Pruning practices influence infection and dissemination of <em>Calosphaeria pulchella<em>, the cause of Calosphaeria canker of sweet cherry

Calosphaeria canker of sweet cherry, caused by Calosphaeria pulchella, is a limiting factor for sweet cherry production, but the role of pruning practices on pathogen dissemination remains unknown. Three experimental treatments were compared during summer and winter seasons, to assess their effects on pathogen transmission. The treatments were: i) using disinfected pruning shears; ii) pruning shears used to cut through diseased branches before each subsequent cut (non-disinfected pruning shears); and iii) artificial inoculation of fresh pruning wounds with C. pulchella. Six months after pruning, branches were cut from trees for disease assessment and fungal isolation. Pruning with non-disinfected pruning shears increased disease incidence and severity, compared with the use of disinfected shears. Artificially inoculated branches gave the greatest disease incidence and severity. Results from the various treatments were consistent for both winter and summer pruning. These confirm that frequent disinfection of pruning tools is advised for the effective management of Calosphaeria canker of sweet cherry

Pruning practices influence infection and dissemination of Calosphaeria pulchella, the cause of Calosphaeria canker of sweet cherry

Calosphaeria canker of sweet cherry, caused by Calosphaeria pulchella, is a limiting factor for sweet cherry production, but the role of pruning practices on pathogen dissemination remains unknown. Three experimental treatments were compared during summer and winter seasons, to assess their effects on pathogen transmission. The treatments were: i) using disinfected pruning shears; ii) pruning shears used to cut through diseased branches before each subsequent cut (non-disinfected pruning shears); and iii) artificial inoculation of fresh pruning wounds with C. pulchella. Six months after pruning, branches were cut from trees for disease assessment and fungal isolation. Pruning with non-disinfected pruning shears increased disease incidence and severity, compared with the use of disinfected shears. Artificially inoculated branches gave the greatest disease incidence and severity. Results from the various treatments were consistent for both winter and summer pruning. These confirm that frequent disinfection of pruning tools is advised for the effective management of Calosphaeria canker of sweet cherry

A qPCR-based method for the detection and quantification of the peach powdery mildew (Podosphaera pannosa) in epidemiological studies

A qPCR-based method was developed to detect and quantify Podosphaera pannosa, the main causal agent of peach powdery mildew. A primer pair was designed to target part of the ITS region of the fungal ribosomal DNA, which proved to be highly specific and sensitive. A minimum of 2.81 pg µL− 1 of P. pannosa DNA and 6 conidia mL− 1 in artificially-prepared conidia suspensions were found to be the limit of detection. Moreover, a quantification of conidia placed on plastic tapes commonly used in volumetric air samplers was performed. Regression equations on conidia quantification obtained either from aqueous conidia suspensions or conidia placed on plastic tapes were similar. The protocol was further validated in field conditions by estimating the number of P. pannosa conidia obtained with an air sampler, by both microscopic and molecular quantification. Both techniques detected the peaks of conidia production during a 4-month sampling period, and a significant correlation (r = 0.772) was observed between both quantification methods. Additionally, the molecular method was applied to detect latent fungal inoculum in different plant parts of peach trees. The pathogen was detected mainly on the bark of affected twigs, and to a lesser extent, in foliar buds. The method developed here can be applied in the study of P. pannosa epidemiology and can help in improving the management of this pathogen through its early detection and quantification.info:eu-repo/semantics/acceptedVersio

Development of a screening test for resistance of cucurbits and Cucurbita hybrid rootstocks to Monosporascus cannonballus

[EN] Screening test resistance of cucurbit plants to Monosporascus cannonballus, responsible of Monosporascus root rot and vine decline was developed. Inocula of two isolates were grown in wheat seeds medium and served for pathogenicity test on watermelon (cv. Charleston gray) using 5 inoculum densities (50, 100, 150, 200 and 250 g of infected wheat seeds/kg of peat). Disease severity was evaluated based on root disease index (RDI), plant height (PH), shoot and root fresh and dry weights (SFW, RFW, SDW, and RDW). Significant differences in RDI records were noted among the 5 inoculum densities tested as compared to the non-inoculated control, and they were negatively correlated with PH, TDW and RDW. Pathogenicity tests on Armenian cucumber (Fakous), muskmelon (cvs. Flamengo and Dziria), watermelon (cv. Charleston gray), and two Cucurbita maxima x C. moschata rootstocks (cvs. Strongtoza and Emphasis), were conducted at the inoculum density of 200 g of inoculum/kg of peat. Characteristic symptoms of the disease were reproduced and the range of responses to M. cannonballus corresponded to those reported by previous research. Watermelon was susceptible to the pathogen, while Cucurbita hybrid rootstocks were the most tolerant. Evaluation of the resistance to M. cannonballus of eight Cucurbita hybrid rootstocks was conducted in a greenhouse experiment with 200 g of inoculum/kg of peat. All rootstocks evaluated seemed to response similarly for the RDI. However, no significant difference was noted for the other evaluated parameters.[FR] Un test de criblage de la résistance des plants de cucurbitacées à Monosporascus cannonballus, responsable du dépérissement a été développé. Deux isolats ont été cultivés sur des grains de blé et ont servi pour le test de la pathogénie sur la pastèque (cv. Charleston gray) selon 5 densités d¿inoculum (50, 100, 150, 200 et 250 g de grains de blé infectés/kg de tourbe). La sévérité de la maladie a été évaluée selon un indice de maladie racinaire (RDI), la hauteur de la plante (HP), les poids frais (SFW et RFW) et secs (SDW et RDW) des parties aérienne et racinaire. Une différence significative a été notée selon l¿indice RDI entre les 5 densités d'inoculum par rapport au témoin, et une corrélation négative avec la réduction des paramètres HP, SDW et RDW a été obtenue. Les tests de pathogénie sur trois espèces de cucurbitacées: concombre arménien (Fakous), melon (cvs. Flamengo et Dziria), pastèque (cv. Charleston gris) et deux porte-greffes Cucurbita maxima x C. moschata (cvs. Strongtoza et Emphasis), ont été effectuées à la densité de 200 g d'inoculum/kg de tourbe. Les symptômes caractéristiques de la maladie ont été reproduits et la gamme des réponses à M. cannonballus correspondaient à ceux rapportés dans la littérature. La pastèque s¿est montrée sensible à cet agent pathogène, tandis que les porte-greffes hybrides du genre Cucurbita étaient les plus tolérants. Un autre essai de la résistance à M. cannonballus a été réalisé sur huit porte-greffes hybrides du genre Cucurbita en culture sous serre avec 200 g d¿inoculum/kg de tourbe. Tous les porte-greffes paraissent réagir de la même façon concernant l¿indice RDI et des différences non significatives pour les autres paramètres évalués ont été notées.Ben Salem, I.; Armengol Fortí, J.; Berbegal Martinez, M.; Boughalleb-Mhamdi, N. (2015). Development of a screening test for resistance of cucurbits and Cucurbita hybrid rootstocks to Monosporascus cannonballus. Tunisian Journal of Plant Protection. 10(1):23-33. http://hdl.handle.net/10251/101851S233310

