Alternative species to replace Monterey pine plantations affected by pitch canker caused by Fusarium circinatum in northern Spain

The pitch canker pathogen Fusarium circinatum was first found to cause damage in nurseries and pine plantations in northern Spain in 2004. Since then, establishment of pine plantations in the region has decreased as a result of the prohibitions placed on planting Pinus spp. and Pseudotsuga menziesii in areas affected by the disease. However, although most pine species have been found to be susceptible to the pathogen under nursery conditions, little is known about how the fungus affects the trees in the field. Furthermore, it is not known whether some of the native or exotic species commonly planted in the area are also susceptible to F. circinatum. The aim of this study was to evaluate the susceptibility of several conifer species commonly planted in northern Spain to the pitch canker pathogen. For this purpose, two different trials were carried out, one under controlled laboratory conditions and the other in the field. Although most of the conifers were affected by the pathogen in the laboratory tests, only Pinus radiata, Pinus nigra, Pinus pinaster and Pinus uncinata were susceptible to the pathogen in the field.     

Differences in constitutive and inducible defences in pine species determining susceptibility to pinewood nematode

The pinewood nematode, Bursaphelenchus xylophilus, originating from North America (NA), is a major invasive pine pest in Eurasia. It was first detected in Portugal in 1999 associated with maritime pine, Pinus pinaster, and has been differently affecting the main local pine species, P. pinaster and P. pinea. Field studies and direct inoculation experiments in Pinus spp. seedlings, under controlled conditions, were performed to assess whether the differences in constitutive and inducible defences are determining the different susceptibility of pine host species to B. xylophilus. Host co‐evolution with the pathogen was also assessed, including the NA P. radiata, widely used in forestry in the northeast of the Iberian peninsula. Pine mortality in the field was positively related with the abundance of B. xylophilus, and concentration of phenolics and condensed tannins in pines. In the greenhouse assay, seedling tissues were analysed for constitutive investment in defences, as well as the potential inducibility of those defences as driven by B. xylophilus inoculation. Slower growing P. pinea presented higher levels of constitutive defences than faster growing P. pinaster, with only P. pinaster being affected by B. xylophilus. Furthermore, co‐evolution with the pathogen is important, with the fast‐growing NA P. radiata presenting an inducible and effective response to B. xylophilus. Results point to the importance of integrating data on pine life history traits, including growth rate, and production of constitutive and inducible defences, into predictive models for this invasive forest pest.     

Occurrence and ITS diversity of wood‐associated Bursaphelenchus nematodes in Scots pine forests in Switzerland

The quarantine pathogen Bursaphelenchus xylophilus (pine wood nematode, PWN) represents a serious threat for Pinus species in Europe. To exclude its presence in Switzerland, in 2010 and 2011 a countrywide survey was conducted in 102 Pinus sylvestris stands, chosen according to whether they contained dying or dead trees or were located in areas at risk of PWN introduction. In total, 285 trees (1–5 per site) were sampled. Nematodes were extracted from wood chips using a standard procedure, and identified to species by internal transcribed spacer (ITS) sequencing. Bursaphelenchus species were present in 34% of the trees, but no B. xylophilus was identified, i.e. PWN is still not present in Switzerland. The nematodes found belonged to seven different species, with B. vallesianus the most frequent species, followed by B. sexdentati, B. mucronatus kolymensis and B. eggersi. Three other species (B. borealis, B. pinophilus, B. poligraphi) were each only present in one or two trees. Three groups of sequences could not be assigned to a species because of the lack of matching reference sequences. The species composition found in Switzerland suggests co‐existence of southern and central European Bursaphelenchus species. Intraspecific ITS variability differed considerably among the four most common species. Bursaphelenchus eggersi, B. mucronatus kolymensis and B. sexdentati had several variable sites in the ITS region, resulting in multiple ITS genotypes in each species. In contrast, all 99 B. vallesianus isolates had an identical ITS region. This could indicate a founder effect, and possibly that B. vallesianus is not native to the Alpine region.     

