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

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.

2009 ◽  
Vol 36 (No. 2) ◽  
pp. 55-60 ◽  
Author(s):  
K. Adamčíková ◽  
M. Kobza ◽  
G. Juhásová

: 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.


2018 ◽  
Vol 108 (7) ◽  
pp. 870-877 ◽  
Author(s):  
Marin Ježić ◽  
Jelena Mlinarec ◽  
Rosemary Vuković ◽  
Zorana Katanić ◽  
Ljiljana Krstin ◽  
...  

Invasive species, especially plant pathogens, have a potential to completely eradicate native plant species and remodel landscapes. Tripartite interactions among sweet chestnut (Castanea sativa), chestnut blight-causing invasive fungus Cryphonectria parasitica, and hyperparasitic virus Cryphonectria hypovirus 1 (CHV1) were studied in two populations. The number of different vegetative compatibility (vc) types of C. parasitica more than doubled over the 10 years, while the hypovirulence incidence dropped in one population and slightly increased in the other one. Over the course of our 3-year monitoring experiment, the prevalence of hypovirulent isolates obtained from monitored cankers increased slowly (i.e., more hypovirulent isolates were being obtained from the same cankers over time). Within studied cankers, considerable changes in vc type and CHV1 presence were observed, indicating a highly dynamic system in which virulent and hypovirulent mycelia, sometimes of discordant vc types, often appeared together. The increase in hypovirulence prevalence did not have any observable curative effect on the cankers and, occasionally, reactivation of healed cankers by new, virulent C. parasitica isolates was observed. Both short- and long-term observations and revalidation of the infected plant populations are necessary to accurately estimate disease progress and formulate an adequate disease management strategy.


2012 ◽  
Vol 51 (No. 6) ◽  
pp. 256-258 ◽  
Author(s):  
P. Haltofová ◽  
L. Jankovský ◽  
D. Palovčíková

The causal agent of the chestnut blight, the fungus Cryphonectria parasitica (Murrill) M. E. Barr (syn. Endothia parasitica (Murrill) P. J. Anderson et H. W. Anderson), was found out at new localities in the Czech Republic. The chestnut blight was observed for the first time in the Czech Republic in 2002. Two new localities were discovered in southern Moravia in May and June 2004. The disease was identified both on the sweet chestnut (Castanea sativa Mill.) and on the red oak (Quercus rubraL.). Infected trees were treated according to the order of the State Phytosanitary Administration of the Czech Republic. 


2011 ◽  
pp. 70-75
Author(s):  
László Radócz ◽  
Gábor Tarcali ◽  
László Irinyi ◽  
Gábor Görcsös

Chryphonectria parasitica (Murr.) Barr, the casual agent of chestnut blight disease, which is one of the most important fungal pathogens of chestnut (Castanea sativa). The disease seriously affected the chestnut in Northern-America and in Europe as well. It is important to mention that the pathogen does not only infect the chestnut but oak species (Quercus spp.) also. In the Carpathian-Basin, the chestnut is endemic in the Mecsek mountains, in Zala, in Somogy counties but it also can be found in the Danube-Bend. In the Carpathian-Basin (outside Hungary) the chestnut is found in Slovakia, Ukraine, Romania. In our study bark samples infected by Cryphonectria parasitica were collected from Bobovyshche, Serednje and Rostovjatica (Ukraine). The rate of infected chestnut tree were higher than 90% around Bobovyshche and beside chestnut, the symptoms were detected on oak trees as well. We collected bark samples from chestnut and oak as well and then we isolated the pathogen Cryphonectria parasitica in the lab of University of Debrecen. Symptomatological observations, laboratory examinations on fungus morphology, as well as comparisons of ITS sequency homology were made and approved that the causal agent of new disease was Cryphonectria parasitica. Our results proved that the Cryphonectria. parasitica infects oak trees beside chestnut in the Carpathian-Basin. Further studies are needed to determine the VCG (Vegatative Compatibility Group) group of the Cryphonectria parasitica found on oak trees. 


Author(s):  
T. Adão ◽  
L. Pádua ◽  
T. M. Pinho ◽  
J. Hruška ◽  
A. Sousa ◽  
...  

<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>


Forests ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 492 ◽  
Author(s):  
Stephanos Diamandis

Sweet chestnut (Castanea sativa Mill.) is an important tree for Greece. The invasive fungus Cryphonectria parasitica, which causes chestnut blight, was first found in Central Greece in 1963. It has since spread all over the country, significantly reducing the national annual nut production. The increasing decline of forests and orchards due to the disease led to a project in 1995, which aimed at studying the feasibility of applying biological control. A prerequisite study of the existing vegetative compatibility types of the pathogen showed only four, and their distribution was mapped. A pilot project (1998–2000) that consisted of clear cutting heavily infected coppice stands and introducing hypovirulence to the remainder was implemented on Mt. Athos on a 7000 ha sweet chestnut forest. Two evaluations (in 2003 and 2011) revealed that hypovirulence was established in the sweet chestnut forests and spread more or less homogeneously. A nationwide project introducing hypovirulence to 29 counties was implemented in two, 3-yr-periods 2007–2009 (17 counties) and 2014–2016 (12 counties). The new evaluations showed that hypovirulence spread profoundly and forests and orchards started recovering. The appearance of natural hypovirulence cannot be predicted. Introduced hypovirulence and silvicultural interventions can be used to manage the disease. It is the responsibility of the forest/orchard manager to decide whether to wait for appearance of natural hypovirulence, or to introduce it for a faster decline in disease.


