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.

Wheat blast is known for developing itself more intensely under relatively high temperature conditions but many aspects related to its epidemiology remain unknown. The objective of this research was to evaluate the sporulative capacity of Pyricularia oryzae Triticum (Pot), the causal agent of wheat blast, in tissues of wheat plants under different temperatures degrees. Wheat plants of the cultivar Anahuac 75, susceptible to blast, were inoculated in the stage of flowering with conidial suspensions (105 conidia/mL) of the Pot isolates Py 12.1.209 and Py 12.1.132. Seven days after the inoculation, plants were cut in the following segments: leaves, stems and rachis (with blast severity ranging from 40 to 60%). Groups of each one of the three plant segments with the lesions were disposed in Petri-dish moist chambers, that were submitted to six different temperature treatments (18, 21, 24, 27, 30 and 33 °C). The most appropriate model that related the conidia production with temperature was identified in the evaluations conducted with stems. The established equations allowed identifying that the highest production of conidia of Pot occurs between 24 and 27 °C.

In this study Pyricularia spp., P. oryzae and the P. oryzae pathotype Triticum (PoT) were detected and identified in leaf segments of forage and invasive grasses located in or next to wheat fields. In 2018 and 2019, 66 samples of lesion leaf segments of Urochloa and other grasses were collected in Londrina (PR), Patos de Minas (MG), and Uberaba (MG). The detection and/or identification of the pathogens on the samples was conducted using moist chamber procedures and with the primers MoT3 and Pot2 by PCR. There were DNA amplification with the primer MoT3 (specific for PoT) for 13 (19.69%) of the samples, all of them from Urochloa. The finding that Urochloa hosts PoT at a relatively high rate raises concerns about the importance which these plants may have on the wheat blast cycle as an alternative host for the pathogen and/or source of inoculum for the disease.

The first report of wheat blast in the world was in Brazil, in 1986. Since then, a great effort has been made towards the development of wheat cultivars resistant to this disease, which is caused by the fungus Pyricularia oryzae Triticum (PoT). The objective of this research was to (i) evaluate the resistance of wheat genotypes to blast and (ii) verify the correlation between disease severity on wheat spikes and sporulation rate of PoT on spike rachises. Plants of 40 cultivars grown in pots, at the flowering stage (stage 65 on the Zadoks scale), were inoculated with a suspension of conidia of a PoT isolate representative of the main variant of the fungus reported in Brazil. Severity of blast on the spikes at 5 and 7 days after inoculation (dai) and the rate of sporulation of the fungus on the rachis (conidia per g of rachis) were evaluated. Eighty percent of the cultivars that were classified in the group with the lowest sporulation rate were also classified in the group with the highest resistance at 7 dai. However, the correlation coefficients of the analysis established between the cultivar severity at 5 and 7 dai averages and the PoT sporulation rate averages were not significant (r=0.2464 and r=0.2047, respectively). Results obtained represent the updated characterization to blast of wheat cultivars in Brazil and constitute an important exploratory framework for the evaluation of the reaction of wheat genotypes based on the sporulation rate of PoT on their tissues.

The use of resistant wheat cultivars is a fundamental strategy to minimize the damages caused by blast, a disease caused by the fungus Pyricularia oryzae Triticum (PoT). The objective of this study was to evaluate (a) the reaction to blast of Brazilian wheat cultivars and (b) to determine whether there is correlation between severity of symptoms on wheat spikes and “rate of sporulation of PoT conidia on wheat spike rachis” (Rscon). Plants of 16 wheat cultivars were grown in greenhouse until flowering (Zadoks stage 65), when their spikes were inoculated with a suspension formed by mixing the conidia of three PoT isolates. The evaluated variables were blast severity on spikes at 5, 7 and 11 days after inoculation (dai) and Rscon. Rachis were evaluated individually to determine the Rscon. Correlation analyzes were carried out between blast severity means on spikes of cultivars at 5, 7 and 11 dai and the log of Rscon. The cultivars ORS Feroz, ORS Destak, CD 116, ORS 1403, ORS 1401, TBIO Aton and TBIO Mestre stood out for being classified in the statistical groups with the highest resistance to blast for the four variables considered in the study. There was a correlation between blast severity on spikes at 5, 7 and 11 dai and Rscon.

RESUMOTanto a cultura da soja (Glycine max L.) quanto a do milho (Zea mays) tem ganhado cada vez mais importância no Brasil e no mundo. Isso porque, a cada safra tem-se aumentado a produtividade de ambas. Nesse contexto, surgiram também várias doenças fúngicas, plantas invasoras e insetos pragas fazendo-se necessário cada vez mais o uso de agroquímicos. É por esse motivo que o presente trabalho teve como objetivo geral fazer uma revisão bibliográfica sobre o tema tecnologia de aplicação de agroquímicos nas culturas de soja e milho, descrevendo algumas vantagens e desvantagens de cada tratamento nas aplicações aéreas e terrestres. Na aplicação aérea os tratamentos com atomizador rotativo e com sistema eletrostático proporcional maior eficiência operacional, além de uma boa cobertura no dossel das plantas quando comparado com aplicação aérea convencional. Já nas aplicações terrestres com tratamentos de diferentes volumes de calda por hectare demostram que volumes de calda maiores que 130 litros por hectare causam menor eficiência operacional quando comparados com volumes de calda de 80 litros por hectare. Pode-se concluir que fazem-se necessários estudos mais aprofundados para ambos os tipos de aplicações. PALAVRAS-CHAVE: Agroquímicos, Pulverização, Tecnologia de Aplicação. ADVANTAGES AND DISADVANTAGES OF AERIAL AND GROUND AGROCHEMICALS APPLICATIONABSTRACT Both the soybean (Glycine max L.) as the corn (Zea mays) has achieved increasing importance in Brazil and in the world. This is because each crop has increased the productivity of them. In this context, there emerged several fungal diseases, weeds and insect pests that are making necessary the use of agrochemicals. For this reason, this study has the major objective to make a literature review on the subject of application technology of agrochemicals in soybean and corn crops, pointing out

Pyricularia oryzae Triticum (PoT) is known to survive in wheat seeds and this condition favors its spread. There are, however, many gaps in knowledge regarding the damage caused by this pathogen in relation to the establishment and sanity of wheat seedlings. The objective of this study was to determine whether there is a correlation between incidence of PoT in wheat seeds and variables associated with the establishment and the sanity of the produced seedlings. Seven samples of wheat seeds naturally infected with the pathogen were used. The incidence of PoT in each of the seed samples was determined via the Blotter test, indicating a variation from 0 to 80.5%. The seeds of each sample were sown in 500 mL plastic pots containing autoclaved sand and the seedlings produced were evaluated in relation to the following aspects; emergency, height, lesions in different segments, mortality, abnormalities and transmissibility of symptoms. The study demonstrated that there is a correlation between incidence of PoT in wheat seeds and the following variables related to the seedlings produced; height at 7 days after sowing (DAS), incidence and severity of symptoms at 7, 14 and 21 DAS, and mortality at 14 and 21 DAS. The results confirmed that the establishment and sanity of wheat seedlings directly depend on incidence of PoT in the seeds.