Viability of Puccinia horiana Teliospores Under Various Environmental Conditions

2014 ◽  
Vol 15 (1) ◽  
pp. 25-28 ◽  
Author(s):  
Morris R. Bonde ◽  
Cristi L. Palmer ◽  
Douglas G. Luster ◽  
Susan E. Nester ◽  
Jason M. Revell ◽  
...  

Puccinia horiana Henn. is a quarantine-significant fungal pathogen and causal agent of chrysanthemum white rust (CWR). The pathogen and disease were first discovered in the United States in 1977 and quickly eradicated. During the early 1990s, CWR reemerged in several instances, but in each instance was declared eradicated. However, since approximately 2004 CWR has reappeared at an accelerated frequency. This has suggested that either P. horiana is entering the country more frequently from foreign locations or that P. horiana is now established in the field, implying that spores are capable of surviving winter conditions in plant debris or soil. As a result of the possibility that the pathogen has become established in the United States, we initiated several lines of research. The objectives of the study reported here were: (i) develop a better and more sensitive method to measure teliospore longevity; and (ii) determine if the pathogen is able to survive northeastern winters as viable teliospores. Results from the study showed that teliospores survived in the greenhouse a maximum of 28 days in dry soil and 7 days in moist soil. In a growth chamber simulating winter temperature conditions in the northeastern United States, teliospores survived a maximum of 35 days. It was concluded that P. horiana teliospores are not able to survive through typical northeastern U.S. winters. Accepted for publication 9 January 2014. Published 18 March 2014.

2013 ◽  
Vol 14 (1) ◽  
pp. 11 ◽  
Author(s):  
Morris R. Bonde ◽  
Cristi L. Palmer ◽  
Douglas G. Luster ◽  
Susan E. Nester ◽  
Jason M. Revell ◽  
...  

Puccinia horiana Henn., a quarantine-significant fungal pathogen and causal agent of chrysanthemum white rust (CWR), was first discovered in the United States in 1977 and later believed to have been eradicated. Recently, however, the disease has sporadically reappeared in the northeastern US. Possible explanations for the reappearance include survival of the pathogen in the local environment, and reintroduction from other locations. To determine the possibility that the pathogen might be overwintering in the field, we undertook the study described here. Results from the study showed that P. horiana teliospores, imbedded in infected leaves, were capable of sporulating 2 weeks after inoculation, and this capacity continued until the leaf became necrotic and desiccated. This is the first report of the extreme susceptibility of P. horiana teliospores to leaf necrosis and desiccation and suggests that field infections following winter are unlikely to originate from teliospores. Teliospore germination on excised leaves was shown to be inhibited by light. Accepted for publication 3 April 2013. Published 23 August 2013.


Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1381-1381 ◽  
Author(s):  
G. O'Keefe ◽  
D. D. Davis

Chrysanthemum white rust (CWR) is a quarantine-significant pest in the United States (Title 7, Code of Federal Regulations, Part 319.37-2). The causal agent of CWR, Puccinia horiana Henn., is an autoecious, microcyclic rust that is pathogenic on chrysanthemum species (Chrysanthemum spp.) and close relatives within the family Asteraceae. CWR is indigenous to Japan, where it was first reported in 1895 (4). By the 1960s, CWR was found throughout Europe and later spread to Africa, Oceana, South America, and other parts of Asia. In North America, CWR was reported in Mexico and in the United States (New Jersey and Pennsylvania [1977], Oregon and Washington [1990], and California [1991]). Additional detections of CWR were later reported in 22 Pennsylvania counties (2004, 2006 to 2010) (3). These later Pennsylvania reports stated that eradication was attempted at some sites, but unconfirmed observations suggested that the rust pathogen might overwinter in volunteer plants (3). Since “CWR is known to overwinter in Europe where chrysanthemums overwinter (average minimum temperatures ranging from –10°F to 10°F)” (2), the unconfirmed Pennsylvania observations prompted us to determine if P. horiana can overwinter in Pennsylvania. During October 2010, we identified CWR on perennial mums planted at six outdoor garden locations in University Park, PA. Symptomatic plants were quarantined and eradication attempted. Eradicated sites were routinely surveyed and CWR confirmed in July 2011 on volunteer plants at two of the originally infested sites. An additional outdoor garden site with CWR was observed in State College, PA, during October 2011 and eradication attempted. The three infested sites were surveyed throughout the fall and winter of 2011 to 2012. During February 2012, two asymptomatic volunteer plants arising from root pieces were collected from each of the three sites. Each sample was washed with tap water to remove excess soil, examined morphologically, surface sterilized with 10% bleach, and divided into two subsamples. One subsample from each site was divided into crown and root portions and DNA extracted using a Qiagen DNeasy Plant Mini Kit. Molecular analysis was performed using modifications of published primers ITS 5 and Rust1 (1,4). Puccinia horiana was detected in plant roots from one site and in plant crowns from two sites. The remaining two subsamples from each site were transplanted into sterilized potting soil and placed in a clean controlled environment chamber at 18°C and 85% relative humidity (RH). After 6 weeks, six actively growing plants were transferred to a second clean controlled environment chamber at 17°C and 90 to 100% RH. On 6 April 2012, CWR symptoms and signs were confirmed morphologically on two plants that had been removed from one site. On 19 April 2012, CWR signs and symptoms were confirmed morphologically and by molecular analysis on leaves of volunteer plants at one University Park site. DNA extractions were sequenced and shared a 100% maximum identity to a known P. horiana accession (EU816920.1) in GenBank. To our knowledge, this is the first confirmed report of P. horiana overwintering in Pennsylvania. References: (1) H. Alaei et al. Mycol. Res. 113:668, 2009. (2) Anon. Chrysanthemum White Rust Bulletin, Syngenta Flowers Inc., Gilroy, CA, 2010. (3) S. Kim et al. Phytopathology 101:S91, 2011. (4) K. Pedley. Plant Dis. 93:1252, 2009.


