scholarly journals Population Structure and Disease Development of Cryphonectria parasitica in European Chestnut Forests in the Presence of Natural Hypovirulence

1997 ◽  
Vol 87 (1) ◽  
pp. 50-59 ◽  
Author(s):  
Martin Bissegger ◽  
Daniel Rigling ◽  
Ursula Heiniger
Keyword(s):  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
First Year ◽  
Mating Types ◽  
Vegetative Compatibility Groups ◽  
European Chestnut ◽  
Repeated Sampling ◽  
Cryphonectria Hypovirus ◽  
Two Populations

The Cryphonectria parasitica populations in two 6-year-old European chestnut (Castanea sativa) coppices were investigated in southern Switzerland over a period of 4 years. Occurrence of white isolates indicating an infection with Cryphonectria hypovirus, vegetative compatibility groups (VCGs), hypovirulence conversion capacity, and mating types were used to characterize the populations. Sampling of randomly chosen cankers in the first year yielded 59% white isolates in one and 40% in the other population. The distribution of the VCGs and mating types was similar among white and orange isolates, indicating a homogeneous infection of the two populations by the hypovirus. Fourteen VCGs were found in the first population, 16 VCGs in the second. Altogether, 21 VCGs were determined. The same three VCGs dominated in both populations, comprising more than 60% of all isolates. Several VCGs were represented only by white isolates. Five of the six most common VCGs were clustered in two hypovirulence conversion groups, with almost 100% hypovirus transmission within each cluster. Repeated sampling of the same cankers in 1990, 1992, and 1994 did not reveal an increase of white isolates. The portion of blighted stems rose from 37% to about 60% in both plots within 4 years. In this time, chestnut blight killed 15% and competition an additional 21% of the sprouts. Predominantly, sprouts with low diameters at breast height were killed. The growth rate of new cankers was high in their first year and decreased gradually in the following years. A role of hypovirulence in the decline of disease severity was evident since (i) cankers yielding white isolates grew slower and killed considerably fewer sprouts than cankers with orange isolates; and (ii) the majority of the cankers yielded white isolates at least once during the 4-year observation period.

scholarly journals Role of Fresh Dead Wood in the Epidemiology and the Biological Control of the Chestnut Blight Fungus

Plant Disease ◽  
2019 ◽  
Vol 103 (3) ◽  
pp. 430-438 ◽  
Author(s):  
Joana Beatrice Meyer ◽  
Loïc Chalmandrier ◽  
Fabio Fässler ◽  
Christopher Schefer ◽  
Daniel Rigling ◽  
...  
Keyword(s):  
Biological Control ◽  
Dead Wood ◽  
Biocontrol Agent ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
Study Sites ◽  
Cryphonectria Hypovirus

The invasive fungus Cryphonectria parasitica, the causal agent of chestnut blight, is able to survive and sporulate on the bark of fresh dead Castanea sativa wood for at least 2 years. Here, we experimentally investigated the role of fresh dead wood in the epidemiology of chestnut blight, specifically in the spread of the hyperparasitic virus Cryphonectria hypovirus 1, which acts as biocontrol agent of C. parasitica. A total of 152 artificially initiated, virulent bark cankers in four chestnut stands were treated with virus-infected asexual spores originating either from sporulating dead wood or from a spore suspension. Molecular markers for both the virus and the fungal carrier were used to examine the spread of the applied biocontrol virus. Fourteen months after treatment, 42 to 76% of the conidial spray-treated cankers and 50 to 60% of the cankers exposed to a sporulating dead stem had been virus infected by the applied hypovirulent conidia in all four study sites. Virus infection reduced canker expansion and promoted canker healing (callusing). Thus, fresh chestnut dead wood may play an important role in supporting the successful spread of natural hypovirulence in chestnut forests. Further, combined with the application of virus-infected conidial suspensions, it may help promote the establishment of artificially released hypoviruses in chestnut stands to control chestnut blight.

