Occurrence of Cryphonectria canker disease of Eucalyptus in Kerala, India*
TL;DR: Cryphonectria cubensis, recorded for the first time in India, is responsible for causing severe stem cankers in Eucalyptus grandis in Kerala.
Abstract: SUMMARY
Cryphonectria cubensis, recorded for the first time in India, is responsible for causing severe stem cankers in Eucalyptus grandis in Kerala. Disease outbreaks are localised and vary in severity with host species, at times affecting up to 30% of the trees in a stand. Infection usually occurs on the main stem 1 to 1 ·5 m above ground and occasionally near ground level. There is evidence of tree to tree spread of the disease from the primary infection foci. The disease also affects coppicing by stumps after harvest. Details on the incidence and epidemiology of the disease are presented.
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TL;DR: This review summarizes the current state of research on this pathogen with a special emphasis on its interaction with a hyperparasitic mycovirus that acts as a biological control agent of chestnut blight.
Abstract: Chestnut blight, caused by Cryphonectria parasitica, is a devastating disease infecting American and European chestnut trees. The pathogen is native to East Asia and was spread to other continents via infected chestnut plants. This review summarizes the current state of research on this pathogen with a special emphasis on its interaction with a hyperparasitic mycovirus that acts as a biological control agent of chestnut blight.
Taxonomy: Cryphonectria parasitica (Murr.) Barr. is a Sordariomycete (ascomycete) fungus in the family Cryphonetriaceae (Order Diaporthales). Closely related species that can also be found on chestnut include Cryphonectria radicalis, Cryphonectria naterciae, and Cryphonectria japonica.
Host range: Major hosts are species in the genus Castanea (Fam. Fagaceae), particularly the American chestnut (C. dentata), the European chestnut (C. sativa), the Chinese chestnut (C. mollissima), and the Japanese chestnut (C. crenata). Minor, incidental hosts include oaks (Quercus spp.), maples (Acer spp.), European hornbeam (Carpinus betulus L.), and American chinkapin (Castanea pumila).
Disease symptoms: C. parasitica causes perennial necrotic lesions (so-called cankers) on the bark of stems and branches of susceptible host trees, eventually leading to wilting of the plant part distal to the infection. Chestnut blight cankers are characterized by the presence of mycelial fans and fruiting bodies of the pathogen. Below the canker the tree may react by producing epicormic shoots. Non-lethal, superficial or callusing cankers on susceptible host trees are usually associated with mycovirus-induced hypovirulence.
Disease control: After the introduction of C. parasitica into a new area, eradication efforts by cutting and burning the infected plants/trees have mostly failed. In Europe, the mycovirus Cryphonectria hypovirus 1 (CHV-1) acts as a successful biological control agent of chestnut blight by causing so-called hypovirulence. CHV-1 infects C. parasitica and reduces its parasitic growth and sporulation capacity. Individual cankers can be therapeutically treated with hypovirus-infected C. parasitica strains. The hypovirus may subsequently spread to untreated cankers and become established in the C. parasitica population. Hypovirulence is present in many chestnut growing regions of Europe, either resulting naturally or after biological control treatments. In North America, disease management of chestnut blight mainly focuses on breeding with the goal to backcross the Chinese chestnut's blight resistance into the American chestnut genome. This article is protected by copyright. All rights reserved.
278 citations
TL;DR: Results show, for the first time, that C. cubensis occurs in Kenya, Malawi, and Mozambique on nonnative Eucalyptus spp.
Abstract: Chrysoporthe cubensis and C. austroafricana, collectively known as Cryphonectria cubensis in the past, are important canker pathogens of Eucalyptus spp. worldwide. Previous studies have suggested that Chrysoporthe austroafricana occurs only in South Africa, whereas C. cubensis occurs in Australia, Cameroon, Tanzania, Democratic Republic of Congo, Republic of Congo, Southeast Asia, and South, Central, and North America. In South Africa, C. austroafricana is a pathogen on nonnative Eucalyptus (Myrtaceae) and Tibouchina (Melastomataceae) spp., both residing in the order Myrtales. Recently, the fungus also has been found on native Syzygium cordatum trees in the country, leading to the hypothesis that it is native to Africa. In contrast, C. cubensis is thought to have been introduced into Africa and is known only on non-native Eucalyptus spp. and S. aromaticum (clove) in four countries. The aim of this study was to consider the distribution of Chrysoporthe spp. on non-native Eucalyptus spp. as well as on native Myrtales in southern and eastern Africa. Isolates were collected from as many trees as possible and characterized based on their morphology and DNA sequence data for two gene regions. Results show, for the first time, that C. cubensis occurs in Kenya, Malawi, and Mozambique on nonnative Eucalyptus spp. C. austroafricana was found for the first time in Mozambique, Malawi, and Zambia on non-native Eucalyptus spp. and native S. cordatum. The known distribution range of C. austroafricana within South Africa also was extended during these surveys.
