Nematodes are non-segmented invertebrate animals, which are one of the major phytosanitary problems worldwide, especially in tropical and subtropical regions, attacking the root system of plants they removing photo-assimilates and reducing the absorption capacity of water and nutrients of plant. In order to avoid economic losses by reducing productivity and quality, synthetic compounds have been developed to control nematodes. The use of these synthetic compounds, known as chemical control, has high economic importance, being the current tool most used by farmers for control of these individuals. Moreover, only in Brazil, the trade of these products reaches hundreds of millions of dollars per year. This review aims to address the fundamental aspects of nematode biology and the chemical control of the major genus (Meloidogyne, Heterodera, and Globodera). It covers the historical evolution of the chemical control agents since its beginning in the nineteenth century until today, their mode of action (fumigants and non-fumigants), mechanisms of action (inhibition of the acetylcholinesterase enzyme, opening of the chloride channel, inhibition of electron transport in the electron transport chain, enzymatic inactivation, as a Dauer phase-inducing agent or agent that ensures the organism remains irreversibly in the Dauer phase), the products available for each crop, including their commercial names and forms of application.

Abstract. In soybeans, the leaves of the upper canopy often act as a shield against fungicide penetration, preventing pesticide deposition on target. Fungicide applications to control Asian soybean rust (ASR) are especially difficult because the infection usually starts on the lower canopy. In this study, soybean plants of an early indeterminate cultivar and a determinate cultivar were sprayed with the fungicide azoxystrobin + benzovindiflupyr at six different times of the day with or without the addition of a curtain of chains on the spray boom, which acted as a canopy opener. The number of uredia of cm-2 and grain yield were measured to evaluate application efficacy. We found that the use of the curtain of chains reduced ASR control on the upper canopy for the indeterminate cultivar; however, less of a negative effect was observed for the determinate cultivar. The curtain of chains improved ASR control on the lower and middle canopies at more hours of the day for the determinate cultivar. For both cultivars, the curtain of chains increased ASR control at 6:00, 9:00, and 18:00 h on the lower canopy. Grain yield was also higher with the curtain of chains at 6:00 and 9:00 h for the determinate cultivar. Our results showed that using the curtain of chains could improve fungicide droplet deposition on the lower canopy, leading to greater ASR control and possibly increasing yield. However, it is important to consider the plant architecture and hour of application to maximize the benefit of the curtain of chains. Keywords: Canopy opener, Fungicide penetration, Phakopsora pachyrhizi, Plant architecture, Spray deposition.

A Ferrugem Asiática (Phakopsora pachyrhizi H. Sydow & P. Sydow), relatada em diversas regiões do globo terrestre de climas tropicais e subtropicais, causa redução significativa na produtividade da soja [Glycine max (L.) Merr.]. Fatores bióticos como interação patógeno-hospedeiro e abióticos influenciam o progresso da doença. Objetivou-se neste trabalho estudar os efeitos da temperatura e de períodos de molhamento foliar no progresso da Ferrugem Asiática nas cultivares Conquista, Savana e Suprema. O experimento foi conduzido no Departamento de Fitopatologia da Universidade Federal de Lavras, em junho de 2004, em câmaras de crescimento vegetal nas temperaturas de 15, 20, 25 e 30 °C e períodos de molhamento foliar de 0, 6, 12, 18 e 24 horas. A inoculação foi realizada pulverizando-se as plantas com suspensão de 10(4) uredósporos de P. pachyrhizi.mL-1 de água. Dados da incidência e da severidade foram utilizados para avaliar o progresso da doença e integrados por meio da área abaixo da curva de progresso da incidência (AACPI) e da severidade (AACPS). Modelos de regressão não-linear foram ajustados para a AACPI e AACPS. Foi calculado o volume abaixo da superfície de resposta para incidência (VASRI) e severidade (VASRS) em relação à temperatura e molhamentos foliares com o objetivo de detectar diferenças entre cultivares. Molhamentos foliares acima de 15 horas e temperaturas próximas a 20 ºC, nas 3 cultivares avaliadas, determinaram maior intensidade da Ferrugem Asiática. Temperaturas próximas a 30 e 15 ºC ocasionaram menor intensidade da doença. Períodos de molhamento foliar abaixo de 6 horas reduziram a intensidade da doença. Todas as cultivares testadas foram suscetíveis à doença, entretanto, a cultivar Conquista apresentou maior VASRI e VASRS da Ferrugem Asiática comparada às cultivares Savana e Suprema, as quais não diferiram estatisticamente. Houve diferença entre as cultivares para AACPI em cada temperatura e molhamento foliar.

Damping‐off of soybean is a common problem in some fields in southern Brazil. Frequently, Phytophthora sojae has been pointed out as the main causal agent. However, questions were raised as to whether other oomycetes could also be present. Hence, the objectives of this study were to isolate, identify, and determine the pathogenicity and aggressiveness of oomycetes isolated from soybean seedlings. Thirty‐three isolates were obtained from 13 fields. Isolates were identified based on morphology and molecular methods. Nine species were recovered: Pythium conidiophorum (n = 14, 42.4%), Globisporangium rostratifingens (n = 7, 21.2%), G. irregulare (n = 2, 6.1%), G. spinosum (n = 1, 3.0%), G. ultimum var. sporangiiferum (n = 2, 6.1%), Pythium acanthicum (n = 2, 6.1%), P. deliense (n = 1, 3.0%), P. inflatum (n = 1, 3.0%), and P. torulosum (n = 3, 9.1%). Pathogenicity and aggressiveness were determined with two soybean cultivars (DM57i52 and NEO530) in a seed rot assay and a root rot assay. All isolates were pathogenic to soybean with variable levels of aggressiveness in both assays. The range of seed disease severity index varied from 7.5 to 100 for DM57i52 and from 23.1 to 100 for NEO530. The mean root disease severity index of the soybean cultivars ranged from 29.4 to 92.8. This is the first official report of G. irregulare, G. rostratifingens, G. spinosum, G. ultimum var. sporangiiferum, P. acanthicum, P. conidiophorum, P. deliense, P. inflatum, and P. torulosum causing damping‐off of soybean in the state of Rio Grande do Sul in southern Brazil.