scholarly journals The role of production site isolation in the plant health situation of sweet chestnut (Castanea sativa)

2017 ◽  
pp. 79-82
Author(s):  
Gabriella Kovács ◽  
László Radócz
Keyword(s):  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Western Slope ◽  
Past Century ◽  
Sweet Chestnut ◽  
European Chestnut ◽  
Disease Occurrence ◽  
New Perspective ◽  
Blight Disease ◽  
Health Situation

The most destructive pathogen for the European chestnut is the blight fungus Cryphonectria parasitica (Murr.) Barr. The spread of the fungus was very fast in Europe within a few decades in the second half of the past century. During the tree-health checking in the chestnut andwalnut plantation in Romania, Hargita county, next to Homoródkarácsonyfalva village, we especially concentraded on the signs of blight disease occurrence. The grove is laying on a western slope, under a pine forest. This favourable geographical space protects it not only from pathogen attacts, but it has a special, mild microclimate for nut and chestnut trees. The European chestnut could be a valuable member of local forests, opening a new perspective under conditions of climate changes.

scholarly journals Έρευνα των παθογόνων ειδών του γένους Cryphonectria (=Endothia) στην Ευρωπαϊκή καστανιά (Castanea sativa)

2002 ◽  
Author(s):  
Χαρίκλεια Περλέρου
Keyword(s):  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Cryphonectria Hypovirus

