Fruit Tree Canker Research Articles

Can choice of rootstock reduce damages caused by fruit tree canker in apple orchards?

Can choice of rootstock reduce damages caused by fruit tree canker in apple orchards?

Genome sequence resources from three isolates of the apple canker pathogen Neonectria ditissima infecting forest trees

Neonectria ditissima is a generalist ascomycete plant pathogen causing canker diseases on a variety of hardwood tree species and can cross-infect many of them. The fungus enters the plants through wounds throughout the year. N. ditissima is considered a major threat to apple production responsible for the fruit tree canker disease which damages trees and causes rotting of fruits in storage. Nearby forests and shelter belts can serve as source of inoculum for well-managed apple orchards. Thus, knowledge about the N. ditissima isolates infecting different host species is essential for designing integrated pest management strategies. Here, we describe the genomes of three N. ditissima isolates, Nd_iso34, Nd_iso35, and Nd_iso36, infecting European beech, American tulip tree, and American beech, respectively. We obtained genome assemblies of ca. 45 megabases for all isolates, covering 94% of the N. ditissima reference annotation, and 97% of the universal single-copy orthologs (BUSCOs). We conclude that these genome assemblies are a highly relevant resource considering the scarcity of genomic data available for N. ditissima.

Bakterioze jabuke

Bacterial diseases of apple are less numerous compared to fungal diseases, but under favorable conditions they can cause enormous damage. This is especially true for fire blight of apple, which can, in some years, cause complete tree death of sensitive cultivars. Fire blight has been present in Serbia for more than 30 years. Growing sensitive apple cultivars and lack of effective bactericides caused the disease to spread in a relatively short time in most of the apple fruit producing regions. Additional troublesome event for producers in Serbia is the ban on the use of antibiotics in plant protection. In addition to fire blight, this paper also describes other bacterial diseases of apple, such as crown gall, caused by Agrobacterium tumefaciens and Rhizobium rhizogenes, and bacterial dieback and canker of fruit trees, caused by Pseudomonas syringae pv. syringae. The aim of this paper is to provide the knowledge on the most important bacterial diseases of apple, their importance in apple production, epidemiology and disease symptoms, as well as protection measures in order to reduce the damage they cause.

Guest Editorial for Special Issue Volume 74S

Special Issue: Fourth International Workshop on European Fruit Tree Canker and Resilient Orchards 2–6 November 2020, New Zealand, online via Zoom

Development of Neonectria ditissima infections initiated at grafting of apple trees

Infections of Neonectria ditissima, the cause of European fruit tree canker, may be initiated during propagation. In a survey of 19 commercial apple orchards in southern Norway in the year of planting or the following year, the graft-union area of 15,270 trees was examined. The disease was found in 53% of the orchards, at a low incidence (<10%) with two exceptions (13 and 42%). Scion wood from mother trees with no, a few or several cankers were used to propagate trees that were surveyed for up to 38 months. In total 20 out of 1116 (1.8%) trees developed canker. The higher the number of cankers was on the mother trees, the higher was the number of trees developing canker after grafting. Infections developed on both cultivars (Discovery, Summerred) and all three rootstocks (Antonovka, B9, M9), but more so on grafted than T-budded trees, and more in 2015 than in 2014. When the scion wood was inoculated at the time of T-budding or grafting, disease development went faster and to a higher incidence on T-budded (94%) than on grafted trees (50%). Dipping the scion wood end in a spore suspension prior to grafting resulted in more infections than when a suspension droplet was placed on the bud and bark surface of the scion wood after grafting. The present investigation documents that scion wood may harbour inoculum of N. ditissima. Furthermore, infections may be initiated at time of propagation, and management practices of both scion wood production and nurseries should encounter that fact.

Sooty Canker of Fruit Trees in Iran

Sooty Canker of Fruit Trees in Iran

Methods for the Quantification of Resistance of Apple Genotypes to European Fruit Tree Canker Caused by Neonectria ditissima

European fruit tree canker, caused by Neonectria ditissima, is an important disease of pome fruit worldwide. Apple cultivars differ in their levels of susceptibility to N. ditissima. In order to design an effective plant resistance test, we examined the effectiveness of two resistance parameters: infection frequency and lesion growth. Both parameters were evaluated in parallel tests using 10 apple cultivars in three experimental years, applying seminatural infection of leaf scars (infection frequency) or inoculation of artificial wounds (lesion growth). We compared six parameters for lesion growth, of which a new parameter, lesion growth rate (LGR), appeared to be the best with respect to reproducibility and statistical significance. LGR is defined as the slope of the regression of lesion size versus time. The slope was estimated for each lesion, employing a common start date and a lesion-specific end date determined by the girdling of the lesion. The two parameters (infection frequency and LGR) were examined in separate experiments and in three successive years, and provided complementary information and resulted in reproducible conclusions on the relative resistance levels to N. ditissima of the tested cultivars. The presented methods can be used to develop strategies for the control of European fruit tree canker (e.g., in the breeding of new apple cultivars with high levels of resistance to N. ditissima).

