scholarly journals First Report of Beech Leaf Disease, Caused by Litylenchus crenatae mccannii, on American Beech (Fagus grandifolia) in Virginia

Plant Disease ◽  
2021 ◽  
Author(s):  
Mihail R. Kantor ◽  
Zafar Ahmad Handoo ◽  
Lynn Carta ◽  
Shiguang Li
Keyword(s):  
North America ◽  
Rhode Island ◽  
Morphological Characteristics ◽  
Pcr Amplification ◽  
Fagus Crenata ◽  
Fagus Grandifolia ◽  
American Beech ◽  
First Report ◽  
Leaf Disease ◽  
Foliar Nematode

Beech leaf disease (BLD) was first reported in 2012 in Lake County, Ohio on American beech trees (Fagus grandifolia Ehrh.). Since then, it spread across the Northeastern United States and has been reported from Ohio, Pennsylvania, New York, New Jersey, Connecticut, Rhode Island, Maine, West Virginia, and Ontario, Canada (Carta et al. 2020; Mara and LaMondia 2020, Reid et al. 2020). The symptoms of BLD are characterized by dark interveinal banding of leaves appearing soon after spring flush that become chlorotic and necrotic through autumn, resulting in canopy thinning in advanced stages, followed in some young trees by death. Litylenchus crenatae mccannii has similar morphological characteristics with Litylenchus crenatae (Kanzaki et al. 2019) reported on Fagus crenata from Japan. However that beech species has not shown BLD symptoms or yielded any L. crenatae mccannii in North America. There are several morphological differences between the two. The North American subspecies have shorter post-uterine sac, narrower body width in mature females, shorter tail in immature females, longer tail in mature females, and longer stylet in males when compared to the Japanese subspecies (Carta et al. 2020). BLD symptoms were found on American beech trees in Prince William Forest Park, Prince William County, Virginia in June, 2021. The affected leaves contained females, males, and juveniles with morphometrics consistent with L. crenatae mccannii (Carta et al. 2020). The crude genomic DNA from a live single Litylenchus was prepared with freeze-thaw lysis (Carta and Li, 2019). The ITS PCR were performed by using the procedures and primer set, ITS-CL-F2 and 28S-CL-R described in the previous study (Carta and Li, 2020). The visualization, the cleanup and the direct DNA sequencing of the PCR products were performed by using the procedures described in the previous studies (Carta and Li, 2018 and 2019). Sequences were submitted to GenBank as accessions MZ611855 and MZ611856. This represents the first report of BLD in Virginia. It is also approximately 300 miles south of the 2020 detection of BLD from New Cumberland, WV, and represents the southernmost detection of the disease and nematode in North America. The author(s) declare no conflict of interest. References Carta, L.K., Li, S. 2018. Improved 18S small subunit rDNA primers for problematic nematode amplification. Journal of Nematology. 50, 533-542. Carta, L.K., Li, S. 2019. PCR amplification of a long rDNA segment with one primer pair in agriculturally important nematodes. Journal of Nematology. 51, e2019-26. Carta, L.K., Li, S. 2020. Improvement of long segment ribosomal PCR amplification for the molecular taxonomic identification of Litylenchus crenatae mccannii in beech trees with beech leaf disease. Journal of Nematology. 52, e2020-016. Kanzaki, N., Ichihara, Y., Aikawa, T., Ekino, T., Masuya, H. 2019. Litylenchus crenatae n. sp. (Tylenchomorpha: Anguinidae), a leaf gall nematode parasitising Fagus crenata Blume Nematology 21 (1), 5-22. http://www.brill.com/nematology doi: 10.1163/15685411-00003190 Marra, R.E., LaMondia, J. 2020. First report of beech leaf disease, caused by the foliar nematode, Litylenchus crenatae mccannii, on American beech (Fagus grandifolia) in Connecticut. Plant Disease (early view). https://doi.org/10.1094/PDIS-02-20-0442-PDN Reed, S. E., Greifenhagen, S., Yu, Q., Hoke A., Burke D. J., Carta L. K., Handoo Z.A., Kantor, M.R., Koch, J. 2020. Foliar nematode, Litylenchus crenatae ssp. mccannii, population dynamics in leaves and buds of beech leaf disease-affected trees in Canada and the US. Forest Pathology 50 (3), e12599.

