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Journal articles on the topic 'Dieback'
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1
Gonthier, Paolo, Luana Giordano, and Giovanni Nicolotti. "Further observations on sudden diebacks of Scots pine in the European Alps." Forestry Chronicle 86, no. 1 (February 1, 2010): 110–17. http://dx.doi.org/10.5558/tfc86110-1.
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Since the beginning of the 1990s, significant mortality of Scots pine trees has been observed in inner valleys of the Alps. The objectives of this work were to investigate and describe the aetiology of a Scots pine dieback in the Aosta Valley (western Italian Alps) in 2005. Surveys were conducted in three forest stands. Crown transparency was assessed to evaluate the incidence and severity of dieback symptoms. Phytosanitary surveys were also performed. The time series of the major climatic parameters was analyzed in order to identify common climatic anomalies between the dieback of 2005 and similar dieback episodes in other periods and in other areas of the western Alps. Dendrochronological analyses were performed to assess the relationship between tree-ring widths and climatic parameters. The lack of primary biotic agents and the low frequency of secondary pathogens suggest an abiotic origin of diebacks. The time series analysis shows that two consecutive years with a value of summer dryness index below 1.5 preceded the diebacks. Tree-ring width and summer dryness index were strongly and significantly associated. Key words: climate change, forest dieback, Scots pine, crown transparency, ecophysiology, tree-ring width
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Hood, Ian. "Kauri dieback." Plant Pathology 70, no. 4 (April 4, 2021): 764–66. http://dx.doi.org/10.1111/ppa.13356.
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Frey, Brent R., Victor J. Lieffers, EH (Ted) Hogg, and Simon M. Landhäusser. "Predicting landscape patterns of aspen dieback: mechanisms and knowledge gaps." Canadian Journal of Forest Research 34, no. 7 (July 1, 2004): 1379–90. http://dx.doi.org/10.1139/x04-062.
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Sudden dieback and deterioration of mature aspen stands is commonly observed throughout North America. This dieback process has tremendous ecological and economic importance, yet remains poorly understood. This paper summarizes our understanding of aspen dieback in North America, identifies potential processes that contribute to reduced vigour and dieback of aspen stands, and examines the scales (stand, ecosite, regional) at which these processes operate. Many factors including pathogens, nutrition, or successional changes may be involved in the decline of aspen vigour and thereby contribute to the dieback process. However, insect defoliation, drought, and thawfreeze events appear to be the most likely factors initiating dieback in mature aspen stands. Further study is clearly needed to elucidate the mechanisms and landscape patterns of dieback. Information needs related to identifying processes and modeling landscape patterns of dieback are indicated.
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Loehle, Craig. "Forest ecotone response to climate change: sensitivity to temperature response functional forms." Canadian Journal of Forest Research 30, no. 10 (October 1, 2000): 1632–45. http://dx.doi.org/10.1139/x00-088.
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Past simulation studies using a variety of models have generally agreed that climatic warming could have adverse effects on forests, including large-scale diebacks in some regions and drastic range shrinkages of many species. These effects should be most evident at biome transition zones. Other studies have pointed out, however, that past models have used a parabolic temperature response function that is based on geographic range limits rather than functional responses or data and that this parabolic model could exaggerate dieback effects. A new model is proposed for growing degree-days temperature response, which is asymptotic rather than parabolic. In this new model, tree height growth rate increases and then levels off with increasing growing degree-days. Species from more southern regions have a higher asymptote. It is shown that this model can be derived from the integration of a parabolic growth response to temperature over a year-long sinusoidal temperature regime. The SORTIE forest simulation model was modified to incorporate this response function. An ecotonal region was simulated under a warming scenario. The traditional parabolic temperature response model produced a wide zone of dieback following warming. In contrast, the new asymptotic response function produced no dieback and a stable ecotone that migrated north at <100 m/100 years.
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Hassanpour, Noorallah, and Mehdi Arzanlou. "Ash Dieback Disease." Plant Pathology Science 8, no. 2 (September 1, 2019): 70–76. http://dx.doi.org/10.29252/pps.8.2.70.
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Crombie, D. Stuart, and J. T. Tippett. "A comparison of water relations, visual symptoms, and changes in stem girth for evaluating impact of Phytophthoracinnamomi dieback on Eucalyptusmarginata." Canadian Journal of Forest Research 20, no. 2 (February 1, 1990): 233–40. http://dx.doi.org/10.1139/x90-032.
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Water relations, stem girth, and crown vigour were measured in jarrah (Eucalyptusmarginata Donn ex Sm.) trees in adjoining areas of healthy and dieback-affected forest. The soil-borne fungus Phytophthoracinnamomi Rands was recovered from soils in the dieback areas, but not from neighbouring healthy forest. Trees on dieback sites were found to be more water stressed (with lower dawn water potentials and daytime stomatal conductances) than healthy trees on nearby areas free of P. cinnamomi. Severe water stress usually preceded crown deaths by several weeks to months. Dawn water potential and midday stomatal conductance were the most useful nondestructive indicators of dieback severity in declining trees. Subjective assessment of crown form was slightly less reliable than water relations as a separator of dieback and healthy trees. Changes in trunk girth were the least sensitive indicators of dieback severity. Midday stomatal conductance is recommended as a useful tool for monitoring short-term changes in vigour of dieback-affected trees.
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Sun, Shoujia, Lanfen Qiu, Chunxia He, Chunyou Li, Jinsong Zhang, and Ping Meng. "Drought-Affected Populus simonii Carr. Show Lower Growth and Long-Term Increases in Intrinsic Water-Use Efficiency Prior to Tree Mortality." Forests 9, no. 9 (September 13, 2018): 564. http://dx.doi.org/10.3390/f9090564.
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The Three-North Shelter Forest (TNSF) is a critical ecological barrier against sandstorms in northern China, but has shown extensive decline and death in Populus simonii Carr. in the last decade. We investigated the characteristics—tree-ring width, basal area increment (BAI), carbon isotope signature (13Ccor), and intrinsic water-use efficiency (iWUE)—of now-dead, dieback, and non-dieback trees in TNSF shelterbelts of Zhangbei County. Results from the three groups were compared to understand the long-term process of preceding drought-induced death and to identify potential early-warning proxies of drought-triggered damage. The diameter at breast height (DBH) was found to decrease with the severity of dieback, showing an inverse relationship. In all three groups, both tree-ring width and BAI showed quadratic relationships with age, and peaks earlier in the now-dead and dieback groups than in the non-dieback group. The tree-ring width and BAI became significantly lower in the now-dead and dieback groups than in the non-dieback group from 17 to 26 years before death, thus, these parameters can serve as early-warning signals for future drought-induced death. The now-dead and dieback groups had significantly higher δ13Ccor and iWUEs than the non-dieback group at 7–16 years prior to the mortality, indicating a more conservative water-use strategy under drought stress compared with non-dieback trees, possibly at the cost of canopy defoliation and long-term shoot dieback. The iWUE became significantly higher in the now-dead group than in the dieback group at 0–7 years before death, about 10 years later than the divergence of BAI. After the iWUE became significantly different among the groups, the now-dead trees showed lower growth and died over the next few years. This indicates that, for the TNSF shelterbelts studied, an abrupt iWUE increase can be used as a warning signal for acceleration of impending drought-induced tree death. In general, we found that long-term drought decreased growth and increased iWUE of poplar tree. Successive droughts could drive dieback and now-dead trees to their physiological limits of drought tolerance, potentially leading to decline and mortality episodes.