Alternatives to hexazinone and terbuthylazine for chemical control of Cytisus scoparius in Pinus radiata plantations in New Zealand

Two herbicides used for post‐plant weed control in commercial forests in New Zealand, terbuthylazine and hexazinone, are not endorsed for use on land certified by the Forest Stewardship Council (FSC). These herbicides are effective for controlling competitive woody weeds, such as Cytisus scoparius (broom). To investigate the potential of non‐residual, alternative herbicides for the control of C. scoparius after planting, a range of treatments were implemented at two trials. The trials were established in newly planted Pinus radiata plantations where C. scoparius dominated. The objectives were to (i) optimise application rates of alternative herbicides and compare their efficacy to current practice and (ii) identify if treatment efficacy varied across sites. Treatments at each site included weedy and weed‐free controls, current practice using terbuthylazine and hexazinone, applied as both spot treatment and broadcast application, and a range of new treatments consisting of different dosage combinations of clopyralid, triclopyr and picloram. Broadcast application of the clopyralid, triclopyr and picloram mixture showed increasing weed‐control efficacy against C. scoparius with increasing dose rate, resulting in increased tree volume. Broadcast application of the clopyralid, triclopyr and picloram mixture at 75% or 100% of a typical industry use rate (100% industry rate includes clopyralid 1.5 kg a.i. ha^?1, triclopyr 0.15 kg a.i. ha^?1 and picloram 0.05 kg a.i. ha^?1) achieved greatest tree volume by year four with tree volumes exceeding that obtained using the operational spot treatment with terbuthylazine and hexazinone. Treatment rankings were similar between locations. The result supports the use of clopyralid, triclopyr and picloram to control C. scoparius during the first year of P. radiata establishment.     

Dothistroma needle blight: an emerging epidemic caused by Dothistroma septosporum in Colombia

Plantation forestry in Colombia is based mainly on non‐native species of Pinus and Eucalyptus. Since 2008, a disease with symptoms similar to those of dothistroma needle blight (DNB) has been found affecting large areas planted to Pinus spp. The aim of this study was to identify the causal pathogen as well as to document the levels of disease incidence and severity. Isolates from each of three forestry zones, collected from different host species, were compared based on rDNA sequence of the ITS regions. These were conclusively identified as Dothistroma septosporum, one of two Dothistroma spp. known to cause DNB. Susceptibility was greatest on low elevation Pinus tecunumanii followed by Pinus kesiya and Pinus oocarpa. Pinus maximinoi and high elevation P. tecunumanii showed tolerance to D. septosporum. The disease incidence in the different zones varied significantly with the North zone being the most severely affected. This constitutes the first report of disease distribution and susceptibility of hosts, as well as the first consideration of the relative importance of D. septosporum in Colombia.     

Phytophthora caryae sp. nov., a new species recovered from streams and rivers in the eastern United States

Members of the Phytophthora citricola complex (Phytophthora clade 2c), such as P. plurivora, are destructive pathogens of trees and shrubs in nursery, landscape and forest settings worldwide. During surveys of Phytophthora species from streams and rivers in Massachusetts and North Carolina, a novel species in the P. citricola complex was recovered. Based on sequences from three nuclear (ITS, β‐tub and tef1) and two mitochondrial (cox1 and nadh1) loci, morphological characters, temperature–growth relationships and host plant inoculations, this novel species is described as Phytophthora caryae sp. nov. Phytophthora caryae resembles several other species in the P. citricola complex, demonstrating homothallism and producing paragynous antheridia and semipapillate and noncaducous sporangia. However, P. caryae exhibits smaller sexual structures, higher rates of oogonia with a tapered base and sporangia with an offset attachment of the sporangiophores. Phylogenetic analyses using maximum likelihood and Bayesian inference placed isolates of P. caryae into a unique clade with significant statistical support. Based on the mitochondrial dataset, P. caryae is most closely related to P. pini and P. citricola III, which are believed to be native in eastern North America. Inoculations of P. caryae on 1‐year‐old twigs of 12 tree species representing nine genera resulted in under‐bark lesions on species of Carya and Juglans. Sapling inoculations under greenhouse conditions suggest that P. caryae may be pathogenic to shagbark hickory (Carya ovata) but not to black walnut (Juglans nigra).     