scholarly journals The First Report of Beech Bark Disease in Ohio Comes Nineteen Years After the First Report of the Initiating Scale

Plant Disease ◽  
2005 ◽  
Vol 89 (2) ◽  
pp. 203-203 ◽  
Author(s):  
M. MacKenzie ◽  
A. J. Iskra
Keyword(s):  
North Carolina ◽  
North America ◽  
West Virginia ◽  
Scale Insect ◽  
Fagus Grandifolia ◽  
Beech Bark Disease ◽  
American Beech ◽  
First Report ◽  
Disease Complex ◽  
Western Pennsylvania

Beech bark disease (BBD) is a two-part disease complex. It first requires the feeding of an initiating insect scale and is only fully developed when scale-altered bark becomes infected by one of two Neonectria species. In Ohio, there was a 19-year lag between discovery of the initiating scale insect and the development of BBD. In September 1984, the BBD-initiating scale (Cryptococcus fagisuga Lind) was discovered in the Holden Arboretum, Geauga County, OH (2). Nineteen years later (December 2003), A. Iskra discovered the exotic BBD-causing fungus, Neonectria coccinea (Pers.:Fr.) Rossman & Samuels var faginata Lohman, Watson & Ayers, on American beech (Fagus grandifolia Ehrh.) in the Holden Arboretum. In 1934, Erlich (1) reported that there was normally a delay of at least 1 year between the appearance of the scale and the first appearance of the Neonectria spp. fungus. In the years immediately after the first report of the scale in Ohio (2), pathologists and arboretum staff made frequent visits to the site in an attempt to find Neonectria spp. fruiting. After a decade of searching, these visits became more infrequent. However, it was on one of these visits that A. Iskra found the fungus. He found it on only four trees, none of which had the extensive bark cankering common in chronic Neonectria spp. infections. In North America, the two species of Neonectria that have been involved in BBD mortality are the native N. galligena (Bres.) Rossman & Samuels, or the exotic N. coccinea var faginata. In the absence of beech scale infestations, reports of the native N. galligena infecting American beech are few. Yet, in West Virginia, western Pennsylvania, Michigan, and possibly North Carolina, the fungus first associated with the killing front has been the native N. galligena and not the exotic variety, N. coccinea var faginata. To our knowledge, this is the first report of BBD in Ohio and it is unique because the associated fungus is the exotic variety. References: (1) J. Erlich. Can. J. Res. 10:593, 1934. (2) M. E. Mielke et al. Plant Dis. 69:905, 1985.

Diarimella laurentidae anam.: sp.nov. from Quebec

1998 ◽  
Vol 76 (12) ◽  
pp. 2037-2041 ◽  
Author(s):  
Vladimir Vujanovic ◽  
Marc St-Arnaud ◽  
Peterjürgen Neumann ◽  
J André Fortin
Keyword(s):  
New Species ◽  
Fagus Grandifolia ◽  
American Beech ◽  
Fungus Species ◽  
First Report ◽  
Ecological Reserve ◽  
A New Species

Diarimella laurentidae, a new species occurring on dead bark and decorticated twigs of American beech (Fagus grandifolia Ehrh.), is reported from the Muir's Wood ecological reserve, located in the centre of the Haut-Saint-Laurent region in the province of Quebec. Diarimella laurentidae is characterized by stromatic, pulvinate, black, setose fructifications composed of a basal stroma of textura angularis, a brown peripheral wall of textura porrecta, conidiomatal setae of two types, and unicellular multisetulate conidia. Its relationships with described Diarimella species is discussed. This is the first report of a species of Diarimella from North America.Key words: Diarimella laurentidae, new fungus species, coelomycete, Fagus grandifolia.