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Nurafida, Desi, Achmad ., and Syamsul Falah. "KEEFEKTIFAN KITOSAN DALAM MENGENDALIKAN Botryodiplodia theobromae Pat. PENYEBAB MATI PUCUK PADA BIBIT JABON (Anthocephalus cadamba (Roxb.) Miq) Chitosan’s Effectiveness in Controlling Dieback by Botryodiplodia theobromae Pat on Jabon Seeding." Journal of Tropical Silviculture 8, no. 3 (March 19, 2018): 170–76. http://dx.doi.org/10.29244/j-siltrop.8.3.170-176.
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Dieback disease by the fungus Botryodiplodia theobromae in Jabon seedlings (Anthocephalus cadamba) inhibits the regeneration of Jabon plant. Synthetic fungicides utilization to several problems such as residue on the environment and pathogen resistance. Chitosan is a potential natural compound used as an alternative to control plant disease.This research aims to examine the effectiveness of chitosan to control B. theobromae as causal agent of dieback on Jabon seedlings and to examine the effect of chitosan to control the viscosity of dieback disease on Jabon seedlings. The results showed that the chitosan solution can decrease the severity of disease in Jabon seedlings. However, it was different with the disease incidence rate parameter. Chitosan solution was not significantly affecting the disease because B. theobromae caused dieback symptoms on Jabon seedlings. The most effective treatment was chitosan solution with a concentration of 0.1% before inoculation with the severity of the disease by 25%. Chitosan solution viscosity was responsible in affecting the percentage of dieback disease in Jabon seeds. The higher the viscosity of chitosan, the higher the percentage of dieback disease attacks. The best viscosity to suppress the development of dieback disease on Jabon seedlings was 8.80 with 7.90% attack.Key words: Anthocephalus cadamba , Botryodiplodia theobromae, chitosan, dieback.
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Roy, Gabriel, Guy R. Larocque, and Colette Ansseau. "Retrospective evaluation of the onset period of the visual symptoms of dieback in five Appalachian sugar maple stand types." Forestry Chronicle 80, no. 3 (June 1, 2004): 375–83. http://dx.doi.org/10.5558/tfc80375-3.
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In the early 1980s, a sharp increase in dieback of sugar maple (Acer saccharum Marsh.) was reported across large areas of the north-eastern American continent. Despite numerous studies, there are conflicting interpretations as to the causes of dieback that can be linked to uncertainties as to when the occurrence of the visual symptoms appeared. Three different approaches were used to determine the onset period of the visual symptoms of dieback in Appalachian sugar maple stands: (1) dendrochronological analysis; (2) retrieval of information in official documents that reported dieback symptoms; and (3) development of a questionnaire sent to private forest land owners. Dieback severity was evaluated annually in 104 Appalachian sugar maple stands in southwestern Quebec. Results indicated that the pattern of dieback progression did not vary significantly among the five different types of sugar maple stand that were examined. The three investigative approaches led to the conclusion that the onset of the visual symptoms occurred between 1974 and 1978. Key words: Acer saccharum Marsh., dieback, sugar maple, symptoms, progression
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Clift, DK, WS Semple, and JC Prior. "A survey of Bladder Saltbush (Atriplex vesicaria Heward ex Benth) dieback on the Riverine Plain of south-eastern Australia from the late 1970s to 1983." Rangeland Journal 9, no. 1 (1987): 39. http://dx.doi.org/10.1071/rj9870039.
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Bladder saltbush (Ahiplex vesicaria Heward ex Benth) is a valuable perennial chenopod shrub of the northem Riverine Plain of south-eastem Australia. From 1977 to 1983, dieback affected stands of this shrub over a wide area, reducing the drought reserves on many pastoral holdings. By early 1983 reports of new outbreaks of dieback had ceased, and by late 1983 regeneration, both vegetatively and from seedlings, was evident in most areas. This study reviews what is known of this dieback event. The extent of healthy bladder saltbush stands, pre-dieback and towards the end of the dieback period was mapped. It was found that the area of leafy bush had declined by 53 per cent, from 1.1 to 0.5 million hectares, by the end of 1983. There was considerable variation in timing, pattern and progress of dieback. The cause was not established.
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Tougiani, Abasse, Moussa Massaoudou, Adamou Haougui, Amadou Laouali, and John C. Weber. "Faidherbia albida (Delile) Tree Dieback Effects on Crop Production in the Parkland Agroforests of Southwestern Niger." International Journal of Forestry Research 2021 (February 10, 2021): 1–6. http://dx.doi.org/10.1155/2021/8895829.
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Faidherbiaalbida is an agroforestry tree species playing important agroecological and socioeconomic roles in arid and semiarid zones in Africa. For many years, anthropogenic and abiotic stresses were considered as the main threats for the species in West African parkland agroforests. Considerable dieback has recently occurred in F. albida trees of parkland agroforests in central southwestern Niger, and the causes are unknown. The objectives of this study are to (i) investigate the magnitude of dieback of F. albida trees and (ii) assess local community perceptions of the effects of F. albida dieback on crop production. The health status and phenology of 213 F. albida trees were observed in the area where the dieback is occurring. Similarly, a sample of 144 people, 86% of which were farmers, was surveyed. Dieback incidence of F. albida trees was 19%, with mortality of 6%. Large-diameter trees had greater dieback than small-diameter trees. The most affected parts of the tree were the branches at 54% and the trunks at 39%. The populations noted a 33–55% reduction in the yields of major crops. This dieback of F. albida trees poses a serious threat to the survival of rural communities. Further studies can be conducted to identify the cause or cause of the dieback to guide the suitable agroforestry parkland management strategies.
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Gunadasa, H. K. S. G., and P. I. Yapa. "Soil Chemical Quality and Forest Dieback." International Journal of Environmental Science and Development 6, no. 1 (2015): 1–8. http://dx.doi.org/10.7763/ijesd.2015.v6.551.
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Auclair, Allan ND. "Patterns and general characteristics of severe forest dieback from 1950 to 1995 in the northeastern United States." Canadian Journal of Forest Research 35, no. 6 (June 1, 2005): 1342–55. http://dx.doi.org/10.1139/x05-066.
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US national and state forest insect and disease surveys provide plentiful information on forest dieback. These data, however, have not been quantified and analyzed systematically to address outstanding questions on the etiology of dieback. This study quantified long-term (19501995) trends in the severity of dieback on Acer saccharum Marsh., Fraxinus spp., Betula spp., and Picea rubens Sarg. in US northern hardwoods. A numeric index (010 scale) of the severity and extent of dieback was applied using key words frequently found in the surveys. The 18 episodes identified showed considerable variability among species at the local scale, yet systematic, repetitive patterns of dieback at the scale of the region and multidecadal time frame. Six dieback characteristics were evident: episodes showed abrupt onset and subsidence, endured 13.6 years on average, were cyclical, with a frequency of 22.3 years between recurrence, and averaged about two-thirds of maximum possible severity. In contrast to the perception that dieback is happenstance and chaotic, this study supports the hypothesis that, by addressing issues of spatial scale and long-term population dynamics, coherent, generic patterns emerge that are cyclic and predictable. Limitations and advantages of the approaches were discussed in terms of meeting needs of the US Forest Health Monitoring Program for innovative approaches to the analysis of the voluminous field data being assembled nationwide. By developing a quantitative database, environmental correlation and modeling of dieback now become possible.
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Campbell, D. J. "Salt-wind induced wave regeneration in coastal pine forests in New Zealand." Canadian Journal of Forest Research 28, no. 7 (July 1, 1998): 953–60. http://dx.doi.org/10.1139/x98-073.
