•Gorse composts exhibit suppressiveness against F. circinatum in pine seedlings.•T34 decreases incidence of F. circinatum on moderately suppressive composts.•Seedlings on suppressive composts ...exhibited greater sizes and higher photosynthesis.•NH4+/NO3− ratio was unrelated to incidence of F. circinatum disease in seedlings.•Composts produced at a small scale had high incidence of the disease.
Fusarium circinatum is a quarantine pathogen in numerous countries that causes important economic losses in forest nurseries and mature pine trees. Alternatives to chemical control of plant diseases such as suppressive composts and the use of biological control agents in growth media can reduce the incidence and spread of disease. In this work, four gorse composts obtained from forest cleaning green wastes and reference compost prepared from the organic fraction of solid urban waste were studied as environmentally sustainable peat substitutes. Their ability to suppress the effects of mating types M1 and M2 of the pathogen F. circinatum on Pinus radiata was evaluated in the presence or absence of the biocontrol agent Trichoderma asperellum strain T34. One of the gorse composts was more suppressive than the reference compost (15% and 55% of disease incidence, respectively). The former had a low EC, moderate amounts of P, Ca, Mg and K, and high levels of NH4+, as well as moderate levels of Ca, B and oligotrophic actinomycetes, the highest levels of total fungi, moderate levels of Trichoderma spp. and the lowest levels of Fusarium spp. Adding T34 to the moderately suppressive and non-suppressive composts decreased pre- and post-emergence incidence of the disease by up to 50%.
In conclusion, one gorse compost decreased the incidence of F. circinatum disease when used as a growth medium for P. radiata seedlings. T. asperellum strain T34 further reduced the incidence of disease and improved the health of pine seedlings grown in moderately non-suppressive composts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Fusarium circinatum Nirenberg & O’Donnell (teleomorph = Gibberella circinata) is the causal agent of pitch canker disease of pines. Since 2004 it has been present in Europe, particularly in northern ...Spain, affecting P. radiata and P. pinaster in plantations and nurseries. The disease has now also spread to other European countries, including France, Italy and Portugal. In this report, we describe three novel members of the genus Mitovirus from a Spanish isolate of F. circinatum: Fusarium circinatum mitovirus 1 (FcMV1), FcMV2-1 and FcMV2-2. Using a mitochondrial translation table, the complete 2419-bp genome of FcMV1 encodes an RNA-dependent RNA polymerase of 731 amino acids (GC-content ca 30 %). The partial genomes of FcMV2-1 and FcMV2-2 (2193 and 1973 bp, respectively) share ca 48 % RdRp sequence similarity at the aa level and might be regarded as conspecific, while FcMV1 is clearly distinct, showing 32-35 % polymerase similarity to the other strains. However, FcMV1 shared 46 % protein-level similarity with Thielaviopsis basicola mitovirus. This is the first study to report viruses in F. circinatum, as well as the first time that mitovirus genome sequences are described from Fusarium spp.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Fusarium circinatum Nirenberg & O’Donnel is listed among the species recommended for regulation as quarantine pests in Europe. Over 60 Pinus species are susceptible to the pathogen and it also causes ...disease on Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and species in genera such as Picea and Larix. The European Food Safety Authority considers the probability of new introductions—via contaminated seeds, wood material, soil and growing substrates, natural means and human activities—into the EU very likely. Due to early detection, constant surveillance and control measures, F. circinatum outbreaks have officially been eradicated in Italy and France. However, the global spread of F. circinatum suggests that the pathogen will continue to be encountered in new environments in the future. Therefore, continuous surveillance of reproductive material, nurseries and plantations, prompt control measures and realistic contingency plans will be important in Europe and elsewhere to limit disease spread and the “bridgehead effect”, where new introductions of a tree pathogen become increasingly likely as new environments are invaded, must be considered. Therefore, survey programs already implemented to limit the spread in Europe and that could be helpful for other EU countries are summarized in this review. These surveys include not only countries where pitch canker is present, such as Portugal and Spain, but also several other EU countries where F. circinatum is not present. Sampling protocols for seeds, seedlings, twigs, branches, shoots, soil samples, spore traps and insects from different studies are collated and compiled in this review. Likewise, methodology for morphological and molecular identification is herein presented. These include conventional PCR with a target-specific region located in the intergenic spacer region, as well as several real-time PCR protocols, with different levels of specificity and sensitivity. Finally, the global situation and future perspectives are addressed.
