ABSTRACT Integrated management is considered the best strategy to mitigate the damage caused by plant-parasitic nematodes. However, there is still limited information regarding some integrated techniques. Thus, this study aimed to assess the effects of genetic management associated with chemical control of Meloidogyne javanica in soybean (Glycine max (L.) Merr.) The experiment was installed in a greenhouse according to an 8×4 factorial design with eight replicates. The first factor was soybean cultivar (HO Juruena IPRO, resistant; Foco IPRO, HO Maracaí IPRO, and CZ 58B28 IPRO, moderately resistant; HO Mamoré IPRO, moderately susceptible; and Extrema IPRO, CZ 48B32 IPRO, and HO Aporé IPRO, susceptible). The second factor consisted of an untreated control and commercial nematicides based on abamectin, thiodicarb+imidacloprid, and fluopyram. Plants were inoculated with 2000 nematode eggs, and nematode and vegetative variables were evaluated at 65 d after inoculation. There was an interaction effect on nematode variables. Furthermore, there was an additive effect of genetic management and chemical control, mainly in resistant cultivars treated with thiodicarb+imidacloprid or fluopyram with controls of up to 69.90% and 96.86%, respectively. The application of fluopyram and the use of ‘HO Juruena IPRO’, ‘Foco IPRO’, or ‘HO Maracaí IPRO’ also contributed to the control of M. javanica. Vegetative variables were studied by analyzing product effects separately, but results were inconclusive.

RESUMO Os nematoides das galhas (Meloidogyne spp.) causam danos severos na cultura do tomateiro. Dessa forma, o presente estudo objetivou avaliar o biocontrole de M. javanica mediado pelo fungo micorrízico arbuscular Rhizophagus clarus comparado aos fungos Trichoderma harzianum e Pochonia chlamydosporia em tomateiro e atividade de enzimas relacionadas à defesa vegetal em raízes micorrizadas. Três experimentos foram realizados a fim de avaliar: a colonização micorrízica, a penetração, desenvolvimento e reprodução de M. javanica, o desenvolvimento do tomateiro e a atividade de enzimas relacionadas a defesa em raízes micorrizadas. Observou-se que a colonização por R. clarus em tomateiro foi crescente com as épocas de avaliação e, apesar de não impedir a penetração e desenvolvimento de M. javanica nas raízes, foi eficiente em reduzir o número total do nematoide. Os tratamentos R. clarus, T. harzianum e P. chlamydosporia reduziram a reprodução do nematoide em 56,5, 54,4 e 56,9%, respectivamente, se comparados à testemunha. Além disso, R. clarus aumentou as massas de parte aérea do tomateiro e a atividade das enzimas fenilalanina amônia-liase e peroxidase.

ABSTRACT Root-knot nematodes (Meloidogyne spp.) cause severe damage to tomato crop. This study aimed to investigate the biocontrol potential of the arbuscular mycorrhizal fungus Rhizophagus clarus compared with that of the fungi Trichoderma harzianum and Pochonia chlamydosporia against Meloidogyne javanica in tomato and assess the activity of defense-related enzymes in mycorrhizal roots. Three experiments were carried out to evaluate mycorrhizal colonization, nematode penetration, development, and reproduction, plant growth, and enzyme activity in mycorrhizal roots. We observed that R. clarus colonization of tomato roots increased with time. Although R. clarus did not prevent nematode penetration or development in roots, it was efficient in reducing total nematode numbers. R. clarus, T. harzianum and P. chlamydosporia treatments reduced nematode reproduction by 56.5, 54.4, and 56.9%, respectively, compared with the control. Moreover, R. clarus increased tomato shoot weight and phenylalanine ammonia-lyase and peroxidase activities.

ABSTRACT Root-knot nematode infection has a direct and negative impact on the commercial value of beet (Beta vulgaris L.) tubers. The aim of this study was to evaluate induced resistance in beet tuberous roots infected with different population levels of Meloidogyne javanica (Treub, 1885) Chitwood, 1949. Plants were inoculated with increasing inoculum levels (0, 1500, 5000, and 10 000 eggs + juveniles %#91;J2%#93;) and treated with different products that can potentially induce resistance: mannan- oligosaccharides (MOS), citrus biomass, and acibenzolar-S-methyl (ASM). Vegetative, nematological, and enzymatic parameters were evaluated after 60 d. In general, when compared to the control (water), inducers did not promote a positive effect on tuber diameter and weight, regardless of the inoculum level. Only the weight of plants inoculated with 5000 eggs + J2 and treated with citrus biomass (40.70 g) increased compared with the control (32.38 g). The treatments did not reduce the number of galls, nematodes per root system, and nematodes per gram of root. Resistance inducers increased catalase activity (CAT) and phenylalanine ammonia-lyase (PAL) and MOS and ASM were the most effective. The highest CAT activity was for ASM and 5000 eggs + J2, resulting in 42.44% compared with the control. The MOS and ASM exhibited the highest PAL activity (0.22 and 0.15 mg trans-amino acid h-1 mg-1 protein, respectively) compared with the control (0.03 mg trans-amino acid h-1 mg-1 protein) in uninoculated plants. Results led us to conclude that inducers should not be used in isolation to control nematodes in beet. However, deformed tubers can be used in manufacturing, thus preventing food waste. In addition, new rates and application intervals should be evaluated to help control nematodes in beet plants.