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Strong onshore winds and airborne sea salt can gradually defoliate trees at the exposed margin of temperate pine stands in New Zealand and induce a slowly moving front of dieback and regeneration. Overcrowded mature stands are vulnerable to crown abrasion: abrasion affects trees 20 m ahead of the dieback front; suppressed trees 12 m ahead die before the front reaches them. At the stand margin, trees die from abrasion and salt wind induced dieback. The dieback zone lets sunlight enter the stand; light-demanding pine seedlings establish, but a gradient of increasing litter depth from the dieback front and summer dryness restrict successful seedling establishment to a narrow zone that moves parallel with the dieback front and 11-13 m ahead of it. Further seedlings establish for 4-10 years before the juveniles form a closed canopy; competing vegetation is partly suppressed by infrequent cattle browsing. Regenerating juvenile maritime pine (Pinus pinaster Ait.), show a strict age-related gradation from the dieback front and indicate that wind and salt deposition have been constant for 30 years. Stands further from the sea, with lower stocking rates and other pine species, did not have a clear-cut regeneration zone, because there were no strong gradients of litter depth and light intensity.
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Sloane, Daniel R., Emilie Ens, Jimmy Wunungmurra, Andrew Falk, Gurrundul Marika, Mungurrapin Maymuru, Gillian Towler, Dave Preece, and the Yirralka Rangers. "Western and Indigenous knowledge converge to explain Melaleuca forest dieback on Aboriginal land in northern Australia." Marine and Freshwater Research 70, no. 1 (2019): 125. http://dx.doi.org/10.1071/mf18009.
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Involvement of Indigenous people and knowledge in conservation science has become a clear directive in international covenants. Currently, approximately one-third of Australia is owned and managed by Indigenous people, including 84% of the Northern Territory coastline, making Indigenous-led and cross-cultural research highly relevant. Recently, the Yolŋu Senior Knowledge Custodians of the Laynhapuy Indigenous Protected Area in northern Australia expressed concern about the dieback of culturally significant coastal Melaleuca (paperbark) stands. A partnership between Senior Knowledge Custodians and Western scientists was used to develop an ecocultural research framework to investigate the dieback. Semistructured interviews about the likely causes were conducted with Senior Knowledge Custodians of five coastal flood plain sites where dieback occurred. At these sites, comparative ecological assessments of paired dieback and healthy Melaleuca stands were conducted to explore relationships between Melaleuca stand health, salt water intrusion, acid sulfate soils and feral ungulate damage. Melaleuca dieback was observed in three species: nämbarra (M. viridiflora), raŋan (M. cajuputi) and gulun’kulun (M. acacioides). The sociocultural and ecological research approaches similarly suggested that ~70% of Melaleuca spp. dieback was attributed to combinations of salinity and feral ungulate damage. An ecocultural approach heightened understanding of Melaleuca dieback because we detected similarities and differences in likely causal factors.
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Zare, Parvin, and Habiballah Hamze Zarghani. "10. Rose Dieback Disease." Plant Pathology Science 10, no. 2 (September 1, 2021): 105–15. http://dx.doi.org/10.52547/pps.10.2.105.
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Carter, M. V. "EUTYPA DIEBACK OF APRICOT." Acta Horticulturae, no. 192 (November 1986): 213–16. http://dx.doi.org/10.17660/actahortic.1986.192.33.
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Rubina, E. V., T. F. Bivol, T. D. Verderevskaja, and E. A. Kukuruzak. "PLUM DIEBACK IN MOLDAVIA." Acta Horticulturae, no. 193 (November 1986): 107–12. http://dx.doi.org/10.17660/actahortic.1986.193.17.
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Mueller-Dombois, Dieter. "Natural Dieback in Forests." BioScience 37, no. 8 (September 1987): 575–83. http://dx.doi.org/10.2307/1310668.
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Waipara, N. W., J. Craw, A. Davis, J. Meys, B. Sheeran, A. Peart, S. Hill, et al. "Management of kauri dieback." New Zealand Plant Protection 62 (August 1, 2009): 407. http://dx.doi.org/10.30843/nzpp.2009.62.4854.
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Kauri illthrift commonly known as Kauri dieback has been identified as an increasing problem affecting kauri (Agathis australis) across the Auckland region A water and soilborne pathogen Phytophthora taxon Agathis (PTA) has been identified as a causal agent of Kauri dieback at some locations particularly within the Waitakeres Ranges Regional Park and Great Barrier Island PTA is associated with a collar rot causing large bleeding basal lesions yellowing foliage and tree death A range of other causal agents including Phytophthora cinnamomi and environmental stress factors were also associated with symptoms at many sites In 2008 Auckland Regional Council implemented a range of standard operational procedures to manage the disease across the region Surveillance surveys are underway to assess overall tree health as well as the potential distribution of PTA in Aucklands kauri forests Survey sites were prioritised in areas with high conservation value iconic trees or high levels of soil disturbance such as tracks intersecting kauri root zones Risk management of the suspected primary vectors of the PTA including people and feral pigs is underway
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Scarrow, Ryan. "Dieback vivifies GM support." Nature Plants 3, no. 9 (August 21, 2017): 682. http://dx.doi.org/10.1038/s41477-017-0009-5.
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IKAGAWA, TOSHIHIKO. "DIEBACK OFLEUCAENA LEUCOCEPHALAIN HAWAII." International Tree Crops Journal 7, no. 4 (January 1993): 223–39. http://dx.doi.org/10.1080/01435698.1993.9752921.
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Kub�kov�, J. "Forest dieback in Czechoslovakia." Vegetatio 93, no. 2 (May 1991): 101–8. http://dx.doi.org/10.1007/bf00033204.
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Martel, J., Y. Mauffette, and S. Tousignant. "SECONDARY EFFECTS OF CANOPY DIEBACK: THE EPIGEAL CARABID FAUNA IN QUÉBEC APPALACHIAN MAPLE FORESTS." Canadian Entomologist 123, no. 4 (August 1991): 851–59. http://dx.doi.org/10.4039/ent123851-4.
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AbstractThe impact of canopy dieback on the activity and diversity of epigeal Carabidae was studied during the summers of 1987 and 1988 in 18 maple stands in southeastern Québec, using pitfall traps. A canopy thinning index (CTI) based on severity and incidence of dieback, and on tree basal area was calculated for each of the 72 stations sampled. An analysis of variance shows that canopy dieback had a significant effect on carabid beetle activity in 1988. The CTI was negatively correlated with the carabid species richness and diversity in 1988. The number of individuals caught per station was negatively correlated with the CTI for all species combined, except for the dominant Pterostichus coracinus Newm. in 1988. These results indicate a negative response of carabid beetles to canopy dieback in 1988; the climate may have tempered the effects of dieback in 1987.
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Crombie, DS, and JA Milburn. "Water Relations of Rural Eucalypt Dieback." Australian Journal of Botany 36, no. 2 (1988): 233. http://dx.doi.org/10.1071/bt9880233.
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The water relations of healthy and dieback-affected individuals of three Eucalyptus species typical of the northern tablelands of New South Wales were compared. Dawn water potentials of healthy and dieback-affected trees were all very similar. Midday water potentials of trees with the most severe dieback symptoms were often lower than those of nearby healthy trees by up to 0.6 MPa. Leaf con- ductances of the most severely dieback-affected trees were usually greater than those of healthy trees. Differences decreased with time and when more trees with less severe symptoms were measured late in the study no significant differences in water relations were found. It seems therefore that the effects of dieback on the water relations of trees are too small for measurements of leaf water potentials or leaf conductances to be useful indicators of disease severity in individual trees.