Η ασθένεια του έλκους της καστανιάς που προκαλεί ο μύκητας Cryphonectria parasitica αποτελεί μια από τις σοβαρότερες ασθένειες που έπληξαν δασικό δένδρο του Β. Ημισφαιρίου κατά τον 20ο αιώνα. Αν και ο μύκητας πρωτοεντοπίσθηκε στην Ελλάδα το 1963 λίγο έχει μελετηθεί μέχρι σήμερα. Σχετικά πρόσφατη έρευνα στην Ευρώπη και ΗΠΑ έδειξε την ύπαρξη στη φύση ενός ιού dsRNA ο οποίος όταν προσβάλλει τις πορτοκαλόχρωμες, παθογόνες απομονώσεις του μύκητα τις μετατρέπει σε λευκές, υποπαθογόνες. Ο ιός αυτός εντάχθηκε στο γένος hypovirus, οικ. Hypoviridae και ονομάστηκε Cryphonectria hypovirus (CHV). Η μεταφορά του κυτταροπλασμικού αυτού ιού είναι εφικτή με αναστόμωση των μυκηλιακών υφών μόνον εάν οι δύο μορφές απομονώσεων ανήκουν στον ίδιο τύπο βλαστικής συμβατότητας. Η ιδιαίτερη αυτή περίπτωση μείωσης της παθογόνου ικανότητας ενός μύκητα αξιοποιήθηκε με την εφαρμογή μεθόδου βιολογικής αντιμετώπισης της ασθένειας που συνίσταται στην εισαγωγή στελεχών με CHV ιό και μειωμένη παθογόνου ικανότητα σε περιοχές όπου αυτά δεν υπάρχουν. Απαραίτητη προϋπόθεση όμως για την εφαρμογή της μεθόδου είναι η λεπτομερής γνώση και γεωγραφική διασπορά των τύπων βλαστικής συμβατότητας σε μια ευρύτερη περιοχή. Έτσι σκοπός της παρούσας έρευνας ήταν ο έλεγχος για την ύπαρξη νέων κηλίδων της ασθένειας πέραν αυτών που έχουν ήδη εντοπισθεί, ο προσδιορισμός, η γεωγραφική διασπορά και η μελέτη των τύπων βλαστικής συμβατότητας του μύκητα C. parasitica στην Ελλάδα, η διερεύνηση της ύπαρξης υποπαθογόνων στελεχών και τέλος η μελέτη της παθογόνου ικανότητας απομονώσεων του μύκητα από διάφορες περιοχές της χώρας. Κατά την έρευνα αυτή διαπιστώθηκε ότι εκτός από τις 4 περιοχές για τις οποίες υπήρχαν αναφορές ύπαρξης της ασθένειας, ήτοι όρος Πήλιο Ν. Μαγνησίας, Άνω Κεράσοβο Ν. Αιτωλοακαρνανίας, Δυτ. Τζουμέρκα Ν. Άρτας και Άγιον Όρος, η ασθένεια έχει εξαπλωθεί στις περισσότερες από τις περιοχές όπου απαντάται η καστανιά στην Ελλάδα. Από 611 απομονώσεις του μύκητα που πραγματοποιήθηκαν σε 12 Νομούς της χώρας, λευκές απομονώσεις με μειωμένη παθογόνο ικανότητα βρέθηκαν μόνο στους Νομούς Μαγνησίας, Ιωαννίνων, Αιτωλοακαρνανίας, Φθιώτιδας και Χαλκιδικής σε συνολικό ποσοστό 11,6% των απομονώσεων. Έλεγχος των ίδιων αυτών απομονώσεων έδειξε ότι στην Ελλάδα υπάρχουν τέσσερις τύποι βλαστικής συμβατότητας, ήτοι οι EU-1, EU-2, EU-10 και EU-12. Ο τύπος EU-12 βρέθηκε και στους 12 Νομούς σε συνολικό ποσοστό 88,4% των απομονώσεων ενώ ο τύπος EU-2 σε 4 Νομούς σε ποσοστό 6,4%. Οι άλλοι δύο τύποι EU-1 και EU-10 βρέθηκαν σε χαμηλότερα ποσοστά (2,1% και 3,1% αντίστοιχα) σε ένα Νομό έκαστος. Η παθογόνος ικανότητα 11 ελληνικών απομονώσεων και μιας ιταλικής προσδιορίσθηκαν από το μέγεθος των ελκών που προκάλεσαν σε πρεμνοβλαστήματα καστανιάς ηλικίας 9 ετών μετά από τεχνητή μόλυνση υπό φυσικές συνθήκες. Οι παρατηρήσεις και μετρήσεις επεκτάθηκαν σε δύο αυξητικές περιόδους (17 μήνες). Έξι πορτοκαλόχρωμες απομονώσεις συμπεριφέρθηκαν ως παθογόνες προκαλώντας εκτεταμένα έλκη που αναπτύχθηκαν και στις δύο αυξητικές περιόδους. Από τις υπόλοιπες έξι λευκές απομονώσεις με τον dsRNA ιό, οι τέσσερις προκάλεσαν μικρά έλκη κατά τους πρώτους δύο μήνες μετά την τεχνητή μόλυνση τα οποία στη συνέχεια επουλώθηκαν, παρέμειναν δε ανενεργά κατά τη δεύτερη αυξητική περίοδο. Οι άλλες δύο απομονώσεις συμπεριφέρθηκαν ως παθογόνες κατά την πρώτη αυξητική περίοδο αλλά ως υποπαθογόνες κατά τη δεύτερη καθόσον τα έλκη παρέμεινα εντελώς ανενεργά ενώ άρχισε να σχηματίζεται και επουλωτικός ιστός. Λόγω του εξαιρετικά μικρού αριθμού των τύπων βλαστικής συμβατότητας και της περιορισμένης γεωγραφικά εμφάνισης των υποπαθογόνων στελεχών του μύκητα, η εφαρμογή βιολογικής καταπολέμησης, είναι δυνατή. Η χώρα όμως θα πρέπει ταυτόχρονα να θωρακισθεί κατά της εισαγωγής και άλλων τόπων βλαστικής συμβατότητας με την αυστηρή εφαρμογή των προτάσεων φυτοελέγχου του ΕΡΡΟ.

