First Report of Branch Blight of Tree Peony Caused by Phoma glomerata in China

Tree peony (Paeonia suffruticosa Andrews) is a perennial woody deciduous shrub native to China and famous for its beautiful flowers. Starting in early autumn 2010, blighted branches of tree peony were detected in the International Peony Garden in Luoyang. The disease incidence was greater than 10% and disease symptoms included bulb atrophy and twig and branch dieback. Pycnidia were embedded within the bark of diseased branches. They were small, black, ostiolate, and measured 145 to 275 × 140 to 251 μm. Pycnoconidia were single-celled, hyaline or sandy beige, rounded to ellipsoidal, and 3.9 to 10.3 × 2.3 to 7.0 μm. Pure cultures were obtained by plating the pycnoconidia on potato dextrose agar (PDA). In culture, the fungus produced a circular, white to pink colony with pyknotic and linter shaped aerial mycelium. Numerous pycnidia, initially brown and dark at maturity, were embedded in the mycelium, especially in the center of the colony, with a few of them scattered in the edge. The morphological characteristics were consistent with Phoma (2). The ITS1-5.8S-ITS2 region of three isolates were PCR amplified and sequenced with primers ITS1 and ITS4. Sequences (GenBank Accession No. JX885584) showed 99% identity with reference isolates of Peyronellaea glomerata (Corda) Goid (AB470906.1 and HQ380779.1) and Phoma glomerata (Corda) Wollenw. & Hochapfel (EU098115.1). These two species are synonyms (1). To test pathogenicity, nine healthy branches of 3-year-old potted tree peony plants were wound-inoculated with a PDA disk containing pycnidia from an actively growing colony of P. glomerata. Three control branches were inoculated with sterile PDA disks. Each inoculated branch was wrapped in a plastic bag and maintained in a greenhouse at 25 to 28°C. After 3 days, brown patches appeared on inoculated branches and extended by up to 1 cm. Pycnidia identical to those observed in the field and in storage appeared on all inoculated branches 7 days after inoculation. Control branches did not show symptoms. The pathogen was reisolated from inoculated branches, fulfilling Koch's postulates. P. glomerata was reported as the causal agent of withering of flowers and young shoots of grapevines in Yugoslavia (3). To our knowledge, P. glomerata and Botryosphaeria dothidea have always been reported together, causing branch wilting or dieback. To our knowledge, this is the first report of branch blight of tree peony caused by P. glomerata in China. References: (1) M. M. Aveskamp et al. Mycol. Soc. Am. 101:363, 2009. (2) G. H. Boerema et al. Studies in Mycology, 3, 1973. (3) A. Šaric-Sabadoš et al. Atti Ist. bot. Univ. Pavia 18:101, 1960.

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First Report of Botryosphaeria dothidea, Diplodia seriata, and Neofusicoccum luteum Associated with Canker and Dieback of Grapevines in Tunisia

Plant Disease ◽

10.1094/pdis-05-13-0530-pdn ◽

2014 ◽

Vol 98 (3) ◽

pp. 420-420 ◽

Cited By ~ 6

Author(s):

S. Chebil ◽

R. Fersi ◽

A. Yakoub ◽

S. Chenenaoui ◽

M. Chattaoui ◽

...

Keyword(s):