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Auclair, Allan N. D., Warren E. Heilman, and Blondel Brinkman. "Predicting forest dieback in Maine, USA: a simple model based on soil frost and drought." Canadian Journal of Forest Research 40, no. 4 (April 2010): 687–702. http://dx.doi.org/10.1139/x10-023.
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Tree roots of northern hardwoods are shallow rooted, winter active, and minimally frost hardened; dieback is a winter freezing injury to roots incited by frost penetration in the absence of adequate snow cover and exacerbated by drought in summer. High soil water content greatly increases conductivity of frost. We develop a model based on the sum of z-scores of soil frost (December–February) and drought in summer (May–September) that accurately predicts timing and severity of dieback on sugar maple ( Acer saccharum Marsh.), Betula spp., Fraxinus spp., and red spruce ( Picea rubens Sarg.) in Maine, USA, during 1920–1995. Discrepancies between predicted and actual dieback relate largely to tree population dynamics. Extraordinary levels of dieback on Betula during 1935–1950 occurred under low stress but in mature populations; under high climate stress during 1951–1975, younger surviving Betula proved resistant and showed little dieback. Severe dieback in Acer stands during 1975–1995 may relate to extensive partial cutting, leaving stands open to frost and high water tables. Widespread use of forwarder feller/buncher and wheeled skidders after 1960 commonly left hummocky, irregular surfaces subject to pooling and accelerated frost penetration. Silvicultural applications include modifying harvesting practices to minimize frost complications and use of the model to track and map climatic risk to avoid conditions and locales subject to dieback.
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Nur'aini, Febrilia. "Control of Vascular Streak Dieback Disease of Cocoa with Flutriafol Fungicides." Pelita Perkebunan (a Coffee and Cocoa Research Journal) 30, no. 3 (December 30, 2014): 229–39. http://dx.doi.org/10.22302/iccri.jur.pelitaperkebunan.v30i3.43.
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Vascular streak dieback caused by the fungus Oncobasidium theobromae is one of the important diseases in cocoa crop in Indonesia. One approach to control the disease is by using fungicides. The aim of this research was to determine the effect of class triazole fungicides to the intensity of the vascular streak dieback disease on cocoa seedling phase, immature and mature cocoa. Experiments were conducted in Kotta Blater, PTPN XII and Kaliwining, Indonesian Coffee and Cocoa Research Institute. Flutriafol 250 g/l with a concentration 0,05%, 0,1% and 0,15% foliar sprayed on cocoa seedlings, immature and mature cocoa. Active compound combination of Azoxystrobin and Difenoconazole with 0,1% concentration used as a comparation fungicides. The result showed that Flutriafol with 0,05%, 0,1% and 0,15% concentration and Azoxystrobin & Difenoconazol with 0,1% concentration could suppress the vascular streak dieback disease on seedlings. On immature plants, the application of Flutriafol was not effectively suppress the vascular streak dieback disease whereas the fungicide comparison could suppress with the efficacy level of 46.22%. On mature plants,both of fungicides could not suppress the vascular streak dieback disease. Key words: Fungicide, cocoa, vascular streak dieback, triazole, flutriafol, azoxystrobin+difenoconazol
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Díaz, Gonzalo A., Adrían Valdez, Francois Halleen, Enrique Ferrada, Mauricio Lolas, and Bernardo A. Latorre. "Characterization and Pathogenicity of Diplodia, Lasiodiplodia, and Neofusicoccum Species Causing Botryosphaeria Canker and Dieback of Apple Trees in Central Chile." Plant Disease 106, no. 3 (March 1, 2022): 925–37. http://dx.doi.org/10.1094/pdis-06-21-1291-re.
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In recent years, the number of apple trees affected by Botryosphaeria cankers and dieback has considerably increased in central Chile. This study aimed to identify the species of Botryosphaeriaceae associated with canker and dieback symptoms, estimate disease incidence and distributions, and study their pathogenicity and virulence on apple and other fruit crops. A field survey of 34 commercial orchards of apple (7 to 30 years old) was conducted in 16 localities, obtaining 270 symptomatic branch and trunk samples in 2017 and 2018 growing seasons. The incidence of Botryosphaeria canker and dieback ranged between 5 and 40%, and a total of 255 isolates of Botryosphaeriaceae spp. were obtained from 238 cankers. Morphological identification along with phylogenetic studies of the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2) of the rDNA, part of the translation elongation factor 1-α (tef1-α), and part of the β-tubulin (tub2) genes allowed us to identify Diplodia mutila (n = 49 isolates), D. seriata (n = 136 isolates), Lasiodiplodia theobromae (n = 16 isolates), and Neofusicoccum arbuti (n = 54 isolates). L. theobromae was isolated mainly from apple dieback from northern localities. All pathogens tested were pathogenic, causing canker and dieback symptoms on lignified twigs of apple, pear, walnut, and green grapevine shoots in the field. Isolates of N. arbuti were the most virulent, reproducing more severe cankers on the lignified tissues inoculated. This study reports, for the first time, D. mutila and L. theobromae associated with Botryosphaeria canker and dieback in Chile, and it is the first description of N. arbuti causing apple dieback worldwide.
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Clift, DK, KL Dalton, and JC Prior. "Bladder Saltbush (Atriplex vesicaria Heward Ex Benth) Regeneration on the Riverine Plain of South-Eastern Australia since 1983." Rangeland Journal 11, no. 1 (1989): 31. http://dx.doi.org/10.1071/rj9890031.
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This study reviews the distribution of healthy bladder saltbush on the Riverine Plain of south-eastern Australia towards the end of 1986, as well as the characteristics of regeneration following the saltbush dieback of 1977-83. The area of bladder saltbush increased by 53 per cent, from 0.53 to 0.81 million ha, in the period 1983-86. A further 0.32 million ha, which previously supported saltbush, failed to regenerate. Variations in the pattern and progress of regeneration were closely related to variations in soil type and the effects of pre- and post-dieback grazing. Although the cause of dieback remains unknown, it would appear that much of the decline in the distribution of bladder saltbush could be attributed to post-dieback mismanagement of affected stands.
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Messenger, A. S., and B. A. Hruby. "Excess Calcium and Magnesium Associated with Lower Crown Mortality of Pin Oak." Arboriculture & Urban Forestry 18, no. 5 (September 1, 1992): 241–48. http://dx.doi.org/10.48044/jauf.1992.047.
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The ornamental value of pin oak trees is reduced when their descending lower branches die. In the upper Midwest, USA, premature dieback of lower branches is common among pin oak trees planted in soils that are calcareous within 1.5 m of the surface. Of 11 mineral nutrients, only Ca and Mg were more concentrated in the leaves of lower branches than in those found higher in the crown. The Ca concentrations of leaves of lower branches of trees showing dieback were much higher than those from trees without dieback. Small necrotic spots of apparently abiotic origin developed in early summer on either green or chlorotic leaves of lower branches and consistently formed before dieback occurred in the subsequent year. Excessive Mg was closely associated with this condition. Green pin oaks at dieback sites had actively absorbing roots within calcareous C horizons of otherwise acidic soils suggesting a source for absorption of the high concentrations of both Ca and Mg in the leaves. Methods of reducing Ca and Mg uptake are discussed.
