Screening of the hatching control of root-knot nematodes using extract concentrations from oat genotypes

Even though oats (Avena spp.) have the capacity to produce numerous compounds with the potential to act antagonistically against plant pathogens, studies on the genotypic effect of this crop focusing on their nematicidal activity are limited. The objective of this study was to verify the effect of the aqueous extracts prepared with the biomass of oat genotypes, on the hatching of second-stage juveniles of root-knot nematodes (Meloidogyne javanica and Meloidogyne incognita). The bioassays were carried out in a completely randomized design with four replications. Eighteen extracts were evaluated, consisting of a combination of six oat genotypes Agro Quaraí, Agro Esteio, Embrapa 139, AF 12202, UPFPS Farroupilha, and AF 1345 Ucraniana, and three extract concentrations (5 %, 10 %, and 20 % w/v). Three additional treatments were added to the study (distilled water, chemical nematicides abamectin, and imidacloprid + thiodicarb). The treatments and the suspension containing nematode eggs were placed in Petri dishes and incubated in a growth chamber for ten days. At the 5 % and 10 % w/v concentration levels, a genotype effect was observed in the hatching of juveniles for both nematode species. For the control of M. javanica the extracts of Embrapa 139 had a better performance, while the extracts of Agro Quaraí and AF1345 Ucraniana performed better when under the control of M. incognita. Thus, oat biomass formation might have the ability to suppress the nematode population in the soil, and could therefore, be used for the management of root-knot nematodes.

Soybean development under different Aphelenchoides besseyi and Meloidogyne incognita populations / Desenvolvimento da soja sob diferentes populações de Aphelenchoides besseyi e Meloidogyne incognita

The green stem Aphelenchoides besseyi and gall Meloidogyne incognita phytonematodes cause soybean yield losses. Thus, the objective of this study was to evaluate the effects of different populations of A. besseyi and M. incognita on soybeans. The experiment had 10 treatment groups [T1: control, T2: A. besseyi (500), T3: M. incognita (2,000), T4: A. besseyi (250) + M. incognita (2,000), T5: A. besseyi (500) + M. incognita (2,000), T6: A. besseyi (250) + M. incognita (4000), T7: A. besseyi (500) + M. incognita (4,000) individuals, T8: A. besseyi (250) + M. incognita (8,000), T9: A. besseyi (500) + M. incognita (5,000), and T10: A. besseyi (1,000) + M. incognita (8,000) individuals] with six replicates. Inoculations were done on day 10 after soybean germination, and evaluations were conducted after 60 d. Plant height, shoot fresh weight, root fresh weight, number of pods (NP), pod fresh weight, number of grains (NG), grain yield (GY), amount of A. besseyi in the shoot, and M. incognita in the roots were analyzed. The 500 A. besseyi + 8,000 M. incognita treatment reduced all variables and led to considerable damage to soybean development. In addition, GY, NG, and NP were reduced in the different nematode population density groups, influencing soybean agronomic characteristics.(AU)

Entre as espécies de fitonematoides que provocam perdas de produção à cultura da soja estão os nematoides da haste verde (Aphelenchoides besseyi) e o das galhas (Meloidogyne incognita). Diante disso, o objetivo deste trabalho foi estudar os efeitos de diferentes níveis populacionais de A. besseyi e M. incognita na soja. O experimento foi realizado com nove combinações de diferentes níveis populacionais dos nematoides (T1 ­ Controle não inoculado, T2 - A. besseyi 500 indivíduos, T3 - M. incognita 2000 indivíduos, T4 - A. besseyi + M. incognita 250 + 2000 indivíduos, T5 - A. besseyi + M. incognita 500 + 2000 indivíduos, T6 - A. besseyi + M. incognita 250 + 4000 indivíduos, T7 - A. besseyi + M. incognita 500 + 4000 indivíduos, T8 - A. besseyi + M. incognita 250 + 8000 indivíduos, T9 - A. besseyi + M. incognita 500 + 8000 indivíduos e T10 - A. besseyi + M. incognita 1000 + 8000 indivíduos) e seis repetições. As variáveis analisadas foram: altura de planta, massa fresca da parte aérea (MPA), massa fresca de raízes (MR), número de vagens (V), massa fresca de vagens (MV), número de grãos (G), massa fresca de grãos (MG), quantidade de A. besseyi na parte aérea e de M. incognita nas raízes. O mapa de calor indicou que populações iniciais inoculadas de 500 A. besseyi + 8000 M. incognita apresentou maiores danos ao desenvolvimento da soja, reduzindo todas as variáveis analisadas. As variáveis MG, G e V reduziram na presença de diferentes densidades populacionais das espécies de fitonematoides nematoides, influenciando negativamente o desenvolvimento da soja.(AU)

Phytonematodes infesting common bean fields in Brazil, and pathogenicity tests with Pratylenchus brachyurus

ABSTRACT Phytonematodes are among the main pathogens of the common bean. In general, control practices that aim to control these pathogens have not been regularly adopted in Brazil. The objectives of the present study were to evaluate the occurrence of phytonematodes in dry bean fields in Paraná and São Paulo states and estimate the pathogenicity of Pratylenchus brachyurus to dry bean in glasshouse experiments. Root and soil were sampled for nematode extraction, identification and estimation of population density. Four glasshouse experiments with different initial population densities were carried out to evaluate the effect of P. brachyurus on the growth of dry bean plants. Six species of phytonematodes were detected, namely Helicotylenchus dihystera, P. brachyurus, Pratylenchus crenatus, Meloidogyne javanica, Meloidogyne incognita and Rotylenchulus sp. The spiral nematode H. dihystera was found in all samples and was the most abundant species in both states. The lesion nematode P. brachyurus was also frequent, reaching 94% in Paraná and 100% in São Paulo. The root-knot nematodes and Rotylenchulus sp. were reported only in São Paulo fields (45% and 18% frequency, respectively), and P. crenatus only in Paraná (12%). The most abundant nematode in the soil was H. dihystera, and in roots was P. crenatus. It was demonstrated that densities of 6.66 specimens of P. brachyurus per cm3 of soil provoke visible and measurable root decay. In conclusion, survey data showed low phytonematode densities and pathogenicity tests demonstrated that densities above 6.67 specimens of P. brachyurus per cm3 of soil cause damage to the dry bean roots.

