First Report of Bitter Rot Caused by Colletotrichum acutatum on Apple in China

Bitter rot of apple caused by Colletotrichum gloeosporioides was first reported in China in 1985 (3). In China, apples are grown on approximately 2 million ha, and bitter rot occurs in almost all production areas, with crop damage ranging from 30 to 70%. During the summer of 2007, fungi were isolated from apple fruit exhibiting bitter rot symptoms in 12 and 9 orchards in Shaanxi and Henan provinces, respectively, in China. Symptoms included 2- to 3-cm-diameter, sunken, brown lesions on the fruit surface that contained black, pinhead-size fruiting structures producing orange conidial masses under high humidity, similar to that of C. gloeosporioides. On potato dextrose agar (PDA), colonies were white, pale gray, or pale orange when grown at 25°C. Conidia were 8 to 16 × 2.5 to 4 μm, fusiform, pointed at one or both ends, one celled, thin walled, aseptate, and hyaline. Appressoria were 6.5 to 11 × 4.5 to 7.5 μm, clavate to circular, and light to dark brown. These characteristics matched published descriptions of C. acutatum (2). To confirm pathogenicity, three mature, healthy apples (cv. Fuji) were surface disinfested with 70% ethanol and then wounded with a sterile needle. After being inoculated with a spore suspension (1 × 105 conidia/ml) prepared from a 2-week-old culture on PDA, these apples were sealed in a plastic bag and incubated at 25°C. Symptoms appeared 3 to 5 days after inoculation and began to enlarge 7 days later, forming lesions with fruiting structures. Under high humidity, cream-to-salmon pink spore masses were produced on lesions. As the lesions enlarged, the rot progressed to the core of the fruit in a V-shaped pattern. When the pathogen was reisolated from lesions of inoculated fruit onto PDA and incubated at 25°C, colony and conidial morphology were identical to those of the original isolates. Tests were performed three times with similar results. PCR with species-specific primer pair CaInt2/ITS4 (1) of genomic DNA from the isolates resulted in an amplification product of approximately 490 bp, which is specific for C. acutatum. The sequences exhibited 99% similarity with those of C. acutatum isolates AB273195 from GenBank. Approximately 20 of 103 symptomatic fruit from the field survey yielded fungal cultures whose morphology was consistent with that of C. acutatum, whereas the other cultures were C. gloeosporioides and Botryosphaeria dothidea. To our knowledge, this is the first report of bitter rot of apple caused by Colletotrichum acutatum in China. References: (1) S. Sreenivasaprasad et al. Plant Pathol. 45:650, 1996. (2) B. C. Sutton. Page 523 in: The Coelomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1980. (3) X. M. Wang. M.S. thesis. (In Chinese). College of Northwest Agriculture, Shaanxi Province, China, 1985.

Download Full-text

Characterization, Virulence, Epidemiology, and Management of Anthracnose in Celery

Plant Disease ◽

10.1094/pdis-09-14-0994-re ◽

2015 ◽

Vol 99 (12) ◽

pp. 1832-1840 ◽

Cited By ~ 2

Author(s):

Lina M. Rodriguez-Salamanca ◽

Lina M. Quesada-Ocampo ◽

Rachel P. Naegele ◽

Mary K. Hausbeck

Keyword(s):