2018 ◽  
pp. 77-81
Author(s):  
Gabriella Kovács ◽  
Dominika Bodnár ◽  
Gábor Tarcali ◽  
László Radócz

The supervision of plant hygiene of sweet chestnut grove on Pécsbánya (South Hungary) started more than four years ago. Hypovirulent strains were applied as a biological process to control Cryphonectria parasitica fungus which causes the chestnut blight disease. By now the performed interventions have shown obvious results, the vitality of the trees has greatly improved, the amount of harvested nuts is increasing, and the hypovirulent strain has been spreading within the area. During plant health inspection the galls of chestnut gall wasp (Dryocosmus kuriphilus) was found in the year of 2015, which is the obvious symptom of new occurrence of the pest. The pest was eradicated by destroy galls, which allows taking out of consideration the damage by now in this area.


1997 ◽  
Vol 87 (1) ◽  
pp. 50-59 ◽  
Author(s):  
Martin Bissegger ◽  
Daniel Rigling ◽  
Ursula Heiniger

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.


Plant Disease ◽  
2014 ◽  
Vol 98 (2) ◽  
pp. 283-283 ◽  
Author(s):  
J. Bascón ◽  
S. Castillo ◽  
C. Borrero ◽  
S. Orta ◽  
A. Gata ◽  
...  

In Europe, chestnut blight caused by Cryphonectria parasitica (Murrill) Barr was first seen in Italy in 1938 (1). In Spain, the disease was first detected in Basque country in 1947 and later in other areas of northern Spain: Galicia, León, Navarra, and Catalonia, and in Trás-os-Montes in Portugal (2). In November 2012, in an orchard (2 ha) in Almonaster la Real (Huelva, Spain), approximately 20 cankered Castanea sativa (sweet chestnut) trees cv. Vazqueño, 40 to 50 years old, were observed. The trees were grafted 2 years before. In May and June 2013, six new disease focuses were detected near the first one. Five focuses were located in the same village and the other in Jabugo (a neighboring village). Diseased trees exhibited sunken cankers, cracked bark with mycelial fan spreads under the bark, and in some cases, orange fungal sporulation was visible on the bark. Samples were collected from two affected trees and symptom-bearing bark pieces were then placed in moist chambers at 20°C for up to 8 days to induce fungal sporulation. Cultures were made from spore masses extruding from the cankered bark and from the edge of necrotic lesions visible in the phloem of cankered bark tissue onto potato dextrose agar (PDA). Monoconidial fungal isolates were obtained from both trees. The morphological structure of two isolated fungi was identical to that described as C. parasitica (3). Species identity was confirmed by analysis of nucleotide sequences of the internal transcribed spacer (ITS) rDNA, using ITS1-ITS4 (4) as primer pairs, respectively. BLAST searches showed a high similarity between collected isolates' DNA sequences and C. parasitica sequences found on GenBank (96% coverage, 99% identity). Our isolates have been included in GenBank as KF220298 and KF220299. The pathogenicity assay of these two isolates was conducted using two cultivars of sweet chestnut (seedlings from Huelva and Granada nurseries). Isolate pathogenicity was tested on 3-year-old chestnut seedlings in a growth chamber at 25°C (day) and 20°C (night) with a 14-h photoperiod. The isolates were cultured on PDA at 25°C for 7 days. Stems were wounded at 10 cm height with a drill. Each isolate was inoculated to 25 replicates per cultivar by placing a mycelia agar plug (4 to 5 mm diameter) in the hole and wrapping the stem with Parafilm. Plants treated identically with sterile agar plugs were used as controls. Plants were then maintained at 100% relative humidity for 2 h. Both isolates induced diseases symptoms and death of seedlings of both cultivars at a mean time of 37.5 days after inoculation. No significant differences between isolates or between cultivars were detected. Twenty control plants similarly treated with sterile PDA discs did not display symptoms. C. parasitica was re-isolated from lesions, confirming Koch's postulates. Andalusia has 14,000 ha of chestnut crops with high commercial value due to their precocity. Dispersion of chestnut blight in this zone can reduce crop productivity. To our knowledge, this is the first report of C. parasitica causing chestnut blight in Andalusia (southern Spain), one of the few areas left in southwestern Europe free of chestnut blight. References: (1) A. Biraghi. Italia Agricola 7:1, 1946. (2) G. González-Varela et al. Eur. J. Plant Pathol. 131:67, 2011. (3) A. Sivanesan and P. Holliday. Cryphonectria parasitica. CMI Descriptions of Pathogenic Fungi and Bacteria. No. 704, Set. 71. Commonwealth Mycological Institute, Kew, UK, 1981. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Amplifications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.


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