scholarly journals First Report of Clubroot on Capsella bursa-pastoris Caused by Plasmodiophora brassicae in Sichuan Province of China

Plant Disease ◽  
2014 ◽  
Vol 98 (5) ◽  
pp. 687-687 ◽  
Author(s):  
L. Ren ◽  
X. P. Fang ◽  
C. C. Sun ◽  
K. R. Chen ◽  
F. Liu ◽  
...  
Keyword(s):  
Plasmodiophora Brassicae ◽  
Tap Water ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Pcr Amplification ◽  
Sichuan Province ◽  
Clubroot Disease ◽  
Cruciferous Vegetable ◽  
First Report ◽  
Resting Spores

Shepherd's purse (Capsella bursa-pastoris (L.) Medicus) is an edible and wild medicinal plant widely distributed in China. This plant has been cultivated in Shanghai, China, since the end of the 19th century. Infection of C. bursa-pastoris by Plasmodiophora brassicae, the causal agent of clubroot disease on Brassica spp. has been reported in Korea (2), but is not known to occur in China. In February of 2011, stunted and wilted shepherd's purse (SP) plants were observed in a field planted to oilseed rapes (B. napus) in Sichuan Province of China. Symptomatic SP plants also exhibited root galls. Disease incidence was 6.2% and 100% for SP and B. napus, respectively. Root galls on diseased SP plants were collected for pathogen identification. Many resting spores were observed when the root galls were examined under a light microscope. The resting spores were circular in shape, measuring 2.0 to 3.1 μm in diameter (average 2.6 μm). PCR amplification was conducted to confirm the pathogen. DNA was extracted from root galls and healthy roots (control) of SP. Two primers, TC2F (5′-AAACAACGAGTCAGCTTGAATGCTAGTGTG-3′) and TC2R (5′-CTTTAGTTGTGTTTCGGCTAGGATGGTTCG-3′) were used to detect P. brassicae (1). No PCR amplifications were observed with the control DNA as template. A fragment of the expected size (approximately 520 bp) was obtained when DNA was amplified from diseased roots of SP. These results suggest that the pathogen in the galled roots of SP is P. brassicae. Pathogenicity of P. brassicae in SP was tested on plants of both SP and Chinese cabbage (CC) (B. campestris ssp. pekinensis). A resting spore suspension prepared from naturally infected SP roots was mixed with a sterilized soil in two plastic pots, resulting in a final concentration of 5 × 106 spores/g soil. Soil treated with the same volume of sterile water was used as a control. Seeds of SP and CC were pre-germinated on moist filter paper for 2 days (20°C) and seeded into the infested and control pots, one seed per pot for planted for CC and four seeds per pot for SP. The pots were placed in a chamber at 15 to 25°C under 12 h light and 12 h dark. Plants in each pot were uprooted after 4 weeks and the roots of each plant were washed under tap water and rated for clubroot disease. No disease symptoms were observed in the control treatments of SP or CC. Plants of both species showed symptoms of clubroot, with the disease incidence of 62.5% and 100% on SP and CC, respectively. The pathogen was isolated from diseased roots of each plant and confirmed as P. brassicae based on morphological characteristics and PCR detection. To our knowledge, this is the first report of clubroot disease on C. bursa-pastoris in Sichuan Province of China. This finding suggests that it may be necessary to manage C. bursa-pastoris in cruciferous vegetable (cabbage, turnip) and oilseed rape production fields. References: (1) T. Cao et al. Plant Dis. 91:80, 2007. (2) W. G. Kim et al. Microbiology 39:233, 2011.

scholarly journals First Report of Gummosis Disease of Japanese Apricot Caused by Botryosphaeria dothidea in Taiwan