Occurrence of Meloidogyne enterolobii in common bean in southern Goiás State, Brazil / Ocorrência de Meloidogyne enterolobii em feijoeiro no Sul Goiano

ABSTRACT: Meloidogyne enterolobii is known as the most aggressive root-knot nematode (RKN) in Brazil. Common bean (Phaseolus vulgaris) cultivated in the experimental field in Morrinhos, Southern Goiás State, exhibited symptoms typical to those caused by RKN. In order to clarify the etiology of the disease, root systems were analyzed. Typical galls of varying thickness were observed, with thickening larger than 3 cm in diameter containing RKN females inside roots and egg masses on the root surface. The identification of the nematode species was confirmed by isoenzyme electrophoresis (esterase and malate dehydrogenase phenotypes). This is the first report of M. enterolobii in Goiás and in Brazil parasitizing common bean under field conditions. This result is an alert to producers and to the State phytosanitary defense authorities, in order to prevent the further dissemination of this pest, especially in fields of common bean and industrial tomato in the State.

RESUMO: Meloidogyne enterolobii é considerada uma das espécies de nematoide de galhas mais agressivas presentes no Brasil. Feijoeiro (Phaseolus vulgaris) cultivado em um campo experimental em Morrinhos, na região sul do estado de Goiás, apresentou sintomas característicos de nematoide de galhas radiculares. Para esclarecer a etiologia da doença, os sistemas radiculares foram analisados. Foram observadas galhas típicas da infecção por Meloidogyne spp., com espessuras maiores que 3 cm de diâmetro, contendo em seu interior fêmeas e massas de ovos na superfície radicular. A identificação foi realizada por meio da eletroforese de isoenzimas (fenótipos esterase e malato desidrogenase). Este é o primeiro relato da diagnose em condições natural de campo de M. enterolobii em Goiás e no Brasil parasitando feijoeiro. Esta ocorrência deve servir de alerta aos produtores e às autoridades de defesa fitossanitária do Estado, a fim de impedir a disseminação desse patógeno, principalmente nos campos da produção de feijoeiro e tomate industrial em Goiás.

Host status of eucalypt species to Pratylenchus brachyurus and Meloidogyne incognita

ABSTRACT Plant parasitic nematodes are major threats to Brazilian and world agriculture. Among them, Pratylenchus brachyurus and Meloidogyne incognita stand out as major pests for several crops, including corn, cotton, soybean among others, which can be components of integrated crop-livestock-forestry systems (ICLFs). In this context, information about the host status of eucalypts (Corymbia spp. and Eucalyptus spp.) to plant parasitic nematodes becomes more relevant in Brazil, due to the use of eucalypts in ICLFs. If tree components used on this system increase the population density of P. brachyurus and M. incognita, it is possible that these pathogens could damage shorter-cycle crops. Since information about the host status of eucalypts to plant parasitic nematodes is scarce, this study evaluated the host status of some eucalypt species to P. brachyurus and M. incognita. Two greenhouse trials were done to evaluate the reproduction of P. brachyurus and one to M. incognita, using some of the most cultivated species and hybrids of eucalypts in Brazil. The population growth of P. brachyurus increased on Corymbia citriodora, Eucalyptus grandis, Eucalyptus dunnii × Eucalyptus urophylla, and E. grandis × E. urophylla after ~90 days of inoculation. Conversely, despite M. incognita reproducing well in the control plants, no individuals were recovered from C. citriodora, E. urophylla and E. grandis × E. urophylla, which were classified as resistant plants. Based on both obtained and available data, M. incognita poses no threat to eucalypt species today. However, P. brachyurus is suggested to be a threat to eucalypts.

Evaluation of eggplant and gilo genotypes and interspecific hybrids as to root-knot nematode resistance / Avaliação de genótipos de berinjela e jiló e híbridos interespecíficos quanto a resistência a nematoides das galhas

No Brasil, as culturas da berinjela e do jiló são importantes para a economia de pequenas propriedades localizadas principalmente nos estados do Sudeste, bem como de outras regiões, com expressivo volume de produção o ano todo nos mercados atacadistas locais. No entanto, essas espécies são muito suscetíveis aos nematoides das galhas e há poucas ou quase nenhuma fonte conhecida de resistência. Desta forma, o objetivo do presente estudo foi buscar fontes de resistência aos nematoides das galhas em genótipos de berinjela e jiló; bem como em híbridos interespecíficos para uso como porta-enxertos. Foram realizados três experimentos: no primeiro, realizado em 2013,foram avaliados 10 acessos experimentais de berinjela, um híbrido entre berinjela e jiló, e um híbrido de Solanum stramonifolium com berinjela para a reação ao Meloidogyne enterolobii. No segundo, em 2016, foram avaliados 20 acessos experimentais de jiló, para a reação ao M. incognita, M. javanica eM. enterolobii. E no terceiro, em 2017, foram avaliados um acesso e dois híbridos experimentais de berinjela, e um híbrido de Solanum scuticum com berinjela, para a reação ao M. incognita, e M. enterolobii. Ambos ensaios foram conduzidos em casa de vegetação, e caracteres relacionados à infeção das raízes pelos nematoides foram avaliados em delineamento inteiramente casualizado, com seis repetições, sendo a unidade experimental uma planta cultivada em um vaso contendo 1,5 L de substrato inoculado com cada espécie de nematoide. Foi verificado que: 1-todos os acessos avaliados de berinjela foram suscetíveis ao M. incognitae ao M. enterolobii, no entanto, o acesso BER 3150 apresentou menor grau de suscetibilidade ao M. incognita. 2-os genótipos de jiló CNPH 056, CNPH 070, CNPH 220 e CNPH 363 apresentaram melhor resposta a M. incógnita e M. javanicado que o padrão de suscetibilidade, o tomateiro ‘Rutgers’. 3-os acessos de jiló CNPH 070, CNPH 219 e CNPH 387, apresentaram resposta melhor ou equivalente ao tomateiro resistente ‘Nemadoro’ para M. enterolobii. 4-o híbrido interespecífico BER EG203 x S. scuticum, pode ser recomendado como porta-enxerto para materiais de berinjela muito suscetíveis ao M. incognita; bem como a solanacea silvestre S. stramonifoliumvar. inerme para o M. enterolobii.

