Etiology, Epidemiology and Management of Asian Soybean Rust (ASR) in Brazil and Vulnerability of Chemical Control of Specific without Multisite Fungicides

Brazil is the first soybean producer in the world, and the largest exporter. In the 2019/20 harvest, the country produced about 124.85 million tons, representing 30% of world production. Global soy production for 2019/20 reached 337.9 million tons. Asian soybean rust (ASR) is the most pathogen on soybean in Brazil in nowadays. Target spot and Septoria leaf spot plus white mold complete these scenarios. ASR emerged in Brazil in 1979. The use of fungicides in the soybean crop in Brazil intensified after the master of 2002 with the resurgence of soybean rust, where the use of triazoles intensified. The massive sprays to pathogen control reached 3.5 sprays per season. In 2006, the first reports of loss of sensitivity of the fungus to the group appeared, notably for the fungicide flutriafol and tebuconazole used in many situations in a curative way or to eradicate the fungus. From that moment on, the productive system sought to use triazoles and strobilurins. In 2011 came the first reports of loss of sensitivity of the fungus in the group of strobilurins. This fact was due to the use of pyraclostrobin in the vegetative phase of soybeans without protection by multisite. That same year, the introduction of the active ingredients in copper oxychloride, mancozeb and chlorothalonil took place in Brazil. In 2015, the first carboxamides ((benzovindiflupyr) (solatenol and fluxpyroxade) associated in triple mode with triazoles and strobilurins were launched on the Brazilian market. Due to the specific mode of action in the metabolism of the fungus (biosynthesis of ergosterol (triazoles), mitochondrial respiration in the cytochrome oxidase enzyme complex - QOIs (strobilurins) and succin dehydrogenase - SDHIs (carboxamides), the need for their association in the sprayings was seen. To multisite (cuprics, dithiocarbamates and nitriles). For the sustainable management of the disease in Brazil, control strategies are recommended, such as the use of systemic fungicides, with a specific biochemical mechanism of action with the adoption of tank mix with multisite, adoption of cultural practices (sanitary emptiness) and sowing schedule and the use of varieties with quantitative resistance (partial or horizontal resistance). These measures will guarantee the sustainability of the culture and the useful life of systemic fungicides or specific sites

Influência do inóculo em diferentes níveis na interação entre Glomus etunicatum e Meloidogyne javanica em feijoeiro

The interaction of endomycorrhizal fungus Glomus etunicatumand the root-knot nematode Meloidogyne javanica, was studied in the greenhouse using different inoculum levels on the bean (Phaseolus vulgaris cv. Costa Rica). Inoculation was performed at sowing, with G. etunicatum inoculum levels of 0, 500, 1,000 and 2,000 chlamydospores per plant and M. javanica levels of 0, 100, 1,000, 5,000 and 10,000 eggs per plant. Root infection rates did not differ 15 days after inoculation of G. etunicatum. With increasing inoculum density of the nematode, plant growth was reduced, but had no effect on mycorrhizal colonization or chlamydospore production by the fungus. There was no significant increase in damage to the bean plant when inoculum levels of M. javanica exceeded 5.000 eggs per plant. Decreased nematode egg production was observed in the presence of G. etunicatum. Levels above 1,000 chlamydospores of G. etunicatum did not differ in stimulating plant growth or in having an antagonistic effect on the root-knot nematode. Foi estudado, em casa de vegetação, o efeito da interação entre o fungo endomicorrízico Glomus etunicatum e o nematóide Meloidogyne javanica, em diferentes níveis de inóculo, sobre o desenvolvimento do feijoeiro (Phaseolus vulgaris L. cv. Costa Rica). A inoculação foi realizada no plantio com G. etunicatum nos níveis de inóculo de 0, 500, 1.000 e 2.000 clamidósporos/planta e M. javanica nos níveis de 0, 100, 1.000, 5.000 e 10.000 ovos/planta. Não houve diferença de infecção de raízes após 15 dias da inoculação com G. etunicatum. O aumento do nível de inóculo do nematoide ocasionou redução do crescimento das plantas, mas não afetou a colonização micorrízica. A inoculação com 10.000 ovos de M. javanica por planta foi similar ao nível de 5.000 ovos, nos danos causados ao feijoeiro. O aumento na densidade de inóculo do fungo micorrízico resultou em incremento significativo no peso da matéria seca do feijoeiro. Foi observado decréscimo na produção de ovos pelo nematóide quando G. etunicatum se encontrava presente na mesma planta. Os níveis de 1.000 e 2.000 clamidósporos de G. etunicatum por planta não diferiram no estímulo ao crescimento do feijoeiro e no efeito antagônico ao nematóide das galhas.