scholarly journals MULTI-PURPOSE CHESTNUT CLUSTERS DETECTION USING DEEP LEARNING: A PRELIMINARY APPROACH

2019 ◽  
Vol XLII-3/W8 ◽  
pp. 1-7 ◽  
Author(s):  
T. Adão ◽  
L. Pádua ◽  
T. M. Pinho ◽  
J. Hruška ◽  
A. Sousa ◽  
...  
Keyword(s):  
Phytophthora Cinnamomi ◽  
Agricultural Practices ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Nutritional Deficiencies ◽  
Strong Increase ◽  
Environmental Disaster ◽  
Gall Wasp ◽  
European Chestnut ◽  
Portuguese Economy

<p><strong>Abstract.</strong> In the early 1980′s, the European chestnut tree (<i>Castanea sativa, Mill.</i>) assumed an important role in the Portuguese economy. Currently, the Trás-os-Montes region (Northeast of Portugal) concentrates the highest chestnuts production in Portugal, representing the major source of income in the region (€50M-€60M).</p> <p>The recognition of the quality of the Portuguese chestnut varieties has increasing the international demand for both industry and consumer-grade segments. As result, chestnut cultivation intensification has been witnessed, in such a way that widely disseminated monoculture practices are currently increasing environmental disaster risks. Depending on the dynamics of the location of interest, monocultures may lead to desertification and soil degradation even if it encompasses multiple causes and a whole range of consequences or impacts. In Trás-os-Montes, despite the strong increase in the cultivation area, phytosanitary problems, such as the chestnut ink disease (<i>Phytophthora cinnamomi</i>) and the chestnut blight (<i>Cryphonectria parasitica</i>), along with other threats, e.g. chestnut gall wasp (<i>Dryocosmus kuriphilus</i>) and nutritional deficiencies, are responsible for a significant decline of chestnut trees, with a real impact on production. The intensification of inappropriate agricultural practices also favours the onset of phytosanitary problems. Moreover, chestnut trees management and monitoring generally rely on in-field time-consuming and laborious observation campaigns. To mitigate the associated risks, it is crucial to establish an effective management and monitoring process to ensure crop cultivation sustainability, preventing at the same time risks of desertification and land degradation.</p> <p>Therefore, this study presents an automatic method that allows to perform chestnut clusters identification, a key-enabling task towards the achievement of important goals such as production estimation and multi-temporal crop evaluation. The proposed methodology consists in the use of Convolutional Neural Networks (CNNs) to classify and segment the chestnut fruits, considering a small dataset acquired based on digital terrestrial camera.</p>

scholarly journals Hail-Induced Infections of the Chestnut Blight Pathogen Cryphonectria parasitica Depend on Wound Size and May Lead to Severe Diebacks

2020 ◽  
Vol 110 (7) ◽  
pp. 1280-1293
Author(s):  
Guglielmo Lione ◽  
Luana Giordano ◽  
Massimo Turina ◽  
Paolo Gonthier
Keyword(s):  
Logistic Model ◽  
Castanea Sativa ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Risk Of Infection ◽  
North West ◽  
The North ◽  
Single Location ◽  
Entry Points ◽  
Cryphonectria Hypovirus

This study combined phytosanitary surveys, laboratory analyses, and mathematical modeling to show how hail-induced wounds can foster the infections of the blight pathogen Cryphonectria parasitica, locally associated with extensive dieback of chestnut (Castanea sativa). Orchards and coppices located within and outside the assessed dieback area in a single location in the North West of Italy were inspected to appraise the abundance of hail-induced wounds and C. parasitica infections. The incidence of C. parasitica was significantly higher within the dieback area compared with outside (92% versus 60%; P < 0.05). Hail-induced wounds were observed on small branches and shoots of all trees sampled within the dieback area, whereas they were less abundant outside (20% of trees), suggesting either that the dieback was directly associated with the injuries caused by the hailstorms or that those injuries may have facilitated infections of C. parasitica. Isolations conducted on 359 branches and shoots showed that hail-induced wounds served as infection courts for C. parasitica and that infections depended on the size rather than on the number of hail wounds. We fitted a logistic model showing that hail-induced wounds whose perimeter was larger than 66 mm were at particular risk of C. parasitica infection. A newly designed geometrical-based model is proposed to relate hailstones size, hail wound perimeter, and the risk of infection. We established that hail-induced wounds are entry points for virulent and hypovirulent strains of C. parasitica, since 6.5% of isolates were infected by Cryphonectria hypovirus-1.

