First report of and as the causal agent of pod and grain rot of soybean in Brazil.

Epidemics of pod and grain rot (PGR) of soybean (Glycine max (L.) Merr.), popularly referred to as "pod anomaly", have economically impacted Brazilian farmers, especially in Mato Grosso (MT), Brazil's largest producer state, where incidence varies from 10 to 40%.

Enhanced white rot control in garlic bulbil using organic-inorganic hybrid materials as coating membranes.

Organic-inorganic hybrid materials have a range of applications due to their unique properties. Their application in agriculture brings alternatives for the controlled release of nutrients in the soil, the seed coating, the transport of herbicides, and the treatment of plant diseases. The present study aimed to investigate the use of fungicides incorporated into hybrid membranes formed by synthetic hectorite (LAPONITE®) and polymers in the pre-treatment of garlic bulbils exposed to the pathogen , which causes white rot.

A Shift in Pathotype Diversity and Complexity of in Brazil.

Soybean root and stem rot caused by the oomycete is a destructive disease worldwide that can affect plants at any growth stage. The use of resistant cultivars is the most effective method of controlling the disease. Therefore, monitoring changes in the population of regarding the dynamics of avirulence genes capable of overcoming resistance genes () is important to reduce yield losses and to enhance the effectiveness of the genes.

The Population of f. sp. in Brazil Is Not Structured by Vegetative Compatibility Group or by Geographic Origin.

Fusarium wilt, caused by the soilborne fungus f. sp. (), is considered one of the most destructive diseases of bananas in Brazil.

Evidence of adaptability to tricyclazole.

Pyricularia oryzae is the etiological agent of rice blast, the most destructive disease in rice crops and chemical control based on fungicide is the main method used in its management. The aim of this study was characterize pathogenicity and identify P. oryzae isolates adapted to tricyclazole.

Incidence, Spatial Pattern and Temporal Progress of Fusarium Wilt of Bananas.

The effective management of Fusarium wilt of bananas (FWB) depends on the knowledge of the disease dynamics in time and space. The objectives of this work were: to estimate disease intensity and impact, and to investigate the spatial and temporal dynamics of FWB. Fields planted with Silk ( = 10), Pome ( = 17), or Cavendish ( = 3) banana subgroups were surveyed in Brazil, totaling 95 ha.

The Population of in Brazil Is Structured by Mycelial Compatibility Groups.

The genetic structure of the population of was analyzed using 238 individuals collected from different hosts. Individuals were characterized for microsatellite genotypes and mycelial compatibility groups (MCGs). A total of 22 MCGs and 64 multilocus lineages (MLLs) were identified.

Weevil Borers Affect the Spatio-Temporal Dynamics of Banana Fusarium Wilt.

Dispersal of propagules of a pathogen has remarkable effects on the development of epidemics. Previous studies suggested that insect pests play a role in the development of Fusarium wilt (FW) epidemics in banana fields. We provided complementary evidence for the involvement of two insect pests of banana, the weevil borer ( L.

Experimental evolution of cowpea mild mottle virus reveals recombination-driven reduction in virulence accompanied by increases in diversity and viral fitness.

Major themes in pathogen evolution are emergence, evolution of virulence, host adaptation and the processes that underlie them. RNA viruses are of particular interest due to their rapid evolution. The in vivo molecular evolution of an RNA plant virus was demonstrated here using a necrotic isolate of cowpea mild mottle virus (CPMMV) and a susceptible soybean genotype submitted to serial inoculations.

First report of Ralstonia solanacearum causing bacterial wilt of eucalyptus in Ecuador.

In January 2018, eucalyptus trees showing wilt symptoms were identified in a commercial plantation located in the Quevedo Cantón, Los Ríos province, Ecuador. Disease incidence reached 40% of the eucalyptus field and affected plants displayed reddening and wilting of the foliage, leaf drop, branch dieback, and reduced growth, resembling bacterial wilting symptoms (Santiago et al., 2014).

Genetic Structure of and in Brazil.

Bacterial wilt-causing threaten numerous crops throughout the world. We studied the population structure of 196 isolates of and 39 isolates of , which were collected from potato- and tomato-growing areas in 19 states of Brazil. Regardless of the species, three groups of isolates were identified.

Green synthesis of silver nanoparticles using tomato leaf extract and their entrapment in chitosan nanoparticles to control bacterial wilt.

Background: Silver nanoparticles (AgNPs), particularly those entrapped in polymeric nanosystems, have arisen as options for managing plant bacterial diseases. Among the biopolymers useful for the entrapment of AgNPs, chitosan is promising because of its low cost, good biocompatibility, antimicrobial properties and biodegradability. The present study aimed: (i) to greenly-synthesize AgNPs using different concentrations of aqueous extract of tomato leaves followed by entrapment of AgNPs with chitosan (CH-AgNPs); (ii) to characterize the optical, structural and biological properties of the nanosystems produced; (iii) to evaluate the antimicrobial activities of AgNPs and nanomaterials; and (iv) to assess the effectiveness of AgNPs and nanomaterials for controlling tomato bacterial wilt caused by Ralstonia solanacearum.

Fusarium Wilt of Banana: Current Knowledge on Epidemiology and Research Needs Toward Sustainable Disease Management.

Banana production is seriously threatened by Fusarium wilt (FW), a disease caused by the soil-borne fungus f. sp. ().

The diversification of begomovirus populations is predominantly driven by mutational dynamics.