Inheritance of coffee leaf rust resistance in Timor Hybrid UFV 443-03

O objetivo deste trabalho foi caracterizar a herança da resistência do Híbrido de Timor UFV 443-03 à ferrugem-do-cafeeiro (Hemileia vastatrix). Para isso, a raça II e o patótipo 001 de ferrugem foram inoculados em 246 plantas da população F2, 115 plantas do retrocruzamento suscetível (RCS) e 87 plantas do retrocruzamento resistente (RCR), originadas do cruzamento entre o genótipo suscetível cv. Catuaí Amarelo IAC 64 e a fonte de resistência Híbrido de Timor UFV 443-03. Para ambos os inóculos, a cv. Catuaí Amarelo IAC 64 foi suscetível, enquanto o Híbrido de Timor UFV 443-03, a planta representante da geração F1 e as plantas do RCR foram resistentes. As plantas F2, quando inoculadas com a raça II, apresentaram dois padrões de segregação significativos: 15:1 e 61:3. A herança da resistência foi confirmada pela inoculação das plantas do RCS, que segregaram na proporção de 3:1, padrão esperado para herança condicionada por dois genes. A hipótese de segregação 7:1 para três genes foi rejeitada. Resultados semelhantes foram obtidos para o patótipo 001. Dois genes dominantes e independentes conferem a resistência genética do Híbrido de Timor UFV 443-03 à raça II e ao patótipo 001 de H. vastatrix.The aim of this work was to characterize the resistance inheritance of the Timor Hybrid UFV 443-03 to coffee leaf rust (Hemileia vastatrix). For this, the race II and pathotype 001 of coffee leaf rust were inoculated in 246 F2 plants, 115 susceptible backcrossing (BCS) plants, and 87 resistant backcrossing (BCR) plants, derived from the crossing between the susceptible genotype 'Catuaí Amarelo' IAC 64 and the resistance source Timor Hybrid UFV 443-03. For both inoculums, the 'Catuaí Amarelo' IAC 64 was susceptible, while the Timor Hybrid, the plant representing F1 generation, and the BCR plants were resistant. The F2 plants inoculated with race II presented two significant segregation ratios: 15:1 and 61:3. The resistance inheritance was verified by the inoculation of the BCS plants, which segregated at a 3:1 ratio, an expected pattern for the inheritance controlled by two genes, whereas the segregation hypothesis of 7:1 for three genes was rejected. Two independent and dominant genes confer the genetic resistance of Timor Hybrid UFV 443-03 to race II and pathotype 001 of H. vastatrix

In silico identification of coffee genome expressed sequences potentially associated with resistance to diseases