Plant Disease ◽  
2011 ◽  
Vol 95 (1) ◽  
pp. 77-77
Author(s):  
Y. Ko ◽  
C. W. Liu ◽  
S. S. Chen ◽  
K. Y. Chiu ◽  
Y. W. Sun ◽  
...  
Keyword(s):  
Direct Sequencing ◽  
Morphological Characteristics ◽  
Pcr Amplification ◽  
Conidial Suspension ◽  
Botryosphaeria Dothidea ◽  
Cortical Cells ◽  
Japanese Apricot ◽  
First Report ◽  
Representative Sequence ◽  
Plastic Bags

Japanese apricot (Prunus mume Sieb. et Zucc.) is an economically important fruit crop grown on more than 10,000 ha in Taiwan. During May 2008, twigs of Japanese apricot trees in the commercial farms of Renai Region (Nantou County) showed symptoms of gummosis disease, with 12 to 18% of the trees affected. The disease was more severe on trees weakened by drought stress. Limb and twig infections began around lenticles as small, sunken, discolored lesions at the margins of wounds. Following infection, cortical cells collapsed, bark became depressed, and blisters developed, which were often cracked with whitish gummy exudation. Necrotic areas were seen on the cortical tissues. Leaves showed yellowing and drooping. In winter months, numerous black pycnidia or perithecia formed on infected twigs. Single conidial isolates of the pathogen were obtained from diseased twigs on acidified potato dextrose agar (PDA) incubated at 25 ± 1°C for 3 days. On the basis of morphological characteristics, the fungus was identified as Botryosphaeria dothidea (3). Conidia (17 to 22.6 × 4.3 to 6.0 μm) were hyaline, unicellular, and spindle shaped. Asci (78 to 125 × 15 to 17 μm) were hyaline, bitunicate, clavate, and eight spored. Ascospores (18 to 22 × 7.0 to 8.2 μm) were hyaline and spindle shaped or fusoid. The pathogen identity was further confirmed by PCR amplification and sequencing of ribosomal DNA internal transcribed spacer from the fungus with the primers ITS5: 5′-GGAAGTAAAAGTCGTAACAAGG-3′ and ITS4: 5′-TCCTCCGCTTATTGATATGC-3′ (4), and a representative sequence was deposited in NCBI GenBank (Accession No. GU594225). The sequence showed 99 to 100% homology with previously characterized strains of B. dothidea (GenBank Accession Nos. EU441944, DQ177876, and AY786320). Pathogenicity tests were conducted with inoculum prepared by culturing the fungus on PDA under a continuous photoperiod of 128 ± 25 μE·m–2·s–1 at 25°C for 3 days. Shallow cuts (3 × 3 × 3 mm) were made on 12- to 15-month-old healthy twigs with a scalpel and inoculated with either a 5-mm mycelial disc or 0.5 ml of conidial suspension (105 conidia/ml) of the fungus. Two twigs on each of six trees were inoculated. Inoculated areas were covered with moist, sterile cotton and the entire twigs were enclosed in plastic bags. Twigs were inoculated with 5-mm PDA discs or sterile water for controls. The symptoms described above were observed on all inoculated twigs 14 days after inoculation, whereas control twigs remained healthy. Reisolation from the inoculated twigs consistently yielded B. dothidea. In Taiwan, B. dothidea has been reported as the causal agent of gummosis of peach (1) and fruit ring rot of pear (2); however, to our knowledge, this is the first report of B. dothidea causing gummosis on Japanese apricot. References: (1) Y. Ko et al. Plant Pathol. Bull. 1:70, 1992. (2) Y. Ko et al. Plant Prot. Bull. (Taiwan) 35:211, 1993. (3) B. Slippers et al. Mycologia 96:83, 2004. (4) T. J. White et al. In: Amplification and Direct Sequencing of Fungal Ribosomal RNA Genes for Phylogenetics. Academic Press. San Diego, CA, 1990.