Comparison of the reproductive potential of <Emphasis Type="Italic">Monochamus galloprovincialis</Emphasis> on two pine species under laboratory conditions

Monochamus galloprovincialis Olivier (Coleoptera: Cerambycidae) is one of the vectors of the pinewood nematode Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle (Nematoda: Parasitaphelenchidae), the causal agent of pine wilt in susceptible pine trees. It is therefore important to study both the biological and ecological characteristics of the beetle. In this study reproductive potentials of female beetles reared on two pine species were investigated under laboratory conditions and compared using fertility tables constructed for beetles reared on each tree species. Beetle population parameters were compared between tree species. The intrinsic rate of increase and associated population parameters of beetles reared on Pinus sylvestris L. were consistently higher than those reared on P. nigra Arnold. This result suggests that P. sylvestris has a significantly greater positive effect on the reproductive potential of M. galloprovincialis populations than does P. nigra.     

Intraspecific variation in susceptibility to dothistroma needle blight within native Scottish Pinus sylvestris

Dothistroma needle blight (DNB), caused by Dothistroma septosporum, is the most important disease currently affecting pine plantations in Britain. Intraspecific variation in susceptibility to DNB has been observed in several pine species, but it is not clear if similar variation occurs in Pinus sylvestris (Scots pine), Britain's only native pine. In three separate experiments 2‐ and 3‐year‐old Scots pine saplings from six native Scottish populations were artificially inoculated with D. septosporum conidial suspensions and incubated under conditions optimal for disease development. Conidial suspensions were produced using a single isolate from northeast Scotland. In one experiment, plants were also treated with various spore suspension concentrations to assess the impact of inoculum load on disease severity. There were no significant interactions between host population, plant height, and experiment/inoculum load (anova , P > 0·05), but population, height and inoculum load all significantly affected disease severity (anova , P < 0·05). Among the 2‐year‐old trees, those from Amat were less susceptible than those from Glen Loyne and Glen Cannich (anova , P < 0·05). Among the 3‐year‐old trees, those from Beinn Eighe were less susceptible than those from Abernethy. Plant height and DNB susceptibility had a slightly negative relationship. The use of a spore suspension with a concentration of 1·6 × 10⁶ spores mL^?1 was optimum for disease development. In an in vitro experiment, production of conidia was greater when cultures were incubated in darkness. This paper is the first to report intraspecific variation in DNB susceptibility within Scots pine.     

Contrasting species boundaries between sections Alternaria and Porri of the genus Alternaria

The fungal genus Alternaria comprises a large number of asexual taxa with diverse ecological, morphological and biological modes ranging from saprophytes to plant pathogens. Understanding the speciation processes affecting asexual fungi is important for estimating biological diversity, which in turn affects plant disease management and quarantine enforcement. This study included 106 isolates of Alternaria representing five phylogenetically defined clades in two sister sub‐generic groups: section Porri (A. dauci, A. solani and A. limicola) and section Alternaria (A. alternata/tenuissima and A. arborescens). Species in section Porri are host‐specific while species in section Alternaria have wider host ranges. For each isolate, DNA sequences of three genes (Alt a1, ATPase, Calmodulin) were used to estimate phylogenies at the population and species levels. Three multilocus haplotypes were distinguished among A. dauci isolates and only one haplotype among A. solani and A. limicola isolates, revealing low or no differentiation within each taxon and strong clonal structure for taxa in this section. In contrast, 37 multilocus haplotypes were found among A. alternata/tenuissima isolates and 21 multilocus haplotypes among A. arborescens isolates, revealing much higher genotypic diversity and multiple clonal lineages within taxa, which is not typical of asexual reproducing lineages. A species tree was inferred using a Yule Speciation model and a strict molecular clock assumption. Species boundaries were well defined within section Porri. However, species boundaries within section Alternaria were only partially resolved with no well‐defined species boundaries, possibly due to incomplete lineage sorting. Significant association with host specificity seems a driving force for speciation.     