Temporal dispersal patterns of Phaeomoniella chlamydospora, causal agent of Petri disease and esca, in vineyards

[EN] Although the fungus Phaeomoniella chlamydospora is the most commonly detected causal agent of Petri disease and esca, two important fungal grapevine trunk diseases, little is known about the dispersal patterns of P. chlamydospora inoculum. In this work, we studied the dispersal of P. chlamydospora airborne inoculum from 2016 to 2018 in two viticultural areas of eastern (Ontinyent) and northern (Logroño) Spain. The vineyards were monitored weekly from November to April using microscope slide traps, and P. chlamydospora was detected and quantified by a specific real-time quantitative (qPCR) method set up in this work. The method was found to be sensitive, and a good correlation was observed between numbers of P. chlamydospora conidia (counted by microscope) and DNA copy numbers (quantified by qPCR). We consistently detected DNA of P. chlamydospora at both locations and in all seasons but in different quantities. In most cases, DNA was first detected in the last half of November, and most of the DNA was detected from December to early April. When rain was used as a predictor of P. chlamydospora DNA detection in traps, false-negative detections were observed, but these involved only 4% of the total. The dispersal pattern of P. chlamydospora DNA over time was best described (R2 = 0.765 and concordance correlation coefficient = 0.870) by a Gompertz equation, with time expressed as hydrothermal time (a physiological time accounting for the effects of temperature and rain). This equation could be used to predict periods with a high risk of dispersal of P. chlamydosporaFinancial support for carrying out this research was provided by transnational funding bodies, being partners of the H2020 ERA-net project, CORE Organic Cofund, and the Cofund from the European Commission (PCI2018-093015/Project BIOVINE). Part of the research was funded by CAR (Government of La Rioja, Spain), project number R-03-16. C. Berlanas was supported by the FPI-INIA program from the INIA. D. Gramaje was supported by the Ramon y Cajal program, Spanish Government (RYC-2017-23098). Financial support for C. Berlanas during her 1-month stay at Universitat Polit`ecnica de Val`encia was provided by the Viticulture Research Network RedVitis (AGL2015-70931-REDT)González-Domínguez, E.; Berlanas, C.; Gramaje, D.; Armengol Fortí, J.; Rossi, V.; Berbegal Martinez, M. (2020). Temporal dispersal patterns of Phaeomoniella chlamydospora, causal agent of Petri disease and esca, in vineyards. Plant Disease. 110(6):1216-1225. https://doi.org/10.1094/PHYTO-10-19-0400-RS12161225110

Phenotypical and molecular characterisation of Fusarium circinatum: correlation with virulence and fungicide sensitivity