63 citations
TL;DR: The results suggest that the South African fungus represents a spe- cies distinct from C. cubensis occurring elsewhere in the world.
Abstract: Cryphonectria cubensis (Bruner) Hodges is the causal agent of an important stem canker disease of Eucalyp- tus. Previous phylogenetic studies based on sequence data have shown that C. cubensis is distinct from other species of Cryphonectria but that C. cubensis isolates reside in two distinct groups, consistent with geographical origin. Thus, iso - lates of C. cubensis from South America and South Africa grouped together but apart from those originating from Southeast Asia and Australia. These results were in contrast with the symptoms of Cryphonectria canker in South Af- rica, which are different from those observed elsewhere in the world. The aim of this study was to use more variable regions of the fungal genome to test whether South African isolates of C. cubensis are genetically distinct from those from other parts of the world. For this comparison, β-tubulin and histone H3 gene sequences were used. Specimens from South America, Southeast Asia, Australia, and South Africa were also compared morphologically. The phylogram emerging from the analysis indicated that South American and Southeast Asian - Australian isolates resided in two well-resolved but closely related clades. However, isolates from South Africa were distinct from other groups. This is consistent with ecological aspects of the South African fungus, although no obvious morphological differences between the fungi from the various regions could be found. Our results suggest that the South African fungus represents a spe- cies distinct from C. cubensis occurring elsewhere in the world.
56 citations
Additional excerpts
...J:\cjb\cjb80\cjb-06\B02-039.vp Tuesday, May 28, 2002 8:25:49 AM Florence et al. 1986; Gibson 1981; Hodges and Reis 1974; Hodges et al. 1979; Sharma et al. 1985a, 1985b; Wingfield et al. 1989)....
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TL;DR: In this article, the authors determined the phylogenetic relationships among strains of C. cubensis, which causes a serious canker disease of Eucalyptus in many tropical areas of the world.
Abstract: Cryphonectria cubensis causes a serious canker disease of Eucalyptus in many tropical areas of the world. The aim of this study was to determine the phylogenetic relationships among strains of C. c...
56 citations
References
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TL;DR: It was concluded that the fungus should be transferred to Cryphonectria.
Abstract: SUMMARY The taxonomy of Diaporthe cubensis, causal agent of a canker disease of Eucalyptus spp., is discussed in relation to its conspecificity with Endothia havanensis and correct generic affinity. It was concluded that the fungus should be transferred to Cryphonectria.
70 citations
Journal Article•
66 citations
01 Jan 1970
TL;DR: Fue detectada en Surinam una seria enfermedad fungosa que causa chancTOs en el tronc o y the muette en ârboles de Eucalyptus grandis y E. havanensis, y el aislamiento, inoculation e identification probe que el agente causal tli la enferme es tl bongo Endothia havanense.
Abstract: Eu 19(>">. fue detectada en Surinam una seria enfermedad fungosa que causa chancTOs en el tronc o y la muette en ârboles de Eucalyptus grandis y E. saligna plantados en 19(>2. En /967, despuéi di un reconocimiento en las plantaciones establecidas it t ttas especit r, r< pudo déterminât qui la enfermedad se ptesentaba en todos las localidades en las cuales ban ùdo introducidas. El aislamiento, inoculation e identification probe que el agente causal tli la enfermedad es tl bongo Endothia havanensis.
56 citations
TL;DR: Large scale mortality of Encalyptus tereticornis and E. grandis caused by Corticium salmonicolor in high rainfall locations in India is reported and possible fungicidal control of the disease is explored.
Abstract: Large scale mortality of Encalyptus tereticornis and E. grandis caused by Corticium salmonicolor in high rainfall locations in India is reported. Symptoms, incidence and epidemiology of the disease and pathogenicity of the fungus are worked out. Suitable alternative species based on performance and field resistance to the discase have been selected. Possibilities of fungicidal control of the disease are explored.
26 citations