First Report of Anthracnose Caused by Colletotrichum gloeosporioides on Soybean (Glycine max) in Malaysia

Soybean (Glycine max L.) is one of the most economically important crops in the world, and anthracnose is known to infect soybean in most countries. Colletotrichum truncatum is the common pathogen causing anthracnose of soybean. However, at least five species of Colletotrichum have been reported on soybean worldwide (2). In July 2010, anthracnose symptoms were observed on soybean in the experimental fields of the agriculture station in Ladang Dua, University Putra Malaysia located in Selangor state of Malaysia. Symptoms were initially observed on a few plants randomly within one field, but after 4 weeks, the disease was found in two additional fields scattered across an area of 1 km2. Pinkish-brown lesions were observed on the pods, and the formation of dark lesions on the leaves and stems was sometimes followed by stem girdling, dieback, and distorted growth. At later stages, numerous epidermal acervuli developed in the lesions, and mucilaginous conidial masses appeared during periods of high relative humidity. Conidia produced in acervuli were straight, cylindric, hyaline, and aseptate, with both ends rounded. Conidia measured (mean ± SD) 14.2 ± 0.6 × 3.6 ± 0.7 μm, and the L/W ratio was 3.95 μm. Six isolates of the fungus were obtained and identified as C. gloeosporioides on the basis of morphological characterization (3). The isolates were deposited in the University Putra of Malaysia Culture Collection (UPMCC). PDA cultures were white at first and subsequently became grayish to pink to reddish-brown. Amplification and sequence analysis of coding and none-coding regions of the ITS-rDNA (GenBank JX669450), actin (JX827430), β-tubulin (JX827454), histone (JX827448), chitin synthase (JX827436), and glyceraldehyde-3-phosphate dehydrogenase (JX827442) obtained from the representative isolate, CGM50, aligned with deposited sequences from GenBank and revealed 99 to 100% sequence identity with C. gloeosporioides strains (JX258757, JX009790, GQ849434, HM575301, JQ005413, and JX00948 from GenBank). One representative isolate, CGM50, was used for pathogenicity testing. Four non-infected detached leaves and pods of 24-day-old G. max var. Palmetto were surface-sterilized and inoculated by placing 10 μl of a conidial suspension (106 conidia ml–1) using either the wound/drop or non-wound/drop method (4), with 10 μl distilled water as a negative control. Leaves and pods were incubated at 25°C, 98% RH. The experiment was repeated twice. Five days after inoculation, the development of typical field symptoms, including acervuli formation, occurred on the leaves and pods of inoculated plants, but not on the negative controls. A fungus with the same colony and conidial morphology as CGM50 was recovered from the lesions on the inoculated leaves and pods. Anthracnose caused by C. gloeosporioides on soybean plants has been reported previously in different countries, but not in Malaysia (3). Geographically, the climate of Malaysia is highly conducive to maintain and cause outbreaks of anthracnose all year round; thus, the development of management recommendations will be inevitable for anthracnose control. To our knowledge, this is the first report of C. gloeosporioides causing anthracnose on soybean in Malaysia. References: (1) U. Damm et al. Fungal Diversity 39:45, 2009. (2) S. L. Chen et al. J. Phytopathol. 154:654, 2006. (3) B. C. Sutton. The Genus Glomerella and its Anamorph Colletotrichum. CAB International, Wallingford, UK, 1992. (4) P. P. Than et al. Plant Pathol. 57:562, 2008. ERRATUM: A correction was made to this Disease Note on May 19, 2014. The author N. Soleimani was added.

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First Report of Alternaria Leaf Spot Caused by Alternaria sp. on Highbush Blueberry (Vaccinium corymbosum) in South Korea

Plant Disease ◽

10.1094/pdis-04-14-0344-pdn ◽

2014 ◽

Vol 98 (10) ◽

pp. 1434-1434

Author(s):

J.-H. Kwon ◽

D.-W. Kang ◽

M.-G. Cheon ◽

J. Kim

Keyword(s):