Disease Incidence ◽

Field Studies ◽

Crop Damage ◽

Apium Graveolens ◽

Colletotrichum Acutatum ◽

Banding Patterns ◽

Growing Seasons ◽

Colletotrichum Acutatum Species Complex ◽

Species Specific ◽

Disease Pressure

Leaf curling and petiole twisting of celery (Apium graveolens) were observed in several commercial fields in five Michigan counties in 2010 through 2012, causing significant crop damage and loss. Prior to this time, the pathogen Colletotrichum acutatum species complex had not been previously associated with celery in Michigan. In this study, the pathogen’s genotype and phenotype were characterized, the influence of environmental conditions determined, and fungicides tested. Pathogen identification was based on conidial morphology and molecular identification using species-specific primers. Intersimple-sequence repeat (ISSR) banding patterns were similar between C. acutatum isolates from celery (n = 51) and blueberry (n = 1) but different from C. dematium and C. gloeosporioides. Four ISSR primers resulted in 4% polymorphism when tested on isolates from celery. Pathogenicity and virulence of C. acutatum sensu lato isolated from celery (n = 81), tomato (n = 2), and blueberry (n = 1) were evaluated in greenhouse experiments, which revealed differences in virulence among isolates but no significant differences specific to collection year, county, or field. In dew chambers and growth chambers, high temperatures (≥25°C) or long leaf wetness duration (>24 h) increased disease incidence. Twelve fungicides were tested in field studies over two growing seasons to determine their efficacy against celery anthracnose. The fungicides azoxystrobin, pyraclostrobin, mancozeb, and chlorothalonil reduced disease by 27 to 50% compared with the untreated control when disease pressure was moderate.

Download Full-text

First report of preharvest fruit rot of ‘Pink Lady’ apples caused by Colletotrichum fructicola in Italy

Plant Disease ◽

10.1094/pdis-11-20-2404-pdn ◽

2021 ◽

Author(s):

Marcel Wenneker ◽

Khanh Pham ◽

Engelien Kerkhof ◽

Dalphy O.C. Harteveld

Keyword(s):

Species Complex ◽

Management Strategies ◽

Morphological Characteristics ◽

Late Summer ◽

Fruit Rot ◽

Colletotrichum Acutatum ◽

Apple Orchards ◽

First Report ◽

Bitter Rot ◽

Colletotrichum Fructicola

In late summer 2019, a severe outbreak of fruit rot was observed in commercial ‘Pink Lady’ apple orchards (>20 ha in total) in the region Emilia-Romagna (Northern Italy). The symptoms on the fruit appeared as small circular red to brown lesions. Disease incidences of over 50% of the fruits were observed. To isolate the causal agent, 15 affected apples were collected and small portions of fruit flesh were excised from the lesion margin and placed on potato dextrose agar (PDA). The plates were incubated at 20°C in the dark, and pure cultures were obtained by transferring hyphal tips on PDA. The cultures showed light to dark gray, cottony mycelium, with the underside of the culture being brownish and becoming black with age. Conidia (n=20) were cylindrical, aseptate, hyaline, rounded at both ends, and 12.5 to 20.0 × 5.0 to 7.5 μm. The morphological characteristics were consistent with descriptions of Colletotrichum species of the C. gloeosporioides species complex, including C. fructicola (Weir et al. 2012). The identity of two representative isolates (PinkL2 & PinkL3) from different apples was confirmed by means of multi-locus gene sequencing. Genomic DNA was extracted using the LGC Mag Plant Kit (Berlin, Germany) in combination with the Kingfisher method (Waltham, USA). Molecular identification was conducted by sequencing the ITS1/ITS4 region and partial sequences of four other gene regions: chitin synthase (CHS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT), and beta-tubulin (TUB). The sequences have been deposited in GenBank under accession numbers MT421924 & MT424894 (ITS), MT424612 & MT424613 (CHS), MT424616 & MT424617 (GAPDH), MT424614 & MT424615 (ACT), and MT424620 & MT424621 (TUB). MegaBLAST analysis revealed that our ITS sequences matched with 100% identity to Colletotrichum fructicola (Genbank JX010177). The CHS, GAPDH, ACT and TUB sequences of both isolates were 100% identical with C. fructicola culture collection sequences in Genbank (JX009807, JX009923, JX009436 and JX010400, respectively), confirming the identity of these isolates as C. fructicola. Koch's postulates were performed with 10 mature ‘Pink Lady’ apples. Surface sterilized fruit were inoculated with 20 μl of a suspension of 105 conidia ml–1 after wounding with a needle. The fruits were incubated at 20˚C at high relative humidity. Typical symptoms appeared within 4 days on all fruit. Mock-inoculated controls with sterile water remained symptomless. The fungus was reisolated and confirmed as C. fructicola by morphology and sequencing of all previously used genes. Until recently the reported causal agents of bitter rot of apple in Europe belong to the Colletotrichum acutatum species complex (Grammen et al. 2019). C. fructicola, belonging to C. gloeosporioides species complex, is known to cause bitter rot of apple in the USA, Korea, Brazil, and Uruguay (Kim et al. 2018; Velho et al. 2015). There is only one report of bitter rot associated with C. fructicola on apple in Europe (France) (Nodet et al. 2019). However, C. fructicola is also the potential agent of Glomerella leaf spot (GLS) of apple (Velho et al. 2015; 2019). To the best of our knowledge this is the first report of C. fructicola on apples in Italy. It is important to stress that the C. gloeosporioides species complex is still being resolved and new species on apple continue to be identified, e.g. C. chrysophilum that is very closely related to C. fructicola (Khodadadi et al. 2020). Given the risks of this pathogen the presence of C. fructicola in European apple orchards should be assessed and management strategies developed.