[EN] 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) 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.M.B. was a contract holder of Campus de Excelencia Internacional-UPV programme. This work was partially funded by PROTREE, a project funded jointly by a grant from BBSRC, Defra, ESRC, the Forestry Commission, NERC and the Scottish Government, under the Tree Health and Plant Biosecurity Initiative, grant number BB/L012243/1. Additional funding and networking support was provided by the PINESTRENGTH COST Action (FP1406).Mullett, M.; Pérez Sierra, AM.; Armengol Fortí, J.; Berbegal Martinez, M. (2017). Phenotypical and molecular characterisation of Fusarium circinatum: correlation with virulence and fungicide sensitivity. Forests. 8(11):1-22. https://doi.org/10.3390/f8110458S122811Martín-Rodrigues, N., Espinel, S., Sanchez-Zabala, J., Ortíz, A., González-Murua, C., & Duñabeitia, M. K. (2013). Spatial and temporal dynamics of the colonization ofPinus radiatabyFusarium circinatum, of conidiophora development in the pith and of traumatic resin duct formation. New Phytologist, 198(4), 1215-1227. doi:10.1111/nph.12222Wingfield, M. J., Hammerbacher, A., Ganley, R. J., Steenkamp, E. T., Gordon, T. R., Wingfield, B. D., & Coutinho, T. A. (2008). Pitch canker caused byFusarium circinatum– a growing threat to pine plantations and forests worldwide. Australasian Plant Pathology, 37(4), 319. doi:10.1071/ap08036Dwinell, L. D. (1985). Pitch Canker: A Disease Complex of Southern Pines. Plant Disease, 69(3), 270. doi:10.1094/pd-69-270VILJOEN, A. (1994). First Reportof Fusarium subglutinansf.sp. pinion Pine Seedlings in South Africa. Plant Disease, 78(3), 309. doi:10.1094/pd-78-0309Fusarium circinatum (GIBBCI)https://gd.eppo.int/taxon/GIBBCI/distributionLanderas, E., García, P., Fernández, Y., Braña, M., Fernández-Alonso, O., Méndez-Lodos, S., … Armengol, J. (2005). Outbreak of Pitch Canker Caused by Fusarium circinatum on Pinus spp. in Northern Spain. Plant Disease, 89(9), 1015-1015. doi:10.1094/pd-89-1015aPérez-Sierra, A., Landeras, E., León, M., Berbegal, M., García-Jiménez, J., & Armengol, J. (2007). Characterization of Fusarium circinatum from Pinus spp. in northern Spain. Mycological Research, 111(7), 832-839. doi:10.1016/j.mycres.2007.05.009Carlucci, A., Colatruglio, L., & Frisullo, S. (2007). First Report of Pitch Canker Caused by Fusarium circinatum on Pinus halepensis and P. pinea in Apulia (Southern Italy). Plant Disease, 91(12), 1683-1683. doi:10.1094/pdis-91-12-1683cBragança, H., Diogo, E., Moniz, F., & Amaro, P. (2009). First Report of Pitch Canker on Pines Caused by Fusarium circinatum in Portugal. Plant Disease, 93(10), 1079-1079. doi:10.1094/pdis-93-10-1079aEPPO PQR—EPPO Database on Quarantine Pestshttp://www.eppo.intBerbegal, M., Pérez-Sierra, A., Armengol, J., & Grünwald, N. J. (2013). Evidence for Multiple Introductions and Clonality in Spanish Populations of Fusarium circinatum. Phytopathology®, 103(8), 851-861. doi:10.1094/phyto-11-12-0281-rGordon, T. R., Okamoto, D., Storer, A. J., & Wood, D. L. (1998). Susceptibility of Five Landscape Pines to Pitch Canker Disease, Caused by Fusarium subglutinans f. sp. pini. HortScience, 33(5), 868-871. doi:10.21273/hortsci.33.5.868Hodge, G. R., & Dvorak, W. S. (2000). New Forests, 19(3), 241-258. doi:10.1023/a:1006613021996Roux, J., Eisenberg, B., Kanzler, A., Nel, A., Coetzee, V., Kietzka, E., & Wingfield, M. J. (2006). Testing of selected South African Pinus hybrids and families for tolerance to the pitch canker pathogen, Fusarium circinatum. New Forests, 33(2), 109-123. doi:10.1007/s11056-006-9017-4Iturritxa, E., Mesanza, N., Elvira-Recuenco, M., Serrano, Y., Quintana, E., & Raposo, R. (2012). Evaluation of genetic resistance in Pinus to pitch canker in Spain. Australasian Plant Pathology, 41(6), 601-607. doi:10.1007/s13313-012-0160-4Martínez-Álvarez, P., Pando, V., & Diez, J. J. (2014). Alternative species to replace Monterey pine plantations affected by pitch canker caused byFusarium circinatumin northern Spain. Plant Pathology, 63(5), 1086-1094. doi:10.1111/ppa.12187Schmale, D. G., & Gordon, T. R. (2003). Variation in susceptibility to pitch canker disease, caused by Fusarium circinatum, in native stands of Pinus muricata. Plant Pathology, 52(6), 720-725. doi:10.1111/j.1365-3059.2003.00925.xKuhlman, E. G. (1985). Pitch Canker Disease of Loblolly and Pond Pines in North Carolina Plantations. Plant Disease, 69(2), 175. doi:10.1094/pd-69-175Elvira-Recuenco, M., Iturritxa, E., Majada, J., Alia, R., & Raposo, R. (2014). Adaptive Potential of Maritime Pine (Pinus pinaster) Populations to the Emerging Pitch Canker Pathogen, Fusarium circinatum. PLoS ONE, 9(12), e114971. doi:10.1371/journal.pone.0114971VILJOEN, A., WINGFIELD, M. J., KEMP, G. H. J., & MARASAS, W. F. O. (1995). Susceptibility of pines in South Africa to the pitch canker fungus subglutinans f.sp. pini. Plant Pathology, 44(5), 877-882. doi:10.1111/j.1365-3059.1995.tb02747.xMuñoz-Adalia, E. J., Flores-Pacheco, J. A., Martínez-Álvarez, P., Martín-García, J., Fernández, M., & Diez, J. J. (2016). Effect of mycoviruses on the virulence of Fusarium circinatum and laccase activity. Physiological and Molecular Plant Pathology, 94, 8-15. doi:10.1016/j.pmpp.2016.03.002Martínez-Álvarez, P., Vainio, E. J., Botella, L., Hantula, J., & Diez, J. J. (2014). Three mitovirus strains infecting a single isolate of Fusarium circinatum are the first putative members of the family Narnaviridae detected in a fungus of the genus Fusarium. Archives of Virology, 159(8), 2153-2155. doi:10.1007/s00705-014-2012-8Agusti-Brisach, C., Perez-Sierra, A., Armengol, J., Garcia-Jimenez, J., & Berbegal, M. (2012). Efficacy of hot water treatment to reduce the incidence of Fusarium circinatum on Pinus radiata seeds. Forestry, 85(5), 629-635. doi:10.1093/forestry/cps074Berbegal, M., Landeras, E., Sánchez, D., Abad-Campos, P., Pérez-Sierra, A., & Armengol, J. (2015). Evaluation ofPinus radiataseed treatments to controlFusarium circinatum: effects on seed emergence and disease incidence. Forest Pathology, 45(6), 525-533. doi:10.1111/efp.12204Van Poucke, K., Franceschini, S., Webber, J. F., Vercauteren, A., Turner, J. A., McCracken, A. R., … Brasier, C. M. (2012). Discovery of a fourth evolutionary lineage of Phytophthora ramorum: EU2. Fungal Biology, 116(11), 1178-1191. doi:10.1016/j.funbio.2012.09.003Brasier, C. M., Franceschini, S., Vettraino, A. M., Hansen, E. M., Green, S., Robin, C., … Vannini, A. (2012). Four phenotypically and phylogenetically distinct lineages in Phytophthora lateralis. Fungal Biology, 116(12), 1232-1249. doi:10.1016/j.funbio.2012.10.002Franceschini, S., Webber, J. F., Sancisi-Frey, S., & Brasier, C. M. (2013). Gene × environment tests discriminate the new EU2 evolutionary lineage ofPhytophthora ramorumand indicate that it is adaptively different. Forest Pathology, 44(3), 219-232. doi:10.1111/efp.12085Robin, C., Brasier, C., Reeser, P., Sutton, W., Vannini, A., Vettraino, A. M., & Hansen, E. (2015). Pathogenicity of Phytophthora lateralis Lineages on Different Selections of Chamaecyparis lawsoniana. Plant Disease, 99(8), 1133-1139. doi:10.1094/pdis-07-14-0720-reAgricolae: Statistical Procedures for Agricultural Researchhttp://tarwi.lamolina.edu.pe/~fmendiburuLê, S., Josse, J., & Husson, F. (2008). FactoMineR: AnRPackage for Multivariate Analysis. Journal of Statistical Software, 25(1). doi:10.18637/jss.v025.i01Bates, D., Mächler, M., Bolker, B., & Walker, S. (2015). Fitting Linear Mixed-Effects Models Usinglme4. Journal of Statistical Software, 67(1). doi:10.18637/jss.v067.i01Kim, Y.-S., Woo, K.-S., Koo, Y.-B., & Yeo, J.-K. (2008). Variation in susceptibility of six pine species and hybrids to pitch canker caused byFusarium  circinatum. Forest Pathology, 38(6), 419-428. doi:10.1111/j.1439-0329.2008.00558.xRunion, G. B. (1988). Effects of Thiabendazole-DMSO Treatment of Longleaf Pine Seed Contaminated with Fusarium subglutinans on Germination and Seedling Survival. Plant Disease, 72(10), 872. doi:10.1094/pd-72-0872Allen, T. ., Enebak, S. ., & Carey, W. . (2004). Evaluation of fungicides for control of species of Fusarium on longleaf pine seed. Crop Protection, 23(10), 979-982. doi:10.1016/j.cropro.2004.02.010Chung, W.-H., Ishii, H., Nishimura, K., Fukaya, M., Yano, K., & Kajitani, Y. (2006). Fungicide Sensitivity and Phylogenetic Relationship of Anthracnose Fungi Isolated from Various Fruit Crops in Japan. Plant Disease, 90(4), 506-512. doi:10.1094/pd-90-0506Secor, G. A., Rivera, V. V., Khan, M. F. R., & Gudmestad, N. C. (2010). Monitoring Fungicide Sensitivity of Cercospora beticola of Sugar Beet for Disease Management Decisions. Plant Disease, 94(11), 1272-1282. doi:10.1094/pdis-07-09-0471Nirenberg, H. I., & O’Donnell, K. (1998). New Fusarium Species and Combinations within the Gibberella fujikuroi Species Complex. Mycologia, 90(3), 434. doi:10.2307/3761403Inman, A. R., Kirkpatrick, S. C., Gordon, T. R., & Shaw, D. V. (2008). Limiting Effects of Low Temperature on Growth and Spore Germination in Gibberella circinata, the Cause of Pitch Canker in Pine Species. Plant Disease, 92(4), 542-545. doi:10.1094/pdis-92-4-054