South Korea ◽

Leaf Spot ◽

Disease Incidence ◽

Vaccinium Corymbosum ◽

Its Rdna ◽

Universal Primers ◽

Conidial Suspension ◽

First Report ◽

Representative Isolate ◽

Alternaria Sp

In South Korea, the culture, production, and consumption of blueberry (Vaccinium corymbosum) have increased rapidly over the past 10 years. In June and July 2012, blueberry plants with leaf spots (~10% of disease incidence) were sampled from a blueberry orchard in Jinju, South Korea. Leaf symptoms included small (1 to 5 mm in diameter) brown spots that were circular to irregular in shape. The spots expanded and fused into irregularly shaped, large lesions with distinct dark, brownish-red borders. The leaves with severe infection dropped early. A fungus was recovered consistently from sections of surface-disinfested (1% NaOCl) symptomatic leaf tissue after transfer onto water agar and sub-culture on PDA at 25°C. Fungal colonies were dark olive and produced loose, aerial hyphae on the culture surfaces. Conidia, which had 3 to 6 transverse septa, 1 to 2 longitudinal septa, and sometimes also a few oblique septa, were pale brown to golden brown, ellipsoid to ovoid, obclavate to obpyriform, and 16 to 42 × 7 to 16 μm (n = 50). Conidiophores were pale to mid-brown, solitary or fasciculate, and 28 to 116 × 3 to 5 μm (n = 50). The species was placed in the Alternaria alternata group (1). To confirm the identity of the fungus, the complete internal transcribed spacer (ITS) rDNA region of a representative isolate, AAVC-01, was amplified using ITS1 and ITS4 primers (2). The DNA products were cloned into the pGEM-T Easy vector (Promega, Madison, WI) and the resulting pOR13 plasmid was sequenced using universal primers. The resulting 570-bp sequence was deposited in GenBank (Accession No. KJ636460). Comparison of ITS rDNA sequences with other Alternaria spp. using ClustalX showed ≥99% similarity with the sequences of A. alternata causing blight on Jatropha curcas (JQ660842) from Mexico and Cajannus cajan (JQ074093) from India, citrus black rot (AF404664) from South Africa, and other Alternaria species, including A. tenuissima (WAC13639) (3), A. lini (Y17071), and A. longipes (AF267137). Two base substitutions, C to T at positions 345 and 426, were found in the 570-bp amplicon. Phylogenetic analysis revealed that the present Alternaria sp. infecting blueberry grouped separately from A. tenuissima and A. alternata reported from other hosts. A representative isolate of the pathogen was used to inoculate V. corymbosum Northland leaves for pathogenicity testing. A conidial suspension (2 × 104 conidia/ml) from a single spore culture and 0.025% Tween was spot inoculated onto 30 leaves, ranging from recently emerged to oldest, of 2-year-old V. corymbosum Northland plants. Ten leaves were treated with sterilized distilled water and 0.025% Tween as a control. The plants were kept in a moist chamber with >90% relative humidity at 25°C for 48 h and then moved to a greenhouse. After 15 days, leaf spot symptoms similar to those observed in the field developed on the inoculated leaves, whereas the control plants remained asymptomatic. The causal fungus was re-isolated from the lesions of the inoculated plants to fulfill Koch's postulates. To our knowledge, this is the first report of Alternaria sp. on V. corymbosum in South Korea. References: (1) E. G. Simmons. Page 1797 in: Alternaria: An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, The Netherlands, 2007. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (3) M. P. You et al. Plant Dis. 98:423, 2014.

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First Report of Diaporthe hongkongensis Causing Fruit rot on Peach (Prunus persica) in China

Plant Disease ◽

10.1094/pdis-07-20-1505-pdn ◽

2021 ◽

Author(s):

Zhou Zhang ◽

Zheng Bing Zhang ◽

Yuan Tai Huang ◽

FeiXiang Wang ◽

Wei Hua Hu ◽

...

Keyword(s):

Prunus Persica ◽

Fruit Rot ◽

Hunan Province ◽

Post Inoculation ◽

Distilled Water ◽

Conidial Suspension ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Representative Isolate ◽

Rot Disease

Peach [Prunus persica (L.) Batsch] is an important deciduous fruit tree in the family Rosaceae and is a widely grown fruit in China (Verde et al., 2013). In July and August 2018, a fruit rot disease was observed in a few peach orchards in Zhuzhou city, the Hunan Province of China. Approximately 30% of the fruit in more than 400 trees was affected. Symptoms displayed were brown necrotic spots that expanded, coalesced, and lead to fruit being rotten. Symptomatic tissues excised from the margins of lesions were surface sterilized in 70% ethanol for 10 s, 0.1% HgCl2 for 2 min, rinsed with sterile distilled water three times, and incubated on potato dextrose agar (PDA) at 26°C in the dark. Fungal colonies with similar morphology developed, and eight fungal colonies were isolated for further identification. Colonies grown on PDA were grayish-white with white aerial mycelium. After an incubation period of approximately 3 weeks, pycnidia developed and produced α-conidia and β-conidia. The α-conidia were one-celled, hyaline, fusiform, and ranged in size from 6.0 to 8.4 × 2.1 to 3.1 μm, whereas the β-conidia were filiform, hamate, and 15.0 to 27.0 × 0.8 to 1.6 μm. For molecular identification, total genomic DNA was extracted from the mycelium of a representative isolate HT-1 and the internal transcribed spacer region (ITS), β-tubulin gene (TUB), translation elongation factor 1-α gene (TEF1), calmodulin (CAL), and histone H3 gene (HIS) were amplified and sequenced (Meng et al. 2018). The ITS, TUB, TEF1, CAL and HIS sequences (GenBank accession nos. MT740484, MT749776, MT749778, MT749777, and MT749779, respectively) were obtained and in analysis by BLAST against sequences in NCBI GenBank, showed 99.37 to 100% identity with D. hongkongensis or D. lithocarpus (the synonym of D. hongkongensis) (Gao et al., 2016) (GenBank accession nos. MG832540.1 for ITS, LT601561.1 for TUB, KJ490551.1 for HIS, KY433566.1 for TEF1, and MK442962.1 for CAL). Pathogenicity tests were performed on peach fruits by inoculation of mycelial plugs and conidial suspensions. In one set, 0.5 mm diameter mycelial discs, which were obtained from an actively growing representative isolate of the fungus on PDA, were placed individually on the surface of each fruit. Sterile agar plugs were used as controls. In another set, each of the fruits was inoculated by application of 1 ml conidial suspension (105 conidia/ml) by a spray bottle. Control assays were carried out with sterile distilled water. All treatments were maintained in humid chambers at 26°C with a 12-h photoperiod. The inoculation tests were conducted twice, with each one having three fruits as replications. Six days post-inoculation, symptoms of fruit rot were observed on inoculated fruits, whereas no symptoms developed on fruits treated with agar plugs and sterile water. The fungus was re-isolated and identified to be D. hongkongensis by morphological and molecular methods, thus fulfilling Koch’s Postulates. This fungus has been reported to cause fruit rot on kiwifruit (Li et al. 2016) and is also known to cause peach tree dieback in China (Dissanayake et al. 2017). However, to our knowledge, this is the first report of D. hongkongensis causing peach fruit rot disease in China. The identification of the pathogen will provide important information for growers to manage this disease.