Fusarium circinatum, causing pine pitch canker, is one of the most damaging pathogens of Pinus species. This study investigated the use of phenotypical and molecular characteristics to delineate ...groups in a worldwide collection of isolates. The groups correlated with virulence and fungicide sensitivity, which were tested in a subset of isolates. Virulence tests of twenty isolates on P. radiata, P. sylvestris and P. pinaster demonstrated differences in host susceptibility, with P. radiata most susceptible and P. sylvestris least susceptible. Sensitivity to the fungicides fludioxonil and pyraclostrobin varied considerably between isolates from highly effective (half-maximal effective concentration (EC50) < 0.1 ppm) to ineffective (EC50 > 100 ppm). This study demonstrates the potential use of simply acquired phenotypical (cultural, morphological) and molecular metrics to gain a preliminary estimate of virulence and sensitivity to certain fungicides. It also highlights the necessity of including a range of isolates in fungicide tests and host susceptibility assays, particularly of relevance to tree breeding programmes.
Recent work has shown that Fusarium circinatum, previously known only as a pathogen of pines (Pinus) and Douglas fir (Picea abies), can also infect species in the grass family Poaceae. The present ...study characterized the ability of F. circinatum to colonize corn (Zea mays), in comparison to closely related Fusarium species known to have endophytic associations with Z. mays. When inoculum was applied to seed, F. circinatum colonized roots, stems and developing ears of Z. mays, roots were colonized on plants grown in infested soil, and corn ears became infected when inoculum was applied to husk wounds or through silk channels without wounding. Colonization was restricted to intercellular growth in the cortical and epidermal tissue. No negative effects on growth or emergence were detected. These results constitute the first description of an endophytic association of F. circinatum with a grass species and are illustrative of ecological activities that may remain undetected where fungi have no visible impact on their plant host.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Fusarium circinatum is the causal agent of pitch canker disease on numerous Pinus spp. This aggressive fungus may infect pine seed cryptically and, therefore, can easily be spread long distances by ...the seed trade. F. circinatum has recently been listed as a quarantine organism in numerous countries throughout the world, which prompted the development of a specific and sensitive tool for the detection of this pathogen in conifer seed. A new detection protocol for F. circinatum based on a biological enrichment step followed by a real-time polymerase chain reaction (PCR) assay was developed. Several enrichment protocols were compared and a 72-h incubation of the seed with potato dextrose broth was the most efficient technique to increase F. circinatum biomass before DNA extraction. The relative accuracy, specificity, and sensitivity of the real-time PCR assay was evaluated in comparison with a previously published conventional PCR test on 420 seed DNA extracts. The real-time PCR described here proved to be highly specific and significantly more sensitive than the conventional PCR, and enabled the detection of F. circinatum in samples artificially contaminated with less than 1/1,000 infected seed, as well as in naturally infected samples. Last, in order to routinely check the quality of the seed DNA extracts, a primer-probe combination that targets a highly conserved region within the 18S ribosomal DNA in plants or fungi was successfully developed. This assay allows for quick and reliable detection of F. circinatum in seed, which can help to prevent long-distance spread of the pathogen via contaminated seed lots.
