Adaptive radiations fuel speciation and are characterized by rapid genetic diversification and expansion into new ecological niches. Historically, these processes were believed to be driven by selection on novel mutations but genomic analyses now indicate that standing variation and gene flow often have prominent roles. How “old” variation is combined, however, and its resulting genetic architecture within newly-adapted populations is not well understood. We reconstructed a recent radiation in the fungus, Pyricularia oryzae, that spawned a population pathogenic to eleven grass genera, and caused two new plant diseases: wheat blast - already a serious threat to global agriculture - and gray leaf spot of ryegrasses. We show that the new population evolved in a multi-hybrid swarm using only the standing variation that was present in seven individuals from five distinct, host-specialized lineages. Sexual and parasexual recombination within the swarm reassorted key host-specificity factors and generated more diversity in possibly just a few weeks than existing lineages had accumulated over hundreds to thousands of years. We suggest that the process was initiated by sexual opportunity arising when a fertile fungal strain was imported into Brazil on Urochloa introduced as forage for beef production; and we further contend that the host range expansion was largely fortuitous, with host selection playing little, if any, role in driving the process. Finally, we believe that our findings point to an overlooked role for happenstance in creating situations that allow organisms to skirt rules that would normally hold evolution in check.Commercial Endorsement DisclaimerMention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.Equal Opportunity/Non-Discrimination StatementUSDA is an equal opportunity provider and employer.

Wheat blast, caused by Pyricularia oryzae Triticum (PoT) lineage, is a major constraint to wheat production, mainly in the tropics of Brazil where severe epidemics are more frequent. We analyzed disease and wheat yield data from 42 uniform field trials conducted during nine years (2012 to 2020) in order to assess whether the percent control and yield response were influenced by fungicide type, region (tropical or subtropical), and year. Six treatments were selected, all evaluated in at least 19 trials. Two fungicides were applied as solo active ingredients: MANCozeb, and TEBUconazole, and four were premixes: AZOXystrobin + TEBU, TriFLoXystrobin + PROThioconazole, TFLX + TEBU, and PYRAclostrobin + EPOXiconazole. Percent control, calculated from back-transforming estimates by a meta-analysis network model fitted to the log of the means, ranged from 43% to 58%, with all but PYRA + EPOX showing efficacy greater than 52% on average, not differing among them. The variation in both efficacy and yield response was explained by region and all but TEBU performed better in the subtropics than in the tropics. Yield response from using three sequential sprays was around two times greater in the subtropics (319 to 532 kg/ha) than in the tropics (149 to 241.3 kg/ha). No significant decline in fungicide efficacy or yield response was observed in nine years of study for any of the fungicides. Our results reinforce the need to improve control by adopting an integrated management approach in the tropics given the poorer performance and lower profitability, especially for the premixes, than in the subtropics.