Morphological Characteristics ◽

Aerial Mycelium ◽

Its2 Region ◽

Pathogenicity Test ◽

Botryosphaeria Dothidea ◽

Diplodia Seriata ◽

First Report ◽

Grapevine Dieback ◽

Pinus Spp ◽

Neofusicoccum Luteum

In 2011, common symptoms of grapevine dieback were frequently observed in 2- to 5-year-old table grape (Vitis vinifera L.) cvs. in four vineyards located in northern Tunisia. The symptoms included dead spur and cordons, shoot dieback, and sunken necrotic bark lesions, which progressed into the trunk resulting in the death of large sections of the vine. Longitudinal and transversal sections of cordons and spurs from symptomatic vines revealed brown wedge-shaped cankers of hard consistency. Twelve symptomatic samples from spur and cordons were collected, surface disinfected by dipping into 5% (v/v) sodium hypochlorite for 2 min, and small pieces from the edge of necrotic and healthy tissue were removed and plated onto potato dextrose agar (PDA) at 25°C in the dark. Based on colony and conidia morphological characteristics, isolates were divided in three species, named Diplodia seriata, Botryosphaeria dothidea, and Neofusicoccum luteum. D. seriata colonies were gray-brown with dense aerial mycelium producing brown cylindric to ellipsoid conidia rounded at both ends and averaged 22.4 × 11.7 μm (n = 50). B. dothidea colonies were initially white with abundant aerial mycelium, gradually becoming dark green olivaceous. Conidia were fusiform to fusiform elliptical with a subobtuse apex and averaged 24.8 × 4.7 μm (n = 50). N. luteum colonies were initially pale to colorless, gradually darkening with age and becoming gray to dark gray producing a yellow pigment that diffuses into the agar. Conidia were hyaline, thin-walled, aseptate, fusiform to fusiform elliptical, and averaged 19.8 × 5.5 μm (n = 50). Identity of the different taxa was confirmed by sequence analyses of the internal transcribed spacer (ITS1-5.8S-ITS2) region of the rDNA and part of the elongation factor 1-alpha (EF1-α) gene. BLAST analysis of sequences indicated that six isolates were identified as D. seriata (GenBank: AY259094, AY343353), one isolate as B. dothidea (AY236949, AY786319) and one isolate as N. luteum (AY259091, AY573217). Sequences were deposited in GenBank under accessions from KC178817 to KC178824 and from KF546829 to KF546836 for ITS region and EF1-α gene, respectively. A pathogenicity test was conducted on detached green shoots cv. Italia for the eight Botryosphaeriaceae isolates. Shoots were inoculated by placing a colonized agar plug (5 mm diameter) from the margin of a 7-day-old colony on fresh wound sites made with a sterilized scalpel. Each wound was covered with moisturized cotton and sealed with Parafilm. Control shoots were inoculated using non-colonized PDA plugs. After 6 weeks, discoloration of xylem and phloem and necrosis with average length of 38.8, 17.6, and 11.2 mm were observed from inoculated shoots with D. seriata, N. luteum, and B. dothidea, respectively, and all three fungi were re-isolated from necrotic tissue, satisfying Koch's postulates. Control shoots showed no symptoms of the disease and no fungus was re-isolated. In Tunisia, Botryosphaeria-related dieback was reported only on citrus tree caused by B. ribis (2), on Pinus spp. caused by D. pinea (4), on Quercus spp. caused by D. corticola (3), and on olive tree (Olea europea) caused by D. seriata (1). To our knowledge, this is the first report of D. seriata, B. dothidea, and N. luteum associated with grapevine dieback in Tunisia. References: (1) M. Chattaoui et al. Plant Dis. 96:905, 2012. (2) H. S. Fawcett. Calif. Citrogr. 16:208, 1931. (3) B. T. Linaldeddu et al. J. Plant Pathol. 91:234. 2009. (4) B. T. Linaldeddu et al. Phytopathol. Mediterr. 47:258, 2008.

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First Report of Colletotrichum siamense Causing Anthracnose of Monstera deliciosa in Zhanjiang, China

Plant Disease ◽

10.1094/pdis-08-20-1839-pdn ◽

2020 ◽

Author(s):

Yue Lian Liu ◽

Jian Rong Tang ◽

Yu Han Zhou

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Pathogenicity Test ◽

Sterile Water ◽

Single Spore ◽

First Report ◽

Rdna Its ◽

Colletotrichum Siamense ◽

Monstera Deliciosa ◽

Pure Cultures

Monstera deliciosa Liebm is an ornamental foliage plant (Zhen et al. 2020De Lojo and De Benedetto 2014). In July of 2019, anthracnose lesions were observed on leaves of M. deliciosa cv. Duokong with 20% disease incidence of 100 plants at Guangdong Ocean University campus (21.17N,110.18E), Guangdong Province, China. Initially affected leaves showed chlorotic spots, which coalesced into larger irregular or circular lesions. The centers of spots were gray with a brown border surrounded by a yellow halo (Supplementary figure 1). Twenty diseased leaves were collected for pathogen isolation. Margins of diseased tissue was cut into 2 × 2 mm pieces, surface-disinfected with 75% ethanol for 30 s and 2% sodium hypochlorite (NaOCl) for 60 s, rinsed three times with sterile water before isolation. Potato dextrose agar (PDA) was used to culture pathogens at 28℃ in dark. Successively, pure cultures were obtained by transferring hyphal tips to new PDA plates. Fourteen isolates were obtained from 20 leaves. Three single-spore isolates (PSC-1, PSC-2, and PSC-3) were obtained ,obtained, which were identical in morphology and molecular analysis (ITS). Therefore, the representative isolate PSC-1 was used for further study. The culture of isolate PSC-1 on PDA was initially white and later became cottony, light gray in 4 days, at 28 °C. Conidia were single celled, hyaline, cylindrical, clavate, and measured 13.2 to 18.3 µm × 3.3 to 6.5 µm (n = 30). Appressoria were elliptical or subglobose, dark brown, and ranged from 6.3 to 9.5 µm × 5.7 to 6.5 µm (n = 30). Morphological characteristics of isolate PSC-1 were consistent with the description of Colletotrichum siamense (Prihastuti et al. 2009; Sharma et al. 2013). DNA of the isolate PSC-1 was extracted for PCR sequencing using primers for the rDNA ITS (ITS1/ITS4), GAPDH (GDF1/GDR1), ACT (ACT-512F/ACT-783R), CAL (CL1C/CL2C), and TUB2 (βT2a/βT2b) (Weir et al. 2012). Analysis of the ITS (accession no. MN243535), GAPDH (MN243538), ACT (MN512640), CAL (MT163731), and TUB2 (MN512643) sequences revealed a 97-100% identity with the corresponding ITS (JX010161), GAPDH (JX010002), ACT (FJ907423), CAL (JX009714) and TUB2 (KP703502) sequences of C. siamense in GenBank. A phylogenetic tree was generated based on the concatenated sequences of ITS, GAPDH, ACT, CAL, and TUB2 which clustered the isolate PSC-1 with C. siamense the type strain ICMP 18578 (Supplementary figure 2). Based on morphological characteristics and phylogenetic analysis, the isolate PSC-1 associated with anthracnose of M. deliciosa was identified as C. siamense. Pathogenicity test was performed in a greenhouse at 24 to 30oC with 80% relative humidity. Ten healthy plants of cv. Duokong (3-month-old) were grown in pots with one plant in each pot. Five plants were inoculated by spraying a spore suspension (105 spores ml-1) of the isolate PSC-1 onto leaves until runoff, and five plants were sprayed with sterile water as controls. The test was conducted three times. Anthracnose lesions as earlier were observed on the leaves after two weeks, whereas control plants remained symptomless. The pathogen re-isolated from all inoculated leaves was identical to the isolate PSC-1 by morphology and ITS analysis, but not from control plants. C. gloeosporioides has been reported to cause anthracnose of M. deliciosa (Katakam, et al. 2017). To the best of our knowledge, this is the first report of C. siamense causing anthracnose on M. deliciosa in ChinaC. siamense causes anthracnose on a variety of plant hosts, but not including M. deliciosa (Yanan, et al. 2019). To the best of our knowledge, this is the first report of C. siamense causing anthracnose on M. deliciosa, which provides a basis for focusing on the management of the disease in future.