Pitch canker is a serious disease of pines caused by the ascomycete fungus Gibberella circinata (anamorph = Fusarium circinatum). Three distinct mitovirus strains have been described in this fungus: ...Fusarium circinatum mitovirus 1 (FcMV1), FcMV2-1 and FcMV2-2. Here, we investigated the frequency and population variation of these viruses and closely related sequence variants in northern Spain using RT-PCR and sequencing. Each virus strain and similar sequence variants shared >95 % sequence identity and were collectively designated as virus types. All virus types were relatively common in Spain, with estimated prevalence of 18.5 %, 8.9 % and 16.3 % for FcMV1, FcMV2-1 and FcMV2-2, respectively.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In November of 2007, dieback symptoms (basal needle dieback, wilting, and dieback of terminal shoot) were observed on plant groups of Pinus radiata and P. pinaster in a tree nursery located in Anadia ...in the central region of Portugal (40°26'N, 08°23'W). Two containers with a total of 112 plants per pine species (with and without symptoms) were collected. Small pieces (5 mm long; two from the roots, stem at the soil level, and the aerial part, totaling six pieces) of 20 symptomatic plants were sterilized with 3% sodium hypochlorite, and isolations were performed on potato dextrose agar (PDA) supplemented with 0.5 mg/ml of streptomycin sulfate. A species of Fusarium was isolated from all infected tissues and pure cultures were obtained by single hyphal tip transfers on PDA and Spezieller Nährstoffarmer agar and incubated at 25°C for 10 days with a 12-h photoperiod. The species was identified as Fusarium circinatum Nirenberg & O'Donnell (= F. subglutinans Wollenweb & Reinking) on the basis of morphological and cultural characteristics (2). They produced white, aerial mycelia, violet pigment, typically three-septate macroconidia with slightly curved walls, single-celled microconidia, and characteristic sterile, coiled hyphae. Microconidia were ovoid or allantoid and born in false heads on aerial polyphialides. The identification was confirmed by PCR with specific primers CIRC1A/CIRC4A, resulting in a 360-bp DNA fragment of the two nuclear ribosomal intergenic spacer regions (3). Pathogenicity tests were performed by inoculating 5- and 9-month-old P. pinaster and P. radiata seedlings, respectively. Plants belonging to P. pinea species (8-month-old), the second most important pine in the country, were also included in the tests. Small strips of bark (10 × 1 mm) were cut from the stems and similar-sized pieces of PDA colonized by two isolates of F. circinatum were placed in contact with the open wounds and covered with Parafilm. Ten seedlings for each pine species, isolate, and control (with sterile PDA) were provided in a total of 90 plants. First symptoms, basal needle and shoot dieback, were observed in P. radiata 8 days after inoculation. One month later, all P. radiata and 70% of the P. pinaster plants were dead. In all P. pinea plants, needles turned red along the main stem, from center to periphery, but only 2% of these plants presented wilting of the terminal shoot after 1 month. No symptoms were observed on control seedlings. F. circinatum was reisolated from symptomatic plants of the three species tested. To our knowledge, this is the first report of F. circinatum in Portugal. Pitch canker, caused by Gibberella circinata (anamorph F. circinatum), is one of the most aggressive pathogens on several pine species in the world (1). In 2005, the fungus was detected in the European continent affecting P. radiata and P. pinaster in northern Spain. References: (1) E. Landeras et al. Plant Dis. 89:1015, 2005. (2) H. I. Niremberg and K. O'Donnell. Mycologia 90:434, 1998. (3) W. Schweigkofler et al. Appl. Environ. Microbiol. 70:3512, 2004.
Pitch canker is a devastating disease of Pinus spp. and Pseudotsuga menziesii (Mirb.) Franco. The pathogen responsible for this disease, Fusarium circinatum Nirenberg & O'Donnell, has spread to many ...countries within the last three decades. The susceptibility of the widely planted commercial species Pinus radiata D.Don to this pathogen has been of concern to pine forest industries worldwide. Using the process-based distribution program CLIMEX, the global risk of pitch canker establishment was predicted based on a number of climatic variables. The predicted risk of pitch canker establishment by CLIMEX fit well with regions known to have the disease, such as the southeastern United States and Spain. Conversely, the model predicted that the climate in California was not optimal for pitch canker, which fits with the observed lower frequency of natural infections and the strong association with insects in this region. Likewise, Chile, which is known to have F. circinatum in the nurseries but not in the plantation forests, was also predicted to have marginal to suitable climatic conditions for pitch canker establishment. Regions of China, Brazil, Australia, and New Zealand were predicted to have optimal climate conditions for disease establishment. Thus, continued strict quarantine regulations are recommended to prevent the establishment and spread of this pathogen in these countries.
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BF, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT The world's oldest ecosystems are found in the tropics. They are diverse, highly evolved, but barely understood. This and subsequent papers describe diseases of tropical, perennial plants ...that are caused by Fusarium spp. Many of these are economically significant, difficult to manage, and of scientific interest. Some represent coevolved patho-systems (e.g., Panama disease, tracheomycosis of coffee, fusariosis of pineapple, and Fusarium wilt of oil palm), whereas others may be new-encounter diseases or are caused by generalist pathogens (cushion gall of cacao). New vector relationships are evident in other pathosystems (e.g., mango malformation), and two or more pathogens have been shown to cause some of the diseases (Panama disease and tracheomycosis of coffee). More work on these pathosystems is warranted as they could reveal much about the evolution of plant pathogens and the important diseases they cause.
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