotiana. benthamiana and Nicotiana. tabacum, necrosis was observed in the leaves and detectable amounts of H2O2 had accumulated when compared to the control plants. Stable transformation of N. benthamiana with the GHNTR1 gene using Agrobacterium induced the expression of defense marker genes PR1, PR2, LOX, and ERF1. In addition, the transgenic N. benthamiana and N. tabacum plants exhibited higher resistance to M. incognita infection. When transgenic N. tabacum were challenged with M. incognita, callose deposition and peroxide accumulation were observed in the roots by aniline-blue and DAB staining, respectively. Sequencing and bioinformatic analysis of small RNA revealed 48 miRNAs were up-regulated and 32 miRNAs were down-regulated. Further, 345 genes were predicted as targets of miRNAs and these included genes that are involved in cell death, death, and stress response. Thus, GHNTR1 is the first gene isolated from cotton that confers resistance against M. incognita and it induced a series of hypersensitive responses in transgenic tobacco. These findings improve our understanding of the molecular mechanisms of the response of upland cotton to M. incognita infection.

Root-knot Control and Yield Response of Corn with Seed Treatment and Granular Nematicides

In Coastal Plain soils of the southeastern United States, the root-knot nematode (RKN) Meloidogyne incognita race 3 causes significant yield loss in corn. Impact of abamectin + thiamethoxam and clothianidin + Bacillus firmus I-1582 nematicide seed treatments along with terbufos granular nematicide on RKN reproduction, plant populations, plant growth, and yield was assessed at two Alabama sites. Thiamethoxam and clothianidin insecticide seed treatments were included as controls. A factorial arranged as split-split plot with year as the main plot, seed treatment as the split plot, and granular nematicide as the split-split-plot treatment was used. Lower plant populations were noted for terbufos-treated corn at one study site. Reduced RKN reproduction was observed with terbufos granular nematicide at both study sites. Fresh seedling weights and yields were usually higher for the terbufos- than non-terbufos-treated corn. At both sites, both nematicide seed treatments and their insecticide seed treatment counterparts had similar plant populations, RKN reproduction rate, and fresh seedling weights. Yield differences were noted at both locations between abamectin + thiamethoxam and thiamethoxam but not clothianidin + Bacillus firmus I-1582 and clothianidin. With mean yield gains up to 13.5%, terbufos was superior to both of the nematicide seed treatments for managing RKN and protecting corn yields. Accepted for publication 19 October 2015. Published 1 November 2015.

Nematode resistance in bitter gourd to Meloidogyne incognita

Bitter gourd (Momordica balsamina L.) – indigenous to tropical areas of Africa – has nutritional, ethnomedicinal, neutraceutical and pesticidal attributes which are potentially attractive to various industries with bias towards rural development. However, the southern root-knot nematode (Meloidogyne incognita, Kofoid & White, Chitwood) and its biological races constitute serious limitation to successful introduction of alternative crops with economic attributes, particularly when the target plants have limited degree of nematode resistance. A pot trial was therefore conducted to determine the degree of nematode resistance in M. balsamina seedlings to M. incognita race 2. Seedlings were inoculated at seven levels of M. incognita race 2, which were laid out in a randomised complete block design, with 12 replications. After three nematode generations, the mean reproductive factor (RF = Pf/Pi) values at all levels of inoculation were less than unity, while nematode infection had no effect on growth of M. balsamina seedlings, which suggested that this plant was resistant to the test nematode. In conclusion, due to its resistance to M. incognita race 2, M. balsamina could serve as an alternative crop for use as vegetable, ethnomedicinal and/or neutraceutical plant in rural communities with high populations of M. incognita race 2.

Phenotypic variability and response of Brazilian oat genotypes to different species of root-knot and root-lesion nematodes

In Brazil, oat (Avena sativa) is widely cultivated as a winter crop mainly in the south region. However, there are several species of nematodes that are of economic importance to oats and knowledge about the reaction of cultivars to root-knot and root-lesion nematodes is sparse. Thereby, in this present work we aimed to characterize the host response of some selected oat genotypes to Meloidogyne incognita (Mi) race 3, M. javanica (Mj), M. paranaensis (Mp), M. enterolobii (Me), and P. brachyurus (Pb) under greenhouse conditions, based on the nematode reproductive factor (RF) and number of nematodes per gram of roots [nem (g root)−1]. We also determined the variance components associated with root-knot and root-lesion resistance. Results revealed variation in the susceptibility of cultivars to nematodes tested, except for M. enterolobii, in which all cultivars tested were highly resistant. The cultivar IPR Afrodite was the most resistant to root knot species (Mi race 3, Mj, Mp and Me), whereas all cultivars tested were considered susceptible to Pb. Data of nem (g root)−1 confirmed the characterization of the cultivars based on RF values.