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First Report of Brown Rot Caused by Monilinia fructicola Affecting Peach Orchards in Slovenia

Plant Disease ◽

10.1094/pdis-94-9-1166a ◽

2010 ◽

Vol 94 (9) ◽

pp. 1166-1166 ◽

Cited By ~ 15

Author(s):

A. Munda ◽

M. Viršček Marn

Keyword(s):

Prunus Persica ◽

Brown Rot ◽

Fruit Rot ◽

Morphological Identification ◽

Monilinia Fructicola ◽

Conidial Suspension ◽

Stone Fruits ◽

The European Union ◽

First Report ◽

Representative Isolate

Monilinia fructicola, the causal agent of brown rot, is a destructive fungal pathogen that affects mainly stone fruits (Prunoideae). It causes fruit rot, blossom wilt, twig blight, and canker formation and is common in North and South America, Australia, and New Zealand. M. fructicola is listed as a quarantine pathogen in the European Union and was absent from this region until 2001 when it was detected in France. In August 2009, mature peaches (Prunus persica cv. Royal Glory) with brown rot were found in a 5-year-old orchard in Goriška, western Slovenia. Symptoms included fruit lesions and mummified fruits. Lesions were brown, round, rapidly extending, and covered with abundant gray-to-buff conidial tufts. The pathogen was isolated in pure culture and identified based on morphological and molecular characters. Colonies on potato dextrose agar (PDA) incubated at 25°C in darkness had an average daily growth rate of 7.7 mm. They were initially colorless and later they were light gray with black stromatal plates and dense, hazel sporogenous mycelium. Colony margins were even. Sporulation was abundant and usually developed in distinct concentric zones. Limoniform conidia, produced in branched chains, measured 10.1 to 17.7 μm (mean = 12.1 μm) × 6.2 to 8.6 μm (mean = 7.3 μm) on PDA. Germinating conidia produced single germ tubes whose mean length ranged from 251 to 415 μm. Microconidia were abundant, globose, and 3 μm in diameter. Morphological characters resembled those described for M. fructicola (1). Morphological identification was confirmed by amplifying genomic DNA of isolates with M. fructicola species-specific primers (2–4). Sequence of the internal transcribed spacer (ITS) region (spanning ITS1 and ITS 2 plus 5.8 rDNA) of a representative isolate was generated using primers ITS1 and ITS4 and deposited in GenBank (Accession No. GU967379). BLAST analysis of the 516-bp PCR product revealed 100% identity with several sequences deposited for M. fructicola in NCBI GenBank. Pathogenicity was tested by inoculating five mature surface-sterilized peaches with 10 μl of a conidial suspension (104 conidia ml–1) obtained from one representative isolate. Sterile distilled water was used as a control. Peaches were wounded prior to inoculation. After 5 days of incubation at room temperature and 100% relative humidity, typical brown rot symptoms developed around the inoculation point, while controls showed no symptoms. M. fructicola was reisolated from lesion margins. Peach and nectarine orchards in a 5-km radius from the outbreak site were surveyed in September 2009 and M. fructicola was confirmed on mummified fruits from seven orchards. The pathogen was not detected in orchards from other regions of the country, where only the two endemic species M. laxa and M. fructigena were present. To our knowledge, this is the first report of M. fructicola associated with brown rot of stone fruits in Slovenia. References: (1) L. R. Batra. Page 106 in: World Species of Monilinia (Fungi): Their Ecology, Biosystematics and Control. J. Cramer, Berlin, 1991. (2) M.-J. Côté et al. Plant Dis. 88:1219, 2004. (3) K. J. D. Hughes et al. EPPO Bull. 30:507, 2000. (4) R. Ioos and P. Frey. Eur. J. Plant Pathol. 106:373, 2000.