In Brazil, eggplant and gilo are important for the economy of small-scale farms located mainly in the southeast states and other regions, with a significant production volume year-round in the wholesale local markets. However, these species are very susceptible to root-knot nematodes, and there are few or almost none known sources of resistance. The objective of this studywas to prospect sources of resistance to root-knot nematodes in eggplant, scarlet eggplant (gilo), as well in interspecific hybrids between these species and with wildSolanumspecies, to be used as rootstocks. In the first experiment, in 2013,10 eggplant accessions, a hybrid between eggplant and gilo, and a Solanum stramonifolium x eggplant hybrid, were evalu41atedfor their reaction to Meloidogyne enterolobii. In the second, in 2016, 20 accessions of gilo were evaluated for their reaction to M. incognita, M. javanica,and M. enterolobii.. And in the third experiment, in 2017,one access and two experimental eggplant hybrids, and one Solanum scuticumx eggplant hybrid, were evaluated for their reaction to M. incognita, and M. enterolobii. All the trials were stablished in a green house, and characters related to root infection were evaluated in a completely randomized design with six replications of one plant per pot, using a 1.5 L pots filled with a mixed substrate inoculated with each nematode species. It was found that all eggplant accessions were susceptible to M. incognita and M. enterolobii, however, BER 3150 presented lower susceptibility to M. incognita. The gilogeno types CNPH 056, CNPH 070, CNPH 220,and CNPH 363 shown better response to M. incognita and M. javanica than the susceptibility pattern, the tomato 'Rutgers'. Other gilo accessions CNPH 070, CNPH 219,and CNPH 387 showed better or equivalent response thanthe resistant tomato 'Nemadoro' for M. enterolobii.4-the BER EG203 x S. scuticuminterspecific hybrid can be recommended as a rootstock for eggplant susceptible to M. incognita, as well the wild S. stramonifolium var. inerme species for M. enterolobii.

Evaluation of eggplant and gilo genotypes and interspecific hybrids as to root-knot nematode resistance / Avaliação de genótipos de berinjela e jiló e híbridos interespecíficos quanto a resistência a nematoides das galhas

No Brasil, as culturas da berinjela e do jiló são importantes para a economia de pequenas propriedades localizadas principalmente nos estados do Sudeste, bem como de outras regiões, com expressivo volume de produção o ano todo nos mercados atacadistas locais. No entanto, essas espécies são muito suscetíveis aos nematoides das galhas e há poucas ou quase nenhuma fonte conhecida de resistência. Desta forma, o objetivo do presente estudo foi buscar fontes de resistência aos nematoides das galhas em genótipos de berinjela e jiló; bem como em híbridos interespecíficos para uso como porta-enxertos. Foram realizados três experimentos: no primeiro, realizado em 2013,foram avaliados 10 acessos experimentais de berinjela, um híbrido entre berinjela e jiló, e um híbrido de Solanum stramonifolium com berinjela para a reação ao Meloidogyne enterolobii. No segundo, em 2016, foram avaliados 20 acessos experimentais de jiló, para a reação ao M. incognita, M. javanica eM. enterolobii. E no terceiro, em 2017, foram avaliados um acesso e dois híbridos experimentais de berinjela, e um híbrido de Solanum scuticum com berinjela, para a reação ao M. incognita, e M. enterolobii. Ambos ensaios foram conduzidos em casa de vegetação, e caracteres relacionados à infeção das raízes pelos nematoides foram avaliados em delineamento inteiramente casualizado, com seis repetições, sendo a unidade experimental uma planta cultivada em um vaso contendo 1,5 L de substrato inoculado com cada espécie de nematoide. Foi verificado que: 1-todos os acessos avaliados de berinjela foram suscetíveis ao M. incognitae ao M. enterolobii, no entanto, o acesso BER 3150 apresentou menor grau de suscetibilidade ao M. incognita. 2-os genótipos de jiló CNPH 056, CNPH 070, CNPH 220 e CNPH 363 apresentaram melhor resposta a M. incógnita e M. javanicado que o padrão de suscetibilidade, o tomateiro ‘Rutgers. 3-os acessos de jiló CNPH 070, CNPH 219 e CNPH 387, apresentaram resposta melhor ou equivalente ao tomateiro resistente ‘Nemadoro para M. enterolobii. 4-o híbrido interespecífico BER EG203 x S. scuticum, pode ser recomendado como porta-enxerto para materiais de berinjela muito suscetíveis ao M. incognita; bem como a solanacea silvestre S. stramonifoliumvar. inerme para o M. enterolobii.(AU)