Reação de genótipos de Capsicum ao nematoide-das-galhas

O objetivo desta pesquisa foi avaliar a reação de híbridos porta-enxerto experimentais de Capsicum annuum ['Hibrido Experimental (HE)' e seu Recíproco (HER)] e genótipos elite do programa de melhoramento da Embrapa Hortaliças de C. chinense, C. frutescense C. baccatumà Meloidogyne incognita raça 1, M. javanica e M. enterolobii. Como testemunha suscetível a M. incognita raça 1 e resistente a M. javanicafoi utilizado o híbrido de pimentão 'Magali R', e como testemunhas resistentes a M. incognita raça 1 e M. javanicaforam utilizados os porta-enxertos 'Silver' e 'Snooker'. Para confirmar a viabilidade do inóculo foi utilizado o tomateiro 'Rutgers'. Dois experimentos foram conduzidos em casa de vegetação, em delineamento inteiramente casualizado com seis repetições. Plântulas com 30 dias de idade foram transplantadas para vasos de 2,0 L contendo substrato composto de solo, areia, esterco de gado e palha de arroz carbonizada (1:1:1:1). As plantas foram inoculadas após o transplantio com a deposição de 5,0 mL de suspensão, contendo 5.000 ovos e J2 de cada espécie. Setenta dias após foram avaliados o índice de massa de ovos e de galhas, o número de ovos por grama de raiz e o fator de reprodução. Os híbridos de C. annuum apresentaram resistência a M. incognita e M. javanica e suscetibilidade a M. enterolobii, assim como as testemunhas 'Silver' e 'Snooker'. O híbrido 'Magali R' apresentou resistência somente a M. javanica. Os genótipos de C. chinense e C. baccatumapresentaram suscetibilidade às três espécies, enquanto genótipos de C. frutescens apresentaram suscetibilidade somente a M. enterolobii.Os híbridos experimentais de pimentão e a maioria dos genótipos de C. frutescens avaliados poderão ser utilizados em áreas de cultivo protegido infestadas com M. incognitaraça 1 e M. javanica. Entretanto, a busca por genótipos resistentes a M. enterolobii, bem como o desenvolvimento e a adoção de estratégias de controle é de suma importância.

Root-knot Nematode Resistance, Yield, and Fruit Quality of Specialty Melons Grafted onto Cucumis metulifer

Interest in specialty melons (Cucumis melo) with distinctive fruit characteristics has grown in the United States in recent years. However, disease management remains a major challenge in specialty melon production. In this study, grafting experiments were conducted to determine the effectiveness of using Cucumis metulifer, a species known for its genetic resistance to root-knot nematodes (RKNs; Meloidogyne spp.), as a potential rootstock for managing RKNs in susceptible specialty melon cultivars. In the greenhouse experiment, honeydew melon ‘Honey Yellow’ was grafted onto C. metulifer and inoculated with M. incognita race 1. The grafted plants exhibited significantly lower gall and egg mass indices and fewer eggs compared with non- and self-grafted ‘Honey Yellow’. Cucumis metulifer was further tested as a rootstock in conventional and organic field trials using honeydew melon ‘Honey Yellow’ and galia melon ‘Arava’ as scions. ‘Honey Yellow’ and ‘Arava’ grafted onto C. metulifer exhibited significantly lower galling and reduced RKN population densities in the organic field; however, total and marketable fruit yields were not significantly different from non- and self-grafted plants. Although the improvement of RKN resistance did not translate into yield enhancements, incorporating grafted specialty melons with C. metulifer rootstock into double-cropping systems with RKN-susceptible vegetables may benefit the overall crop production by reducing RKN population densities in the soil. At the conventional field site, which was not infested with RKNs, ‘Honey Yellow’ grafted onto C. metulifer rootstock had a significantly lower total fruit yield than non-grafted ‘Honey Yellow’ plants; however, fruit yields were similar for ‘Arava’ grafted onto C. metulifer rootstock and non-grafted ‘Arava’ plants. Although no significant impacts on the fruit quality attributes of ‘Honey Yellow’ were observed, grafting onto C. metulifer decreased the flesh firmness of ‘Arava’ in both field trials and resulted in a reduction in total soluble solids content under conventional production. In summary, grafting RKN-susceptible melons onto C. metulifer rootstock offers promise for growing these specialty melons; however, more studies are needed to elucidate the scion–rootstock interaction effect on fruit yield and quality.

Management of Root-Knot Disease on Tomato with Bioformulated Paecilomyces lilacinus and Leaf Extract of Lantana camara

Glasshouse experiments were conducted to evaluate the efficacy of application frequency of a bioformulated Paecilomyces lilacinus in combination with five concentration of Lantana camara crude aqueous leaf extract against Meloidogyne incognita race I on tomato. The experiment was a 3x5 factorial laid out in a completely randomized design (CRD) with four replications. Each seedling was inoculated with 5000 eggs of M. incognita. Application of the bionematicide and L. camara leaf extract alone significantly (P≤ 0.05) inhibited root galling and egg production compared with their respective control. However, the severity of root galling and egg mass production was more significantly (P< 0.05) suppressed with the application of P. lilacinus than L. camara leaf extract. Double inoculation with P. lilacinus in combination with 0.80 g mL-1 of the L. camara leaf extract changed the susceptibility of the tomato cultivar with gall index (GI=4.00) to GI=1.50. Application of P. lilacinus twice (at transplanting and two weeks after transplanting) in combination with 0.80g mL-1 of L. camara leaf extract was the most effective treatment in gall and egg mass inhibition, growth enhancement and dry matter accumulation. This environment-friendly approach could be incorporated into integrated root-knot disease management in tomato.