Sequences potentially associated with coffee resistance to diseases were identified by in silico analyses using the database of the Brazilian Coffee Genome Project (BCGP). Keywords corresponding to plant resistance mechanisms to pathogens identified in the literature were used as baits for data mining. Expressed sequence tags (ESTs) related to each of these keywords were identified with tools available in the BCGP bioinformatics platform. A total of 11,300 ESTs were mined. These ESTs were clustered and formed 979 EST-contigs with similarities to chitinases, kinases, cytochrome P450 and nucleotide binding site-leucine rich repeat (NBS-LRR) proteins, as well as with proteins related to disease resistance, pathogenesis, hypersensitivity response (HR) and plant defense responses to diseases. The 140 EST-contigs identified through the keyword NBS-LRR were classified according to function. This classification allowed association of the predicted products of EST-contigs with biological processes, including host defense and apoptosis, and with molecular functions such as nucleotide binding and signal transducer activity. Fisher's exact test was used to examine the significance of differences in contig expression between libraries representing the responses to biotic stress challenges and other libraries from the BCGP. This analysis revealed seven contigs highly similar to catalase, chitinase, protein with a BURP domain and unknown proteins. The involvement of these coffee proteins in plant responses to disease is discussed

Partial map of Coffea arabica L. and recovery of the recurrent parent in backcross progenies

A partial map of Coffea arabica L. was constructed based on a backcross population and RAPD markers.From a total of 178 markers evaluated, only 134 that segregated 1:1 (P>0.05) were used to develop the map. Seventeenmarkers were not linked, while 117 formed 11 linkage groups, covering a genome distance of 803.2 cM. The maximumdistance between adjacent markers was 26.9 cM, and only seven intervals exceeded 20 cM. The markers were further used forassisted selection of the plants closest to the recurrent parent, to accelerate the introgression of rust resistance genes in thecoffee breeding program. Three BC1 plants resistant to coffee leaf rust and with high genetic similarity to Catuaí wereselected and integrated in the following backcross cycles

Potato early blight epidemics and comparison of methods to determine its initial symptoms in a potato field.

The influence of an early blight epidemic on potato tuber yield was evaluated in three field experiments during 2000 to 2002 crop seasons under Viçosa, Minas Gerais state growing conditions. Through a disease severity gradient method, used four different dosages of fungicide chloratalonil were obtained four epidemic levels with severity range of D1 (maximum), plot without fungicide treatment, to D4 (minimum), plot with fully dosage fungicide commercial recommended, were obtained, which allowed for comparison of the epidemic effect on plant growth and tuber yield, and indicated the time for initiating of the first early blight (AlternariaM solani) lesions on potato foliage The disease was predicted by using the methods based either degree days (DD) with base temperature of 7oC and physiological days (PD) having minimum, optimum and maximum temperature of 7, 21 and 30oC, respectively, accumulated during the period between planting and the first symptom appearance. Plots with higher disease levels along the gradient had significantly loss tuber yield in all trials. The highest yield reduction of 49,6; 52,7 and 58,2% occurred in D1, plots without fungicide treatment, during the years 2000, 2001 and 2002, respectively. The epidemic prediction through accumulated DD or PD did not indicate the appropriate time to initiate the epidemic control. However, the PD method that predicted the first symptoms between 240 and 333 accumulated PDs was found to be more adequate. The data revealed that green leaf area and tuber yield reduction caused by the early blight is dependent upon the disease severity. Compared to the others, the PD method appears to be most suitable to determine when the disease will establish, and thus can be recommended to initiate the disease management at 250 accumulated PDs, under disease-favorable climatic conditions

Escória silicatada combinada com tubuconazol no manejo da mancha de olho pardo do cafeeiro