scholarly journals The development of population structure of Cryphonectria parasitica on European chestnut (Castanea sativa Mill.) in the Experimental Castanetarium Horné Lefantovce, observed over a 12-year study period

2009 ◽  
Vol 36 (No. 2) ◽  
pp. 55-60 ◽  
Author(s):  
K. Adamčíková ◽  
M. Kobza ◽  
G. Juhásová
Keyword(s):  
Population Structure ◽  
Castanea Sativa ◽  
Morphological Characters ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Experimental Plot ◽  
Disease Symptoms ◽  
European Chestnut ◽  
Blight Disease ◽  
First Time

: We studied occurrence of chestnut blight disease in the Experimental Castanetarium Horné Lefantovce, SW Slovakia. The study ran in years 2006–2007 on a set consisting of 889 chestnut trees growing in the clonal orchard on Biological Plot 105. From this number, 857 trees were found healthy without disease symptoms. The chestnut blight disease was identified on 32 of them. The infected trees were examined for presence of pycnidia and perithecia of the causal agent. In all positive cases, the observed morphological characters indicated virulency of the obtained isolates. No hypovirulent isolate was detected on the evaluated experimental plot. In total, six vegetative compatibility (vc) types were specified in the sample consisting of 31 isolates. Our vc types corresponded to the European vc types EU 2, EU 12, EU 13, EU 14, EU 17, EU 19. Two vc types – EU 2 and EU 19 – were dominant. Vc type EU 19 accounted 35.5% and EU 2 32.2% of isolates. The vc type EU 19, which was the most frequent one in the evaluated site, was detected in Slovakia for the first time.

scholarly journals Characterization of a Hypovirus-Regulated Septin Cdc11 Ortholog, CpSep1, from the Chestnut Blight Fungus Cryphonectria parasitica

2019 ◽  
Vol 32 (3) ◽  
pp. 286-295 ◽  
Author(s):  
Myeongjin Jo ◽  
Kum-Kang So ◽  
Yo-Han Ko ◽  
Jeesun Chun ◽  
Jung-Mi Kim ◽  
...  
Keyword(s):  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Null Mutant ◽  
Wild Type ◽  
Chestnut Blight Fungus ◽  
Germination Process ◽  
Cryphonectria Hypovirus ◽  
Null Mutants

We identified a protein spot showing downregulation in the presence of Cryphonectria hypovirus 1 and tannic acid supplementation as a septin subunit with the highest homology to the Aspergillus nidulans aspA gene, an ortholog of the Saccharomyces cerevisiae Cdc11 gene. To analyze the functional role of this septin component (CpSep1), we constructed its null mutant and obtained a total of eight CpSep1-null mutants from 137 transformants. All CpSep1-null mutants showed retarded growth, with fewer aerial mycelia and intense pigmentation on plates of potato dextrose agar supplemented with L-methionine and biotin. When the marginal hyphae were examined, hyperbranching was observed in contrast to the wild type. The inhibition of colonial growth was partially recovered when the CpSep1-null mutants were cultured in the presence of the osmostabilizing sorbitol. Conidia production of the CpSep1-null mutants was significantly increased by at least 10-fold more. Interestingly, the conidial morphology of the CpSep1-null mutants changed to circular in contrast to the typical rod-shaped spores of the wild type, indicating a role of septin in the spore morphology of Cryphonectria parasitica. However, no differences in the germination process were observed. Virulence assays using excised chestnut bark, stromal pustule formation on chestnut stems, and apple inoculation indicated that the CpSep1 gene is important in pathogenicity.

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