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First Report of Leaf Spot Caused by Ascochyta marginata on Aralia elata in Korea

Plant Disease ◽

10.1094/pdis-08-11-0658 ◽

2012 ◽

Vol 96 (1) ◽

pp. 147-147

Author(s):

S. H. Lee ◽

C. K. Lee ◽

M. J. Park ◽

H. D. Shin

Keyword(s):

East Asia ◽

Leaf Spot ◽

Morphological Characteristics ◽

Culture Collection ◽

Research Report ◽

Conidial Suspension ◽

First Report ◽

Commercial Cultivation ◽

Aralia Elata ◽

Initial Symptoms

Aralia elata (Miq.) Seem., known as Japanese angelica tree, is a deciduous shrub belonging to the Araliaceae, which is native to East Asia. The young shoots have long been used in various dishes in East Asia. Commercial cultivation of this shrub, especially in polytunnels, is expanding in Korea. Several diseases including Sclerotinia rot have been known to be present on this plant (1,2). In early September 2007, leaf spot symptoms were first observed on several trees in Hongcheon, Korea. Microscopic observations revealed that the leaf spots were associated with an Ascochyta sp. Further surveys of the Ascochyta leaf spot showed the occurrence of the disease in approximately 5 to 10% of the trees in the 3 ha of commercial fields surveyed in Chuncheon, Gapyeong, Inje, and Jinju, Korea. Initial symptoms on leaves were circular to irregular, brown to dark brown, becoming zonate, and finally fading to grayish brown in the center with a yellow halo. Representative samples were deposited in the herbarium of Korea University. Conidiomata on leaf lesions were pycnidial, amphigenous, but mostly epiphyllous, immersed or semi-immersed in host tissue, light brown to olive brown, and 60 to 200 μm in diameter. Ostioles were papillate, 20 to 35 μm wide, and surrounded by a ring of darker cells. Conidia were hyaline, smooth, cylindrical to clavate, straight to mildly curved, slightly constricted at the septa, medianly one-septate, sometimes aseptate, 8 to 16 × 2.5 to 3.5 μm, and contained small oil drops. These morphological characteristics were consistent with the previous reports of Ascochyta marginata J.J. Davis (3,4). A monoconidial isolate was cultured on potato dextrose agar (PDA) plates and accessioned in the Korea Agricultural Culture Collection (Accession KACC43082). The conidia were readily formed on PDA. Inoculum for the pathogenicity tests was prepared by harvesting conidia from 30-day-old cultures of KACC43082 and a conidial suspension (approximately 2 × 106 conidia/ml) was sprayed onto leaves of three healthy seedlings. Three noninoculated seedlings served as controls. Inoculated and noninoculated plants were covered with plastic bags for 48 h in a glasshouse. After 7 days, typical leaf spot symptoms started to develop on the leaves of the inoculated plants. The fungus, A. marginata, was reisolated from those lesions, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in Japan (4) and China (3). To our knowledge, this is the first report of A. marginata on Japanese angelica trees in Korea. According to our field observations in Korea, the Ascochyta leaf spot mostly occurred on plants growing in a humid environment, especially during the rainy season. The seedlings as well as the trees growing in sunny, well-ventilated plots were nearly free from this disease. Therefore, the growing conditions seemed to be the most important factor for the development and severity of the disease. References: (1) C. K. Lee et al. Plant Pathol. J. 26:426, 2010. (2) S. H. Lee et al. Diseases of Japanese Angelica Tree and Their Control. Research Report 08-10. Korea Forest Research Institute. Seoul, Korea, 2008. (3) J. Sun et al. Acta Mycol. Sin. 14:107, 1995. (4) M. Yoshikawa and T. Yokoyama. Mycoscience 36:67, 1995.

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Identification of Fusarium commune, the Causal Agent of Postharvest Zinnia Meltdown Disease in Tennessee

HortTechnology ◽

10.21273/horttech04795-21 ◽

2021 ◽

pp. 1-8

Author(s):

Ravi Bika ◽

Fulya Baysal-Gurel

Keyword(s):