The aim of this trial was to evaluate silicon absorption and the effect of silicate slag application combined with triazole fungicide in control of brown eye leaf spot under greenhouse conditions, using coffee seedlings of the cultivar Catuaí Vermelho 144. A completely randomized 5x2 experimental design was used, with and without application of the fungicide tebuconazole, with eight replications. The mixtures (M) used on the soil were defined as based on the liming needs of the soil: M1- 0% de silicated slag (slag) and 100% limestone (lim); M2- 25% slag and 75% lim; M3-50% slag and 50% lim; M4- 75% slag and 25% lim; M5- 100% slag, with or without application of the fungicide tebuconazole. The fungicide tebuconazole (0.5 g of a.i./L) was applied on coffee seedlings through five pair of leaves. Twenty-four hours after fungicide application, each coffee seedling was inoculated with a conidial suspension of 2.0 x 105 /mL. The severity and the defoliation caused by disease were evaluated every five days from 20 to 45 days after inoculation. With the severity and defoliation data, the area under the brown eye spot disease progress curve (AUCPBES) and the area under the defoliation curve (AUCPDESF) were calculated. The application of increasing doses of silicate slag on the soil did not reduce AUCPBES and AUCPDESF, and no increase in Si content in the root, stem or leaf was observed. Tebuconazole reduced AUCPBES and AUCPDESF.Objetivou-se, neste ensaio avaliar a absorção de silício e o efeito da aplicação de escória silicatada combinada com fungicida triazol no controle da mancha de olho pardo em casa de vegetação, utilizando mudas de café da cultivar Catuaí Vermelho 144. O experimento seguiu o delineamento inteiramente casualizado 5x2 com e sem aplicação do fungicida tebuconazole, utilizando oito repetições. As misturas (M) utilizadas no solo foram definidos com base na necessidade decalagem do solo: M1-0% de escória silicatada (ESC) e 100% de calcário (CAL); M2 -25% ESC e 75% CAL; M3-50% ESC e 50% CAL; M4-75% ESC e CAL 25%; M5 -100% ESC com ou sem aplicação de fungicida tebuconazole. O fungicida tebuconazole (0,5 g de ia / L) foi aplicado em mudas de café com cinco pares de folhas. Vinte e quatro horas após a aplicação do fungicida, cada muda de café foi inoculada com uma suspensão de conídios de 2,0 x 105 mL-1. A severidade e a desfolha causada pela doença foram avaliadas a cada cinco dias dos 20 aos 45 dias após a inoculação. Com os dados de severidade e desfolha,foram calculadas a área abaixo da curva de progresso da severidade da mancha de olho pardo (AACPMOP) e a área abaixo da curva de progresso da desfolha (AACPDESF). A aplicação de doses crescentes de escória silicatada no solo não reduziu AUCPBES e a AUCPDESF e nenhum aumento no teor de Si na raíz, caule ou folha foi observado. O tebuconazole reduziu AUCPBES e AUCPDESF

Utilização de multilinhas dinâmicas para o manejo da antracnose do sorgo

O objetivo deste trabalho foi avaliar a eficiência do uso de multilinhas dinâmicas, por meio de misturas genéticas em populações de híbridos triplos, no manejo da antracnose do sorgo, causada pelo fungo Colletotrichum sublineolum. Foram obtidos 18 híbridos triplos a partir de sete linhagens que continham genes distintos para resistência à doença. Os 25 genótipos de híbridos e linhagens foram avaliados em campo. Verificou-se, em alguns híbridos, grau de resistência superior ao observado para a linhagem mais resistente utilizada nos cruzamentos, o que indica efeito aditivo dos genes de resistência das diferentes linhagens na composição da resistência final dos híbridos. O uso das multilinhas dinâmicas reduziu a intensidade da doençano campo e aumentou a produtividade. Essa estratégia torna possível a utilização de linhagens que apresentam características agronômicas desejáveis, mas são suscetíveis à antracnose.The objective of this work was to evaluate the efficiency of dynamic multilines, using genetic mixing in populations of three‑way hybrids, in the management of sorghum anthracnose, caused by the fungus Colletotrichum sublineolum. Eighteen three‑way hybrids were obtained from seven different lines containing genes for resistance to the disease. The 25 genotypes of hybrids and lines were evaluated in field conditions. In some hybrids, a higher resistance level was observed when compared to that of the more resistant line used in the crosses, indicating an additive effect of the resistance genes of the different lineages in the composition of the final resistance of hybrids. The use of dynamic multilines reduced the disease intensity in field and increased productivity. This strategy makes it possible to use lineages that have desirable agronomic characteristics, but are susceptible to anthracnose