Download Full-text

First Report of Colletotrichum acutatum Causing a Leaf Spot on Myrica cerifera in Florida

Plant Disease ◽

10.1094/pd-90-1263b ◽

2006 ◽

Vol 90 (9) ◽

pp. 1263-1263 ◽

Cited By ~ 1

Author(s):

S. J. Mackenzie ◽

L. M. Takahashi ◽

J. C. Mertely ◽

T. E. Seijo ◽

N. A. Peres

Keyword(s):

Colletotrichum Acutatum ◽

Rrna Gene ◽

Single Spore ◽

Myrica Cerifera ◽

First Report ◽

Central Florida ◽

Potted Plants ◽

5.8S Rrna Gene ◽

Young Leaves ◽

Plastic Bag

Wax myrtle (Morella cerifera (synonym Myrica cerifera) (L.) Small) is a native tree used in Florida landscapes. In the summer of 2005 and spring of 2006, small necrotic spots were observed on young leaves in two commercial nurseries in central Florida. Lesions were dark brown-to-black and eventually coalesced to form large, irregular necrotic areas. Leaves with large lesions abscised prematurely, defoliating the entire plant. Conidia formed on acervuli were observed on the surface of the largest lesions and were tentatively identified as a Colletotrichum sp. Isolations from the edges of lesions were made on potato dextrose agar (PDA) after surface disinfestation of leaf pieces in 0.6% NaOCl for 30 sec. Red chromogenic colonies developed after 5 days of incubation at 24°C. Colonies produced hyaline, oblong conidia with pointed ends averaging 14 × 4 μm and were identified as Colletotrichum acutatum J.H. Simmonds (1). The sequence from internal transcribed spacer regions 1 and 2 and the 5.8s rRNA gene of the rDNA repeat for an isolate (GenBank Accession No. DQ839609) was 100% identical to sequence from the same region of 36 C. acutatum isolates in the NCBI database. These isolates came from at least 16 different hosts, including seven ornamental hosts. There were three isolates from blueberry among the matches (Accession Nos. AB219029, AJ301911, and AJ301905), and the rDNA sequence was also identical to the sequence obtained in our laboratory for a chromogenic C. acutatum isolate from blueberry. Three single-spore isolates were tested for pathogenicity on potted plants in the greenhouse. Two young shoots were spray inoculated with a suspension (1 × 106 conidia/ml) of each isolate. Shoots were covered with a plastic bag for 24 h and maintained at 26.5°C. Two shoots were sprayed with sterile water as a control and similarly covered. All isolates produced brown spots on the youngest leaves 3 to 5 days after inoculation; no symptoms developed on control shoots. The fungus was reisolated from all inoculated shoots. To our knowledge, this is the first report of C. acutatum on wax myrtle in Florida. The disease has a potential to spread and become a significant problem for the cultivation of this species in ornamental nurseries in Florida. Reference: (1) J. H. Simmonds. Qld. J. Agric. Anim. Sci. 22:437, 1965.