2015 ◽  
Vol 105 (1) ◽  
pp. 91-98 ◽  
Author(s):  
M. R. Bonde ◽  
C. A. Murphy ◽  
G. R. Bauchan ◽  
D. G. Luster ◽  
C. L. Palmer ◽  
...  

Puccinia horiana, causal agent of the disease commonly known as chrysanthemum white rust (CWR), is a quarantine-significant fungal pathogen of chrysanthemum in the United States and indigenous to Asia. The pathogen was believed to have been eradicated in the United States but recently reappeared on several occasions in northeastern United States. The objective of the study presented here was to determine whether P. horiana could systemically infect chrysanthemum plants, thus providing a means of survival through winters. Scanning and transmission electron microscopy revealed the development of P. horiana on the surface and within leaves, stems, or crowns of inoculated chrysanthemum plants artificially exposed to northeastern U.S. winter temperatures. P. horiana penetrated leaves directly through the cuticle and then colonized the mesophyll tissue both inter- and intracellularly. An electron-dense material formed at the interface between fungal and host mesophyll cells, suggesting that the pathogen adhered to the plant cells. P. horiana appeared to penetrate mesophyll cell walls by enzymatic digestion, as indicated by the absence of deformation lines in host cell walls at penetration sites. The fungus was common in vascular tissue within the infected crown, often nearly replacing the entire contents of tracheid cell walls. P. horiana frequently passed from one tracheid cell to an adjacent tracheid cell by penetration either through pit pairs or nonpitted areas of the cell walls. Individual, presumed, fungal cells in mature tracheid cells of the crown and stems arising from infected crowns suggested that the pathogen might have been moving at least partially by means of the transpiration stream. The demonstration that chrysanthemum plants can be systemically infected by P. horiana suggests that additional disease control measures are required to effectively control CWR.


Author(s):  
Patricia J. Vittum

This chapter studies Coleopteran pests. The larvae of turfgrass-infesting species of the family Scarabaeidae constitute a large complex whose members (white grubs) are similar in general appearance, in habits, and in the turfgrass damage they cause. At least 10 species of scarabs, belonging to five subfamilies, are pests of turfgrass in the United States. The larvae of this family are known also as grubs, a term applied to the larvae of several Coleoptera (beetles) and Hymenoptera (ants, bees, and wasps) in general. Grubs of the Scarabaeidae are the most serious turfgrass pests in the northeastern United States, and are considered a major pest in the Midwest, Southeast, and parts of the southwestern United States. Their subterranean habits make them among the most difficult of turfgrass insects to manage.


2018 ◽  
Vol 26 (2) ◽  
pp. 113-120 ◽  
Author(s):  
Jean-David Moore ◽  
Josef H. Görres ◽  
John W. Reynolds

Exotic species invasions are among the most significant global-scale problems caused by human activities. They can seriously threaten the conservation of biological diversity and of natural resources. Exotic European earthworms have been colonizing forest ecosystems in northeastern United States and southern Canada since the European settlement. By comparison, Asian earthworms began colonizing forests in the northeastern United States more recently. Since Asian species have biological traits compatible with a greater potential for colonization and disturbance than some European species, apprehension is growing about their dispersal into new territories. Here we review the extent of the current northern range of Asian earthworms in northeastern North America, the factors facilitating or limiting their propagation and colonization, and the potential effects of their invasion on forest ecosystems. Data compilation shows that Asian earthworms are present in all northeastern American states. So far, only one mention has been reported in Canada. Data confirm that their distribution has now reached the Canadian border, particularly along the Michigan–Ontario, New York–Ontario, Maine–New Brunswick, and Vermont–Québec frontiers. Studies report that the presence of Asian earthworms is strongly associated with human activities such as horticulture, vermicomposting, and the use of worms as fish bait. Some climatic (temperature, soil moisture) and edaphic (soil pH) factors may also influence their distribution. Controlling their dispersal at the source is essential to limiting their spread, as there is currently no effective way to eradicate established earthworm populations without unacceptable nontarget effects. Proposed management options in the United States include the prohibition of fish bait disposal and better management of the international trade of horticultural goods, commercial nurseries, and vermicomposting industries. We conclude that although regulations and awareness may delay their expansion, Asian earthworms are likely to spread further north into Canada. They are expected to cause important changes to biodiversity and dynamics of the newly invaded forest ecosystems.