scholarly journals First Report of Mango Dieback Caused by Pseudofusicoccum stromaticum in Brazil

Plant Disease ◽  
2012 ◽  
Vol 96 (1) ◽  
pp. 144-144 ◽  
Author(s):  
M. W. Marques ◽  
N. B. Lima ◽  
S. J. Michereff ◽  
M. P. S. Câmara ◽  
C. R. B. Souza
Keyword(s):  
Uv Light ◽  
Mangifera Indica ◽  
Morphological Characteristics ◽  
Pcr Amplification ◽  
Molecular Techniques ◽  
Northeastern Brazil ◽  
Universal Primers ◽  
Rrna Gene ◽  
First Report ◽  
Length Width

From September to December 2010, mango (Mangifera indica L.) stems showing dieback symptoms were collected during a survey conducted in São Francisco Valley, northeastern Brazil. Small pieces (4 to 5 mm) of necrotic tissues were surface sterilized for 1 min in 1.5% NaOCl, washed twice with sterile distilled water, and plated onto potato dextrose agar (PDA) amended with 0.5 g liter–1 streptomycin sulfate. Plates were incubated at 25°C in the dark for 14 to 21 days and colonies that were morphologically similar to species of Botryosphaeriaceae were transferred to PDA. Colonies developed a compact mycelium that was initially white, but becoming gray dark after 4 to 6 days of incubation at 25°C in darkness. Identification was made using morphological characteristics and DNA based molecular techniques. Pycnidia were obtained on 2% water agar with sterilized pine needles as substratum after 3 weeks of incubation at 25°C under near-UV light. Pycnidia were large, multilocular, eustromatic, covered with hyphae; locule totally embedded without ostioles, locule walls consisting of a dark brown textura angularis, becoming thinner and hyaline toward the conidiogenous region. Conidia were hyaline, thin to slightly thickened walled, aseptate, with granular contents, bacilliform, straight to slightly curved, apex and base both bluntly rounded or just blunt, 15.6 to 25.0 (20.8) μm long, and 2.7 to 7.9 (5.2) μm wide, length/width = 4.00. According to these morphological characteristics, three isolates (CMM1364, CMM1365, and CMM1450) were identified as Pseudofusicoccum stromaticum (1,3,4). PCR amplification by universal primers (ITS4/ITS5) and DNA sequencing of the internal transcribed spacer (ITS1-5.8S-ITS2 rRNA gene cluster) were conducted to confirm the identifications through BLAST searches in GenBank. The isolates were 100% homologous with P. stromaticum (3) (GenBank Accession Nos. AY693974 and DQ436935). Representative sequences of the isolates were deposited in GenBank (Accession Nos. JF896432, JF966392, and JF966393). Pathogenicity tests were conducted with the P. stromaticum strains on 5-month-old mango seedlings (cv. Tommy Atkins). Mycelial plugs taken from the margin of actively growing colonies (PDA) of each isolate were applied in shallow wounds (0.4 cm in diameter) on the stem (center) of each plant. Inoculation wounds were wrapped with Parafilm. Control seedlings received sterile PDA plugs. Inoculated and control seedlings (five each) were kept in a greenhouse at 25 to 30°C. After 5 weeks, all inoculated seedlings showed leaf wilting, drying out of the branches, and necrotic lesions in the stems. No symptoms were observed in the control plants. P. stromaticum was successfully reisolated from symptomatic plants to fulfill Koch's postulates. P. stromaticum was described from Acacia, Eucalyptus, and Pinus trees in Venezuela (3,4), and there are no reports of this fungus in other hosts (2). To our knowledge, this is the first report of P. stromaticum causing mango dieback in Brazil and worldwide. References: (1) P. W. Crous et al. Stud. Mycol. 55:235, 2006. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , 18 May 2011. (3) S. Mohali et al. Mycol. Res. 110:405, 2006. (4) S. R. Mohali et al. Fungal Divers. 25:103, 2007.