Download Full-text

First Report of Anthracnose of Lycium barbarum Caused by Colletotrichum acutatum in China

Plant Disease ◽

10.1094/pdis-92-10-1471a ◽

2008 ◽

Vol 92 (10) ◽

pp. 1471-1471 ◽

Cited By ~ 1

Author(s):

G. Y. Sun ◽

J. Q. Cui ◽

S. F. Wang ◽

R. Zhang ◽

M. L. Gleason

Keyword(s):

Its Region ◽

Colletotrichum Acutatum ◽

Pathogenicity Test ◽

Commonwealth Mycological Institute ◽

Lycium Barbarum ◽

Autonomous Region ◽

First Report ◽

Ningxia Hui Autonomous Region ◽

Fruit Samples ◽

Plant Pathol

Barbary wolfberry (Lycium barbarum, Solanaceae) is an important Chinese traditional medicine that is widely planted in northwestern China (6.7 × 104 ha under cultivation, including Ningxia Hui Autonomous Region). After a recent, large increase in the planting area and density, anthracnose has become more damaging. In China, Colletotrichum gloeosporioides was assumed to be the sole causal agent of anthracnose on L. chinense (wolfberry) (3), whereas in Korea, C. dematium was reported to cause anthracnose on wolfberry (4). During the summer and autumn of 2007, 29 barbary wolfberry fruit samples were collected from three orchards in Zhongning County, Ningxia Hui Autonomous Region. Conidia were 8.5 to 16.5 × 2.5 to 4 μm and fusiform or pointed at one or both ends. Slow-growing colonies on potato dextrose agar were white to orange or pink; sclerotia and setae were absent. The morphological traits were identical to those of C. acutatum and clearly distinct from those of C. gloeosporioides (conidia cylindrical with both ends rounded, gray colony color) or C. dematium (conidia falcate, sclerotia and setae abundant) (2–4). Koch's postulates were performed to verify that the isolates were capable of causing anthracnose on wolfberry. Six wolfberry fruits were surface sterilized with 70% alcohol, allowed to dry 1 min, then wounded with a sterile needle, and dipped in 6 ml of spore suspension (1 × 105 conidia/ml). Anthracnose symptoms were observed on inoculated fruit after 3 days, whereas control fruits inoculated with sterile water did not develop symptoms. The pathogenicity test was performed three times; in each trial, fungi reisolated from symptomatic tissue were morphologically identical to those that had been used as inoculum. Amplification of the internal transcribed spacer (ITS) region of rDNA with primers ITS1 and ITS4 resulted in bands of approximately 600 bp. The sequences of both isolates were compared with sequences deposited in the GenBank database and demonstrated 99% similarity to C. acutatum isolate DQ286123. PCR amplification of the ITS region was also carried out using species-specific primer CaInt2 in conjunction with the universal primer ITS4 (1). A DNA fragment of approximately 500 bp was amplified from all isolates, whereas no amplification products were obtained from reference cultures of C. gloeosporioides and C. dematium. To our knowledge, this is the first report of C. acutatum causing anthracnose on L. barbarum. References: (1) S. Sreenivasaprasad et al. Plant Pathol. 45:650, 1996. (2) B. C. Sutton. Page 523 in: The Coelomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1980. (3) X. M. Wang and J. Y. Li. Acta Mycol. Sinica 6:211, 1987. (4) S. H. Yu. Korean J. Plant Pathol. 2:31, 1986.