Foliar Spray ◽

Morphological Characterization ◽

Causal Agent ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Cut Flower ◽

Cut Flowers ◽

Flower Bud ◽

Golden Yellow ◽

Management Recommendations

The cut flower growers of the eastern and southern United States are threatened with postharvest meltdown of zinnia (Zinnia elegans), which reduces yield and income as well as limiting opportunities for production expansion. Disease symptoms such as bending of the stem just below the flower were visually apparent on zinnia cut flowers. The objective of this study was to identify the causal agent related to zinnia meltdown. A total of 20 symptomatic zinnia cut flower stems were collected from Tennessee. Several Fusarium-like colonies with micro and macroconidia were isolated from the base and bend area of stems on potato dextrose agar (PDA) and Fusarium-selective media. Morphological characterization, polymerase chain reaction, and sequencing of three representative isolates, FBG2020_198, FBG2020_199, and FBG2020_201, were conducted to confirm pathogen identification. The sequence identity of the isolates was >99% identical to Fusarium commune, and a combined phylogenetic tree grouped the isolates with the clade of F. commune from different host and geographical locations. To accomplish Koch’s postulates, a pathogenicity test was performed on ‘Benary’s Giant Golden Yellow’, ‘Benary’s Giant Lime’, and ‘Benary’s Giant Pink’ zinnia plants at vegetative (2 weeks after transplantation) or flower bud stage (1 month after transplantation) by drench, stem injection, and foliar spray of conidial suspension (1 × 105 conidia/mL). Similar symptoms of meltdown (floral axis bending just below the flower) were observed on inoculated zinnia cultivars 2 days after harvesting. Fusarium commune was re-isolated from the infected flower stems of all three cultivars but not from the noninoculated zinnia flower stems. Zinnia stem colonization by F. commune was statistically similar in all three tested cultivars regardless of plant growth stage and method of inoculation. This study confirms F. commune as being the causal agent of postharvest zinnia flower meltdown issue in Tennessee. In the future, possible sources of pathogen will be screened, and disease management recommendations will be developed.

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First Report of Fusarium proliferatum Causing Fruit Rot of Grapes (Vitis vinifera) in Pakistan

International Journal of Phytopathology ◽

10.33687/phytopath.007.02.2589 ◽

2018 ◽

Vol 7 (2) ◽

pp. 85-88 ◽

Cited By ~ 1

Author(s):

Salman Ghuffar ◽

Gulshan Irshad ◽

Fengyan Zhai ◽

Asif Aziz ◽

Hafiz M. Asadullah M. Asadullah ◽

...

Keyword(s):

Vitis Vinifera ◽

Negative Control ◽

Fusarium Proliferatum ◽

Fruit Rot ◽

Pathogenicity Test ◽

Distilled Water ◽

Conidial Suspension ◽

Fruit Crop ◽

First Report ◽

Thin Walled

Grapes (Vitis vinifera) are the important fruit crop in Pakistan, mostly cultivated for edible purpose. In September 2016, unusual fruit rot symptoms were observed 3-5 days after harvesting on grapes cv. Kishmishi in post-harvest packing houses in Jehlum district (32°56'22.3"N 73°43'31.4"E) of Punjab province. To determine the disease incidence, a total of 10 boxes of grapes from 5 different locations were selected randomly. Each box contained average 12 bunches and 30 bunches out of 120 inspected bunches displayed typical symptoms of the disease. The initial Symptoms were small, round, water-soaked lesions that rapidly developed into soft, white to light pink mycelium near the centre of infected fruits (Figure 1). A total of 186 symptomatic berries were surface sterilized with 1% sodium hypochlorite, rinsed three times with sterile distilled water and dried by placing on filter paper for 45 sec. Sterilized tissues (approximately 4 mm3) were excised and incubated on potato dextrose agar (PDA) medium at 25 ± 4°C. One week after incubation, colonies with abundant aerial mycelium were initially white, cottony and turned to violet and dark purple with age (Figure 2). A total of 25 isolates were examined morphologically. Macroconidia were slender, thin-walled, 3 to 5 septate, curved apical cell, with 20.9 to 45.2 × 3.2 to 7.1 μm and Microconidia were thin-walled, aseptate, club-shaped with 4.5 to 11.2 × 2.3 to 4.1 μm (Figure 3). These characteristics best fit for the description of Fusarium proliferatum (Leslie and Summerell, 2006). Portions of the internal transcribed spacer (ITS) region were sequenced (White et al., 1990). Sequences of two isolates Fus 07 and Fus 09 (GenBank Accessions; MH444366 and MH464139) showed 100% identity to the corresponding gene sequences of Fusarium proliferatum (GenBank Accessions; MH368119, MF033172 and KU939071) (Figure 4). Pathogenicity test was performed by inoculation with 50-μl conidial suspension (1 × 106conidia/ml) of two isolates onto three non-wounded and four wounded asymptomatic grapes berries. Sterile distilled water was used for a negative control (Figure 5). The experiment was conducted twice and berries were incubated at 25 ± 2°C in sterile moisture chambers (Ghuffar et al., 2018). White to light pink mycelium in appearance with the original symptoms were observed on both wounded and non-wounded inoculated berries after 3 days, whereas no symptoms were observed on the negative control. The morphology of the fungus that was re-isolated from each of the inoculated berries was identical to that of the original cultures. Fusarium proliferatum, one of the destructive species, causes diseases like foot-rot of corn (Farr et al., 1990), root rot of soybean (Díaz Arias et al., 2011), bakanae of rice (Zainudin et al., 2008), wilt of date palm (Khudhair et al., 2014), tomato wilt (Chehri, 2016) and tomato fruit rot (Murad et al., 2016). To our knowledge, this is the first report of Fusarium proliferatum causing fruit rot of grapes in Pakistan, where the disease poses a significant threat to the sustainability of this major fruit crop.