scholarly journals Interference to Hardwood Regeneration in Northeastern North America: Ecological Characteristics of American Beech, Striped Maple, and Hobblebush

2006 ◽  
Vol 23 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Ralph D. Nyland ◽  
Amy L. Bashant ◽  
Kimberly K. Bohn ◽  
Jane M. Verostek
Keyword(s):  
North America ◽  
Woody Species ◽  
Ground Level ◽  
Fagus Grandifolia ◽  
Limited Information ◽  
Beech Bark Disease ◽  
American Beech ◽  
Northeastern North America ◽  
A Site ◽  
Palatable Species

Abstract Several woody species may inhibit regeneration of desirable northern hardwoods. This includes a dense understory of American beech (Fagus grandifolia Ehrh.) that commonly occurs in stands infected with beech bark disease. Root injuries during logging and by natural causes alsopromote new suckers that, along with some stump sprouts, often maintain or increase the abundance of beech saplings. Additionally, browsing deer primarily bypass beech in favor of more palatable species. Where any of these factors has resulted in a dense understory of small beech, overstorycutting will promote its development, increase ground-level shading, and lead to a site conversion to beech. Similarly, striped maple (Acer pensylvanicum L.) often interferes with hardwood regeneration after overstory cutting. This species persists in heavy shade, grows rapidly afterrelease, and produces abundant seed. When dense, striped maple may interfere with the regeneration of other species. Hobblebush (Viburnum alnifolium Marsh.), a shrub, reproduces by rhizomes to form thickets when damaged during overstory cutting. Heavy shade by these thickets may preventregeneration of trees. This review summarizes characteristics of these three species with respect to their interference with desirable hardwoods in northeastern North America. It highlights the limited information about striped maple and hobblebush, and the abundance of sources that deal withAmerican beech.

scholarly journals First Report of Oak Anthracnose Caused by Apiognomonia errabunda on Oriental White Oak in Korea

Plant Disease ◽  
2013 ◽  
Vol 97 (8) ◽  
pp. 1121-1121
Author(s):  
C. K. Lee ◽  
S. H. Lee ◽  
J. H. Park ◽  
S. E. Cho ◽  
H. D. Shin
Keyword(s):  
North America ◽  
Morphological Characteristics ◽  
Its Region ◽  
Culture Collection ◽  
Deciduous Tree ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Natural Forests ◽  
White Oak ◽  
First Report