In Brazil, eggplant and gilo are important for the economy of small-scale farms located mainly in the southeast states and other regions, with a significant production volume year-round in the wholesale local markets. However, these species are very susceptible to root-knot nematodes, and there are few or almost none known sources of resistance. The objective of this studywas to prospect sources of resistance to root-knot nematodes in eggplant, scarlet eggplant (gilo), as well in interspecific hybrids between these species and with wildSolanumspecies, to be used as rootstocks. In the first experiment, in 2013,10 eggplant accessions, a hybrid between eggplant and gilo, and a Solanum stramonifolium x eggplant hybrid, were evalu41atedfor their reaction to Meloidogyne enterolobii. In the second, in 2016, 20 accessions of gilo were evaluated for their reaction to M. incognita, M. javanica,and M. enterolobii.. And in the third experiment, in 2017,one access and two experimental eggplant hybrids, and one Solanum scuticumx eggplant hybrid, were evaluated for their reaction to M. incognita, and M. enterolobii. All the trials were stablished in a green house, and characters related to root infection were evaluated in a completely randomized design with six replications of one plant per pot, using a 1.5 L pots filled with a mixed substrate inoculated with each nematode species. It was found that all eggplant accessions were susceptible to M. incognita and M. enterolobii, however, BER 3150 presented lower susceptibility to M. incognita. The gilogeno types CNPH 056, CNPH 070, CNPH 220,and CNPH 363 shown better response to M. incognita and M. javanica than the susceptibility pattern, the tomato 'Rutgers'. Other gilo accessions CNPH 070, CNPH 219,and CNPH 387 showed better or equivalent response thanthe resistant tomato 'Nemadoro' for M. enterolobii.4-the BER EG203 x S. scuticuminterspecific hybrid can be recommended as a rootstock for eggplant susceptible to M. incognita, as well the wild S. stramonifolium var. inerme species for M. enterolobii.(AU)

Control of Meloidogyne paranaensis mediated by silicon

The potential of silicon (Si) to control nematodes is often reported in association with the resistance induction mechanism. The objective of this work was to evaluate the hypothesis of resistance induction in plants against nematodes through the application of Si. In vitro experiments were carried out to evaluate the effect of Si and potassium chloride (KCl) on the hatching and mortality of Meloidogyne paranaensis juveniles. For the purpose of a greenhouse experiment, tomato plants were used as a model for bifurcated roots, using the respective control treatments, KCl and distilled water. Ten days after treatment, 2,000 eggs of M. paranaensis were inoculated. At 55 days post-inoculation, the reproduction factor and number of nematodes per gram of root were evaluated. Additionally, the tissue nutrient concentration and gas exchange variables were analyzed. Silicon reduces nematode viability, when in direct contact with the nematode in in vitro experiments and in bifurcated plants. When plants were treated with Si on one side of the root, no nematode control was observed on the opposite corresponding side. Results suggested that Si has a positive effect on the reduction of M. paranaensis population, but probably induced resistance to nematode only through direct action.

Control of Meloidogyne paranaensis mediated by silicon

The potential of silicon (Si) to control nematodes is often reported in association with the resistance induction mechanism. The objective of this work was to evaluate the hypothesis of resistance induction in plants against nematodes through the application of Si. In vitro experiments were carried out to evaluate the effect of Si and potassium chloride (KCl) on the hatching and mortality of Meloidogyne paranaensis juveniles. For the purpose of a greenhouse experiment, tomato plants were used as a model for bifurcated roots, using the respective control treatments, KCl and distilled water. Ten days after treatment, 2,000 eggs of M. paranaensis were inoculated. At 55 days post-inoculation, the reproduction factor and number of nematodes per gram of root were evaluated. Additionally, the tissue nutrient concentration and gas exchange variables were analyzed. Silicon reduces nematode viability, when in direct contact with the nematode in in vitro experiments and in bifurcated plants. When plants were treated with Si on one side of the root, no nematode control was observed on the opposite corresponding side. Results suggested that Si has a positive effect on the reduction of M. paranaensis population, but probably induced resistance to nematode only through direct action.(AU)

Phytonematodes infesting common bean fields in Brazil, and pathogenicity tests with Pratylenchus brachyurus

Phytonematodes are among the main pathogens of the common bean. In general, control practices that aim to control these pathogens have not been regularly adopted in Brazil. The objectives of the present study were to evaluate the occurrence of phytonematodes in dry bean fields in Paraná and São Paulo states and estimate the pathogenicity of Pratylenchus brachyurus to dry bean in glasshouse experiments. Root and soil were sampled for nematode extraction, identification and estimation of population density. Four glasshouse experiments with different initial population densities were carried out to evaluate the effect of P. brachyurus on the growth of dry bean plants. Six species of phytonematodes were detected, namely Helicotylenchus dihystera, P. brachyurus, Pratylenchus crenatus, Meloidogyne javanica, Meloidogyne incognita and Rotylenchulus sp. The spiral nematode H. dihystera was found in all samples and was the most abundant species in both states. The lesion nematode P. brachyurus was also frequent, reaching 94% in Paraná and 100% in São Paulo. The root-knot nematodes and Rotylenchulus sp. were reported only in São Paulo fields (45% and 18% frequency, respectively), and P. crenatus only in Paraná (12%). The most abundant nematode in the soil was H. dihystera, and in roots was P. crenatus. It was demonstrated that densities of 6.66 specimens of P. brachyurus per cm3 of soil provoke visible and measurable root decay. In conclusion, survey data showed low phytonematode densities and pathogenicity tests demonstrated that densities above 6.67 specimens of P. brachyurus per cm3 of soil cause damage to the dry bean roots.

Host status of eucalypt species to Pratylenchus brachyurus and Meloidogyne incognita

Plant parasitic nematodes are major threats to Brazilian and world agriculture. Among them, Pratylenchus brachyurus and Meloidogyne incognita stand out as major pests for several crops, including corn, cotton, soybean among others, which can be components of integrated crop-livestock-forestry systems (ICLFs). In this context, information about the host status of eucalypts (Corymbia spp. and Eucalyptus spp.) to plant parasitic nematodes becomes more relevant in Brazil, due to the use of eucalypts in ICLFs. If tree components used on this system increase the population density of P. brachyurus and M. incognita, it is possible that these pathogens could damage shorter-cycle crops. Since information about the host status of eucalypts to plant parasitic nematodes is scarce, this study evaluated the host status of some eucalypt species to P. brachyurus and M. incognita. Two greenhouse trials were done to evaluate the reproduction of P. brachyurus and one to M. incognita, using some of the most cultivated species and hybrids of eucalypts in Brazil. The population growth of P. brachyurus increased on Corymbia citriodora, Eucalyptus grandis, Eucalyptus dunnii × Eucalyptus urophylla, and E. grandis × E. urophylla after ~90 days of inoculation. Conversely, despite M. incognita reproducing well in the control plants, no individuals were recovered from C. citriodora, E. urophylla and E. grandis × E. urophylla, which were classified as resistant plants. Based on both obtained and available data, M. incognita poses no threat to eucalypt species today. However, P. brachyurus is suggested to be a threat to eucalypts.