Begomoviruses (single-stranded DNA plant viruses) are responsible for serious agricultural threats. Begomovirus populations exhibit a high degree of within-host genetic variation and evolve as quickly as RNA viruses. Although the recombination-prone nature of begomoviruses has been extensively demonstrated, the relative contribution of recombination and mutation to the genetic variation of begomovirus populations has not been assessed.

Independently founded populations of Sclerotinia sclerotiorum from a tropical and a temperate region have similar genetic structure.

Sclerotinia sclerotiorum populations from tropical agricultural zones have been suggested to be more variable compared to those from temperate zones. However, no data were available comparing populations from both zones using the same set of markers. In this study, we compared S.

Analysis of Tc1-Mariner elements in Sclerotinia sclerotiorum suggests recent activity and flexible transposases.

Background: Sclerotinia sclerotiorum is a necrotrophic fungus that is pathogenic to many plants. Genomic analysis of its revealed transposable element expansion that has strongly influenced the evolutionary trajectory of several species. Transposons from the Tc1-Mariner superfamily are thought to be ubiquitous components of fungal genomes and are generally found in low copy numbers with large numbers of deleterious mutations in their transposase coding sequence.

Erasing the past: a new identity for the Damoclean pathogen causing South American leaf blight of rubber.

Background: South American leaf blight (SALB) of rubber has been the main constraint to production in its neotropical centre of origin since commercial plantations were first established. The fungal causal agent was identified and described more than a century ago but its precise placement within the Ascomycota still remains uncertain. Indeed, such is the ambiguity surrounding the pathogen that each of the spore morphs would, according to their present classification, be placed in different ascomycete families: the Microcyclus sexual morph in the Planistromellaceae and the two purported asexual morphs--Fusicladium and Aposphaeria--in the Venturiaceae and Lophiostomataceae, respectively.

Contrasting genetic structure between two begomoviruses infecting the same leguminous hosts.

Begomoviruses are whitefly-transmitted, ssDNA plant viruses and are among the most damaging pathogens causing epidemics in economically important crops worldwide. Wild/non-cultivated plants play a crucial epidemiological role, acting as begomovirus reservoirs and as 'mixing vessels' where recombination can occur. Previous work suggests a higher degree of genetic variability in begomovirus populations from non-cultivated hosts compared with cultivated hosts.

Characterization and potential evolutionary impact of transposable elements in the genome of Cochliobolus heterostrophus.

Background: Cochliobolus heterostrophus is a dothideomycete that causes Southern Corn Leaf Blight disease. There are two races, race O and race T that differ by the absence (race O) and presence (race T) of ~ 1.2-Mb of DNA encoding genes responsible for the production of T-toxin, which makes race T much more virulent than race O.

Begomovirus diversity in tomato crops and weeds in Ecuador and the detection of a recombinant isolate of rhynchosia golden mosaic Yucatan virus infecting tomato.

Viral diseases caused by begomoviruses are of economic importance due to their adverse effects on the production of tropical and subtropical crops. In Ecuador, despite reports of significant infestations of Bemisia tabaci in the late 1990s, only very recently has a begomovirus, tomato leaf deformation virus (ToLDeV, also present in Peru), been reported in tomato. ToLDeV is the first monopartite begomovirus discovered that originated in the Americas, and its presence in Ecuador highlights the need for a wider survey of tomato-infecting begomoviruses in this country.

Yet more "weeds" in the garden: fungal novelties from nests of leaf-cutting ants.

Background: Symbiotic relationships modulate the evolution of living organisms in all levels of biological organization. A notable example of symbiosis is that of attine ants (Attini; Formicidae: Hymenoptera) and their fungal cultivars (Lepiotaceae and Pterulaceae; Agaricales: Basidiomycota). In recent years, this mutualism has emerged as a model system for studying coevolution, speciation, and multitrophic interactions.

Mycosphaerella musicola Identified as the Only Pathogen of the Sigatoka Disease Complex Present in Minas Gerais State, Brazil.

A thorough assessment of the distribution of Mycosphaerella spp. associated with banana in Minas Gerais State, Brazil, was conducted after Mycosphaerella fijiensis was first reported to occur in this region in 2005. From 2009 to 2011, 80 fields located in 20 municipalities including the same fields where the disease was first reported were sampled.

Use of the IRAP marker to study genetic variability in Pseudocercospora fijiensis populations.

Pseudocercospora fijiensis is the etiological agent of black Sigatoka, which is currently considered as one of the most destructive banana diseases in all locations where it occurs. It is estimated that a large portion of the P. fijiensis genome consists of transposable elements, which allows researchers to use transposon-based molecular markers in the analysis of genetic variability in populations of this pathogen.

Rust disease of eucalypts, caused by Puccinia psidii, did not originate via host jump from guava in Brazil.

The rust fungus, Puccinia psidii, is a devastating pathogen of introduced eucalypts (Eucalyptus spp.) in Brazil where it was first observed in 1912. This pathogen is hypothesized to be endemic to South and Central America and to have first infected eucalypts via a host jump from native guava (Psidium guajava).

Brazilian begomovirus populations are highly recombinant, rapidly evolving, and segregated based on geographical location.

The incidence of begomovirus infections in crop plants sharply increased in Brazil during the 1990s following the introduction of the invasive B biotype of the whitefly vector, Bemisia tabaci. It is believed that this biotype transmitted begomoviruses from noncultivated plants to crop species with greater efficiency than indigenous B. tabaci biotypes.