Oriental white oak, Quercus aliena Blume, is native to East Asia including Korea. It is one of the major deciduous tree species in natural forests in Korea. In May 2012, several hundred trees were found to be heavily damaged by a previously unknown leaf disease in a forest near Songjiho Lake in Goseong County of central Korea. Leaf symptoms began as small, water-soaked, pale greenish to grayish lesions, which enlarged to follow the veins or midribs and to be bounded by them, often killing part of the leaf. Leaf distortion and blight resulted in the later stage of disease development. A number of grayish brown to nearly black acervuli were formed on the lesions, especially on the midribs and veins. Acervuli were mostly hypophyllous, intraepidermal, erumpent, circular to ellipsoid in outline, cushion-like, and 70 to 220 μm in diameter. Conidia (n = 30) were elliptical to fusiform-elliptical, occasionally obclavate, aguttulate or guttulate, hyaline, aseptate, and 7.5 to 20 × 5 to 7.5 μm (mean 14.6 × 6.1 μm). These morphological characteristics of the fungus were consistent with the description of conidial state of Apiognomonia errabunda (Roberge ex Desm.) Höhn. (3,4). Voucher specimens were deposited in the Korea University Herbarium (KUS). An isolate obtained from KUS-F26690 was deposited in the Korean Agricultural Culture Collection (Accession No. KACC46842). Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced. The resulting 549-bp sequence was deposited in GenBank (KC426947). This showed >99% similarity with sequences of A. errabunda (AJ888475 to 888477). For pathogenicity test, inoculum was prepared by harvesting conidia from 4-week-old cultures on potato dextrose agar. A conidial suspension (1 × 106 conidia/ml) was sprayed onto young leaves of three potted seedlings. Three seedlings treated with sterile distilled water served as controls. Plants were covered with plastic bags to maintain 100% relative humidity for 24 h and then kept in a greenhouse (20 to 26°C and 60 to 80% RH). After 26 days, typical leaf spot symptoms, identical to the ones observed in the field, developed on the inoculated leaves. No symptoms were observed on controls. A. errabunda was reisolated from the lesions of inoculated plants, fulfilling Koch's postulates. Oak anthracnose associated with A. errabunda (including A. quercina) has been recorded in Europe and North America (1,4). Oak anthracnose of evergreen Quercus glauca Thunb. (syn. Cyclobalanopsis glauca (Thunb.) Oerst.) associated with A. supraseptata in Japan is not related to this disease (2). To our knowledge, this is the first report of oak anthracnose of Q. aliena globally and also the first finding of A. errabunda in Asia as well as in Korea. This pathogen is known as one of the major forest pathogens in oak stand in Europe and North America (3). Pending further studies, including a risk assessment, A. errabunda may be considered as a potentially new and serious threat in native and planted ranges of Q. aliena in Korea. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, retrieved February 18, 2013. (2) S. Kaneko and T. Kobayashi. Trans. Mycol. Soc. Japan 25:11, 1984. (3) A. Ragazzi et al. Phytopathol. Mediterr. 46:295, 2007. (4) M. V. Sogonov et al. Mycol. Res. 111:693, 2007.

scholarly journals First Report of Phytophthora palmivora Causing Fruit Rot of Fig (Ficus carica L.) in China

Plant Disease ◽  
2013 ◽  
Vol 97 (9) ◽  
pp. 1252-1252 ◽  
Author(s):  
C. Zhang ◽  
W. Zhang ◽  
H. Q. Ma ◽  
G. Z. Zhang
Keyword(s):  
Large Scale ◽  
Morphological Characteristics ◽  
Pcr Amplification ◽  
Daily Rainfall ◽  
Ficus Carica ◽  
Fruit Rot ◽  
Phytophthora Palmivora ◽  
Universal Primers ◽  
First Report ◽  
Immature Fruit

Fresh fig (Ficus carica L.) has been grown on a large scale in Beijing, China, since 2011. In late July 2012, a rot disease occurred on immature fruit of fig after a heavy rain (average daily rainfall 170 mm) in Fangshan District, Beijing, which caused about 30% incidence of green fruit on trees. The symptom first appeared as a water-soaked lesion that was covered with a white, fluffy mass of mycelia, followed by a soft, mushy rot of infected area on the fruit. To isolate the causal agent, mycelia and sporangia from 10 symptomatic fruits were suspended in sterile water, spread on potato dextrose agar (PDA) plates, and incubated at 25°C for 18 h. The isolates from each diseased fruit showed the same colonial characteristics. A single sporangium was isolated under a dissecting microscope and transferred onto PDA to obtain a pure culture. On carrot agar, the colony was white and homogeneous with tidy edge, with a few aerial hyphae. Sporangia were obpyriform with obvious papillae and measured 54.7 to 63.8 (59.3) × 26.5 to 36.3 (30.7) μm. The chlamydospores produced in culture were spherical. The pathogen was identified as Phytophthora palmivora based on the morphological characteristics (3) and confirmed with ITS sequences by PCR amplification using rDNA universal primers ITS1 and ITS4. The resulting sequence (Accession No. KC131229) had a 99% identity to that of P. palmivora (JQ354937) isolated from Pachira aquatica. Koch's postulates were conducted by inoculating six surface-sterilized figs with a PDA plug from a 7-day-old culture, with six noninoculated (PDA plugs only) fruits serving as controls. The inoculated fruits were incubated at room temperature in a plastic box covered with film. Symptoms similar to those on the naturally infected fruits began on wounded fruits 48 h after inoculation and on non-wounded fruits 60 h after inoculation, while the six control fruits remained healthy. P. palmivora was reisolated from the symptomatic fruit tissue. P. palmivora is one of the most severe pathogens on edible figs, being reported by Japanese in 1941 (2). Fruit rot of fig caused by the pathogen was reported in Florida in 1984 (1). To our knowledge, this is the first report of P. palmivora leading to fruit rot on fig in China. References: (1) N. E. El-Gholl and S. A. Alfieri, Jr. Proc. Fla. State Hort. Soc. 97:327, 1984. (2) Y. Nisikado et al. Ber. Ohara Inst. 8:427, 1941. (3) Y. N. Yu. Flora Fungorum Sinicorum: Peronosporales (in Chinese) Vol. 6. Science Press, Beijing, 1998.