Phytophthora pachypleura sp. nov., a new species causing root rot of Aucuba japonica and other ornamentals in the United Kingdom

Isolates of an unknown Phytophthora species from the ‘Phytophthora citricola complex’ have been found associated with mortality of Aucuba japonica in the UK. Based on morphological characteristics, growth–temperature relationships, sequences of five DNA regions and pathogenicity assays, the proposed novel species is described as Phytophthora pachypleura. Being homothallic with paragynous antheridia and semipapillate sporangia, P. pachypleura resembles other species in the ‘P. citricola complex’ but can be discriminated by its distinctively thick‐walled oospores with an oospore wall index of 0·71. In the phylogenetic analysis based on three nuclear (ITS, β‐tubulin, EF‐1α) and two mitochondrial (cox1, nadh1) DNA regions, P. pachypleura formed a distinct clade within the ‘P. citricola complex’ with P. citricola s. str., P. citricola E and P. acerina as its closest relatives. Phytophthora pachypleura is more aggressive to A. japonica than P. plurivora and P. multivora and has the potential to affect other ornamental species.     

Species composition and genetic structure of Fusarium graminearum species complex populations affecting the main barley growing regions of South America

Members of the Fusarium graminearum species complex (FGSC), such as F. graminearum and F. asiaticum, are the main cause of fusarium head blight (FHB) of wheat and barley worldwide. In this study, 117 FGSC isolates obtained from commercial barley grain produced in Argentina (n = 43 isolates), Brazil (n = 35), and Uruguay (n = 39) were identified to species and trichothecene genotypes, and analysed using amplified fragment length polymorphism (AFLP) and sequence‐related amplified polymorphism (SRAP) markers. In addition, reductase (RED) and trichothecene 3‐O‐acetyltransferase (Tri101) were sequenced for a subset of 24 isolates. The majority of the isolates (n = 103) were identified as F. graminearum, which was the only species found in Argentina. In Uruguay, only one F. cortaderiae isolate was found among F. graminearum isolates. In Brazil, F. graminearum also dominated the collection (22/35), followed by F. meridionale (8/35), F. asiaticum (2/35), F. cortaderiae (2/35) and F. austroamericanum (1/35). Species were structured by trichothecene genotype: all F. graminearum were of the 15‐acetyldeoxynivalenol (ADON), F. meridionale, F. asiaticum and F. cortaderiae were of the nivalenol (NIV), and F. austroamericanum was of the 3‐ADON genotype. Both AFLP and SRAP data showed high levels of genetic variability, which was higher within than among countries. Isolates were not structured by country of origin. SRAP analysis grouped F. graminearum in a separate cluster from the other species within the complex. However, AFLP analysis failed to resolve the species into distinct clades with partial clustering of F. meridionale, F. austroamericanum, F. asiaticum and F. graminearum isolates.     

Chloroplast DNA markers for Echinochloa taxa

The genus Echinochloa (Poaceae) includes numerous problematic weeds over a wide range of ecoregions in the world. To date, molecular markers for species identification and assessing phylogenetic relationship are still limited in the genus Echinochloa. In this study, we developed seven chloroplast molecular markers based on divergent chloroplast regions of E. crus‐galli and E. oryzicola. Furthermore, Marker #1 (psbA) was examined in more than 200 Echinochloa accessions and a phylogenetic tree grouped these Echinochloa accessions into four clades. Additionally, two different E. crus‐galli varieties (E. crus‐galli var. crus‐galli, E. crus‐galli var. praticola) and E. colona were successfully distinguished by this marker. The developed molecular markers contribute to better identification of Echinochloa taxa.     