Complex molecular relationship between vegetative compatibility groups (VCGs) in Verticillium dahliae: VCGs do not always align with clonal lineages

Verticillium wilts caused by the soilborne fungus Verticillium dahliae are among the most challenging diseases to control. Populations of this pathogen have been traditionally studied by means of vegetative compatibility groups (VCGs) under the assumption that VCGs comprise genetically related isolates that correlate with clonal lineages. We aimed to resolve the phylogenetic relationships among VCGs and their subgroups based on sequences of the intergenic spacer region (IGS) of the ribosomal DNA and six anonymous polymorphic sequences containing single-nucleotide polymorphisms (VdSNPs). A collection of 68 V dahliae isolates representing the main VCGs and subgroups (VCGs 1A, 1B, 2A, 2B, 3, 4A, 4B, and 6) from different geographic origins and hosts was analyzed using the seven DNA regions. Maximum parsimony (MP) phylogenies inferred from IGS and VdSNP sequences showed five and six distinct clades, respectively. Phylogenetic analyses of individual and combined data sets indicated that certain VCG subgroups (e.g., VCGs 1A and 1B) are closely related and share a common ancestor; however, other subgroups (e.g., VCG 4B) are more closely related to members of a different VCG (e.g., VCG 2A) than to subgroups of the same VCG (VCG 4B). Furthermore, MP analyses indicated that VCG 2B is polyphyletic, with isolates placed in at least three distinct phylogenetic lineages based on IGS sequences and two lineages based on VdSNP sequences. Results from our study suggest the existence of main VCG lineages that contain VCGs 1A and 1B; VCGs 2A and 4B; and VCG 4A, for which both phylogenies agree; and the existence of other VCGs or VCG subgroups that seem to be genetically heterogeneous or show discrepancies in their phylogenetic placement: VCG 2B, VCG 3, and VCG 6. These results raise important caveats regarding the interpretation of VCG analyses: genetic homogeneity and close evolutionary relationship between members of a VCG should not be assumed.This research was partially funded by the Sarah Chinn Kalser Faculty Research Assistance Endowment, College of Agricultural Sciences, The Pennsylvania State University. We thank all suppliers of V. dahliae isolates; J. Yanez, S. Colihan, C. Barrett, C. Black, and C. Olivares-Garcia for excellent technical support; and D. Geiser for helpful discussions during the preparation of this manuscript.Jiménez Gasco, MDM.; Malcolm, GM.; Berbegal Martinez, M.; Armengol Fortí, J.; Jimenez Diaz, R. (2014). Complex molecular relationship between vegetative compatibility groups (VCGs) in Verticillium dahliae: VCGs do not always align with clonal lineages. Phytopathology. 104(6):650-659. doi:10.1094/PHYTO-07-13-0180-RS650659104