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First Report of Colletotrichum acutatum on Strawberry in Northwestern Argentina

Plant Disease ◽

10.1094/pdis.2000.84.6.706b ◽

2000 ◽

Vol 84 (6) ◽

pp. 706-706 ◽

Cited By ~ 5

Author(s):

C. J. Ramallo ◽

L. D. Ploper ◽

M. Ontivero ◽

M. P. Filippone ◽

A. Castagnaro ◽

...

Keyword(s):

Colletotrichum Acutatum ◽

Conidial Suspension ◽

Disease Symptoms ◽

Northwestern Argentina ◽

First Report ◽

Surface Control ◽

Detached Leaves ◽

Strawberry Anthracnose ◽

Pathogenicity Tests ◽

Necrotic Spots

Isolates were obtained from strawberry tissue with anthracnose symptoms from several locations near Tucumán, Argentina. Isolates were characterized using several criteria. Isolates produced fusiform conidia, tapered to a point at both ends, and averaged 13.5 × 4.9 μm. On potato dextrose agar, colonies produced a white cottony mycelial colony that turned orange in older cultures. Compared with Colletotrichum fragariae, the new isolates produced fewer appressoria. Pathogenicity tests were conducted on detached leaves and plants in the greenhouse and field. Detached immature leaves of cvs. Chandler, Fern, and Sweet Charlie were inoculated with a 20-μl droplet of an aqueous conidial suspension (106 conidia per ml) placed on the adaxial surface. Control leaves were inoculated with sterile distilled water. Leaves were maintained under white light (2,000 lux, 12 h/day) at 26°C, and 100% relative humidity. Necrotic spots were visible 4 days after inoculation. Greenhouse and field plants were spray-inoculated and covered for 48 h. Disease symptoms were mainly observed on petioles and runners 9 days after inoculation. No lesions were observed on control detached leaves or plants. Koch's postulates were confirmed in all cases. Based on morphological and cultural characteristics, isolates were identified as C. acutatum Simmonds (1). This is the first report of C. acutatum causing strawberry anthracnose in northwestern Argentina. Reference: (1) B. Smith and L. L. Black. Plant Dis. 74:69, 1990.

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First Report of Anthracnose of Tricyrtis macropoda Caused by Colletotrichum gloeosporioides in Korea

Plant Disease ◽

10.1094/pdis-03-12-0277-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1070-1070 ◽

Cited By ~ 1

Author(s):

J. H. Park ◽

K. S. Han ◽

Y. D. Kwon ◽

H. D. Shin

Keyword(s):

Colletotrichum Gloeosporioides ◽

Morphological Characteristics ◽

Its Region ◽

Culture Collection ◽

Perennial Herb ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Natural Habitats ◽

First Report ◽

Small Water

Tricyrtis macropoda Miq. (syn. T. dilatata Nakai), known as speckled toadlily, is a perennial herb native to China, Japan, and Korea. The plant has been highly praised for its beautiful flowers and rare populations in natural habitats. In September 2006, several dozen plants were heavily damaged by leaf spots and blight in cultivated plantings in the city of Pocheon, Korea. The infections with the same symptoms were repeated every year. In July 2011, the same symptoms were found on T. macropoda in the cities of Gapyeong and Osan, Korea. The leaf lesions began as small, water-soaked, pale greenish to grayish spots, which enlarged to form concentric rings and ultimately coalesced. A number of blackish acervuli were formed in the lesions. Acervuli were mostly epiphyllous, circular to ellipsoid, and 40 to 200 μm in diameter. Setae were two- to three-septate, dark brown at the base, paler upwards, acicular, and up to 100 μm long. Conidia (n = 30) were long obclavate to oblong-elliptical, sometimes fusiform-elliptical, guttulate, hyaline, and 12 to 20 × 4 to 6.5 μm (mean 15.4 × 5.2 μm). These morphological characteristics of the fungus were consistent with the description of Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. (2). Voucher specimens (n = 7) were deposited in the Korea University herbarium (KUS). Two isolates, KACC46374 (ex KUS-F25916) and KACC46405 (ex KUS-F26063), were deposited in the Korean Agricultural Culture Collection. Fungal DNA was extracted and the complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced. The resulting sequences of 549 bp were deposited in Genbank (Accession Nos. JQ619480 and JQ619481). They showed 100% similarity with a sequence of C. gloeosporioides (EU32619). Isolate KACC46374 was used in a pathogenicity test. Inoculum was prepared by harvesting conidia from 3-week-old cultures on potato dextrose agar. A conidial suspension (2 × 106 conidia/ml) was sprayed onto 15 leaves of three plants. Three noninoculated plants served as controls. Plants were covered with plastic bags to maintain 100% relative humidity for 24 h and then kept in a greenhouse (22 to 28°C and 70 to 80% RH). After 5 days, typical leaf spot symptoms, identical to the ones observed in the field, started to develop on the leaves of inoculated plants. No symptoms were observed on control plants. C. gloeosporioides was reisolated from the lesions of inoculated plants, thus fulfilling Koch's postulates. An anthracnose associated with C. tricyrtii (Teng) Teng was recorded on T. formosana and T. latifolia in China (3) and on T. formosana in Taiwan (1), respectively, without etiological studies. The morphological features of C. tricyrtii are within the variation of C. gloeosporioides (2). To our knowledge, this is the first report of anthracnose of T. macropoda. This report has significance to indigenous plant resource conservation managers and scientists because T. macropoda has been listed as one of the 126 “Rare and Endangered Plants” by the Korea Forest Service since 1991. References: (1) K. Sawada. Rep. Dept. Agric. Gov. Res. Inst. Formosa 87: 1, 1944. (2) B. C. Sutton. Pages 1–27 in: Colletotrichum Biology, Pathology and Control. J. A. Bailey and M. J. Jeger, eds. CAB International, Wallingford, U.K. 1992. (3) S. C. Teng. Contrib. Biol. Lab. Sci. Soc. China 8:36, 1932.