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Hopkin, Anthony A., and Gordon M. Howse. "A Survey to Evaluate Crown Condition of Forest, Roadside, and Urban Maple Trees in Ontario, 1987-1995." Northern Journal of Applied Forestry 15, no. 3 (September 1, 1998): 141–45. http://dx.doi.org/10.1093/njaf/15.3.141.
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Abstract Surveys of sugar maple trees, conducted in Ontario between 1987 and 1995, showed a general improvement in crown condition after 1990. Plots on the shallow soils of the Precambrian shield in central Ontario showed the highest levels of crown dieback in all years. This area was also defoliated at moderate-to-severe levels in 1988. Dieback levels on undefoliated plots were high in 1987-1988, but plots improved after 1988. Defoliated plots showed no improvement, and dieback remained high through 1995. Crown dieback was lower in forest and urban situations than at roadside plots. Roadside plots showed high levels of dieback and should be considered poor indicators of forest condition. Pest damage was recorded on all plot types. Sugar maple in both urban and roadside locations had a higher incidence of stem defects, stem canker, and stem insect damage than trees in forest plots. Root rots were most prevalent at roadside locations. Stem cankers, stem defects, and root rot were most common in the northern forest plots. North. J. Appl. For. 15(3): 141-145.
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SUSANNA, Susanna, Meity Suradji SINAGA, Suryo WIYONO, and Hermanu TRIWIDODO. "Diagnosis of Dieback Disease of the Nutmeg Tree in Aceh Selatan, Indonesia." Walailak Journal of Science and Technology (WJST) 17, no. 8 (August 1, 2020): 801–10. http://dx.doi.org/10.48048/wjst.2020.4379.
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Effective control disease measures require a great deal of knowledge about the pathogen, which is also applied to dieback disease of the nutmeg tree in Aceh Selatan District, Province of Aceh, Indonesia. The objectives of this study were to identify the causal agent of dieback disease on a nutmeg plantation and to assess the effect of drought stress on the development of dieback disease. Pathogen identification was carried out by observing the symptoms of infected plants, morphological characters of the isolated pathogens, Koch’s postulates, and molecular analysis and pure pathogen cultures. The samples were taken from an infected part of the nutmeg plant (twigs, stems, and roots) in 6 subdistricts at the center of the nutmeg plantation in Aceh Selatan. Koch's postulates were performed by using the mycelia of pathogens on 1-year-old nutmeg seedlings. Drought stress was simulated everyday, and then once every 2 weeks, to study the effect of drought stress on dieback. The results showed that there were 4 genera of fungal pathogens (Botryodiplodia theobromae, Fusarium solani, Graphium euwallaceae, and Rigidoporus microporus) out of 6 fungi associated with dieback disease. However, B. theobromae Pat. turned out to be the dominant fungi associated with dieback on the nutmeg tree in Aceh Selatan. Drought stress was proven to be a predisposing factor for explaining this problem epidemic in Aceh Selatan.
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Reich, Richard W., and Bart J. van der Kamp. "Frost, canker, and dieback of Douglas-fir in the central interior of British Columbia." Canadian Journal of Forest Research 23, no. 3 (March 1, 1993): 373–79. http://dx.doi.org/10.1139/x93-054.
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The relationships between dieback severity of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), growing-season frosts, and invasion by canker pathogens in plantations >10 years old in central British Columbia are described. The coincidence of frosts and dieback events was determined by dissection and by mapping dieback damage in arid around frost pockets. Putative canker pathogens were isolated from bark and fruiting bodies. The timing of significant dieback events coincided with major growing-season frosts, as determined by the formation of frost rings. Damage was most severe in shallow depressions and valley bottoms. Early flushing trees were more severely affected than late flushing trees in two of three plantations. Seven weak canker parasites were isolated from dead Douglas-fir bark. Among these, Sclerophomasemenospora Funk was restricted to tissues killed by frost or other factors, while Leucocytosporakunzei (Fr.:Fr.) Munk and a Sirodothis sp. accounted for about 65% of isolates from recently killed bark. Outside frost prone areas, these fungi were common as small latent branch cankers, but caused no further discernable damage. Areas of high dieback hazard could be identified from topographic features seen on aerial photographs. Of the area of Douglas-fir plantations >10 years old, 4.7% was severely damaged by dieback. It is recommended that lodgepole pine (Pinusconforta Dougl.) be planted in frost-prone areas.
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Guthrie, J. N., D. T. White, K. B. Walsh, and P. T. Scott. "Epidemiology of Phytoplasma-Associated Papaya Diseases in Queensland, Australia." Plant Disease 82, no. 10 (October 1998): 1107–11. http://dx.doi.org/10.1094/pdis.1998.82.10.1107.
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Three phytoplasma-related diseases of papaya (Carica papaya), dieback, yellow crinkle, and mosaic, are recognized within Australia. Immature leaf material was sampled every week for 8 months from a cohort of 60 female plants, located within a commercial papaya plantation, to determine the minimum time between infection and symptom expression. Phytoplasma DNA was detected using the polymerase chain reaction (PCR) with primers specific for phytoplasmas in general, and for the stolbur group of phytoplasmas. The dieback-associated phytoplasma was detected 1 week prior to (four cases) or the same week (nine cases) as symptom expression, while phytoplasma DNA was detected between 3 and 11 weeks prior to expression of mosaic symptom (six cases). Lateral shoot regrowth on the lower stem of plants which had suffered dieback disease failed to generate stolbur-specific PCR products in 15 cases. A dual infection with dieback and yellow crinkle or mosaic was diagnosed in a further two cases, using restriction fragment length polymorphism digests, and both cases were interpreted as secondary infections by the dieback-associated phytoplasma. Regrowth in three of seven cases of yellow crinkle- and three of nine cases of mosaic-affected plants tested positive for phytoplasma-specific DNA. Ratooning of dieback-affected plants and removal of yellow crinkle- or mosaic-affected plants is suggested for the management of these diseases.
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Defitri, Yuza. "PENYAKIT Vascular Streak Dieback (VSD ) PADA TANAMAN KAKAO (Theobroma cacao, L. ) SERTA PERSENTASE SERANGANNYA." Jurnal Media Pertanian 3, no. 2 (October 22, 2018): 99. http://dx.doi.org/10.33087/jagro.v3i2.70.