Development of a qPCR detection procedure for fruit tree canker caused byNeonectria ditissima

Development of a qPCR detection procedure for fruit tree canker caused by<i>Neonectria ditissima</i>

Pre-breeding for future challenges in Nordic apples: susceptibility to fruit tree canker and storage diseases

Pre-breeding for future challenges in Nordic apples: susceptibility to fruit tree canker and storage diseases

Assessment of diversity and genetic relationships of Neonectria ditissima: the causal agent of fruit tree canker.

Background Neonectria ditissima is one of the most important fungal pathogens of apple trees, where it causes fruit tree canker. Information about the amount and partitioning of genetic variation of this fungus could be helpful for improving orchard management strategies and for breeding apple cultivars with high levels of genetically determined resistance. In this study single-spore Neonectria isolates originating from both the same and from different perithecia, apple cultivars and apple orchards in Sweden and Belgium, were evaluated for AFLP- and SSR-based genetic similarity and for mating system.ResultsSeven SSR loci produced a total of 31 alleles with an average of 4 alleles per locus, while 11 AFLP primer combinations produced an average of 35 fragments per primer combination and 71 % polymorphic fragments. An AFLP-based analysis of molecular variance (AMOVA) revealed that 89 % of the variation was found within orchards and 11 % between orchards. Genetic similarity among the studied isolates was illustrated with a principal coordinate analyseis (PCoA) and a dendrogram. AFLP-based Jaccard’s similarity coefficients were the highest when single-ascospore isolates obtained from the same perithecium were compared, medium-high for isolates from different perithecia on the same tree, and lowest when isolates from different trees were compared.ConclusionsBased on the results of PCoA and AMOVA analysis, isolates from the same or geographically close orchards did not group together. Since AFLP profiles differed also when single-ascospore isolates from the same perithecium were compared, the mating system of N. ditissima is most likely heterothallic.

Cut-off shoots method for estimation of partial resistance in apple cultivars to fruit tree canker caused by Neonectria ditissima

Fruit tree canker, caused by the fungus Neonectria ditissima, is an economically devastating disease in apple orchards, especially in north-western Europe. Complete resistance has not yet been reported in apple, but variation in levels of partial resistance has been described and could be valuable in plant breeding programmes. A screening method based on spore inoculation of manually inflicted leaf scars on cut shoots was evaluated for reliability and repeatability in discrimination of 11 apple cultivars during two years – 2012 and 2013 – in two different facilities – biotron and standard greenhouse – and different time periods (February–May). The resulting cankers were counted (infection percentage), first appearance noted (incubation period) and lesion size measured at regular intervals during a period of 25–29 days for comparison of resistance levels. Results of two-way analysis of variance and correlation analyses showed that the area under the disease progress curve yielded the most robust data. This parameter was then applied for screening 30 apple cultivars using the same cut-shoot method. ‘Elise’ showed very high susceptibility, while the ornamental ‘Prairifire’ showed the highest level of partial resistance. Results suggested that cut shoots can be used to assess levels of resistance among cultivars, but great care must be taken to provide stable experimental conditions.

INTERACTIVE USE OF DISEASE MODELS USING A SMARTPHONE

Fruit tree canker (Neonectria ditissima syn. Nectria galligena Bres.) is an important fungal disease in apple (Malus × domestica Borkh.). Leaf fall is the predominant infection period for this disease. However, in The Netherlands and Belgium, no historical data on leaf fall of apple are available. In practice, collecting leaf fall data is a problem. An innovative approach was chosen to collect leaf fall data and introduce the Nectria model, according to Latorre, to fruit tree growers at the same time. An Android 2.2 Nectria application was developed. During leaf fall, growers received advice twice a week and used the smartphone application to send data and pictures, directly from the field. The general response of the first fruit tree growers who used the smartphone was very positive.