Distribution of Meloidogyne species in carrot in Brazil / Distribuição de espécies de Meloidogyne em cenoura no Brasil

Root-knot nematodes (RKN - Meloidogyne spp.) are one of the most serious threats to carrot production worldwide. In Brazil, carrots are grown throughout the year, and economic losses due to RKN are reported. Since little is known on the distribution of RKN species in carrot fields in Brazil, we collected plant and soil samples from 35 fields across six states. Based on the morphology of perineal patterns, esterase phenotypes and species-specific PCR, three Meloidogyne species were identified: 60% of the fields were infested with Meloidogyne incognita, M. javanica was reported in 42.9% of the areas, whereas M. hapla was detected in 17.1% of carrot fields. Mixed populations were reported in 20% of the areas with a predominance of M. incognita + M. javanica. The combination of morphological, biochemical, and molecular techniques is a useful approach to identify RKN species.(AU)

Os nematoides-das-galhas (RKN - Meloidogyne spp.) são uma das mais sérias ameaças à produção de cenoura no mundo. No Brasil, as cenouras são cultivadas ao longo do ano, e as perdas econômicas devido à RKN são frequentemente relatadas. Como pouco se sabe sobre a distribuição de espécies RKN em campos de cenoura no Brasil, coletamos amostras de plantas e solo de 35 campos em seis estados. Baseado na morfologia do padrão perineal, fenótipos de esterase e/ou PCR espécie-específica, três espécies de Meloidogyne foram identificadas: 60% dos campos estavam infestados por Meloidogyne incognita, M. javanica foi encontrada em 42,9% das áreas, enquanto M. hapla foi detectada em 17,1% dos campos de cenoura. Populações mistas foram encontradas em 20% das áreas, com predominância de M. incognita + M. javanica. A combinação de técnicas morfológicas, bioquímicas e moleculares é uma abordagem útil para identificar espécies de RKN.(AU)

Occurrence of Meloidogyne enterolobii in common bean in southern Goiás State, Brazil / Ocorrência de Meloidogyne enterolobii em feijoeiro no Sul Goiano

Meloidogyne enterolobii is known as the most aggressive root-knot nematode (RKN) in Brazil. Common bean (Phaseolus vulgaris) cultivated in the experimental field in Morrinhos, Southern Goiás State, exhibited symptoms typical to those caused by RKN. In order to clarify the etiology of the disease, root systems were analyzed. Typical galls of varying thickness were observed, with thickening larger than 3 cm in diameter containing RKN females inside roots and egg masses on the root surface. The identification of the nematode species was confirmed by isoenzyme electrophoresis (esterase and malate dehydrogenase phenotypes). This is the first report of M. enterolobii in Goiás and in Brazil parasitizing common bean under field conditions. This result is an alert to producers and to the State phytosanitary defense authorities, in order to prevent the further dissemination of this pest, especially in fields of common bean and industrial tomato in the State.

Meloidogyne enterolobii é considerada uma das espécies de nematoide de galhas mais agressivas presentes no Brasil. Feijoeiro (Phaseolus vulgaris) cultivado em um campo experimental em Morrinhos, na região sul do estado de Goiás, apresentou sintomas característicos de nematoide de galhas radiculares. Para esclarecer a etiologia da doença, os sistemas radiculares foram analisados. Foram observadas galhas típicas da infecção por Meloidogyne spp., com espessuras maiores que 3 cm de diâmetro, contendo em seu interior fêmeas e massas de ovos na superfície radicular. A identificação foi realizada por meio da eletroforese de isoenzimas (fenótipos esterase e malato desidrogenase). Este é o primeiro relato da diagnose em condições natural de campo de M. enterolobii em Goiás e no Brasil parasitando feijoeiro. Esta ocorrência deve servir de alerta aos produtores e às autoridades de defesa fitossanitária do Estado, a fim de impedir a disseminação desse patógeno, principalmente nos campos da produção de feijoeiro e tomate industrial em Goiás.

Occurrence of Meloidogyne enterolobii in common bean in southern Goiás State, Brazil / Ocorrência de Meloidogyne enterolobii em feijoeiro no Sul Goiano

Meloidogyne enterolobii is known as the most aggressive root-knot nematode (RKN) in Brazil. Common bean (Phaseolus vulgaris) cultivated in the experimental field in Morrinhos, Southern Goiás State, exhibited symptoms typical to those caused by RKN. In order to clarify the etiology of the disease, root systems were analyzed. Typical galls of varying thickness were observed, with thickening larger than 3 cm in diameter containing RKN females inside roots and egg masses on the root surface. The identification of the nematode species was confirmed by isoenzyme electrophoresis (esterase and malate dehydrogenase phenotypes). This is the first report of M. enterolobii in Goiás and in Brazil parasitizing common bean under field conditions. This result is an alert to producers and to the State phytosanitary defense authorities, in order to prevent the further dissemination of this pest, especially in fields of common bean and industrial tomato in the State.(AU)