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First Report of a Chaetomella sp. Causing a Leaf Spot on Sansevieria trifasciata in China

Plant Disease ◽

10.1094/pdis-10-12-0993-pdn ◽

2013 ◽

Vol 97 (7) ◽

pp. 992-992 ◽

Cited By ~ 4

Author(s):

Y. L. Li ◽

Z. Zhou ◽

W. Lu ◽

J. R. Ye

Keyword(s):

Leaf Spot ◽

Disease Incidence ◽

Morphological Characteristics ◽

Leaf Tissue ◽

Aerial Mycelium ◽

Control Treatment ◽

Distilled Water ◽

First Report ◽

Potted Plants ◽

Fungal Isolates

Sansevieria trifasciata originates from tropical West Africa. It is widely planted as a potted ornamental in China for improving indoor air quality (1). In February 2011, leaves of S. trifasciata plants in an ornamental market of Anle, Luoyang City, China, were observed with sunken brown lesions up to 20 mm in diameter, and with black pycnidia present in the lesions. One hundred potted plants were examined, with disease incidence at 20%. The symptomatic leaves affected the ornamental value of the plants. A section of leaf tissue from the periphery of two lesions from a plant was cut into 1 cm2 pieces, soaked in 70% ethanol for 30 s, sterilized with 0.1% HgCl2 for 2 min, then washed five times in sterilized distilled water. The pieces were incubated at 28°C on potato dextrose agar (PDA). Colonies of two isolates were brown with submerged hyphae, and aerial mycelium was rare. Abundant and scattered pycnidia were reniform, dark brown, and 200 to 350 × 100 to 250 μm. There were two types of setae on the pycnidia: 1) dark brown setae with inward curved tops, and 2) straight, brown setae. Conidia were hyaline, unicellular, cylindrical, and 3.75 to 6.25 × 1.25 to 2.50 μm. Morphological characteristics suggested the two fungal isolates were a Chaetomella sp. To confirm pathogenicity, six mature leaves of a potted S. trifasciata plant were wounded with a sterile pin after wiping each leaf surface with 70% ethanol and washing each leaf with sterilized distilled water three times. A 0.5 cm mycelial disk cut from the margin of a 5-day-old colony on a PDA plate was placed on each pin-wounded leaf, ensuring that the mycelium was in contact with the wound. Non-colonized PDA discs were placed on pin-wounded leaves as the control treatment. Each of two fungal isolates was inoculated on two leaves, and the control treatment was done similarly on two leaves. The inoculated plant was placed in a growth chamber at 28°C with 80% relative humidity. After 7 days, inoculated leaves produced brown lesions with black pycnidia, but no symptoms developed on the control leaves. A Chaetomella sp. was reisolated from the lesions of inoculated leaves, but not from the control leaves. An additional two potted plants were inoculated using the same methods as replications of the experiment, with identical results. To confirm the fungal identification, the internal transcribed spacer (ITS) region of rDNA of the two isolates was amplified using primers ITS1 and ITS4 (2) and sequenced. The sequences were identical (GenBank Accession No. KC515097) and exhibited 99% nucleotide identity to the ITS sequence of an isolate of Chaetomella sp. in GenBank (AJ301961). To our knowledge, this is the first report of a leaf spot of S. trifasciata caused by Chaetomella sp. in China as well as anywhere in the world. References: (1) X. Z. Guo et al. Subtropical Crops Commun. Zhejiang 27:9, 2005. (2) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