Magnaporthe oryzae (anamorphic synonym Pyricularia oryzae) pathotype Triticum (MoT) is the causal agent of wheat blast. The pathogen can infect all the aboveground tissues of wheat plants, where different types of lesions can be observed. However, the most destructive symptom occurs in wheat spikes that become discolored (bleached). Usually, this discoloration begins upward from the penetration site of the pathogen on the rachis, where a black and bright lesion is formed. The colonization of rachis tissues by MoT prevents the passage of sap to the grain filling. Infected spikes present partial or total sterility, with small and wrinkled grains. Significant yield losses

The objective of this study was to evaluate the influence of two tillage programs (conventional and no-tillage) and different rotations with soybeans and corn on the occurrence of Fusarium species. The work was conducted in the experimental field and Seed Laboratory at Iowa State University. The treatments were: tillage (no-tillage and conventional tillage), crop (corn and soybeans) and three different cropping sequences for corn and soybeans, respectively. Treatment with corn: (1) the first year after four years of soybeans (1C); (2) alternating corn and soybeans each year (C / SB); (3) Continuous corn (C). Treatment with soybeans; (1) the first year after four years of corn (1S); (2) alternating soybeans and corn each year (SB / C); (3) Continuous soybeans (S). Two plant counts were performed in two stages in soybean (VC and V3) and corn (V1 and V3). The root system of ten plants were collected in the vegetative stages V2 and V5 for soybeans and corn. The fungi were isolated from the roots, and the Fusarium species were identified based on the most distinctive morphological characteristics. Nine species were identified in both soybeans and corn, namely F. acuminatum, F. equiseti, F. graminearum, F. oxysporum, F. proliferatum, F. solani, F. subglutinans, F. verticillioides and F. virguliforme. There were no significant differences among the treatments concerning the Fusarium species composition, for both soybeans and corn. In soybeans Fusarium oxysporum was the most frequently observed saprophyte species, followed by F. solani. For corn the main trends in the data was the predominance in all treatments of F. solani, whose highest frequency was in the no-tillage system.

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In the 2012/13 growing season, soybean was grown in an area of 27 million hectares, under no till and monoculture, which contributes to an increasing intensity of current and emergent diseases Soybean crop is attacked by many diseases caused by nematodes, viruses, bacteria and fungi. The latter cause root rot, damping-off, cankers, stem rot, leaf spots, and pod and seed diseases (1, 2, 4). In most soybean fields, weakened plants with thinner stems and leaf yellowing followed by early defoliation are observed. This symptomatology is similar to that of charcoal root rot caused by Macrophomina phaseolina (Tass.) Goid, which leads weakened plants to death next to harvest. Uneven crop ripening and yellowing and normal green areas characterize the secondary symptoms of the disease.In a survey of damages caused by root rot to soybean crops in southern Brazil for several years, a root rot caused by Phomopsis sp has been found as most frequent (4). The primary symptoms are seen when the main root is cut longitudinally, evidencing the death of the white-colored wood which shows well-defined lines forming no defined drawing. Plants manifesting the first secondary symptoms already have RESUMO Palavras-chave adicionais: Glycine max, geográfico, Phomopsis phaseoli, seca-da-haste e da-vagem.Em levantamento de danos causados por podridões radiculares da soja, em lavouras do sul do Brasil durante vários anos, tem sido encontrado com maior frequência uma podridão radicular causada por Phomopsis sp. Os sintomas primários são visualizados quando se corta longitudinalmente a raiz principal, observando-se a morte do lenho ostentando coloração branca, com linhas negras bem definidas, sem um formato definido. Por isso, por semelhança, tem sido chamada de podridão radicular de geográfico, pelo aspecto que lembra as linhas irregulares separando regiões num mapa. Isolamentos foram feitos durante várias Ghissi, V. V.; Reis, E. M.; Deuner, C. C. Etiologia da podridão radicular de Phomopsis em soja. Summa Phytopathologica, v.40, n.3, p.270-272, 2014. safras e feita a prova de patogenicidade. Nos isolamentos tem predominado colônias e os esporos alfa de Phomopsis sp. A prova de patogenicidade foi feita pela inoculação no colo de plantas cultivadas em câmara de crescimento. Reproduziram-se os sintomas de geográfico nas plantas e foi reisolado o fungo Phomopsis sp. Em hastes de soja naturalmente infectadas pela seca-da-haste e da-vagem são encontrados sintomas de geográfico causados por Phomopsis phaseoli. Aos sintomas conhecidos em hastes, vagens e grãos acrescenta-se agora o de podridão radicular causada por P. phaseoli. the geographic symptoms in the taproot. The primary symptoms can be observed even after mechanical harvesting in dead plant stumps. NOTAS CIENTÍFICAS Etiology of phomopsis root rot in soybeanTo diagnose the geographic root rot, removing the root epidermis and observing the presence of geographic symptoms is sufficient. Geographic root rot is easily recognized when the main root of dead or dying plants is cut longitudinally. T...