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Kakao merupakan salah satu hasil komoditi perkebunan yang memiliki nilai ekonomis yang cukup tinggi diantara tanaman perkebunan yang lainnya dan berperan penting sebagai sumber devisa Negara melalui ekspor dan mendorong ekonomi daerah terutama di pedesaan.Untuk peningkatan produksi tanaman kakao di Desa Betung Kecamatan Kumpeh Ilir, perlu diketahui keadaan tanaman kakao yang terserang penyakit dan berapa persentase serangan penyakit tersebut. Hal ini berguna untuk melakukan teknik pengendalian penyakit pada tanaman kakao.Penelitian ini bertujuan untuk mengetahui tentang Penyakit Vascular Streak Dieback(VSD ) serta berapa persentase serangan Penyakit Vascular Streak Dieback (VSD ) tersebut.Penelitian dilakukan dengan metode Simple Random Sampling. Pengambilan sampel tanaman dilakukan secara acak di perkebunan kakao rakyat. Lalu kumpulkan data dengan menghitung seluruh tanaman baik yang sehat maupun yang sakit sehingga didapat persentase tanaman terserang penyakit. Sampel bagian tanaman kakao yang terserang penyakit Vascular Streak Dieback(VSD) di identifikasi di Laboratorium Dasar Unbari.Hasil penelitian menunjukkan bahwa persentase serangan penyakit Vascular Streak Dieback (VSD)yang disebabkan oleh jamur Oncobasidium theobromae pada lahan yang tidak dirawat adalah 80 % yang berarti serangan penyakit ini termasuk berat karena lebih setengahnya buah kakao terserang penyakit. Sedangkan pada lahan yang dilakukan perawatan intensif serangan penyakit Vascular Streak Dieback (VSD)hanya 30 % ini berarti serangan penyakit ringan.Kata Kunci : Penyakit Streak Dieback(VSD ), Oncobasidium theobromaeABSTRACTCocoa is one of the plantation commodities that have high economic value among other plantation crops and plays an important role as a source of foreign exchange through export and encourages regional economics, especially in rural areas.To increase the production of cocoa crops in Betung Village, Kumpeh Ilir District, it is necessary to know the condition of cocoa plants that have the disease and what percentage of the disease attack. It is useful to perform disease control techniques on cocoa plants.This study aims to find out about Vascular Streak Dieback Disease (VSD) and how many percentages of attacks Vascular Streak Dieback disease (VSD).The research was done by Simple Random Sampling method. Crop sampling was done randomly at smallholder cocoa plantations. Then collect the data by counting all the plants both healthy and sick to get the percentage of plants attacked by using the formula P = n / N x 100%. The sample of the cocoa plant affected by Vascular Streak Dieback disease (VSD) was identified in the Unbari Basic Laboratory.The result showed that there were the attackingof foul fruit disease caused by a Oncobasidium theobromae fungus on passing in land was 80 % which was means it was hard level of disease as more than half cocoafruit were foul. While it showed a light of disease attacking on unpassing in land its only 30 %.Key words : Vascular Streak Dieback(VSD ), Oncobasidium theobromae
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TOMOIAGA, Liliana Lucia, and Veronica Sanda CHEDEA. "Grapevine Trunk Diseases Management in Vineyards from Central Transylvania." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Horticulture 77, no. 1 (June 3, 2020): 117. http://dx.doi.org/10.15835/buasvmcn-hort:2019.0041.
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Grapevine trunk diseases (GTD) are among the most important diseases reported in vineyards in central Transylvania. On average, up to 5% of the vineyards are affected by the GTD although there are also vineyards where the incidence of the attack exceeds 15%. Recent studies show that the importance of pathogens in wood is so great that they are considered limiting factors that affect the stability of the world’s vineyards. The main objective of this study is to develop new sustainable management alternatives for the GTD control. For this purpose, an agroecological variant including prophylactic and cultural measures and two treatments with biofungicides based on: Trichoderma atroviride strain 8, Trichoderma atroviride strain B11 and Trichoderma harzianum, were tested. The frequency of the attack of the main four GTD diseases (Esca complex, Phomopsis dieback, Eutypa dieback and Crown gall) on the SCDVV Blaj homologated grapevine varieties, ‘Astra’, ‘Amurg’, ‘Brumariu’, ‘Blasius’ ‘Radames’, ‘Rubin’ and ‘Selena’, was assessed showing that these had a lower frequency of the symptoms compared with the widely cultivated variety ‘Feteasca regala’. Also the effect of training system (Classical versus semi-high Guyot) on GTD is presented. The classical system had decreased the frequency of crown gall and Phomopsis dieback, and the semi-high Guyot system had decreased Eutypa dieback’s frequency, indicating that the training system is an important tool of the agroecological system in maintaing the health of grapevine. Biofungicides tested help reduce the symptoms of GTD, but not enough to help reduce the premature death of grapevine.
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Singh, Raghuwinder, and Vinson P. Doyle. "Boxwood Dieback Caused By Colletotrichum theobromicola: A Diagnostic Guide." Plant Health Progress 18, no. 3 (January 1, 2017): 174–80. http://dx.doi.org/10.1094/php-04-17-0024-dg.
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Boxwood (Buxus spp.) is a popular perennial landscape shrub in the United States grown for its vibrant green color and evergreen growth. Several important plant diseases are known to occur on boxwood. In 2015, a new disease of boxwood called boxwood dieback was identified in Louisiana and is the first known report in the United States. Boxwood dieback is a stem/shoot disease caused by a fungal pathogen, Colletotrichum theobromicola. This manuscript presents a comprehensive guide to diagnose and identify boxwood dieback caused by C. theobromicola.
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Stagg, Camille LaFosse, Michael J. Osland, Jena A. Moon, Laura C. Feher, Claudia Laurenzano, Tiffany C. Lane, William R. Jones, and Stephen B. Hartley. "Extreme Precipitation and Flooding Contribute to Sudden Vegetation Dieback in a Coastal Salt Marsh." Plants 10, no. 9 (September 5, 2021): 1841. http://dx.doi.org/10.3390/plants10091841.
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Climate extremes are becoming more frequent with global climate change and have the potential to cause major ecological regime shifts. Along the northern Gulf of Mexico, a coastal wetland in Texas suffered sudden vegetation dieback following an extreme precipitation and flooding event associated with Hurricane Harvey in 2017. Historical salt marsh dieback events have been linked to climate extremes, such as extreme drought. However, to our knowledge, this is the first example of extreme precipitation and flooding leading to mass mortality of the salt marsh foundation species, Spartina alterniflora. Here, we investigated the relationships between baseline climate conditions, extreme climate conditions, and large-scale plant mortality to provide an indicator of ecosystem vulnerability to extreme precipitation events. We identified plant zonal boundaries along an elevation gradient with plant species tolerant of hypersaline conditions, including succulents and graminoids, at higher elevations, and flood-tolerant species, including S. alterniflora, at lower elevations. We quantified a flooding threshold for wetland collapse under baseline conditions characterized by incremental increases in flooding (i.e., sea level rise). We proposed that the sudden widespread dieback of S. alterniflora following Hurricane Harvey was the result of extreme precipitation and flooding that exceeded this threshold for S. alterniflora survival. Indeed, S. alterniflora dieback occurred at elevations above the wetland collapse threshold, illustrating a heightened vulnerability to flooding that could not be predicted from baseline climate conditions. Moreover, the spatial pattern of vegetation dieback indicated that underlying stressors may have also increased susceptibility to dieback in some S. alterniflora marshes.Collectively, our results highlight a new mechanism of sudden vegetation dieback in S. alterniflora marshes that is triggered by extreme precipitation and flooding. Furthermore, this work emphasizes the importance of considering interactions between multiple abiotic and biotic stressors that can lead to shifts in tolerance thresholds and incorporating climate extremes into climate vulnerability assessments to accurately characterize future climate threats.
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Sholberg, P. L., and H. A. Quamme. "Dieback of pome fruit rootstocks caused by Pseudomonas syringae." Canadian Journal of Plant Science 79, no. 3 (July 1, 1999): 387–94. http://dx.doi.org/10.4141/p98-067.