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First Report of Crown and Root Rot Caused by Rhizoctonia solani AG-4 on Banana Passionflower (Passiflora mollissima) in Italy

Plant Disease ◽

10.1094/pdis-05-11-0411 ◽

2011 ◽

Vol 95 (9) ◽

pp. 1194-1194 ◽

Cited By ~ 2

Author(s):

G. Polizzi ◽

D. Aiello ◽

V. Guarnaccia ◽

A. Panebianco ◽

P. T. Formica

Keyword(s):

Rhizoctonia Solani ◽

Root Rot ◽

Disease Incidence ◽

Morphological Characteristics ◽

Fluorescent Light ◽

Disease Symptoms ◽

First Report ◽

Pathogenicity Tests ◽

Crown And Root Rot ◽

Safranin O

The genus Passiflora (Passifloraceae family) contains more than 500 species and several hybrids. In Italy, some of these species and hybrids are grown as ornamental evergreen vines or shrubs. During August and September 2010, a crown and root rot was observed in a stock of approximately 6,000 potted 2-year-old plants of Passiflora mollissima (Kunth) Bailey, commonly known as the banana passionflower, in a nursery located in eastern Sicily (southern Italy). Disease incidence was approximately 20%. Disease symptoms consisted of water-soaked lesions at the crown and a root rot. Successively, older crown lesions turned light brown to brown and expanded to girdle the stem. As crown and root rot progressed, basal leaves turned yellow and gradually became necrotic and infected plants wilted and died. A fungus with mycelial and morphological characteristics of Rhizoctonia solani Kühn was consistently isolated from crown lesions and brown decaying roots when plated on potato dextrose agar (PDA) amended with streptomycin sulfate at 100 μg/ml. Fungal colonies were initially white, turned brown with age, and produced irregularly shaped, brown sclerotia. Mycelium was branched at right angles with a septum near the branch with a slight constriction at the branch base. Hyphal cells removed from 10 representative cultures grown at 25°C on 2% water agar were determined to be multinucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400. Anastomosis groups were determined by pairing isolates on 2% water agar in petri plates (4). Pairings were made with tester strains of AG-1, AG-2, AG-3, AG-4, AG-5, AG-6, and AG-11. Anastomosis was observed only with tester isolates of AG-4 (3). Pathogenicity tests were performed on container-grown, healthy, 3-month-old cuttings. Twenty plants of P. mollissima were inoculated near the base of the stem with five 1-cm2 PDA plugs from 5-day-old mycelial plugs obtained from two representative cultures. The same number of plants served as uninoculated controls. Plants were maintained at 25°C and 95% relative humidity with a 12-h fluorescent light/dark regimen. Wilt symptoms due to crown and root rot, identical to ones observed in the nursery, appeared 7 to 8 days after inoculation with either of the two isolates and all plants died within 20 days. No disease was observed on control plants. R. solani AG-4 was reisolated from symptomatic tissues and identified as previously described, confirming its pathogenicity. Damping-off or crown and root rot due to R. solani were previously detected on P. edulis in Brazil, Africa, India, Oceania, and Australia (2). To our knowledge, this is the first report of R. solani causing crown and root rot on P. mollissima. References: (1) R. J. Bandoni. Mycologia 71:873, 1979. (2) J. L. Bezerra and M. L. Oliveira. Fitopathol. Brasil. 9:273, 1984. (3) D. E. Carling. Page 37 in: Grouping in Rhizoctonia solani by Hyphal Anastomosis Reactions. Kluwer Academic Publishers, the Netherlands, 1996. (4) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.

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First Report of Fruit Rot and Associated Branch Dieback of Almond in California Caused by a Phomopsis Species Tentatively Identified as P. amygdali

Plant Disease ◽

10.1094/pdis.1999.83.11.1073c ◽

1999 ◽

Vol 83 (11) ◽

pp. 1073-1073 ◽

Cited By ~ 7

Author(s):