-The ramularia leaf spot (RLS) disease causes cotton yield losses. Choosing a less susceptible cultivar and a sowing time that are less favorable to the pathogen contribute to the management of this disease. The objective of this work was to evaluate the severity of ramularia leaf spot on cotton cultivars sowed in two different times. The experiment was conducted in a triple factorial design (4x3x2), consisted of four cultivars, the three thirds of the plant and two sowing times, with four replications. Each plot was divided in two twin plots, one with fungicide application (with disease control) and the other without fungicide application (without disease control). The severity assessments were performed every seven days, considering each third of the plant with a diagrammatic scale. Yield was evaluated in each plot. There was a significant interaction between sowing times and the thirds of the plant in the plots without disease control for RLS severity, with the highest values of area under the disease progress curve (AUDPC) in the first sowing time (ST1) and in the lower third of the plant. The FMT705 cultivar had the highest and FM951LL the lowest value of AUDPC. The AUDPC of these cultivars were no statistically different in the second sowing time (ST2), but they had higher AUDPC values in the lower third. Highest yields were found with ST1 in plots with disease control, with no differences between the cultivars, however, lower yields were found in plots without disease control.Keywords: Gossypium hirsutum L. Ramularia areola. Thirds of the plant. RELAÇÃO ENTRE SEVERIDADE DA MANCHA DE RAMULÁRIA E PRODUTIVIDADE DE ALGODOEIRO EM DUAS ÉPOCAS DE SEMEADURARESUMO -A mancha de ramulária promove perdas de produtividade do algodoeiro, em que a escolha da cultivar menos suscetível e a época de semeadura menos favorável ao patógeno contribuem para o manejo da doença. O objetivo deste estudo foi avaliar a severidade da mancha de ramulária em cultivares de algodão conduzido em duas épocas de semeadura. O experimento foi conduzido em esquema fatorial triplo (4x3x2), sendo quatro cultivares, três terços da planta e duas épocas de semeadura, com quatro repetições. Cada parcela foi dividida em duas parcelas gêmeas, onde uma parcela recebeu aplicação de fungicidas (com controle) e a outra parcela não recebeu aplicação de fungicidas (sem controle). As avaliações de severidade foram feitas a cada sete dias, considerando cada terço da planta com auxílio de uma escala diagramática. A produtividade foi avaliada na área útil de cada parcela gêmea. Houve interação significativa entre as épocas de semeadura e terços da planta nas parcelas sem controle, onde os maiores valores da área abaixo da curva de progresso da severidade (AACPS) da mancha de ramulária foram observados na primeira época de semeadura (ES1) e no terço inferior da planta. As cultivares FMT 705 e FM 951 LL apresentaram menor e maior valor de AACPS, respectivamente. Na segunda época de semeadura (ES2), as cultivares não diferiram estatisticamente para AACPS,...

As propriedades físicas do solo exercem influencia no crescimento radicular das plantas, que dependendo do nível de restrição, a produtividade da cultura é reduzida. O objetivo deste estudo foi verificar os efeitos da adubação biológica e plantas de cobertura sobre as propriedades físicas do solo. O estudo foi desenvolvido em duas safras (2015/16 e 2016/17), onde o delineamento experimental foi em blocos casualizados em esquema fatorial duplo: adubo biológico (com e sem) e condições de cobertura vegetal do solo (milheto, crotalária e pousio limpo), e um fragmento de floresta como testemunha. A adubação biológica e as plantas de cobertura do solo promoveram incrementos significativos na umidade do solo, macroporosidade e porosidade total, além de reduzir a microporosidade e a resistência do solo a penetração. Deste modo, as propriedades físicas do solo foram incrementadas com o uso de adubo biológico, milheto e crotalária como cobertura do solo. O adubo biológico não promoveu incrementos de produtividade da soja e do milho, entretanto, estas apresentaram incrementos significativos com o uso de milheto e crotalária.

Wheat blast, caused by the Triticum lineage ofPyricularia oryzae(PoT), is a serious disease that first emerged in Brazil and quickly spread to neighboring countries. The recent appearance of this disease in Bangladesh and Zambia highlights a need to understand the population biology and epidemiology of the disease so as to mitigate pandemic outbreaks. Current knowledge in these areas is largely based on analyses of wheat blast isolates collected in Brazil, and their comparison with isolates from non-wheat, endemic grasses. Those studies concluded that wheat blast is caused by a highly diverseP. oryzaepopulation that lacks host specificity and, as a result, undergoes extensive gene flow with populations infecting non-wheat hosts. Additionally, based on genetic similarity between wheat blast and isolates infectingUrochloaspecies, it was proposed that the disease originally emerged via a host jump from this grass, and the widespread use ofUrochloaas a pasture grass likely plays a central role in wheat blast epidemiology. Inconsistencies with earlier phylogenetic studies prompted us to re-analyze the Brazilian data in the context of a comprehensive, global, phylogenomic dataset. We now show that the seminal studies failed to sample theP. oryzaepopulations normally found on endemic grasses and, instead, repeatedly sampled PoT andP. oryzaeLolium (PoL) members that happened to be present in these hosts. The resulting lack of accurate and representative information about the grass-infecting populations in Brazil means that current conclusions about wheat blast evolution, population biology and epidemiology are unsubstantiated and could be equivocal.