Species of the Colletotrichum gloeosporioides and C. boninense complexes associated with olive anthracnose

The taxonomic status of Colletotrichum gloeosporioides sensu lato (s.l.) associated with olive anthracnose is still undetermined and the pathogenic ability of this species complex is controversial. In the present study, isolates obtained from olive and provisionally identified as C. gloeosporioides s.l. on the basis of morphological and cultural features were reclassified using ITS and TUB2 as DNA barcode markers and referred to seven distinct species, recently separated within C. gloeosporioides (C. aenigma, C. gloeosporioides sensu stricto (s.s.), C. kahawae, C. queenslandicum, C. siamense and C. theobromicola) and C. boninense (C. karstii) species complexes. Furthermore, isolates of C. kahawae were ascribed to the subspecies ciggaro by analysing the GS gene. A single isolate, not in either of these two species complexes, was not identified at the species level. In pathogenicity tests on detached olive drupes some of these species, including C. aenigma, C. kahawae subsp. ciggaro, C. queenslandicum, C. siamense and C. karstii, were shown to be weakly pathogenic. Moreover, they were found very sporadically on olive. In contrast, some isolates of C. gloeosporioides s.s. and isolates of C. theobromicola proved to be virulent on both green and ripening olives. This study gives a better insight into both the aetiology and the epidemiology of olive anthracnose and might have implications for biosecurity and quarantine because C. theobromicola has never been reported in major European olive‐producing countries.     

Susceptibility evaluation of Picea abies and Cupressus lusitanica to the pine wood nematode (Bursaphelenchus xylophilus)

Pine wilt disease (PWD), recently introduced into Europe, is caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus and is a devastating illness that affects mainly pine trees. It is known that the PWN is capable of infecting other conifers; however, there is currently no information on which other plant species may be susceptible to PWD. In this study, the potential susceptibility of two common species of European forests, Picea abies and Cupressus lusitanica, to PWN was assessed through the monitoring of visual external symptoms, dimension and localization of the nematode population in stems, quantification of total chlorophyll, total soluble phenolics and lignin, at 7, 14, 21 and 28 days after inoculation. The degree of susceptibility was established through the comparison of symptoms with Pinus pinaster, a well‐known PWN host. Furthermore, the stem ultrastructure of P. abies, C. lusitanica and Pn. pinaster was analysed by scanning electron microscopy. The results suggest that P. abies and C. lusitanica are resistant to PWN, and that lignin biosynthesis in these species is affected at an early stage of the infestation. Nevertheless, P. abies seems to be a compatible host that could act as a repository for PWN.     

Pathogenicity of Hymenoscyphus fraxineus towards leaves of three European ash species: Fraxinus excelsior,F. angustifolia and F. ornus

This study aimed to demonstrate the association of the ash dieback pathogen Hymenoscyphus fraxineus with leaf symptoms on Fraxinus excelsior and to test its pathogenicity towards leaves of three European ash species, F. excelsior, F. angustifolia and F. ornus, in wound inoculation experiments. On F. excelsior, H. fraxineus was isolated from 94% of leaf rachises with necrotic lesions and from 74% of necrotic leaflet midribs. Following wound inoculation of leaf rachises, in two separate experiments performed in 2010 and 2011, the ash dieback pathogen caused symptoms (necrotic rachis lesions, leaf wilting and premature leaf shedding) on all three ash species, while control leaves remained symptomless. Hymenoscyphus fraxineus was consistently reisolated from fungus‐inoculated rachises. All 10 isolates tested were pathogenic to the three ash species and varied in virulence. Koch's postulates for H. fraxineus as causal agent of leaf symptoms on F. excelsior were fulfilled in this study. Complemented with the isolation of the fungus from naturally infected, symptomatic leaf rachises of F. angustifolia and F. ornus in previous investigations, H. fraxineus was confirmed to be a leaf pathogen of these ash species as well. The leaf inoculation experiments showed that F. excelsior was highly susceptible to H. fraxineus, F. angustifolia was equally or slightly less susceptible, whereas F. ornus was the least affected species; however, F. ornus should also be regarded as a host tree for the ash dieback pathogen. This susceptibility ranking corresponds well with field observations and previous stem inoculation experiments.     