J. E. Adaskaveg ◽

H. Förster ◽

J. H. Connell

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

The United States ◽

Tree Canopy ◽

Fruit Rot ◽

Control Treatment ◽

Field Inoculation ◽

First Report ◽

Branch Dieback ◽

Summer Fruit

A fruit rot of almond (Prunus dulcis (Mill.) D. Webb.) was observed in an orchard in Durham, CA (Butte County), in June of 1998 after an unusually wet spring with a total precipitation of 17.2 cm for April and May. Disease incidence on fully developed fruit of almond cv. Sonora was nearly 90% in the lower tree canopy by July. Almond cv. Nonpareil grown in alternate rows in the same orchard was much less affected. Fruit symptoms included extensive grayish brown discolored and shriveled hulls, often associated with a clear gum secretion and shriveled kernels. Affected fruit frequently abscised. Leaf symptoms and branch dieback were not associated with the disease in 1998. In May of 1999, however, extensive twig dieback was observed on almond cv. Sonora in the same orchard. Isolations from more than 100 symptomatic fruit were conducted from 9 sampling sites in the 9-ha orchard. Based on morphological characteristics, the same fungus was isolated from 93% of the fruit. The fungus also was isolated consistently from samples exhibiting twig dieback. During a major disease survey conducted in 1998, the fungus was only incidentally isolated from almond fruit from other California orchards. Ascomata were not observed in vivo or in vitro. The fungus produced alpha and beta spores in pycnidia when cultured on potato dextrose agar. Spore measurements were obtained from 10 spores for each of 3 isolates obtained from fruit or twig dieback of almond cv. Sonora. Conidial dimensions of fruit and twig isolates were very similar. Based on spore sizes, with alpha spores measuring 5.3 to 7.5 (to 8) × 1.7 to 2.5 μm and beta spores measuring12.8 to 29.8 × 0.6 to 0.7 μm, the fungus was tentatively identified as Phomopsis amygdali (Del.) Tuset & Portilla (2). Previous reports on this fungus (2), however, indicated that beta spores are not produced in culture, and disease symptoms have not been observed on fruit. The fungus was morphologically different from other species of Phomopsis reported from almond and other Prunus species, including P. mali Roberts, P. padina (Sacc. & Roum.) Died., P. parabolica Petrak, P. perniciosa Grove, P. pruni (Ellis & Dearn.) Wehm., P. prunorum (Cooke) Grove, P. ribetejana Camara, and P. stipata (Lib.) Sutton (3). Field inoculation studies were performed in May of 1999 on almond cvs. Carmel and Mission. Almond fruit were wounded (2 × 2 × 2 mm) or left unwounded and were sprayed with water (control) or a suspension of alpha spores (105 spores per ml). Branches were bagged for 4 days to maintain high humidity. Fruit symptoms on cv. Carmel were observed after 4 weeks on wounded and nonwounded inoculated fruit, and P. amygdali was successfully reisolated from diseased tissue. No symptoms were observed in the control treatment for almond cv. Carmel or in any treatment for cv. Mission. This is the first report of P. amygdali causing a late spring and summer fruit rot and associated branch dieback of almond in North America (1). References: (1) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN. (2) J. J. Tuset and M. T. Portilla. Taxonomic status of Fusicoccum amygdali and Phomopsis amygdalina. Can. J. Bot. 67:1275, 1989. (3) F. A. Uecker. 1988. A World List of Phomopsis Names with Notes on Nomenclature, Morphology, and Biology. Mycologia Memoir No. 13. J. Cramer, Berlin.

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First Report of Anthracnose Caused by Glomerella cingulata on Passion Fruit in Argentina

Plant Disease ◽

10.1094/pdis.2000.84.6.706a ◽

2000 ◽

Vol 84 (6) ◽

pp. 706-706 ◽

Cited By ~ 4

Author(s):

S. Wolcan ◽

S. Larran

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Passion Fruit ◽

High Yield ◽

Conidial Suspension ◽

Glomerella Cingulata ◽

First Report ◽

Plastic Bags ◽

Subtropical Fruit

Passion fruit (Passiflora edulis Sims.) is a subtropical fruit recently cultivated in Misiones Province, Argentina. In spring 1997, a severe epidemic of anthracnose was observed. Disease incidence was ≍95%, causing high yield losses. Sunken, gray lesions on the whole surface of young fruits were observed. Under humid conditions, acervuli containing masses of spores and dark setae were found within lesions. On leaves, tendrils, and twigs, circular and irregular brown spots with darker edges were observed. Abortion of flowers also was recorded. Cultures on potato dextrose agar yielded abundant, gray aerial mycelium and one-celled, hyaline, oblong conidia with obtuse or rounded ends (11.2 to 15.0 × 3.8 to 4.6 μm). Perithecia were scarce (90.2 to 220.0 μm). Asci were not conspicuous, and ascospores measured 10.8 to 23.4 × 3.5 to 7.0 μm. Based on morphological characteristics, the fungus was identified as Glomerella cingulata (anamorph Colletotrichum gloeosporioides) (2). Fruits and leaves of P. edulis with and without wounds were sprayed with a conidial suspension (106/ml) and incubated in plastic bags for 48 h. Lesions similar to original symptoms were observed after 2 weeks only on wounded leaves and fruits. G. cingulata was reisolated, confirming Koch's postulates. This disease has been recorded in Brazil and Japan (1). This is the first report of G. cingulata on passion fruit in Argentina. Reference: (1) E. Francisco Neto et al. Summa Phytopathol. 21:25, 1995. (2) J. A. von Arx. Phytopathol. Z. 29:413, 1957.