A cultura do milho apresenta importância econômica no cenário agrícola, de modo que a região Centro Oeste detém a maior media de produtividade do Brasil. O objetivo deste estudo foi avaliar o efeito de doses de gesso agrícola sobre a produtividade de milho cultivado em segunda safra e seus efeitos químicos no solo. O experimento foi realizado no Campus experimental da UNEMAT, Tangará da Serra – MT. O delineamento experimental foi em blocos casualizados (DBC) com cinco tratamentos (0 kg ha-1, 1.000 kg ha-1, 2.000 kg ha-1, 3.000 kg ha-1 e 4.000 kg ha-1 de gesso agrícola) com quatro repetições, totalizando 20 parcelas. Foi utilizado o híbrido de milho DKB 390 VT Pro2, e as parcelas foram constituídas de cinco metros de comprimento por quatro de largura, com espaçamento entre linhas de 0,50 m. Foi aplicado calcário dolomítico e gesso agrícola aos 60 e 30 dias antes da semeadura, respectivamente. Somente a variável diâmetro do caule e produtividade apresentou diferença significativa entre os tratamentos, onde os diâmetros superiores foram observados nas doses acima 2.000 kg ha-1 e a maior produtividade obtida na dose de 4.000 kg ha-1 de gesso. O efeito da aplicação do gesso proporcionou aumento na concentração de enxofre, cálcio e magnésio no subsolo, assim como redução nos teores de alumino. A dose de 4.000 kg ha-1 de gesso promoveu a maior produtividade.

Com base nisso, o objetivo deste estudo foi fazer uma análise do perfil e produção cientifica dos mestrandos do Programa de Pós-Graduação em Ambiente e Sistemas de Produção Agrícola. Foi realizado a coleta de dados das turmas de 2011, 2012 e 2013, sendo coletadas via análise documental no Currículo Lattes e na página do PPGASP. Para análise dos dados nominais foram atribuídos valores numéricos, que permitiu aplicação da estatística quantitativa descritiva, enquanto que para as variáveis publicação total de artigos e publicação por gênero foi aplicada a estatística inferencial. No geral verificouse maior participação feminina, de acadêmicos que concluíram a graduação na UNEMAT, sendo formados na maioria, Bacharel em Agronomia e Ciências Biológicas. Grande parte dos ingressantes no mestrado são recémformados e as três áreas de concentração profissional dos egressos foram: serviços públicos, docência e doutorado. A produção de artigos não apresentou diferença significativa entre as turmas, entretanto, diferiu quanto ao Qualis do periódico, sendo que os NC, B3 e B1 foram mais representativos. Para publicação por gênero masculino e feminino não se observou diferença significativa. Com isso, verificou-se que o PPGASP proporciona condições para a continuidade da formação acadêmica para pesquisa e docência.

-The objective of this work was to evaluate the agronomic performance and estimate the genetic divergence of 18 cotton genotypes grown in the main season (sowed in December, 2012) and off season (sowed in January, 2013), considering their agronomic characteristics and resistance to Ramularia leaf spot. A randomized block experimental design was used, with five replications. The characteristics evaluated were plant height, first branch height, position of first fruiting branch, height of first fruiting branch, length between nodes, number of nodes, average number of bolls per plant, average boll weight, area under the disease progress curve (AUDPC) related to the Ramularia leaf spot severity, weight of 100-seed from the plant middle third, fiber percentage, average production per plant, yield and cotton fiber quality. The results were subjected to individual and joint analysis of variance and the genetic divergence was estimated according to multivariate procedures (Mahalanobis' generalized distance and Tocher's optimization method). The dissimilarity matrices were summed to estimate the genetic divergence, considering both growing periods. Genetic variability was found among the genotypes evaluated, in both the main season and off season. The characteristic that most contributed to the genetic divergence in the main season was the production per plant and, in the off season, was the fiber percentage. According to the results of the present work, the crosses between the genotypes BRS- 335 and FMT-707; FM-910 and FMT-707; and IMA-08-12427 and FMT-707 are recommended.