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Dieback (bark necrosis) of pome fruit rootstocks occurred in cuttings, potted plants in the greenhouse, and plants in the nursery when the freshly cut stems were inoculated with bacterial isolate ARS4, identified as Pseudomonas syringae pv syringae. Isolate ARS4, originally isolated from a diseased Malling 9 (M.9) rootstock from a commercial nursery, also caused papery bark (bark shredding) on apple and pear rootstocks indicative of severe dieback. Isolate 980 also identified as P. syringae pv. syringae, isolated from a sweet cherry branch canker, was associated with dieback of pome fruit rootstocks in greenhouse trials but was generally less pathogenic than isolate ARS4. Isolate ARS4 labelled with resistance to nalidixic acidic was recovered from lesions on five of nine M.9 rootstocks at the lesion boundary indicating that the isolate was present in diseased rootstock tissue. Of nine apple rootstock cultivars tested for susceptibility to isolate ARS4, M.4 and M.9 were more susceptible than the other five rootstock cultivars. The effect of inoculation during thawing of frozen M.9 rootstocks in pots led to significantly more dieback than if rootstocks were not frozen. Contamination of buds did not lead to dieback but isolate 980 reduced McIntosh bud growth to 1.7% of the total number of buds that were tested. Leaving a stub above the scion bud on M.9 rootstocks to control dieback did not affect bud development or rootstock stem diameter. Key words: Pseudomonas cichorii, Pseudomonas fluorescens, necrosis, papery bark, lesions, blister spot
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González de Andrés, Ester, María Laura Suárez, José Ignacio Querejeta, and J. Julio Camarero. "Chronically Low Nutrient Concentrations in Tree Rings Are Linked to Greater Tree Vulnerability to Drought in Nothofagus dombeyi." Forests 12, no. 9 (August 31, 2021): 1180. http://dx.doi.org/10.3390/f12091180.
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Forest dieback and mortality episodes triggered by droughts are receiving increasing attention due to the projected increases in these extreme climate events. However, the role played by nutrient impairment in dieback is understudied, despite interactions among carbon-water balances and nutrition. Here, we followed a comparative analysis of long-term growth, intrinsic water-use efficiency (iWUE), oxygen isotopes (δ18O) and wood-nutrient composition patterns between living (L) and dead (D) trees of a Nothofagus dombeyi population, showing dieback in Argentina. The onset of the growth decline of D trees occurred ca. 40 years before death. These trees showed higher iWUE, pointing to higher drought stress. Their lower δ18O values, together with the uncoupling between δ18O and leaf-level processes, suggested a deeper source of water uptake for this vigor class. D trees showed a poorer nutritional status than L trees that likely amplified the dieback. This was supported by numerous positive associations of P- and K-concentrations in wood and related ratios with iWUE, δ18O and tree growth. Therefore, drought-related nutrient deterioration can significantly contribute to dieback and be an early warning signal of impending tree death.
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Worrall, James J. "Dieback and Mortality of Alnus in the Southern Rocky Mountains, USA." Plant Disease 93, no. 3 (March 2009): 293–98. http://dx.doi.org/10.1094/pdis-93-3-0293.
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Dieback and mortality of Alnus incana subsp. tenuifolia in the Southern Rocky Mountains apparently began by the late 1980s and have become a concern to land managers. A survey of alder including 68 transects from southern Wyoming to northern New Mexico indicated that, of 6,503 standing stems, 37% were dead, 29% had dieback, and 34% were healthy. Transects intercepted 1,479 m of live and 1,177 m of dead alder canopy. A second, more localized survey with 32 transects in the upper Gunnison River watershed of Colorado yielded similar results. Abundance of live sprouts was inversely related to amount of dieback and mortality in a genet, suggesting that affected genets are dying and not replacing themselves. Damage did not vary substantially by geographic area and was not related to elevation, animal browsing, or distance to nearest road. Distance to nearest stream was weakly, inversely related to severity of dieback and mortality. Symptoms were not consistent with disease of alder caused by Phytophthora alni in Europe, and isolations for Phytophthora species were negative. Cytospora canker, caused by Valsa melanodiscus (anamorph Cytospora umbrina), is the proximate cause of the dieback and mortality.
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Grosdidier, Marie, Thomas Scordia, Renaud Ioos, and Benoit Marçais. "Landscape epidemiology of ash dieback." Journal of Ecology 108, no. 5 (April 15, 2020): 1789–99. http://dx.doi.org/10.1111/1365-2745.13383.
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Tantau, Hanny, Steffi Renk, Dorothee Schultz, Heidrun Meyer, Jana Schulze, Denise Palm, Annika Stubbe, et al. "Infectivity Assays and Sequence Analyses for Unassigned Pseudomonas Species as Putative Cause of Dieback Disease of Dalbergia sissoo Roxb. in Bangladesh." Plant Tissue Culture and Biotechnology 21, no. 2 (December 31, 2011): 101–13. http://dx.doi.org/10.3329/ptcb.v21i2.10214.
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identified unequivocally. Putative microbial pathogens (fungi and bacteria) were studied in dieback affected sissoo trees collected from Bangladesh, using plant pathological techniques combined with molecular tools. DNA based characteri-zation showed the presence of heterogeneous patterns of various fungi (mostly saprophytic). It did not support the hypothesis of Fusarium solani being the cause of sissoo dieback. In contrast, isolation and molecular characterisation of bacteria from dieback affected sissoo revealed the presence of Pseudomonas in 83% of the samples. Sequencing the gene of 16S ribosomal RNA, the rpoD-gene, the gacA-gene and the rnpB-gene strongly suggested that these isolates belong most probably to a still unassigned Pseudomonas species. Hypersensitivity response assays and infection studies using sissoo seedlings demonstrated their pathogenic potential. Key words: Sissoo, dieback, Pseudomonas, fungal pathogens D.O.I. 10.3329/ptcb.v21i2.10214 Plant Tissue Cult. & Biotech. 21(2): 101-113, 2011 (December)
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Papic, Slavica, Roman Longauer, Ivan Milenkovic, and Jiří Rozsypálek. "Genetic predispositions of common ash to the ash dieback caused by ash dieback fungus." Genetika 50, no. 1 (2018): 221–29. http://dx.doi.org/10.2298/gensr1801221p.
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The paper reviews information on ash dieback, a serious disease of common ash and its causing agent ash dieback fungus Hymenoscyphus fraxineus. This paper covers biology and genetics of the causing agent. Main emphasis is given to the genetic predisposition of the tolerance to the disease. Strong genetic control of the infection-tolerance opens the possibility for selection of hyposensitive trees for the establishment of seed orchards, which will produce offspring with improved tolerance to H. fraxineus.
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Waipara, N. W., S. Hill, L. M. W. Hill, E. G. Hough, and I. J. Horner. "Surveillance methods to determine tree health distribution of kauri dieback disease and associated pathogens." New Zealand Plant Protection 66 (January 8, 2013): 235–41. http://dx.doi.org/10.30843/nzpp.2013.66.5671.
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Kauri dieback is a pest issue that is increasingly affecting kauri forests A water and soilborne pathogen Phytophthora taxon Agathis (PTA) has been identified as a causal agent of kauri dieback at multiple locations particularly within Auckland and Northland In 2008 a passive surveillance and adaptive management programme was initiated to manage the disease across the natural range of kauri Surveys were initially undertaken to determine the distribution and rate of spread of kauri dieback on private land in the Auckland region Methods to evaluate and monitor overall tree health disease symptoms and other potential contributing factors were developed Diagnostic sampling was undertaken to isolate and identify pathogens associated with kauri dieback Along with PTA other Phytophthora species and environmental stress were frequently associated with symptoms at over 400 properties inspected Further management is now required to develop control tools and mitigate further spread
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Liu, B., DT White, KB Walsh, and PT Scott. "Detection of phytoplasmas in dieback, yellow crinkle, and mosaic diseases of papaya using polymerase chain reaction techniques." Australian Journal of Agricultural Research 47, no. 3 (1996): 387. http://dx.doi.org/10.1071/ar9960387.