Download Full-text

First Report of Sooty Blotch and Flyspeck Caused by Species of Dissoconium, Mycosphaerella, and Peltaster on Hawthorn Fruit in China

Plant Disease ◽

10.1094/pdis-93-6-0670a ◽

2009 ◽

Vol 93 (6) ◽

pp. 670-670 ◽

Cited By ~ 3

Author(s):

H. Y. Li ◽

R. Zhang ◽

G. Y. Sun ◽

M. Tang ◽

M. L. Gleason

Keyword(s):

Apple Fruit ◽

Shaanxi Province ◽

Nuclear Ribosomal Dna ◽

Economic Losses ◽

First Report ◽

Sooty Blotch ◽

Putative Species ◽

Sooty Blotch And Flyspeck ◽

Hawthorn Fruit ◽

Reservoir Hosts

Sooty blotch and flyspeck (SBFS), a disease complex comprised of as many as 30 putative species of fungi, occurs on the cuticle of pome fruits in moist production regions worldwide, inciting cosmetic damage that causes significant economic losses (1). Chinese hawthorn (Crataegus pinnatifida Bge.) is an economically important tree species in China. Its fruit are sold fresh or dried and are used as a culinary spice as well as an ingredient in Chinese traditional medicine. In October of 2007, Chinese hawthorn fruit exhibiting SBFS signs were sampled from supermarkets in Yangling, Shaanxi Province and Luoyang, Henan Province, China. Thalli directly from the hawthorn fruit were transferred onto potato dextrose agar (PDA) slants under a dissecting microscope and cultured at 22 ± 1°C in darkness. DNA was extracted from pure isolates and the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA (nrDNA) was amplified and sequenced using primers ITS-1F and ITS4 (3). Phylogenetic analysis of the ITS sequences revealed that the 35 isolates generated in this study included five species in three genera: Dissoconium sp. (18 isolates), Mycosphaerella sp. (5 isolates), and Peltaster sp. 1 (4 isolates), Peltaster sp. 2 (4 isolates), and Peltaster sp. 3 (4 isolates). To fulfill Koch's postulates and verify that these fungi could also infest apple fruit, two representative isolates of each putative species were inoculated onto mature intact hawthorn and apple (cv. Fuji) fruit that had been surface disinfested with 75% ethanol and allowed to dry. Inoculum was prepared by comminuting 1-month-old cultures growing on PDA into a suspension of mycelial fragments and conidia (105 to ~106 CFU/ml) in a blender with sterile deionized water (SDW). Each isolate was inoculated on three hawthorn and three apple fruit by using cotton swabs. As controls, two surface-disinfested hawthorn and apple fruit were swabbed with SDW. After the inoculated hawthorn and apple fruit had been incubated in a moist chamber at 22 ± 1°C for 1 month, all inoculated hawthorn and apple fruit exhibited SBFS signs similar to those of the original colonies on hawthorn fruit, but the controls did not. Reservoir hosts have been inferred to play an important role in SBFS by providing the fungi with overwintering habitat and inoculum for infestations on apple. Many reservoir hosts have been reported in the United States and Japan (2). To our knowledge, this is the first report of fungi in the SBFS complex on hawthorn fruit and the first confirmation that fungi growing on hawthorn fruit can produce SBFS signs on apple fruit. These results identify hawthorn as a potential inoculum source for SBFS in apple orchards. References: (1) J. C. Batzer et al. Mycologia 97:1283, 2005. (2) K. Hemnani et al. Phytopathology 98(suppl):S66, 2008. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

Download Full-text

Detection and Monitoring of Greeneria uvicola and Colletotrichum acutatum Development on Grapevines by Real-Time PCR

Plant Disease ◽

10.1094/pdis-07-10-0537 ◽

2011 ◽

Vol 95 (3) ◽

pp. 298-303 ◽

Cited By ~ 13

Author(s):

Suren K. Samuelian ◽

Lindsay A. Greer ◽

Sandra Savocchia ◽

Christopher C. Steel

Keyword(s):