ABSTRACT Maize (Zea mays L.) is one crop of major relevance in Brazil; however, nematodes are limiting factors in maize growth and productivity due to the difficulty to control them. Studies point out that arbuscular mycorrhizal fungi (AMF) increase plant tolerance to nematodes. Thus, the aim of this study was to assess the association between AMFs and Pratylenchus brachyurus in maize growth. Six AMF species (Rhizophagus clarus, Claroideoglomus etunicatum, Gigaspora rosea, G. margarita, Scutellospora calospora, S. heterogama), as well as a control treatment free of mycorrhizae, were assessed under two different nematode inoculum conditions (presence and absence). Plants were collected and analyzed 60 d after inoculation. The nematode population was higher in the treatments inoculated with AMFs. On the other hand, just the plants inoculated with R. clarus did not present improved development in comparison to the control. Nematodes increased AMF spore density, but despite the fact that AMFs have presented different root colonization capacity (ranging from 2.3% to 95.0%), such capacity was not affected by the nematodes

The aim of this study was to evaluate the activity of elicitor, acibenzolar-S-methyl (ASM), in inducing resistance to Meloidogyne javanica in soybean and in enhancing plant development. Plantlets of the soybean susceptible cultivar BRSMT-Pintado and the resistant cultivar MG/BR 46 Conquista were treated with ASM (0.5 g/L) at three different times: seven days before, one day before and seven days after inoculation with 2000 eggs/plant. Untreated inoculated plants and untreated non-inoculated plants were used as controls. Sixty days after inoculation, the number of galls, eggs/g root and vegetative parameters (height, aerial part fresh and dry mass and root fresh mass) were evaluated. The experiments were conducted over two different periods (Experiments 1 and 2). Only in Experiment 2 treatment "seven days before inoculation" reduced the number of eggs/g root, irrespective of the cultivar evaluated, but the number of galls was not affected. Stronger plant development was observed in the susceptible soybean cultivar treated seven days before inoculation in Experiment 2.

Nesse trabalho, o objetivo foi avaliar a reação de oito porta-enxertos de videira aos nematoides das lesões radiculares. As estacas dos porta-enxertos Kober, SO4, 101-14, R99, 420-A, Rupestris du Lot, Riparia do Traviú e Telek 5C, cedidas pelo Centro APTA de Frutas/IAC, foram plantadas em vasos contendo mistura de solo:areia na proporção 2:1 (v:v) e mantidas em casa de vegetação. Após quatro meses, os porta-enxertos foram inoculados com 1.200 espécimes de Pratylenchus brachyurus ou P. zeae, e o milho foi usado para comprovar a viabilidade do inóculo. Aos 180 dias após a inoculação, avaliou-se o número de nematoides por sistema radicular e em 100 cm³ de solo. O milho foi avaliado aos 90 dias após a inoculação e cada vaso recebeu uma nova planta, que foi avaliada juntamente com os porta-enxertos. No milho, as populações finais de P. brachyurus e P. zeae foram respectivamente iguais a 8.040 e 6.940 indivíduos. Todos os porta-enxertos comportaram-se como imunes a P. brachyurus e P. zeae, isto é, a população final dos nematoides e o fator de reprodução foram iguais a zero. Recuperaram-se seis e 11 espécimes de P. zeae nas amostras de solo cultivadas com os porta-enxertos Kober e 420-A, respectivamente. Conclui-se que os porta-enxertos estudados apresentam potencial para serem usados em áreas infestadas com esses nematoides das lesões.

The aim of this study was to evaluate the reaction of eight grapevine rootstocks to root-lesion nematodes. Cuttings of the rootstocks Kober, SO4, 101-14, R99, 420-A, Rupestris du Lot, Riparia do Traviú and Telek 5C, provided by the Centro APTA de Frutas/IAC, were planted in 5-L pots containing a 2:1 (v:v) soil and sand mixture, and kept in greenhouse. After four months, they were inoculated with 1,200 specimens of Pratylenchus brachyurus or P. zeae. Maize was used for detecting the inoculum viability. After 180 days of the inoculation, the root systems of the plants were collected along with 100 cm³ soil for evaluating the number of nematodes. Maize plants were evaluated 90 days after inoculation and each pot received a new seedling, which was evaluated along with the rootstocks. All rootstocks exhibited immunity to P. brachyurus and P. zeae, because the final populations in the root systems and the reproduction factor were zero. It was recovered six and 11 specimens of P. zeae in samples from cultivated soil with Kober and 420-A rootstock, respectively. In the maize, the respective average populations of P. brachyurus and P. zeae were 8,040 and 6,940. The rootstocks are potentially valuable for infested areas.