Taxa de progresso da doença e resistência de cultivares de cevada à mancha-marrom

The disease progress rate and the level of resistance to brown spot was evaluated in barley cultivars.The field experiment was carried out at Embrapa Trigo Experimental Station in Coxilha, Rio Grande do Sul, Brazil. Cultivars BR 2, MN 698, Embrapa 128, Embrapa 129, and CI 9539 showed statistical differences from one another regarding reaction to and severity of seed infection by brown spot, based on the scales of Fetch & Steffeson (1999) and Anderson & Banttari (1976), respectively. Cultivars BR 2, Embrapa 128, Embrapa 129, andMN 698 showed the greatest increase in the rate of the disease progress, which varied from 2.92 to 3.62 compared to access CI 9539, even though there was no statistical difference (P > 0.05) among those cultivars. Access CI 9539 showed the lowest rate of disease progress (1.17).Foi avaliado o progresso da doença e a resistência de cultivares de cevada à Bipolaris sorokiniana. O ensaio foi realizado no campo experimental da Embrapa Trigo em Coxilha, RS. Comparou-se, na taxa de progresso da doença, resistência e severidade de ponta-preta nos grãos, baseando-se estas na escalas de Fetch & Steffeson (1999) e Anderson & Banttari (1976), respectivamente. As cultivares BR 2, MN 698, Embrapa 128, Embrapa 129 e CI 9539 diferiram quanto à taxa de progresso da doença, graus de doença e severidade de ponta--preta nos grãos. As cultivares BR 2, Embrapa 128, Embrapa 129 e MN 698 apresentaram as maiores taxas de progresso da doença, variando de 2,92 a 3,62 quando comparadas com o acesso CI 9539, mas não diferiram entre si pelo teste de Tukey a 5% de probabilidade. O acesso CI 9539 apresentou a menor taxa de progresso da doença (1,17)

Reação de clones de seringueira a vários isolados de Microcyclus ulei

The reactions of 33 clones of Hevea to various M. ulei isolates collected from rubber plantations in different regions of Brazil were studied. Isolates were inoculated with a concentration of 2 x 105 conidia/ml with 70% - 80% of germination rate. The subculturing was made with a 12-day old culture macerated in distilled sterilized water. The reaction presented by clones of Hevea spp varied with isolates and with clones. Most of the clones showed complete resistance to some of the isolates, but the same clones were susceptible or highly susceptible to the others. Some clones showed complete resistance and varying levels of incomplete resistance. It was verified that both the latent period and the diameter of lesions may be related to rubber tree resistance to M. ulei, but these two parameters are not sufficient to explain this resistance. The association of various resistance components is needed. Among these components, the "sporulation on the lesions" is the most important. The incubation period and number of lesions are not good parameters for analyzing the rubber tree resistance to M. ulei. Estudou-se a reação de 33 clones de seringueira à infecção por vários isolados de Microcyclus ulei, provenientes de várias regiões heveícolas do Brasil. As inoculações foram feitas em condições climáticas controladas, utilizando-se 2 x 105 conídios/ml com 70% a 80% de germinação, provenientes de culturas com doze dias de idade. As reações apresentadas pelos clones variaram com os isolados. Os clones, em sua maioria, apresentaram resistência completa a determinados isolados e foram suscetíveis ou altamente suscetíveis a outros. Alguns clones apresentaram resistência completa a alguns isolados e incompleta a outros, mas em níveis variados. Verificou-se que o período latente e o diâmetro médio das lesões podem estar relacionados com a resistência dos clones de seringueira ao M. ulei, mas somente estes parâmetros não explicam essa resistência, sendo necessária a associação de vários componentes, dentre os quais o mais importante é a esporulação do tecido infectado. O período de incubação e o número de lesões não são bons parâmetros para análise da resistência da seringueira ao M. ulei