Validation of a mechanistic model for predicting fruit scab infection on different loquat cultivars

Scab, caused by Fusicladium eriobotryae, is the main disease affecting loquat (Eriobotrya japonica) in the Mediterranean basin. A mechanistic epidemiological model developed in Spain to predict infection of loquat fruit by conidia was assessed in the main loquat cultivated area of Italy (Sicily). A 3-year study (2014–2016) was carried out in an experimental orchard on three loquat cultivars: Algerie, Peluche and San Filipparo. For each cultivar, output of the model was compared with observed scab development on fruits. The scab epidemics observed were different in different years and cultivars, representing a suitable data set for model validation. The model correctly predicted loquat scab, as demonstrated by the goodness of fit between model predictions and observed disease incidence on fruits (R2 &gt; 0.85), confirming the accuracy and robustness of the model for predicting scab development in loquat orchards. The use of the model for fungicide scheduling against F. eriobotryae may improve the management of loquat scab by reducing the number of required fungicide applications

Root infection of canker pathogens, Fusarium circinatum and Diplodia sapinea, in asymptomatic trees in Pinus radiata and Pinus pinaster plantations

[EN] The existence of a latent stage within host tissue of the pine pathogens Fusarium circinatum and Diplodia sapinea, the causal agents of pitch canker and shoot blight disease respectively, has previously been cited. However, studies on this cryptic phase in each disease lifecycle has only been focused on the host aerial parts but not on the roots. Therefore, our objective was to analyze the presence of both pathogens in roots of non-symptomatic mature trees in plantations where the pathogens are known to be causing canker symptoms. For that, we sampled roots from ten non-symptomatic and ten symptomatic trees in three Pinus radiata and one Pinus pinaster plantations in Basque Country, Spain. Both pathogens were isolated from roots of non-symptomatic trees in a higher frequency than from roots of symptomatic trees, 23.3% and 6.6% respectively for D. sapinea and 16.6% and 3.3% respectively for F. circinatum. Neither pathogens was detected in the P. pinaster plantation. The two pathogens were never isolated from the same tree. A high molecular variability was observed for D. sapinea isolates with six different haplotypes and two mating types for the eleven characterized isolates, but only one haplotype and mating type was found for F. circinatum, with all isolates of both fungi being proved pathogenic. These results evidence the importance root infection may have in the disease lifecycle and, therefore, disease management.We acknowledge Maria Teresa Morales Clemente for her excellent technical assistance. Laura Hernandez-Escribano was supported by a fellowship from INIA (FPI-INIA). Financial support for this research was provided by project RTA2013-00048-C03-01, RTA2017-00063-C04-01 and C04-03 (National Progamme I + D + I, INIA, Spain) and the Project Healthy Forest LIFE14 ENV/ES/000179. This article is-based upon work from COST Action FP1406, Pine pitch canker-strategies for management of Gibberella circinata in greenhouses and forests (PINESTRENGTH), supported by COST (European Cooperation in Science and Technology).Hernandez-Escribano, L.; Iturritxa, E.; Aragonés, A.; Mesanza, N.; Berbegal Martinez, M.; Raposo, R.; Elvira-Recuenco, M. (2018). Root infection of canker pathogens, Fusarium circinatum and Diplodia sapinea, in asymptomatic trees in Pinus radiata and Pinus pinaster plantations. Forests. 9(3):1-15. https://doi.org/10.3390/f9030128S11593Nirenberg, H. I., & O’Donnell, K. (1998). New Fusarium Species and Combinations within the Gibberella fujikuroi Species Complex. Mycologia, 90(3), 434. doi:10.2307/3761403Phillips, A. J. L., Alves, A., Abdollahzadeh, J., Slippers, B., Wingfield, M. J., Groenewald, J. Z., & Crous, P. W. (2013). The Botryosphaeriaceae: genera and species known from culture. Studies in Mycology, 76, 51-167. doi:10.3114/sim0021Wingfield, M. J., Hammerbacher, A., Ganley, R. J., Steenkamp, E. T., Gordon, T. R., Wingfield, B. D., & Coutinho, T. A. (2008). Pitch canker caused byFusarium circinatum– a growing threat to pine plantations and forests worldwide. Australasian Plant Pathology, 37(4), 319. doi:10.1071/ap08036Burgess, T. I., Wingfield, M. J., & Wingfield, B. D. (2004). Global distribution ofDiplodia pineagenotypes revealed using simple sequence repeat (SSR) markers. Australasian Plant Pathology, 33(4), 513. doi:10.1071/ap04067Bihon, W., Wingfield, M. J., Slippers, B., Duong, T. A., & Wingfield, B. D. (2014). MAT gene idiomorphs suggest a heterothallic sexual cycle in a predominantly asexual and important pine pathogen. Fungal Genetics and Biology, 62, 55-61. doi:10.1016/j.fgb.2013.10.013Swart, W. J. (1991). Biology and Control ofSphaeropsis sapineaonPinusSpecies in South Africa. Plant Disease, 75(8), 761. doi:10.1094/pd-75-0761Blodgett, J. T., Kruger, E. L., & Stanosz, G. R. (1997). Sphaeropsis sapinea and Water Stress in a Red Pine Plantation in Central Wisconsin. Phytopathology®, 87(4), 429-434. doi:10.1094/phyto.1997.87.4.429Inman, A. R., Kirkpatrick, S. C., Gordon, T. R., & Shaw, D. V. (2008). Limiting Effects of Low Temperature on Growth and Spore Germination in Gibberella circinata, the Cause of Pitch Canker in Pine Species. Plant Disease, 92(4), 542-545. doi:10.1094/pdis-92-4-0542Landeras, E., García, P., Fernández, Y., Braña, M., Fernández-Alonso, O., Méndez-Lodos, S., … Armengol, J. (2005). Outbreak of Pitch Canker Caused by Fusarium circinatum on Pinus spp. in Northern Spain. Plant Disease, 89(9), 1015-1015. doi:10.1094/pd-89-1015aBragança, H., Diogo, E., Moniz, F., & Amaro, P. (2009). First Report of Pitch Canker on Pines Caused by Fusarium circinatum in Portugal. Plant Disease, 93(10), 1079-1079. doi:10.1094/pdis-93-10-1079aCarlucci, A., Colatruglio, L., & Frisullo, S. (2007). First Report of Pitch Canker Caused by Fusarium circinatum on Pinus