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First Report of Penicillium carneum Causing Blue Mold on Stored Apples in Pennsylvania

Plant Disease ◽

10.1094/pdis-06-12-0541-pdn ◽

2012 ◽

Vol 96 (12) ◽

pp. 1823-1823 ◽

Cited By ~ 4

Author(s):

K. A. Peter ◽

I. Vico ◽

V. Gaskins ◽

W. J. Janisiewicz ◽

R. A. Saftner ◽

...

Keyword(s):

Negative Control ◽

Penicillium Expansum ◽

Malt Extract ◽

Conidial Suspension ◽

Blue Mold ◽

Separate Species ◽

First Report ◽

Golden Delicious ◽

Apple Fruits ◽

Β Tubulin

Blue mold decay occurs during long term storage of apples and is predominantly caused by Penicillium expansum Link. Apples harvested in 2010 were stored in a controlled atmosphere at a commercial Pennsylvania apple packing and storage facility, and were examined for occurrence of decay in May 2011. Several decayed apples from different cultivars, exhibiting blue mold symptoms with a sporulating fungus were collected. One isolate recovered from a decayed ‘Golden Delicious’ apple fruit was identified as P. carneum Frisvad. Genomic DNA was isolated, 800 bp of the 3′ end of the β-tubulin locus was amplified using gene specific primers and sequenced (4). The recovered nucleotide sequence (GenBank Accession No. JX127312) indicated 99% sequence identity with P. carneum strain IBT 3472 (GenBank Accession No. JF302650) (3). The P. carneum colonies strongly sporulated and had a blue green color on potato dextrose agar (PDA), Czapek yeast autolysate agar (CYA), malt extract agar (MEA), and yeast extract sucrose agar (YES) media at 25°C after 7 days. The colonies also had a beige color on plate reverse on CYA and YES media. The species tested positive for the production of alkaloids, as indicated by a violet reaction for the Ehrlich test, and grew on CYA at 30°C and on Czapek with 1,000 ppm propionic acid agar at 25°C; all of which are diagnostic characters of this species (2). The conidiophores were hyaline and tetraverticillate with a finely rough stipe. Conida were produced in long columns, blue green, globose, and averaged 2.9 μm in diameter. To prove pathogenicity, Koch's postulates were conducted using 20 ‘Golden Delicious’ apple fruits. Fruits were washed, surface sterilized with 70% ethanol, and placed onto fruit trays. Using a nail, 3-mm wounds were created and inoculated with 50 μl of a 106/ml conidial suspension or water only as a negative control. The fruit trays were placed into boxes and were stored in the laboratory at 20°C for 7 days. The inoculated fruit developed soft watery lesions, with hard defined edges 37 ± 4 mm in diameter. The sporulating fungus was reisolated from infected tissue of all conidia inoculated apples and confirmed to be P. carneum by polymerase chain reaction (PCR) using the β-tubulin locus as described. Water inoculated control apples were symptomless. Originally grouped with P. roqueforti, P. carneum was reclassified in 1996 as a separate species (1). P. carneum is typically associated with meat products, beverages, and bread spoilage and produces patulin, which is not produced by P. roqueforti (1,2). Our isolate of P. carneum was susceptible to the thiabendazole (TBZ) fungicide at 250 ppm, which is below the recommended labeled application rate of 600 ppm. The susceptibility to TBZ suggests that this P. carneum isolate has been recently introduced because resistance to TBZ has evolved rapidly in P. expansum (4). To the best of our knowledge, P. carneum has not previously been described on apple, and this is the first report of P. carneum causing postharvest decay on apple fruits obtained from storage in Pennsylvania. References: (1) M. Boyson et al. Microbiology 142:541, 1996. (2) J. C. Frisvad and R. A. Samson. Stud. Mycol. 49:1, 2004. (3) B. G. Hansen et al. BMC Microbiology 11:202, 2011. (4) P. L. Sholberg et al. Postharvest Biol. Technol. 36:41, 2005.