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First Report of Lasiodiplodia pseudotheobromae Causing Stem End Rot of Mango Fruit in Pakistan

Plant Disease ◽

10.1094/pdis-01-21-0099-pdn ◽

2021 ◽

Author(s):

Muhammad Waqar Alam ◽

Arif Malik ◽

Abdul Rehman ◽

Mubeen Sarwar ◽

Tahir Shafeeq ◽

...

Keyword(s):

Disease Incidence ◽

Mangifera Indica ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Postharvest Disease ◽

Single Spore ◽

Mango Fruit ◽

First Report ◽

Field Samples ◽

Rot Disease

Mango (Mangifera indica L.) is considered a desirable fruit in international markets and is grown throughout tropical and sub-tropical countries around the world (Alemu, 2014). Stem end rot is the most damaging and complex postharvest disease of mango, resulting in losses of up to 40% in Pakistan, which is the leading producer and exporter (Alam et al. 2017). A field survey was conducted in June of 2017 and 2018 in the Rahim Yar Khan and Multan- major mango producing regions of Punjab Province. After mature but unripe mango fruit (cv. Samar Bahisht Chaunsa) were stored at 12°C for 2 weeks to permit ripening, water-soaked, dark brown to purplish black decay began to appear around the stem end portion. The decay gradually enlarged and covered the whole fruit after 7 days. Disease incidence was estimated at 30%. Small pieces (3 to 4 mm2) from the periphery of 15 diseased fruit were surface disinfected with 1% sodium hypochlorite for 2 min, rinsed three times in sterilized distilled water, air dried, and then placed aseptically onto potato dextrose agar (PDA) medium and incubated at 25°C under a 12-h light/dark photoperiod for 7 days. Twelve single-spore isolates with similar morphology were isolated from the infected tissues. Initially the fungus produced thick, fluffy and greyish-white aerial mycelium, that later turned into dark gray colonies. Conidia were unicellular, ellipsoidal, and initially hyaline, but with age became dark brown and developed a central septum. Conidia measured 24.5 to 31.5 × 11.4 to 15.7 µm (n = 60). Conidiophores were inflated at their base with one diaphragm which reduced to conidiogenous cells. Conidiogenous cells were hyaline and cylindrical. On the basis of morphological characteristics, the fungus was tentatively identified as Lasiodiplodia sp., a member of the family Botryosphaeriaceae (Alves et al. 2008). For molecular identification, genomic DNA was extracted from mycelium following the CTAB method. The internal transcribed spacer (ITS) region of rDNA and translation elongation factor 1-alpha (TEF1-α) gene were amplified using ITS1/ITS4 (White et al. 1990) and EF1-728F/EF1-986R primer sets (Carbone and Kohn 1999), respectively. BLASTn searches of sequences revealed 99% to 100% identity with the reference sequences of various Lasiodiplodia pseudotheobromae isolates (GenBank accession nos. MH057189 for ITS; MN638768 for TEF-1a). The sequences were deposited in GenBank (accession nos. MW439318, MW433883 for ITS; and MW463346, MW463347 for TEF-1a). To fulfill Koch’s postulates, a suspension of 105 conidia/ml from a 7-day-old culture of L. pseudotheobromae was used to inoculate fully mature but unripe mango fruit (cv. Samar Bahisht Chaunsa). Fruit were pricked with a sterilized needle to a depth of 4 mm at the stem end portion, injected with 50 μl of the prepared spore suspension (Awa et al. 2012), and stored at 12°C for 3 weeks under 70 to 80% RH. Twenty mango fruit were inoculated, and 10 were inoculated with sterile water only. After 15 days, most fruit showed typical symptoms at the stem end. Reisolations from symptomatic fruit following the procedures described above for isolating and identifying the fungal cultures from infected field samples, consistently yielded a fungus identical to L. pseudotheobromae. Control fruit remained disease-free. Although L. pseudotheobromae was previously reported on several forest and fruit trees (Alves et al. 2008; Awan et al. 2016), this is the first report of the pathogen causing stem end rot disease of mango in Pakistan. This report is important for the new studies aiming at management of stem end rot disease of mango caused by L. pseudotheobromae in Pakistan.