halepensis and P. pinea in Apulia (Southern Italy). Plant Disease, 91(12), 1683-1683. doi:10.1094/pdis-91-12-1683cBihon, W., Slippers, B., Burgess, T., Wingfield, M. J., & Wingfield, B. D. (2012). Diverse sources of infection and cryptic recombination revealed in South African Diplodia pinea populations. Fungal Biology, 116(1), 112-120. doi:10.1016/j.funbio.2011.10.006KAY, S. J., AH CHEE, A., SALE, P. O., TAYLOR, J. T., HADAR, E., HADAR, Y., & FARRELL, R. L. (2002). Variation among New Zealand isolates of Sphaeropsis sapinea. Forest Pathology, 32(2), 109-121. doi:10.1046/j.1439-0329.2002.00273.xSmith, H., Wingfield, M. J., de Wet, J., & Coutinho, T. A. (2000). Genotypic Diversity of Sphaeropsis sapinea from South Africa and Northern Sumatra. Plant Disease, 84(2), 139-142. doi:10.1094/pdis.2000.84.2.139Zwolinski, J. B., Swart, W. J., & Wingfield, M. J. (1990). Economic impact of a post-hail outbreak of dieback induced by Sphaeropsis sapinea. Forest Pathology, 20(6-7), 405-411. doi:10.1111/j.1439-0329.1990.tb01155.xStanosz, G. R., Trobaugh, J., Guthmiller, M. A., & Stanosz, J. C. (2004). Sphaeropsis shoot blight and altered nutrition in red pine plantations treated with paper mill waste sludge. Forest Pathology, 34(4), 245-253. doi:10.1111/j.1439-0329.2004.00366.xDesprez-Loustau, M.-L., Robin, C., Reynaud, G., Déqué, M., Badeau, V., Piou, D., … Marçais, B. (2007). Simulating the effects of a climate-change scenario on the geographical range and activity of forest-pathogenic fungi. Canadian Journal of Plant Pathology, 29(2), 101-120. doi:10.1080/07060660709507447Keen, A., & Smits, T. F. C. (1989). Application of a mathematical function for a temperature optimum curve to establish differences in growth between isolates of a fungus. Netherlands Journal of Plant Pathology, 95(1), 37-49. doi:10.1007/bf02000880Storer, Gordon, & Clark. (1998). Association of the pitch canker fungus,Fusarium subglutinansf.sp.pini, with Monterey pine seeds and seedlings in California. Plant Pathology, 47(5), 649-656. doi:10.1046/j.1365-3059.1998.00288.xIturritxa, E., Mesanza, N., Elvira-Recuenco, M., Serrano, Y., Quintana, E., & Raposo, R. (2012). Evaluation of genetic resistance in Pinus to pitch canker in Spain. Australasian Plant Pathology, 41(6), 601-607. doi:10.1007/s13313-012-0160-4Broaddus, J. B.-. (1990). Colonization of Cones and Seed of Loblolly Pine Following Inoculation with Fusarium subglutinans. Plant Disease, 74(12), 1002. doi:10.1094/pd-74-1002Anderson, R. L. (1986). New Method for Assessing Contamination of Slash and Loblolly Pine Seeds byFusarium moniliformevar.subglutinans. Plant Disease, 70(5), 452. doi:10.1094/pd-70-452VILJOEN, A. (1994). First Reportof Fusarium subglutinansf.sp. pinion Pine Seedlings in South Africa. Plant Disease, 78(3), 309. doi:10.1094/pd-78-0309Whitehill, J. G. A., Lehman, J. S., & Bonello, P. (2007). Ips pini (Curculionidae: Scolytinae) Is a Vector of the Fungal Pathogen, Sphaeropsis sapinea (Coelomycetes), to Austrian Pines, Pinus nigra (Pinaceae). Environmental Entomology, 36(1), 114-120. doi:10.1603/0046-225x(2007)36[114:ipcsia]2.0.co;2Stanosz, G. R., Swart, W. J., & Smith, D. R. (1999). RAPD marker and isozyme characterization of Sphaeropsis sapinea from diverse coniferous hosts and locations. Mycological Research, 103(9), 1193-1202. doi:10.1017/s0953756299008382Palmer, M. A. (1985). Shoot Blight and Collar Rot ofPinus resinosaCaused bySphaeropsis sapineain Forest Tree Nurseries. Plant Disease, 69(9), 739. doi:10.1094/pd-69-739Stanosz, G. R., Smith, D. R., & Leisso, R. (2007). Diplodia shoot blight and asymptomatic persistence of Diplodia pinea on or in stems of jack pine nursery seedlings. Forest Pathology, 37(3), 145-154. doi:10.1111/j.1439-0329.2007.00487.xFlowers, J., Nuckles, E., Hartman, J., & Vaillancourt, L. (2001). Latent Infection of Austrian and Scots Pine Tissues by Sphaeropsis sapinea. Plant Disease, 85(10), 1107-1112. doi:10.1094/pdis.2001.85.10.1107Flowers, J., Hartman, J., & Vaillancourt, L. (2003). Detection of Latent Sphaeropsis sapinea Infections in Austrian Pine Tissues Using Nested-Polymerase Chain Reaction. Phytopathology®, 93(12), 1471-1477. doi:10.1094/phyto.2003.93.12.1471Smith, H., Wingfied, M. ., & Coutinho, T. . (2002). The role of latent Sphaeropsis sapinea infections in post-hail associated die-back of Pinus patula. Forest Ecology and Management, 164(1-3), 177-184. doi:10.1016/s0378-1127(01)00610-7Vujanovic, V., St-Arnaud, M., & Neumann, P.-J. (2000). Susceptibility of cones and seeds to fungal infection in a pine (Pinus spp.) collection. Forest Pathology, 30(6), 305-320. doi:10.1046/j.1439-0329.2000.00211.xBihon, W., Slippers, B., Burgess, T., Wingfield, M. J., & Wingfield, B. D. (2010). Sources of Diplodia pinea endophytic infections in Pinus patula and P. radiata seedlings in South Africa. Forest Pathology, 41(5), 370-375. doi:10.1111/j.1439-0329.2010.00691.xFABRE, B., PIOU, D., DESPREZ-LOUSTAU, M.-L., & MARÇAIS, B. (2011). Can the emergence of pine Diplodia shoot blight in France be explained by changes in pathogen pressure linked to climate change? Global Change Biology, 17(10), 3218-3227. doi:10.1111/j.1365-2486.2011.02428.xSwett, C. L., Kirkpatrick, S. C., & Gordon, T. R. (2016). Evidence for a Hemibiotrophic Association of the Pitch Canker Pathogen Fusarium circinatum with Pinus radiata. Plant Disease, 100(1), 79-84. doi:10.1094/pdis-03-15-0270-reMartín-Rodrigues, N., Sanchez-Zabala, J., Salcedo, I., Majada, J., González-Murua, C., & Duñabeitia, M. K. (2015). New insights into radiata pine seedling root infection byFusarium circinatum. Plant Pathology, 64(6), 1336-1348. doi:10.1111/ppa.12376Swett, C. L., & Gordon, T. R. (2016). Exposure to a pine pathogen enhances growth and disease resistance inPinus radiataseedlings. Forest Pathology, 47(1), e12298. doi:10.1111/efp.12298Stanosz, G. R., Blodgett, J. T., Smith, D. R., & Kruger, E. L. (2001). Water stress and Sphaeropsis sapinea as a latent pathogen of red pine seedlings. New Phytologist, 149(3), 531-538. doi:10.1046/j.1469-8137.2001.00052.xBihon, W., Burgess, T., Slippers, B., Wingfield, M. J., & Wingfield, B. D. (2011). Distribution