Identification and differentiation of Phyllosticta species causing freckle disease of banana using high resolution melting (HRM) analysis

Freckle disease of banana is caused by three closely related species of Phyllosticta, namely P. musarum, P. maculata and P. cavendishii. In this study, a high resolution melting (HRM) analysis assay was developed and its potential to identify these three fungal species is reported. The assay, which targets the ITS of the nuclear rDNA of the fungal species, generates three distinct melt profiles for the three Phyllosticta species. It is also able to distinguish a combination of up to three co‐infecting species by generating a deviant melt curve. Thirty‐five fungal cultures and infected herbarium leaf specimens, previously characterized using nucleotide sequencing as belonging to one of the three Phyllosticta species, were used for validation of the HRM analysis assay. The normalized curves generated differentiated all samples, with samples from each species correctly identified. The assay was further evaluated against 18 uncharacterized infected leaf specimens from various geographic locations and the results were verified by subsequent nucleotide sequencing. This HRM analysis assay allows rapid identification and differentiation of the three Phyllosticta species using a single primer pair in a one‐step closed‐tube system without labelled fluorescence probes. This novel assay format has potential for simultaneously identifying and differentiating other closely related species of plant pathogens, as well as the classification of infected historic specimens.     

Magnesium oxide nanoparticles induce systemic resistance in tomato against bacterial wilt disease

Bacterial wilt is a serious problem affecting many important food crops. Recent studies have indicated that treatment with biotic or abiotic stress factors may increase the resistance of plants to bacterial infection. This study investigated the effects of magnesium oxide nanoparticles (MgO NP) on disease resistance in tomato plants against Ralstonia solanacearum, as well as its antibacterial activity. The roots of tomato seedlings were inoculated with R. solanacearum and then immediately treated with MgO NP; the treated plants showed very little inhibition of bacterial wilt. In contrast, when roots were drenched with a MgO NP suspension prior to inoculation with the pathogen, the incidence of disease was significantly reduced. Rapid generation of reactive oxygen species such as O₂^?˙ radicals was observed in tomato roots treated with MgO NP. Further O₂^?˙ was rapidly generated when tomato plant extracts or polyphenols were added to the MgO NP suspension, suggesting that the generation of O₂^?˙ in tomato roots might be due to a reaction between MgO NP and polyphenols present in the roots. Salicylic acid‐inducible PR1, jasmonic acid‐inducible LoxA, ethylene‐inducible Osm, and systemic resistance‐related GluA were up‐regulated in both the roots and hypocotyls of tomato plants after treatment of the plant roots with MgO NP. Histochemical analyses showed that β‐1,3‐glucanase and tyloses accumulated in the xylem and apoplast of pith tissues of the hypocotyls after MgO NP treatment. These results indicate that MgO NP induces systemic resistance in tomato plants against R. solanacearum.     