scholarly journals First Report of the Aecial State of Melampsora larici-populina on Larix spp. in North America

Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1242-1242 ◽  
Author(s):  
J. Grondin ◽  
M. Bourassa ◽  
R. C. Hamelin
Keyword(s):  
Life Cycle ◽  
North America ◽  
Morphological Characteristics ◽  
Pcr Amplification ◽  
Eastern North America ◽  
Populus Balsamifera ◽  
Specific Primers ◽  
Complete Life Cycle ◽  
Pathogenic Variation ◽  
The Many

Melampsora larici-populina Kleb. was reported for the first time in eastern North America during 2002, on Populus spp., its telial host (1). M. larici-populina, a heteroecious rust, alternates between species of Populus and Larix. Since M. larici-populina was observed again in 2003, we investigated the possibility that its basidiospores may infect larch (Larix spp.) resulting in spermogonia and aecia. Identification of Melampsora species from aeciospore morphology is difficult but urediniospores are distinctive. This is important since the native M. medusae also alternates between Populus and Larix spp. During the spring of 2004, aecia were observed on needles of exotic (Larix decidua Mill. and L. leptolepis (Siebold and Zucc.) Gordon) and indigenous (L. laricina (K. Koch)) larch in an arboretum in Lotbinière (Quebec, Canada) where M. larici-populina has previously been found. Larch needles with yellow blister-like fructifications were collected in May 2004 and fixed on top of petri plates to allow aeciospore release onto leaves of Jackii poplar (Populus balsamifera L. × P. deltoides Marsh.). After approximately 10 days, uredinia appeared on the abaxial surface of the poplar leaves. Some of the many needles collected yielded uredinia cultures on Jackii poplars. The majority of these cultures were identified as being M. larici-populina; one was M. medusae. M. larici-populina urediniospores were 32 to 48 μm long and possessed a characteristic apical bald spot. DNA was extracted from aecia and uredinia, and the internal transcribed spacer (ITS) of the ribosomal RNA gene was amplified in real-time polymerase chain reaction (PCR) by specific primers for M. medusae or M. larici-populina created from sequences (GenBank Accession Nos. AY429656 and AY429657). The 120 base pairs target fragments amplified only with the M. larici-populina specific primers with the 14 samples that were identified as M. larici-populina by morphological characteristics of the urediniospores. No PCR amplification was obtained with M. medusae primers. These results were not unexpected since larch has been previously reported as an aecial host of M. larici-populina elsewhere (2). The ability of M. larici-populina to overwinter and complete its life cycle has important consequences since it proves that it is established and can go through sexual reproduction. A complete life cycle in eastern North America may allow M. larici-populina to generate pathogenic variation that will challenge poplar breeders in this region. References: (1) L. Innes et al. Plant Dis. 88:85, 2004. (2) G. Newcombe et al. Plant Dis. 78:1218, 1994.

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