of Diplodia pinea and its genotypic diversity within asymptomatic Pinus patula trees. Australasian Plant Pathology, 40(5), 540-548. doi:10.1007/s13313-011-0060-zAegerter, B. J., & Gordon, T. R. (2006). Rates of pitch canker induced seedling mortality among Pinus radiata families varying in levels of genetic resistance to Gibberella circinata (anamorph Fusarium circinatum). Forest Ecology and Management, 235(1-3), 14-17. doi:10.1016/j.foreco.2006.07.011Nirenberg, H. I. (1981). A simplified method for identifying Fusarium spp. occurring on wheat. Canadian Journal of Botany, 59(9), 1599-1609. doi:10.1139/b81-217Slippers, B., Crous, P. W., Denman, S., Coutinho, T. A., Wingfield, B. D., & Wingfield, M. J. (2004). Combined multiple gene genealogies and phenotypic characters differentiate several species previously identified asBotryosphaeria dothidea. Mycologia, 96(1), 83-101. doi:10.1080/15572536.2005.11833000Alves, A., Linaldeddu, B. T., Deidda, A., Scanu, B., & Phillips, A. J. L. (2014). The complex of Diplodia species associated with Fraxinus and some other woody hosts in Italy and Portugal. Fungal Diversity, 67(1), 143-156. doi:10.1007/s13225-014-0282-9Hyde, K. D., Nilsson, R. H., Alias, S. A., Ariyawansa, H. A., Blair, J. E., Cai, L., … Zhou, N. (2014). One stop shop: backbones trees for important phytopathogenic genera: I (2014). Fungal Diversity, 67(1), 21-125. doi:10.1007/s13225-014-0298-1Dissanayake, A. (2016). Botryosphaeriaceae: Current status of genera and species. Mycosphere, 7(7), 1001-1073. doi:10.5943/mycosphere/si/1b/13Linaldeddu, B. (2016). Botryosphaeriaceae species associated with lentisk dieback in Italy and description of Diplodia insularis sp. nov. Mycosphere, 7(7), 962-977. doi:10.5943/mycosphere/si/1b/8Ariyawansa, H. A., Hyde, K. D., Jayasiri, S. C., Buyck, B., Chethana, K. W. T., Dai, D. Q., … Lücking, R. (2015). Fungal diversity notes 111–252—taxonomic and phylogenetic contributions to fungal taxa. Fungal Diversity, 75(1), 27-274. doi:10.1007/s13225-015-0346-5Úrbez-Torres, J. R., Castro-Medina, F., Mohali, S. R., & Gubler, W. D. (2016). Botryosphaeriaceae Species Associated With Cankers and Dieback Symptoms of Acacia mangium and Pinus caribaea var. hondurensis in Venezuela. Plant Disease, 100(12), 2455-2464. doi:10.1094/pdis-05-16-0612-reSmith, D. R., & Stanosz, G. R. (2006). A Species-Specific PCR Assay for Detection of Diplodia pinea and D. scrobiculata in Dead Red and Jack Pines with Collar Rot Symptoms. Plant Disease, 90(3), 307-313. doi:10.1094/pd-90-0307Schweigkofler, W., O’Donnell, K., & Garbelotto, M. (2004). Detection and Quantification of Airborne Conidia of Fusarium circinatum, the Causal Agent of Pine Pitch Canker, from Two California Sites by Using a Real-Time PCR Approach Combined with a Simple Spore Trapping Method. Applied and Environmental Microbiology, 70(6), 3512-3520. doi:10.1128/aem.70.6.3512-3520.2004Wallace, M. M., & Covert, S. F. (2000). Molecular Mating Type Assay forFusarium circinatum. Applied and Environmental Microbiology, 66(12), 5506-5508. doi:10.1128/aem.66.12.5506-5508.2000Berbegal, M., Pérez-Sierra, A., Armengol, J., & Grünwald, N. J. (2013). Evidence for Multiple Introductions and Clonality in Spanish Populations of Fusarium circinatum. Phytopathology®, 103(8), 851-861. doi:10.1094/phyto-11-12-0281-rIturritxa, E., Ganley, R. J., Wright, J., Heppe, E., Steenkamp, E. T., Gordon, T. R., & Wingfield, M. J. (2011). A genetically homogenous population of Fusarium circinatum causes pitch canker of Pinus radiata in the Basque Country, Spain. Fungal Biology, 115(3), 288-295. doi:10.1016/j.funbio.2010.12.014Elvira-Recuenco, M., Iturritxa, E., Majada, J., Alia, R., & Raposo, R. (2014). Adaptive Potential of Maritime Pine (Pinus pinaster) Populations to the Emerging Pitch Canker Pathogen, Fusarium circinatum. PLoS ONE, 9(12), e114971. doi:10.1371/journal.pone.0114971Garbelotto, M., Smith, T., & Schweigkofler, W. (2008). Variation in Rates of Spore Deposition of Fusarium circinatum, the Causal Agent of Pine Pitch Canker, Over a 12-Month-Period at Two Locations in Northern California. Phytopathology®, 98(1), 137-143. doi:10.1094/phyto-98-1-0137Serra-Varela, M. J., Alía, R., Pórtoles, J., Gonzalo, J., Soliño, M., Grivet, D., & Raposo, R. (2017). Incorporating exposure to pitch canker disease to support management decisions of Pinus pinaster Ait. in the face of climate change. PLOS ONE, 12(2), e0171549. doi:10.1371/journal.pone.0171549Hernandez-Escribano, L., Iturritxa, E., Elvira-Recuenco, M., Berbegal, M., Campos, J. A., Renobales, G., … Raposo, R. (2018). Herbaceous plants in the understory of a pitch canker-affected Pinus radiata plantation are endophytically infected with Fusarium circinatum. Fungal Ecology, 32, 65-71. doi:10.1016/j.funeco.2017.12.001Smith, H., Wingfield, M. J., Coutinho, T. A., & Crous, P. W. (1996). Sphaeropsis sapinea and Botryosphaeria dothidea endophytic in Pinus spp. and Eucalyptus spp. in South Africa. South African Journal of Botany, 62(2), 86-88. doi:10.1016/s0254-6299(15)30596-2Santini, A., Pepori, A., Ghelardini, L., & Capretti, P. (2008). Persistence of some pine pathogens in coarse woody debris and cones in a Pinus pinea forest. Forest Ecology and Management, 256(3), 502-506. doi:10.1016/j.foreco.2008.05.010Oblinger, B. W., Smith, D. R., & Stanosz, G. R. (2011). Red pine harvest debris as a potential source of inoculum of Diplodia shoot blight pathogens. Forest Ecology and Management, 262(4), 663-670. doi:10.1016/j.foreco.2011.04.038Eyles, A., Bonello, P., Ganley, R., & Mohammed, C. (2009). Induced resistance to pests and pathogens in trees. New Phytologist, 185(4), 893-908. doi:10.1111/j.1469-8137.2009.03127.xJunker, C., Draeger, S., & Schulz, B. (2012). A fine line – endophytes or pathogens in Arabidopsis thaliana. Fungal Ecology, 5(6), 657-662. doi:10.1016/j.funeco.2012.05.002Flowers, J. L., Hartman, J. R., & Vaillancourt, L. J. (2006). Histology of Diplodia pinea in diseased and latently infected Pinus nigra shoots. Forest Pathology, 36(6), 447-459. doi:10.1111/j.1439-0329.2006.00473.