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Oligonucleotide primers complementary to regions specific to plant-pathogenic mycoplasma-like organisms (phytoplasmas) were used in polymerase chain reactions on tissue samples from dieback, yellow crinkle, and mosaic affected papaya plants. The primer pair P068/P069, which hybridise to internal regions of the 16s rRNA gene, amplified an approximately 560 bp product in dieback, yellow crinkle and mosaic affected papaya. The primer pair P3/P7, which hybridise to the spacer region between the 16s and 23s rRNA genes, amplified an approximately 300 bp fragment in yellow crinkle and mosaic affected papaya, with no product from dieback affected plants. No PCR product was obtained with either set of primers from healthy plants. An identical Alu I restriction enzyme profile was obtained with all three 560 bp products. This study provides the first evidence for the association of phytoplasmas with papaya mosaic and Australian papaya dieback.
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Sippo, James Z., Isaac R. Santos, Christian J. Sanders, Patricia Gadd, Quan Hua, Catherine E. Lovelock, Nadia S. Santini, et al. "Reconstructing extreme climatic and geochemical conditions during the largest natural mangrove dieback on record." Biogeosciences 17, no. 18 (September 28, 2020): 4707–26. http://dx.doi.org/10.5194/bg-17-4707-2020.
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Abstract. A massive mangrove dieback event occurred in 2015–2016 along ∼1000 km of pristine coastline in the Gulf of Carpentaria, Australia. Here, we use sediment and wood chronologies to gain insights into geochemical and climatic changes related to this dieback. The unique combination of low rainfall and low sea level observed during the dieback event had been unprecedented in the preceding 3 decades. A combination of iron (Fe) chronologies in wood and sediment, wood density and estimates of mangrove water use efficiency all imply lower water availability within the dead mangrove forest. Wood and sediment chronologies suggest a rapid, large mobilization of sedimentary Fe, which is consistent with redox transitions promoted by changes in soil moisture content. Elemental analysis of wood cross sections revealed a 30- to 90-fold increase in Fe concentrations in dead mangroves just prior to their mortality. Mangrove wood uptake of Fe during the dieback is consistent with large apparent losses of Fe from sediments, which potentially caused an outwelling of Fe to the ocean. Although Fe toxicity may also have played a role in the dieback, this possibility requires further study. We suggest that differences in wood and sedimentary Fe between living and dead forest areas reflect sediment redox transitions that are, in turn, associated with regional variability in groundwater flows. Overall, our observations provide multiple lines of evidence that the forest dieback was driven by low water availability coinciding with a strong El Niño–Southern Oscillation (ENSO) event and was associated with climate change.
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Saragih, Syaiful Amri, Dai Kusumoto, Shuhei Takemoto, Masato Torii, and Naoto Kamata. "Virulence of Fungi Isolated from Ambrosia Beetles to Acer amoenum Branches." Plant Disease 105, no. 10 (October 1, 2021): 3087–91. http://dx.doi.org/10.1094/pdis-11-20-2543-re.
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In Japan, no association between the ambrosia beetle and their fungal symbionts causing branch dieback or tree mortality on maple, Acer amoenum, has been reported. However, we identified dieback of several branches and numerous holes created by three species of ambrosia beetles, Euwallacea fornicatus, Euwallacea interjectus, and Platypus calamus, on Acer amoenum trees at the University of Tokyo Tanashi Forest, Tokyo Metropolis, Japan, in 2016. The high attack density of the beetles was observed on the weakened trees; however, the contribution of the associated fungi to the branch dieback was still unknown. We isolated fungi carried by these three beetles and inoculated them to Acer amoenum cut main trunks and sapling branches to determine whether the associated fungi caused the branch dieback. Fusarium euwallaceae was isolated from all Euwallacea fornicatus and Euwallacea interjectus, whereas Arthrinium phaeospermum, Raffaelea cyclorhipidia, and Epicoccum nigrum were isolated from P. calamus, with 35, 15, and 5% isolation frequencies, respectively. Inoculation with F. euwallaceae and R. cyclorhipidia induced statistically significantly wider sapwood discoloration (six and four times wider for F. euwallaceae and R. cyclorhipidia, respectively) than the controls, and larger water-conductance loss (2 and 1.7 times larger for F. euwallaceae and R. cyclorhipidia, respectively) than the controls. However, the observed lesions were not large enough to cause discoloration, and symptoms of dieback were not observed, even 13 months after the inoculation. Therefore, we concluded that the virulence of the four investigated fungi to Acer amoenum was very low and that these fungi were likely not the primary cause of the branch dieback.
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Hosseini, Ahmad, and Seyed Mohsen Hosseini. "Contrasting foliar and soil nutrients responses to drought induced crown dieback in a Quercus brantii forest." Dendrobiology 87 (April 7, 2022): 101–12. http://dx.doi.org/10.12657/denbio.087.007.
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Evidence has shown that drought-induced crown dieback has significant interaction with soil-plant water and nutrients relationships, but there isn’t sufficient knowledge of the water and nutrients connections in declining Persian oak (Quercus brantii) trees. To investigate the relationships between crown dieback and leaf nutrients concentrations, leaf water content, soil nutrients concentrations and soil moisture, one of the dieback affected stands was selected. This stand was located in Shalam forested area in northern Ilam province, west of Iran. Persian oak trees were evaluated using a crown dieback classification and divided into four classes with four replicates based on the severity of crown dieback. Sampling from leaves of trees and soil was implemented randomly in four sides of tree crown in August. Trees with moderate to severe declining showed reduced leaf water content (WC) and reduced relative leaf water content (RWC). Leaf N and P concentration of declining trees was significantly (p-value <0.05) more than that of healthy trees. The leaf K concentration of declining trees was significantly (p-value <0.10) more than that of the healthy. The leaf N:P amounts of oak trees was statistically different among crown dieback classes. But no significant differences was observed between the healthy and declining trees in terms of soil N, P, K, Ca and Mg concentrations and soil moisture. It was concluded that drought has effects on the nutrients status in the leaves of Persian oak trees and their changing in the declining trees is for resistance to drought condition, improving water use efficiency and possibly performance of vital activities.
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McDougall, K. L., G. E. St J. Hardy, and R. J. Hobbs. "Distribution of Phytophthora cinnamomi in the northern jarrah (Eucalyptus marginata) forest of Western Australia in relation to dieback age and topography." Australian Journal of Botany 50, no. 1 (2002): 107. http://dx.doi.org/10.1071/bt01040.
Full textAbstract:
The spatial distribution of Phytophthora cinnamomi Rands at seven dieback sites in the jarrah (Eucalyptus marginata Donn. ex Smith) forest of Western Australia was determined by the following two baiting techniques: in situ baiting with live Banksia grandis Willd. seedlings and ex situ baiting of sampled soil and root material. Four areas within each site were sampled, reflecting dieback age and position in the landscape. Approximate dieback ages of 50, 20 and 5 years were determined by aerial photography. The 50-year-old age class was divided into wet valley floor and dry gravelly slope. Phytophthora cinnamomi was recovered most frequently from the 5-year-old (dieback fronts) and wet 50-year-old areas by both baiting techniques. It was recovered from more than twice as many areas and about five times as many samples when in situ B. grandis baits were used compared with ex situ soil and root baiting. Almost all recoveries from in situ baits were made between October and December. From both methods, it appears that P. cinnamomi has a patchy distribution within dieback sites in the northern jarrah forest. It is easily detected only on dieback fronts and wet valley floors. On dry gravelly sites affected 20 years or more ago, P. cinnamomi is rare and may even be absent at some sites. This makes confident detection of the pathogen difficult. In situ baiting at least allows a temporal component to the sampling and will be a useful method of detection in areas where P. cinnamomi is rare or transient.