Outcome of the consultation with Member States and EFSA on the basic substance application for calcium hydroxide and the conclusions drawn by EFSA on the specific points raised

EFSA Supporting PublicationsVolume 10, Issue 10 488E Technical reportOpen Access Outcome of the consultation with Member States and EFSA on the basic substance application for calcium hydroxide and the conclusions drawn by EFSA on the specific points raised European Food Safety Authority (EFSA), European Food Safety Authority (EFSA)Search for more papers by this author European Food Safety Authority (EFSA), European Food Safety Authority (EFSA)Search for more papers by this author First published: 18 October 2013 https://doi.org/10.2903/sp.efsa.2013.EN-488Citations: 1 Published date: 18 October 2013 Question number: EFSA-Q-2013-00402 AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat References Anonymous, 2003. Title: Calcium balance in orchards on different soil types, treated with calcium hydroxide against fruit tree canker Source: Request to amend Annex IIB-Pesticides, Annex I. van Rooijen, H, 2006. Title: Evaluation of calcium hydroxide and anti-clotting agents in surface water. Source: Hoogheemraadschap De Stichtse Rijnlanden, Houten (NL). Evaluation based on the criteria in CIW report “Het beoordelen van stoffen en preparaten voor de uitvoering van het emissiebeleid water” (judgement of substances and preparations in the framework of emission management water). Details of the evaluation not available. Schärer, HJ. A., Häseli, C., Daniel, J., Fuchs, L., Tamm; 2010. Title: Praxisversuche 2010 mit Löschkalk und Hanfextrakt gegen Feuerbrand. Source: Öffentlicher Schlussbericht 2010. SCOEL (Scientific Committee on Occupational Exposure Limits), 2008. Recommendation from the Scientific Committee on Occupational Exposure Limits for Calcium oxide (CaO) and calcium hydroxide (Ca(OH)2). SCOEL/SUM/137. February 2008. Citing Literature Volume10, Issue10October 2013488E ReferencesRelatedInformation

'XENIA', A NEW PEAR CULTIVAR FROM MOLDOVA, FIRST RESULTS IN THE NETHERLANDS

The pear cultivar `Xenia? (synonym `Noiabriskaia?) from Moldova is a selection from a cross between `Triomphe de Vienne? and `Nicolai Krier?. In The Netherlands, `Xenia? has been tested since 2001. So far, trees have given early and high yields and required little thinning. Up to now, a very low to moderate susceptibility to scab (Venturia pirinia) and a very low susceptibility to fruit tree canker (Nectria galligena) have been observed. The trees showed a medium vigour and there was a low tendency to biennial bearing. With the relatively young trees, the average fruit size of `Xenia? fruits at full crop was 250-300 g. The harvest window was wide. Fruits of `Xenia? had a green ground colour at harvest and were moderately bronzed. `Xenia? had a spherical pear shape. The fruits had a strong fruit skin. The firmness was higher than that of `Conference?. The juiciness varied from juicy to very juicy, depending on the maturity stage. `Xenia? had a good eating quality: fresh, slightly aromatic with a typical aroma. The storability of the fruits was very good and the shelf life of `Xenia? proved to be much better than of `Conference?. Summarizing, the first results show a good potential for commercial fruit growing.

Genomic variation within Monilinia laxa, M. fructigena and M. fructicola, and application to species identification by PCR.

Brown rot and twig canker of fruit trees are caused by Monilinia laxa, M. fructigena and M. fructicola. The Internal Transcribed Spacer (ITS) between the 18S and the 28S rRNA genes of four M. laxa and four M. fructigena isolates collected in France was amplified by Polymerase Chain Reaction (PCR) using universal primers and sequenced. Multiple alignment of the ITS sequences and comparison with published sequences revealed very little intraspecific variation and a low interspecific polymorphism clustered in two regions. Species-specific PCR primers were designed to amplify a 356 bp fragment for each of the three species. The specificity of the three primer pairs was successfully tested with a collection of 17 M. laxa, 18 M. fructigena and 6 M. fructicola isolates collected from different hosts and different countries, unequivocally confirming the identification of each isolate based on morphological and cultural traits. Using stringent PCR conditions, no cross-reaction was observed with any of the isolates tested. The specificity of the PCR assays was also successfully confirmed with DNA extracted from different fungal species, either phylogenetically close to the genus Monilinia or commonly found on diseased fruits. Using this new reliable technique, doubtful isolates can be directly identified in a single PCR run. Moreover, detection and identification of the Monilinia species were successfully achieved directly on diseased fruits. This simple and rapid method can be particularly useful to detect M. fructicola which is a listed quarantine fungus in all European countries.

Papery Bark Canker of Fruit Trees in Relation to Silver Leaf Disease

(1943). Papery Bark Canker of Fruit Trees in Relation to Silver Leaf Disease. Journal of Pomology and Horticultural Science: Vol. 20, No. 4, pp. 144-146.