Hospedeiros alternativos de fitonematoides podem causar restrição nutricional e afetar a capacidade de infecção e fertilidade dos nematoides. Nesse trabalho, avaliou-se o efeito da planta hospedeira na viabilidade do inóculo de H. glycines raça 3 e a sobrevivência desse inóculo no solo. O nematoide foi multiplicado em feijoeiro resistente (linhagem L2300), suscetível (cv. Ouro) e soja suscetível (cv. FT-Cristalina), e as suspensões de ovos foram preparadas a partir de fêmeas coletadas nesses hospedeiros. Para avaliar a penetração dos juvenis de segundo estádio e o desenvolvimento do nematóide até a fase adulta, suspensões de 2000 ovos foram colocadas em plantas de soja 'FT-Cristalina' (planta teste). Aos 10 dias após a inoculação, avaliou-se o número de juvenis que penetraram nas raízes. O número de fêmeas por sistema radicular foi avaliado aos 30 dias. O inóculo obtido a partir da linhagem L2300 resultou no menor número de juvenis e de fêmeas no interior das raízes da planta teste. O inóculo obtido na soja foi o que resultou na maior penetração e desenvolvimento do nematoide. Para avaliar a sobrevivência do inóculo, cistos de H. glycines produzidos nos diferentes hospedeiros permaneceram no solo, sem planta, por 18 meses. O menor percentual de ovos que sobreviveram no solo foi originário de cistos multiplicados em feijoeiro, da linhagem L2300 ou cv. Ouro. Conclui-se que o inóculo de H. glycines produzido em feijoeiro, resistente ou suscetível, apresenta menor viabilidade e sobrevivência no solo.

Alternative hosts of phytonematodes can cause nutritional restriction and affect infectivity and fertility of the nematode. In this study, we evaluated the effect of the host plant on inoculum viability of Heterodera glycines race 3 and survival of this inoculum in soil. The nematode was multiplied in resistant (line L2300) and susceptible (cv. Ouro) beans and susceptible soybeans (cv. FT-Cristalina), and the egg suspensions were prepared from females collected on these hosts. To evaluate penetration of second stage juveniles and development of the nematode to the adult phase, suspensions of 2,000 eggs were placed in soybean 'FT- Cristalina' plants (test plant). At ten days after inoculation, we evaluated the number of juveniles that penetrated the roots. The number of females per root system was evaluated at 30 days. The inoculum obtained from line L2300 resulted in fewer juveniles and females inside the roots of the test plant. The inoculum obtained from soybean resulted in higher penetration and development of the nematode. To evaluate the survival of the inoculum, cysts of H. glycines produced in the different hosts remained in the soil, without plants, for 18 months. The lower percentage of eggs that survived in the soil was originated from cysts multiplied in beans, line L2300 or cv. Ouro. It can be concluded that the inoculum of H. glycines produced in bean plants, resistant or susceptible, has lower viability and survival in the soil.

Objetivou-se estudar a reação de adubos verdes de verão ao nematóide T. tuxaua. Ensaios em casa-de-vegetação e em campo foram desenvolvidos em delineamento experimental inteiramente casualisado com cinco tratamentos e quatro repetições, tendo sido testados os adubos verdes Crotalaria juncea (crotalária), Mucuna aterrima (mucuna preta), Mucuna deeringiana (mucuna anã), Canavalia ensiformis (feijão de porco), além de Zea mays (milho) cv. Dekalb 390 como testemunha. Para ambos os ensaios, foram estudadas as variáveis população inicial e final do nematóide por parcela, altura de plantas, massas seca e fresca da parte aérea e massa seca de raiz. Em vasos houve diferença estatística entre tratamentos para as variáveis altura de plantas e massa seca de raiz e em campo para as variáveis altura, massa fresca e massa seca de plantas. A população final de nematóides, tanto em vasos quanto em campo, diminuiu durante o período de realização dos ensaios. Todos os adubos verdes testados mostraram suscetibilidade ao nematóide. Altura de plantas foi a variável mais adequada para avaliação de danos ocasionados por T. tuxaua em campo e em vasos.

The aim of this work was to study summer green manures as hosts to the nematode T. Tuxaua in western Paraná. Pot and field assays followed a completely randomized design with five treatments and 4 replications. The green manures tested were Crotalaria juncea, Canavalia ensiformis, Mucuna deeringiana and Mucuna aterrima, besides the control Zea mays 'Dekalb 390'. For both assays, the evaluation was carried out considering the variables: initial and final nematode densities, plant height, dry and fresh shoot weight and dry mass of roots. In pots, significant differences occurred between non-inoculated and inoculated plants of Z. mays, M. deeringiana and M. aterrima for the variable plant height. Assessing the same variable in the field, non-infested plots showed statistical differences to infested plots for all the treatments. The nematode densities decreased both in pots and in the field during the experimentation periods. All the green manures tested showed susceptibility to the nematode T. tuxaua. Plant height seems to be the most appropriate variable to evaluate the damages caused by T. tuxaua on plants under field and pot conditions.