Meloidogyne enterolobii é considerada uma das espécies de nematoide de galhas mais agressivas presentes no Brasil. Feijoeiro (Phaseolus vulgaris) cultivado em um campo experimental em Morrinhos, na região sul do estado de Goiás, apresentou sintomas característicos de nematoide de galhas radiculares. Para esclarecer a etiologia da doença, os sistemas radiculares foram analisados. Foram observadas galhas típicas da infecção por Meloidogyne spp., com espessuras maiores que 3 cm de diâmetro, contendo em seu interior fêmeas e massas de ovos na superfície radicular. A identificação foi realizada por meio da eletroforese de isoenzimas (fenótipos esterase e malato desidrogenase). Este é o primeiro relato da diagnose em condições natural de campo de M. enterolobii em Goiás e no Brasil parasitando feijoeiro. Esta ocorrência deve servir de alerta aos produtores e às autoridades de defesa fitossanitária do Estado, a fim de impedir a disseminação desse patógeno, principalmente nos campos da produção de feijoeiro e tomate industrial em Goiás.(AU)

Parasitism of Meloidogyne exigua races 1 and 2 in coffee plants derived from Timor Hybrid / Parasitismo de Meloidogyne exigua raças 1 e 2 em cafeeiros derivados do Híbrido de Timor

To investigate the degree of parasitism of two populations of Meloidogyne exigua, the gall index (GI) and the reproduction factor (RF) of M. exigua races 1 (Est E2) and 2 (Est E1) were analyzed in 47 progenies on F3:4 or F4:5 generation derived from the crossing between Coffea arabica cv. Catuaí Amarelo and Timor Hybrid. C. canephora cv. Apoatã IAC 2258 and C. arabica cv. Catuaí Vermelho IAC 144 were used as resistance and susceptibility checks, respectively. The genotypes that were classified as resistant or susceptible by RF were similarly classified by GI, showing a close relationship between both methodologies. The data also indicated no differences in virulence between the nematode populations, since the progenies showed similar resistance reactions to the M. exigua races 1 and 2. According to GI from the 47 mother plants evaluated, 27 progenies (57.4%) were classified as resistant to M. exigua races 1 and 2, with GI ranging from 0.0 to 1.4 and 20 progenies (42.6%) were susceptible with GI from 2.6 to 4.4. These results showed that most of the evaluated germplasm was very promising in relation to the development of new Arabica coffee cultivars with resistance to M. exigua.(AU)

Com o objetivo de investigar o grau de parasitismo de duas populações de Meloidogyne exigua, o índice de galhas (IG) e o fator de reprodução (FR) de M. exigua raças 1 (Est E2) e 2 (Est E1) foram analisados em 47 progênies na geração F3:4 ou F4:5, derivadas do cruzamento entre Coffea arabica cv. Catuaí Amarelo e Híbrido de Timor. Plantas de C. canephora cv. Apoatã IAC 2258 e C. arabica cv. Catuaí Vermelho IAC 144 foram usadas como padrão de resistência e de suscetibilidade, respectivamente. Os genótipos que foram classificados como resistentes ou suscetíveis pelo FR foram similarmente classificados pelo IG, mostrando uma estreita relação entre as duas metodologias para a avaliação da resistência. Os dados também indicaram que não houve diferenças quanto à virulência entre as duas populações do nematoide, uma vez que as progênies mostraram similar reação de resistência a M. exigua raça 1 e 2. De acordo com o IG, das 47 plantas-mãe avaliadas, 27 progenies (57,4%) foram classificadas como resistentes a M. exigua raças 1 e 2, com IG variando de 0,0 a 1,4 e 20 progenies (42,6%) foram suscetíveis, com IG variando de 2,6 a 4,4. Esses resultados mostraram que a maioria dos germoplasmas avaliados foi muito promissora em relação ao desenvolvimento de novas cultivares de café Arábica com resistência a M. exigua.(AU)

Root-knot nematode, Meloidogyne javanica, in response to soil fertilization / Nematoide-das-galhas, Meloidogyne javanica, em resposta à fertilização do solo

Root-knot nematodes (RKNs) (Meloidogyne spp.) are well known disease problem causing major losses in vegetable crops. Although, chemical nematicides have been used as one of the primary means for controlling RKNs, reliance on these nematicides is associated with heavy costs and negative effects on human health and environment. In this research, the suppressing potential of 6 Iranian commercial fertilizers on RKNs was investigated in laboratory and greenhouse conditions as an alternative to reduce the use of chemical nematicides. For this purpose, M. javanica inoculum was thoroughly mixed with autoclaved sandy loam soil. Then, 6 fertilizers (biofertilizer, phosphate chemical fertilizer (phosphate), potassium chemical fertilizer (potassium), peat moss, vermicompost, and leaf mold) were added individually to the inoculated soil, according to the defined treatments. The nematicide Cadusafos was used as a positive control. A negative control was also included in the experiment (including no fertilizer and no nematicide). Four-leaf seedlings of the tomato (Super Chief cv.) were transferred to the pots filled using 2 kg of the treated soil. After 60 days, reproduction factor (RF), egg mass, and root galling of the nematode were recorded. The results showed that, fertilizer-treated soils had significantly (P0.05) lower root galling, egg mass, and RF compared to the negative control. After the nematicide treatment, the highest suppression capability on the RKN was obtained in treatments of phosphate, biofertilizer, potassium, vermicompost, peat moss, and leaf mold, respectively. It can be concluded that, replacing chemical nematicides with fertilizers may be considered as a successful nematode management in tomato fields.(AU)