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First Report of Forsythia Shoot Blight Caused by Phytophthora nicotianae in Connecticut

Plant Disease ◽

10.1094/pdis-03-14-0297-pdn ◽

2014 ◽

Vol 98 (9) ◽

pp. 1278-1278

Author(s):

J. A. LaMondia ◽

D. W. Li ◽

A. M. Madeiras ◽

R. L. Wick

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Phytophthora Nicotianae ◽

First Report ◽

Sterile Needle ◽

Shoot Blight ◽

Pathogenicity Tests ◽

Half Strength ◽

Internal Necrosis

Blighting of Forsythia × intermedia ‘Showoff’ was first observed affecting several hundred plants in a commercial nursery in Connecticut in September 2012. Symptoms included wilting, leaf and stem blight, and dieback progressing to plant death. A Phytophthora sp. was isolated from symptomatic tissues on half-strength potato dextrose agar (½PDA). Colonies were white and cottony on ½PDA, reaching 9 mm in 15 days at 25°C, but colorless and inconspicuous on pimaricin, ampicillin, rifampicin, pentachloronitrobenzene agar (PARP) with sparse and limited aerial mycelium, reaching 60 mm in 15 days at 25°C. The characteristics of the pathogen were observed and measured from a 3-month-old colony on ½PDA. Sporangia were abundant, various in shape, ovoid, ellipsoid to pyriform or limoniform, occasionally gourd shaped or irregular; (17.9) 27.2 to 41.4 (47.3) × (12.6) 19.1 to 30.5 (36.7) μm (n = 30), length/breadth ratio 1.4 ± 0.2, papillate and noncaducous. Papillae measured 2.9 ± 0.8 × 3.4 ± 0.8 μm (n = 10). Chlamydospores were present, 23.4 ± 3.1 × 22 ± 3.3 μm (n = 10). Oogonia and oospores were not observed. Arachnoid mycelia were present. These morphological characteristics are consistent with Phytophthora nicotianae Breda de Haan (1). The identity of the pathogen was confirmed as P. nicotianae by BLAST analysis of ITS, Cox II, and beta tubulin gene sequences (99% match for the three sequences, E value = 0). Pathogenicity tests were conducted four times on healthy liners of Forsythia × intermedia ‘Showoff’ grown in 10-cm-diameter pots. Leaves and stems were wounded by pricking with a sterile needle and six plants were inoculated with 0.25 cm2 plugs of the pathogen growing on ½PDA placed on three leaves and in three stem nodes and covered with Parafilm. Controls consisted of an equal number of plants wounded and inoculated with ½PDA alone. All plants were placed inside high humidity chambers for 24 h and then transferred to a greenhouse for up to 1 month. Typical symptoms developed within 1 week of inoculation and the pathogen was re-isolated from diseased tissue. Disease incidence was nearly 100% of inoculated leaves and stems and not observed in control plants without the pathogen. Three replicate 6-week-old broadleaf tobacco ‘C9’ plants were each inoculated with tobacco or forsythia isolates of P. nicotianae or sterile media alone, by wounding stems and placing colonized 0.25 cm2 ½PDA plugs into wounds and covering with Parafilm. After 1 week, stems were split and the length of internal necrosis in the stem measured. Disease resulted from inoculation with both the tobacco and forsythia isolates and stem necrosis averaged 43 and 23 mm for tobacco or forsythia isolates, respectively. No necrosis was observed in the pathogen-free controls. P. nicotianae has been reported from the basal stem and roots of F. viridissima in Italy (2) and from shoots of Forsythia × intermedia in Virginia (3). To our knowledge, this is the first report of P. nicotianae causing shoot blight on Forsythia in the northeastern United States. References: (1) J. van. Breda de Haan. Mededeelingenuit's Lands Plantentuin Batavia. 15:57, 1896. (2) S. O. Cacciola et al. Plant Dis. 78:525, 1994. (3) C. X. Hong et al. Plant Dis. 89:430, 2005.

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First Report of Pilidium concavum on Paeonia suffruticosa in China

Plant Disease ◽

10.1094/pdis-94-2-0271b ◽

2010 ◽

Vol 94 (2) ◽

pp. 271-271 ◽

Cited By ~ 2

Author(s):

Y. B. Duan ◽

Y. B. Kang ◽

Z. Z. Yu

Keyword(s):