Effect of different hosts onThaumetopoea pityocampa populations in northeast Portugal

A study was carried out at the Natural Park of Montesinho, NE Portugal, in order to evaluate the effect of different pine species (Pinus pinaster Ait.,P. nigra Arn. andP. sylvestris L.) onThaumetopoea pityocampa populations. The structure of the egg batches, the impact of the egg parasitoids on natural mortality of the pest and the species of parasitoids present, as well as their emergence dynamics, were analyzed. The length of the egg batches varied among pine species with the longest ones onP. nigra. The mean number of eggs per batch differed betweenP. sylvestris and the two other hosts studied, with fewer eggs per batch on the first. No differences were found in the size of eggs among pine species. The egg mortality varied between 25.8% and 33.0%, with no differences among hosts. Parasitism was the main cause of death.Baryscapus servadeii (Mercet.) was the most abundant parasitoid species, followed byOoencyrtus pityocampae (Dom.) andTrichogramma embryophagum Htg.B. servadeii dominated in the egg batches collected fromP. pinaster andP. nigra, whereasO. pityocampae was most frequent onP. sylvestris. The emergence ofB. servadeii started in the middle of March and continued until August, with the emergence peak at the end of May. The emergence ofO. pityocampae started at the end of April and continued throughout September, with maximum values in June. http://www.phytoparasitica.org posting Sept. 20, 2006.     

Pathogenicity of 21 newly described Phytophthora species against seven Western Australian native plant species

The pathogenicity of some Phytophthora species recently described from Western Australia, together with P. cinnamomi as a control, was tested against seven Western Australian native plant species in the glasshouse. Host species were Banksia grandis, B. littoralis, B. occidentalis, Casuarina obesa, Corymbia calophylla, Eucalyptus marginata and Lambertia inermis. Twenty‐two Phytophthora species were grown on a vermiculite, millet seed and V8 substrate and used as soil inoculum when the plant hosts were approximately 3 months old. Pathogenicity was assessed after 6 weeks and plants were scored for death, root damage, and percentage reduction of shoot growth compared with control plants. The pathogenicity of P. cinnamomi was confirmed. Phytophthora niederhauserii was shown to be similar to P. cinnamomi in pathogenicity and of concern ecologically. Other species that killed one or more hosts were P. boodjera, P. constricta, P. elongata, P. moyootj and P. rosacearum, while P. condilina, P. gibbosa, P. gregata, P. litoralis and P. ‘personii’ caused significant reduction to shoot and/or root growth, but did not kill plants. Host species susceptible to the highest number of Phytophthora species were B. grandis, B. littoralis, B. occidentalis and E. marginata. No Phytophthora species tested killed C. calophylla.     

Widespread distribution of Xanthomonas perforans and limited presence of X. gardneri in Brazil

Tomato bacterial spot is caused by Xanthomonas euvesicatoria, X. vesicatoria, X. perforans and X. gardneri. In order to determine the distribution, frequency of occurrence, and diversity of these species in the Brazilian commercial tomato fields, a survey was conducted between 2009 and 2012. In this period, 204 strains were obtained from 33 counties (22 with processing tomatoes and 11 with fresh‐market tomatoes). Pathogenicity tests, BOX‐PCR, PCR with species‐specific primers, and sequence analysis of the avirulence gene avrXv3 were performed in order to identify the strains at species and race level. Xanthomonas perforans predominated among the strains (92%) and was present in most counties. In addition, this species was prevalent in most areas of both fresh‐market tomatoes (63.6% of counties surveyed) and processing tomatoes (95.4% of counties surveyed). Fifteen strains (7.5%) were identified as X. gardneri, which was found mostly in fresh‐market fields located at regions with altitude higher than 900 m, and only one strain of X. euvesicatoria (0.5%) was found in a processing tomato field. High genetic diversity was observed within X. perforans, with 137 BOX‐PCR haplotypes. Race T3 prevailed (97.5%), but reported here for the first time is the occurrence of five strains identified as race T4 in fresh‐market fields in the state of São Paulo. The race T4 phenotype of these strains resulted from the presence of an 859 bp insertion in the avirulence gene avrXv3. This insertion is related to amino acid sequences of a transposase found in X. gardneri, and to amino acid sequences of X. campestris.