Nematoides-das-galhas das raízes (RKNs) Meloidogyne spp. causam perdas consideráveis na produção de hortaliças em todo o mundo. Embora o uso de nematicidas químicos seja um dos principais meios de controle de RKNs, a dependência nesses nematicidas está associada aos altos custos e impactos negativos à saúde humana e ao meio ambiente. No presente estudo, foi investigado o potencial de supressão de seis fertilizantes comerciais iranianos em RKNs em condições de laboratório e estufa, a fim de reduzir o uso de nematicidas químicos. Para este propósito, o inóculo de M. javanica foi totalmente misturado com o solo franco-arenoso autoclavado. Em seguida, os fertilizantes (biofertilizante, fertilizante químico de fosfato (fosfato), fertilizante químico de potássico (potássio), musgo de turfa, vermicompostagem e bolor) foram adicionados e misturados individualmente ao solo inoculado, de acordo com os tratamentos definidos. O nematicida Cadusafós foi utilizado como controle positivo. Um controle negativo também foi considerado (sem fertilizante e sem nematicida). Mudas de quatro folhas do tomate (Super Chief cv.) foram transferidas para vasos cheios de 2 kg de solo tratado. Após 60 dias, o fator de reprodução (FR), a massa de ovos e o número de galhas foram registrados. Os resultados mostraram que os tratamentos com fertilizantes apresentaram significativamente (P0,05) menor número de galhas nas raízes, massa de ovos e FR, em comparação com o controle negativo. Depois do controle positivo, a maior capacidade de supressão de M. javanica foi obtida nos tratamentos com fosfato, biofertilizante, potássio, vermicompostagem, turfa e bolor, respectivamente. Conclui-se que a substituição de nematicidas químicos por fertilizantes pode ser uma estratégia aceitável para se alcançar uma gestão bem-sucedida de nematoides em campos de tomate.(AU)

Influence of Meloidogyne incognita race 1 on the development of clones of Coffea canephora, variety "Jequitibá Incaper 8122" / Influência de Meloidogyne incognita raça 1 no desenvolvimento de clones de Coffea canephora, variedade "Jequitibá Incaper 8122"

Root-knot nematode is one of the most important phytosanitary problems for Conilon coffee, as it reduces productivity and is difficult to handle. We aimed at studying the infectivity and damage caused by M. incognita race 1 in the "Jequitibá Incaper 8122" intermediate maturity coffee variety. The experiment was conducted in a greenhouse, in completely randomized design, with five replicates. The clones composing the variety "Jequitibá Incaper 8122" were inoculated with 2,000 eggs + second-stage juveniles of M. incognita race 1. Uninoculated plants were the control. Evaluations were performed 180 days after inoculation, considering the plant height (H), stem diameter (SD), number of leaves (NOL), leaf area (LA), number of plagiotropic branches (NPB), number of nodes (NN), chlorophyll content (CHLO), shoot dry matter (SDM), root fresh matter (RFM), final population (FNP), and reproduction factor (NRF). The nematode reduced NOL in clones 208 and 209, NRF in clones 201, 203, 207 and 208, NN in clones 203, 207, 208 and 209, CHLO in clones 201, 204, 206, 207 and 209, SDM in clones 201, 203, 204 and 205 and RFM in clones 205 and 207. M. incognita race 1 FNP and NRF were larger in clones 208, 201, 207 and 203. Clone 202 had FNP and NRF equal to zero, being immune to the nematode. Clone 206 presented the lowest NRF value among clones parasitized by M. incognita.(AU)

O nematoide-das-galhas é um dos mais importantes problemas fitossanitários para o cafeeiro conilon, por reduzir a produtividade e ser de difícil manejo. Objetivou-se estudar a infectividade e os danos causados por M. incognita raça 1 na variedade de café conilon de maturação intermediária "Jequitibá Incaper 8122". O experimento foi conduzido em casa de vegetação, em DIC, com cinco repetições. Os clones que compõem a variedade "Jequitibá Incaper 8122" foram inoculados com 2.000 ovos + juvenis de segundo estádio de M. incognita raça 1. Plantas não inoculadas constituíram a testemunha. As avaliações foram realizadas 180 dias após a inoculação, sendo avaliados: altura da planta (ALT), diâmetro do caule (DCA), número de folhas (NFO), área foliar (AFO), número de ramos plagiotrópicos (NRP), número de nós (NN), teor de clorofila (CLO), massa seca da parte aérea (MSA), matéria fresca da raiz (MFR), população final (PFN) e fator de reprodução (FRE). O nematoide reduziu o NFO nos clones 208 e 209, NRP nos clones 201, 203, 207 e 208, NN nos clones 203, 207, 208 e 209, CLO nos clones 201, 204, 206, 207 e 209, MSA nos clones 201, 203, 204 e 205 e MFR nos clones 205 e 207. PFN e FRE de M. incognita raça 1 foram maiores nos clones 208, 201, 207 e 203; o clone 202 teve a PFN e a FRE igual a zero, apresentando-se imune ao nematoide. O clone 206 apresentou o menor valor de FRE entre os clones parasitados por M. incognita.(AU)

Influence of Meloidogyne incognita race 1 on the development of clones of Coffea canephora, variety "Jequitibá Incaper 8122" / Influência de Meloidogyne incognita raça 1 no desenvolvimento de clones de Coffea canephora, variedade "Jequitibá Incaper 8122"

Root-knot nematode is one of the most important phytosanitary problems for Conilon coffee, as it reduces productivity and is difficult to handle. We aimed at studying the infectivity and damage caused by M. incognita race 1 in the "Jequitibá Incaper 8122" intermediate maturity coffee variety. The experiment was conducted in a greenhouse, in completely randomized design, with five replicates. The clones composing the variety "Jequitibá Incaper 8122" were inoculated with 2,000 eggs + second-stage juveniles of M. incognita race 1. Uninoculated plants were the control. Evaluations were performed 180 days after inoculation, considering the plant height (H), stem diameter (SD), number of leaves (NOL), leaf area (LA), number of plagiotropic branches (NPB), number of nodes (NN), chlorophyll content (CHLO), shoot dry matter (SDM), root fresh matter (RFM), final population (FNP), and reproduction factor (NRF). The nematode reduced NOL in clones 208 and 209, NRF in clones 201, 203, 207 and 208, NN in clones 203, 207, 208 and 209, CHLO in clones 201, 204, 206, 207 and 209, SDM in clones 201, 203, 204 and 205 and RFM in clones 205 and 207. M. incognita race 1 FNP and NRF were larger in clones 208, 201, 207 and 203. Clone 202 had FNP and NRF equal to zero, being immune to the nematode. Clone 206 presented the lowest NRF value among clones parasitized by M. incognita.(AU)