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First Report of Diaporthe novem Causing Postharvest Rot of Kiwifruit During Controlled Atmosphere Storage in Chile

Plant Disease ◽

10.1094/pdis-02-14-0183-pdn ◽

2014 ◽

Vol 98 (9) ◽

pp. 1274-1274 ◽

Cited By ~ 5

Author(s):

G. A. Díaz ◽

B. A. Latorre ◽

S. Jara ◽

E. Ferrada ◽

P. Naranjo ◽

...

Keyword(s):

Aerial Mycelium ◽

Soft Rot ◽

Storage Conditions ◽

Negative Control ◽

Its2 Region ◽

Conidial Suspension ◽

Controlled Atmosphere ◽

First Report ◽

Postharvest Rot ◽

Negative Controls

Chile is considered the third major exporter of kiwifruits (Actinidia deliciosa (A. Chev.) C. F. Liang & A. R. Ferguson) worldwide after Italy and New Zealand (1). The genus Diaporthe Nitschke (anamorph: genus Phomopsis) has been reported as causing postharvest rot in kiwifruit (4). During the current study, 1,400 fruits arbitrarily collected from seven controlled atmosphere (CA) rooms after 90 days of storage conditions (2% O2, 5% CO2) determined that 21.5% of the fruit were affected by decay and 0.86% developed symptoms different than those caused by Botrytis cinerea, the main postharvest pathogen associated to kiwifruit. Symptoms were soft rot with brown skin that started at the stem-end and in severe cases affected the entire fruit. Internally, affected fruit showed browning and watery tissues. Twelve affected fruits were surface disinfested (75% ethanol) and small pieces of internal rotten tissues were placed on acidified potato dextrose agar (APDA) for 7 days at 20°C. Twelve isolates were obtained, and four of them were identified morphologically and molecularly as Diaporthe ambigua, a species that has been previously described causing rot in stored kiwifruits in Chile (2). However, eight other flat, white to grayish colonies with sparse dirty-white aerial mycelium at the edge of the dish were obtained (3). Black pycnidia contained unicellular, hyaline, biguttulate, oval to cylindrical alpha conidia, with obtuse ends of (7.9) 6.7 (5.3) × (2.9) 2.5 (2.1) μm (n = 30). These isolates were tentatively identified as a Diaporthe sp. The species identification was determined by sequencing comparison of the internal transcribed spacer (ITS1-5.8S-ITS2) region of the rDNA (GenBank Accession Nos. KJ210020 to 24, KJ210027, and KJ210033) and a portion of beta-tubulin (BT) (KJ210034 to 38, KJ210041, and KJ210047) using primers ITS4-ITS5 and Bt2a-Bt2b, respectively. BLAST analyses showed 99 to 100% identity with D. novem J.M. Santos, Vrandecic & A.J.L Phillips reference ex-type (KC343156 and KC344124 for ITS and BT, respectively) (3). Eighteen mature kiwifruits cv. Hayward were inoculated using a sterile cork borer on the surface of the fruit and placing 5-mm agar plugs with mycelial of D. novem (DN-1-KF). An equal number of fruits treated with sterile agar plugs were used as negative controls. After 30 days at 0°C under CA, all inoculated fruit showed rot symptoms with lesions 7.8 to 16.4 mm in diameter. The same D. novem isolate was inoculated with 30 μl of a conidial suspension (106 conidia/ml) on the surface of 18 ripe kiwifruits that were previously wounded and non-wounded as described above. An equal number of wounded and non-wounded fruits, treated with 30 μl sterile water, were used as negative controls. All inoculated wounded fruits developed rot symptoms with necrotic lesions of 14.1 to 20.2 mm of diameter after 14 days at 25°C. Inoculated non-wounded and negative control fruits remained symptomless. Koch's postulates were fulfilled by re-isolating D. novem only from the symptomatic fruits. To our knowledge, this is the first report of rot caused by D. novem on kiwifruit during cold storage in Chile and worldwide. Therefore, both Diaporthe species appears to be associated to Diaporthe rot of kiwifruit in Chile. References: (1) Belrose, Inc. World Kiwifruit Review. Belrose, Inc. Publishers, Pullman, WA, 2012. (2) J. Auger et al. Plant Dis. 97:843, 2013. (3) R. Gomes et al. Persoonia 31:1, 2013. (4) L. Luongo et al. J. Plant Pathol. 93:205, 2011.

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