Real Time ◽

Real Time Pcr ◽

Epidemiological Studies ◽

Colletotrichum Acutatum ◽

Internal Transcribed Spacer Region ◽

Bitter Rot ◽

Pcr Method ◽

Polymerase Chain ◽

Species Specific ◽

And Control

Bitter rot (Greeneria uvicola) and ripe rot (Colletotrichum acutatum, syn. C. simmondsii) occur frequently in subtropical grape-growing regions of Australia, where they cause yield loss and bitter taints in wine. To further advance the epidemiological studies of G. uvicola and C. acutatum and contribute toward their effective management and control, a rapid and reliable species-specific real-time polymerase chain reaction (PCR) method was developed based on the polymorphic portion of the internal transcribed spacer region of the two fungi. It was found that, within 6 to 8 h postinoculation, the assay could detect as little as 20 fg of genomic DNA and 10 conidia for both species. Artificially and naturally infected grape inflorescences and mature berries were analyzed by both conventional plating methods and real-time PCR. Fungal presence was demonstrated on all plant material but development was observed only on mature berries. The results demonstrate that the real-time PCR technique is a highly specific, rapid, and sensitive method that can be used to detect and study the dynamics of G. uvicola and C. acutatum during different stages of infection and on different grape tissues.

Download Full-text

First Report of Damping-Off on Strawberry Tree Caused by Colletotrichum acutatum and C. simmondsii in Italy

Plant Disease ◽

10.1094/pdis-07-11-0567 ◽

2011 ◽

Vol 95 (12) ◽

pp. 1588-1588 ◽

Cited By ~ 9

Author(s):

G. Polizzi ◽

D. Aiello ◽

V. Guarnaccia ◽

A. Vitale ◽

G. Perrone ◽

...

Keyword(s):

Gene Sequence ◽

Morphological Characteristics ◽

Colletotrichum Acutatum ◽

Commonwealth Mycological Institute ◽

Damping Off ◽

Pcr Assay ◽

Single Spore ◽

First Report ◽

Strawberry Tree ◽

Colletotrichum Spp

In June 2010, a widespread damping-off was noticed in a commercial nursery in eastern Sicily on ~20,000 potted 2-month-old strawberry tree (Arbutus unedo L.) seedlings. More than 40% of the seedlings showed disease symptoms including brown lesions at the seedling crown above and below the soil line that expanded rapidly to girdle the stem. Stem lesions were followed by death of the entire seedling in a few days. Diseased stem and crown tissues of 20 seedlings were surface disinfested for 2 min in 1% NaOCl, rinsed in sterile water, plated on potato dextrose agar amended with 100 mg/liter of streptomycin sulfate, and incubated at 25°C in the dark. Fungal isolates with mycelial and morphological characteristics of Colletotrichum spp. were isolated from all seedlings. Fungal colonies were pale orange or gray without carmine pigments. On carnation leaf agar (CLA), single-spore isolates produced many orange masses of hyaline, aseptate conidia with a cylindrical to ellipsoidal shape, rounded apex, and 11 to 15 μm long and 3 to 4.5 μm wide (average 13.2 × 3.7 μm). The pointed conidia of 10 isolates were morphologically similar. DNA isolation was performed with the Wizard Magnetic DNA Purification Kit (Promega, Madison, WI) following the manufacturer's instructions with some modifications. A PCR assay was conducted on two representative isolates (ITEM 13492 and ITEM 13493) by analyzing sequences of gene benA (coding β-tubulin protein) using the primers T1 and T10 reported by O'Donnell and Cigelnik (1). BenA gene sequence of ITEM 13492 exhibited an identity of 99.8% to C. simmondsii strain BRIP 4704 (GenBank No. GU183277), while BenA gene sequence of ITEM 13493 exhibited an identity of 100% to C. acutatum strain BRIP52695 (GenBank No. GU183314). The identification of these two species was made by comparing the internal transcribed spacer region and BenA sequences of these two strains with that deposited by Shivas and Tan (2). Morphological characteristics, as well as the PCR assay, identified the isolates as Colletotrichum acutatum J.H. Simmonds and C. simmondsii R.G. Shivas & Y. P. Tan (2,3). Pathogenicity tests were carried out on 2-month-old seedlings of strawberry tree grown on alveolar trays. Conidial suspensions of two isolates (ITEM 13492 and ITEM 13493) were obtained from 14-day-old single-spore colonies on CLA, then adjusted to 105 conidia per ml and sprayed on seedlings. Fifty seedlings for each isolate were used. The same number of seedlings was mock inoculated with sterile distilled water. All seedlings were enclosed for 4 days in plastic bags and placed in a growth chamber at 24 ± 1°C for 45 days. Identical symptoms to those observed in the nurseries appeared 30 days after inoculation, and after 45 days, 80% of the plants were dead. No difference in virulence between the two isolates was observed and no symptoms were detected on the control plants. C. acutatum and C. simmondsii were successfully reisolated from all symptomatic tissues and identified as previously described, completing Koch's postulates. To our knowledge, this is the first report in the world of C. acutatum and C. simmondsii on strawberry tree. This suggests that Colletotrichum spp. may be important pathogens of young seedlings of strawberry tree in nurseries. References: (1) K. O'Donnell and E. Cigelnik. Mol. Phylo. Evol. 7:103, 1997. (2) R. G. Shivas and Y. P. Tan. Fungal Divers. 39:111, 2009. (3) B. C. Sutton. Page 523 in: The Coelomycetes. Commonwealth Mycological Institute, Kew, Surrey, England, 1980.