O nematoide-das-galhas é um dos mais importantes problemas fitossanitários para o cafeeiro conilon, por reduzir a produtividade e ser de difícil manejo. Objetivou-se estudar a infectividade e os danos causados por M. incognita raça 1 na variedade de café conilon de maturação intermediária "Jequitibá Incaper 8122". O experimento foi conduzido em casa de vegetação, em DIC, com cinco repetições. Os clones que compõem a variedade "Jequitibá Incaper 8122" foram inoculados com 2.000 ovos + juvenis de segundo estádio de M. incognita raça 1. Plantas não inoculadas constituíram a testemunha. As avaliações foram realizadas 180 dias após a inoculação, sendo avaliados: altura da planta (ALT), diâmetro do caule (DCA), número de folhas (NFO), área foliar (AFO), número de ramos plagiotrópicos (NRP), número de nós (NN), teor de clorofila (CLO), massa seca da parte aérea (MSA), matéria fresca da raiz (MFR), população final (PFN) e fator de reprodução (FRE). O nematoide reduziu o NFO nos clones 208 e 209, NRP nos clones 201, 203, 207 e 208, NN nos clones 203, 207, 208 e 209, CLO nos clones 201, 204, 206, 207 e 209, MSA nos clones 201, 203, 204 e 205 e MFR nos clones 205 e 207. PFN e FRE de M. incognita raça 1 foram maiores nos clones 208, 201, 207 e 203; o clone 202 teve a PFN e a FRE igual a zero, apresentando-se imune ao nematoide. O clone 206 apresentou o menor valor de FRE entre os clones parasitados por M. incognita.(AU)

Host status of soybean genotypes to Meloidogyne arenaria and Meloidogyne morocciensis / Hospedabilidade de genótipos de soja a Meloidogyne arenaria e Meloidogyne morocciensis

Soybean crop productivity is limited by several biotic factors, particularly plant-parasitic nematodes. Several species have been reported to cause crop damage, especially those of the genus Meloidogyne. Therefore, the aim of this study was to evaluate, the reaction of 28 soybean genotypes to Meloidogyne arenaria and M. morocciensis in a greenhouse. The soybean genotypes were the same for experiments with different species of plant-parasitic nematodes and were individually inoculated with 5,000 eggs + second-stage juveniles (J2) of Meloidogyne and kept in a greenhouse. After 60 days of inoculation, the roots of each plant were assessed for the number of galls, final population, and reproduction factor (RF = final population/initial population). The averages of the different variables were then compared to each other by the Scott-Knott cluster analysis at a significance level of 5%. All of the soybean genotypes in the study were susceptible to both nematodes, with RF ranging from 3.5 to 24.1 for M. arenaria and 5.3 to 37.5 for M. morocciensis.

A cultura da soja tem sua produtividade limitada por diversos fatores bióticos, dentre estes destacam-se os fitonematoides. Várias espécies já foram relatadas causando danos à cultura, especialmente as do gênero Meloidogyne.  Diante disso, o objetivo do trabalho foi avaliar, em casa de vegetação, a reação de 28 cultivares de soja a M. arenaria e M. morocciensis. As cultivares de soja testadas foram as mesmas para os dois ensaios, sendo individualmente inoculadas com 5.000 ovos + juvenis do segundo estádio (J2) de Meloidogyne mantidas em casa de vegetação. Decorridos 60 dias da inoculação, as raízes de cada planta foram avaliadas quanto ao número de galhas, população final e fator de reprodução (FR = população final/população inicial). A seguir, as médias das diferentes variáveis foram comparadas entre si pelo teste de agrupamento de Scott e Knott a 5%. Todas as cultivares de soja avaliadas comportaram-se como suscetíveis a ambos nematoides, com FR variando 3,5 a 24,1 para M. arenaria, e de 5,3 a 37,5 para o M. morocciensis.

Host status of soybean genotypes to Meloidogyne arenaria and Meloidogyne morocciensis / Hospedabilidade de genótipos de soja a Meloidogyne arenaria e Meloidogyne morocciensis

Soybean crop productivity is limited by several biotic factors, particularly plant-parasitic nematodes. Several species have been reported to cause crop damage, especially those of the genus Meloidogyne. Therefore, the aim of this study was to evaluate, the reaction of 28 soybean genotypes to Meloidogyne arenaria and M. morocciensis in a greenhouse. The soybean genotypes were the same for experiments with different species of plant-parasitic nematodes and were individually inoculated with 5,000 eggs + second-stage juveniles (J2) of Meloidogyne and kept in a greenhouse. After 60 days of inoculation, the roots of each plant were assessed for the number of galls, final population, and reproduction factor (RF = final population/initial population). The averages of the different variables were then compared to each other by the Scott-Knott cluster analysis at a significance level of 5%. All of the soybean genotypes in the study were susceptible to both nematodes, with RF ranging from 3.5 to 24.1 for M. arenaria and 5.3 to 37.5 for M. morocciensis.(AU)

A cultura da soja tem sua produtividade limitada por diversos fatores bióticos, dentre estes destacam-se os fitonematoides. Várias espécies já foram relatadas causando danos à cultura, especialmente as do gênero Meloidogyne.  Diante disso, o objetivo do trabalho foi avaliar, em casa de vegetação, a reação de 28 cultivares de soja a M. arenaria e M. morocciensis. As cultivares de soja testadas foram as mesmas para os dois ensaios, sendo individualmente inoculadas com 5.000 ovos + juvenis do segundo estádio (J2) de Meloidogyne mantidas em casa de vegetação. Decorridos 60 dias da inoculação, as raízes de cada planta foram avaliadas quanto ao número de galhas, população final e fator de reprodução (FR = população final/população inicial). A seguir, as médias das diferentes variáveis foram comparadas entre si pelo teste de agrupamento de Scott e Knott a 5%. Todas as cultivares de soja avaliadas comportaram-se como suscetíveis a ambos nematoides, com FR variando 3,5 a 24,1 para M. arenaria, e de 5,3 a 37,5 para o M. morocciensis.(AU)