2017 ◽  
Vol 2017 ◽  
pp. 1-3
Author(s):  
Preston M. Luong ◽  
Basilio Kalpakian ◽  
Lawrence J. Jaeger ◽  
Timothy Lahey ◽  
Christopher B. Chapman ◽  
...  

Endogenous endophthalmitis is a rare but feared infectious ocular complication of injection drug use (IDU). The recent opioid epidemic in the United States threatens to increase the incidence of this disease. We report the first case of endogenous endophthalmitis in the United States caused by the emerging fungal pathogenRhodotorulain an injection drug user which led to no light perception vision (NLP). Worldwide experience withRhodotorulaendogenous endophthalmitis is limited, but existing cases suggest infection by this particular fungal genus has a grim prognosis.


2014 ◽  
Vol 44 (10) ◽  
pp. 1244-1252 ◽  
Author(s):  
A. Boraks ◽  
K.D. Broders

Butternut (Juglans cinerea L.) trees are being extirpated from their natural range by an epidemic caused by a fungal pathogen. Widespread mortality is reminiscent of past epidemics on American chestnut (Castanea dentata (Marsh.) Borkh.) and American elm (Ulmus americana L.). Butternut has remained relatively understudied, resulting in unsampled areas and gaps in our understanding of this forest epidemic and the future outlook of this species in North America. The previously unsampled area consisting of the northeastern United States was surveyed for the presence of J. cinerea, and several population health metrics were recorded, including recruitment, disease pressure, and hybridization. A total of 252 butternut trees were sampled. Analysis indicates that there is insufficient J. cinerea recruitment to maintain population sizes. Further compounding low recruitment, butternut saplings demonstrate elevated levels of disease impact from the fungal pathogen Ophiognomonia clavigignenti-juglandacearum Broders & Boland. Natural hybridization of butternut with introduced congenics such as Juglans ailantifolia Carrière is strongly associated with lower disease impact. Hybrid trees displayed an average of 2.4 cankers per tree compared with 4.5 cankers for nonhybrid butternut. Further niche and resistance studies are required to assess whether butternut hybrids can replace butternut in a natural setting. It still remains uncertain whether tree size or habitat affect disease impact; however, smaller trees, often residing in riparian habitats, were found to have a greater number of cankers. The data presented here, combined with past studies, provide critical information for use in butternut management strategy plans.


2019 ◽  
Vol 20 (3) ◽  
pp. 178-178 ◽  
Author(s):  
Nathan M. Kleczewski ◽  
James Donnelly ◽  
Russ Higgins

Tar spot on corn (Zea mays L.), caused by the obligate fungal pathogen Phyllachora maydis Maubl., was first detected in the United States in 2015. Currently, the disease has been detected in 172 counties across Florida, Illinois, Indiana, Iowa, Michigan, Ohio, and Wisconsin. Although observations indicate that P. maydis likely overwinters in the region, this has not been conclusively proven. Samples of corn foliage heavily infected with P. maydis were recovered from two fields in northern Illinois in March 2019. Ascospores were extracted and were applied to corn seedlings under controlled greenhouse conditions. Symptoms of tar spot were observed 17 days after inoculation, and ascospores were extracted from stromata to confirm P. maydis. This is the first conclusive proof that P. maydis can overwinter the United States. We also present a preliminary greenhouse method that, if optimized, may be used to study this pathosystem under controlled conditions.


2010 ◽  
Vol 25 (4) ◽  
pp. 1082-1102 ◽  
Author(s):  
Peter C. Banacos ◽  
Michael L. Ekster

Abstract The occurrence of rare but significant severe weather events associated with elevated mixed-layer (EML) air in the northeastern United States is investigated herein. A total of 447 convective event days with one or more significant severe weather report [where significant is defined as hail 2 in. (5.1 cm) in diameter or greater, a convective gust of 65 kt (33 m s−1) or greater, and/or a tornado of F2 or greater intensity] were identified from 1970 through 2006 during the warm season (1 May–30 September). Of these, 34 event days (7.6%) were associated with identifiable EML air in regional rawinsondes preceding the event. Taken with two other noteworthy events in 1953 and 1969, a total of 36 significant severe weather events associated with EML air were studied via composite and trajectory analysis. Though a small percentage of the total, these 36 events compose a noteworthy list of historically significant derechos and tornadic events to affect the northeastern United States. It is demonstrated that plumes of EML air emanating from the Intermountain West in subsiding, anticyclonically curved flows can reinforce the capping inversion and maintain the integrity of the EML across the central United States over a few days. The EML plume can ultimately become entrained into a moderately fast westerly to northwesterly midtropospheric flow allowing for the plume’s advection into the northeastern United States. Resultant thermodynamic conditions in the convective storm environment are similar to those more typically observed closer to the EML source region in the Great Plains of the United States. In addition to composite and trajectory analysis, two case studies are employed to demonstrate salient and evolutionary aspects of the EML in such events. A lapse rate tendency equation is explored to put EML advection in context with other processes affecting lapse rate.


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