Aerial Mycelium ◽

Causal Agent ◽

Its2 Region ◽

Paeonia Suffruticosa ◽

Humid Atmosphere ◽

First Report ◽

Leaf Spots ◽

Initial Symptoms ◽

Perennial Shrub ◽

Pure Cultures

Paeonia suffruticosa Andrews, a deciduous perennial shrub, is known for its beautiful and charming flowers. It is regarded as the flower symbol of China and cultivated throughout the country. Since 2006, large, brown necrotic spots have been observed on numerous P. suffruticosa plants in gardens in Luoyang, China. Spots appeared each year and were observed on more than 50% of the plants, sometimes affecting more than half of the leaf. Initial symptoms appeared as small, round, water-soaked lesions in the middle or on the margin of leaves. These areas enlarged up to 1 to 3 cm in diameter and were circular or irregular, brown to dark brown, and pale brown on the margins. In a humid atmosphere, black, sessile, discoid conidiomata developed on the spots and exuded a pink spore mass that turned brown with age. Conidiophores were hyaline, unicellular, cylindrical, and fusiform and 5.0 to 8.0 μm long and 1.4 to 2.0 μm wide. Pure cultures were obtained by plating the spores on potato dextrose agar (PDA) medium. In culture, the fungus produced a gray-to-brown colony with whitish aerial mycelium. The morphology and size of conidia were comparable with previous descriptions of Pilidium concavum (Desm.) Höhn. (1). The ITS1-5.8S-ITS2 region of the isolate was amplified by PCR with primers ITS1 and ITS4 and sequenced. The 472-nt sequence was 100% identical to that of the Pilidium concavum specimen voucher BPI 1107275 (GenBank Accession No. AY487094). To validate Koch's postulates, pathogenicity was tested by inoculating 10 leaves of P. suffruticosa with mycelia plugs from a colony growing on PDA; leaves inoculated with the plugs of PDA medium only served as the control. Leaves were covered with plastic for 24 h to maintain high relative humidity. After 7 days, 100% of the mycelium-inoculated leaves showed symptoms identical to those observed on P. suffruticosa leaves affected in the field, whereas all leaves inoculated with PDA medium only remained free of symptoms. Reisolation of the fungus from leaf lesions confirmed that the causal agent was Pilidium concavum. Thus, we concluded that Pilidium concavum is the causal agent of leaf spots of P. suffruticosa. This disease has been reported to be frequently occurring on P. suffruticosa stems imported from Japan (1), but to our knowledge, this is the first report of Pilidium concavum on P. suffruticosa in China. References: (1) M. E. Palm. Mycologia 83:787, 1991.

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First Report of a Branch Dieback of Olive Trees in Tunisia Caused by a Phoma sp.

Plant Disease ◽

10.1094/pdis-94-5-0636c ◽

2010 ◽

Vol 94 (5) ◽

pp. 636-636 ◽

Cited By ~ 7

Author(s):

A. Rhouma ◽

M. A. Triki ◽

S. Krid ◽

J. J. Tuset ◽

M. Msallem

Keyword(s):

Disease Incidence ◽

Olive Tree ◽

Conidial Suspension ◽

Internal Transcribed Spacer Region ◽

Canker Disease ◽

First Report ◽

Brown Discoloration ◽

Plastic Bag ◽

Olive Trees ◽

Branch Dieback

From 2007 to 2008, a new dieback of branches of olive trees was observed in several orchards in central and southern Tunisia. The appearance of this new syndrome coincided with warm temperatures and frequent rainfall from February to April 2007. Affected trees were observed in seven commercial orchards; disease incidence ranged from 1 to 9% and affected trees were randomly distributed in each orchard. Symptoms included abundant dead branches and wilted leaves remained attached. Distinct brown areas appeared on the bark of current-year shoots as well as on larger branches. Cankers on branches that were >2 years old were difficult to detect but were conspicuous in current-year shoots. To determine the etiology of this new syndrome, a study was carried out on samples of affected branches collected from 2007 to 2008 from different areas of the country. Unidentified species of Chaetomium and Phoma were isolated from the margins of the cankers. Koch's postulates were performed with one isolate each of a Chaetomium sp. and a Phoma sp on 2-year-old olive trees, cv. Chemlali, grown in 13-cm-diameter pots containing a sand/lime/peat mixture. Stems were inoculated by placing 10 μl of conidial suspension (106 conidia/ml) on 1-cm-long longitudinal stem wounds that had been made with a sterile scalpel. Control plants were wounded, but inoculum was replaced with sterile distilled water. Three sets of 10 plants each were wound inoculated with each of the fungi on the same day. Inoculated plants were covered with a polyethylene plastic bag to retain moisture and incubated for 2 months at 30°C with a 12-h photoperiod. After 45 days, only branches inoculated with the Phoma isolate showed brown discoloration areas at the inoculation sites. A Phoma sp. was recovered from necrotic bark from each of the 10 inoculated plants. Conidia were hyaline, unicellular, slightly ellipsoidal, and 4.8 to 6.3 × 1.8 to 2.2 μm. To confirm the identification, DNA extraction was done with hyphae collected from a 7-day-old culture on PDA after incubation at 25°C (1). Fungal primers ITS1 and ITS4 (3) were used for amplification. Purified amplicons were directly sequenced using the ITS1 and ITS4 primers for the internal transcribed spacer region of rDNA. A BLAST search of the GenBank database revealed 96% homology with Phoma sp. isolate (AJ972865.1) and 98% homology with Phoma medicaginis isolate (DQ026014.1). P. incompta has been reported as responsible for branch dieback of olive tree in Italy (2). To our knowledge, this is the first report of a canker disease of olive caused by a Phoma sp. in Tunisia. References: (1) S. R. Tendulkar et al. Biotechnol. Lett. 22:1941, 2003. (2) L. Tosi and A. Zazzerini. Petria 4:161, 1994. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

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