Download Full-text

First Report of Colletotrichum acutatum on Kalmia

Plant Disease ◽

10.1094/pdis.2001.85.4.447a ◽

2001 ◽

Vol 85 (4) ◽

pp. 447-447 ◽

Cited By ~ 7

Author(s):

S. R. H. Langrell ◽

S. J. Irvine

Keyword(s):

Laboratory Strain ◽

Pathogenic Fungi ◽

The United States ◽

Test Material ◽

Colletotrichum Acutatum ◽

Infected Leaf ◽

First Report ◽

Slow Development ◽

Species Specific ◽

The Uk

Colletotrichum acutatum J. H. Simmonds was isolated from diseased leaves of ornamental Kalmia latifolia L. (mountain laurel) cvs. Carousel and Peppermint on plants imported from the United States to Edinburgh, Scotland, in December 1999. Symptoms included sunken, desiccated, darkened necrotic areas, primarily at the leaf tip. Necrotic areas advanced toward the leaf base and were bordered by purple/red pigmentation. Isolations were made from salmon colored conidiomata that developed on abaxial leaf surfaces following incubation in a humidity box at 25°C for 7 to 10 days. White aerial mycelia, becoming gray to grayish beige, and producing salmon to orange colored conidial masses, formed on potato dextrose agar after 10 to 14 days. Conidia were hyaline, aseptate, fusiform to slightly irregular, and measured 13.4 to 13.8 × 4.3 to 4.9 μm. Both morphological and conidial characteristics were consistent with the description of C. acutatum (2). The identity of isolates was further verified by positive plate-trapped antigen ELISA of conidial preparations using a species-specific monoclonal antibody (1). Pathogenicity was assessed by inoculating the adaxial surface of healthy leaves of both cultivars of the imported plants with colonized agar disks and a range of spore suspensions (30, 300, and 3,000 spores delivered in 30 μl volumes) from test fungal isolates and a confirmed laboratory strain (three replicates per treatment). To ensure inoculum uptake, two 5 mm2 areas of cuticle on either side of the mid-rib of each leaf were lightly scratched with a sterile hyperdermic needle prior to inoculation. Inoculated leaves were incubated in a humidity box at 25°C for up to 3 weeks. Symptom development was progressive but relatively slow on both cultivars. The relatively slow development on artificially infected leaf material may be partly attributable to residual fungicide treatment as prescribed by the Scottish Plant Health Service at the time of planting out. Symptoms produced on fruits (apple, banana, and strawberry), inoculated with both test and laboratory strains of the fungus, were identical. Symptoms did not occur on control leaves or fruits inoculated with sterile distilled water or uninoculated agar disks. Koch's postulates were confirmed by consistently reisolating isolates with morphological and immunological characteristics identical to the fungal isolate used to initially inoculate test material. Over the same period, additional symptoms, identical to those originally described at the time of interception, continued to develop on leaf tips of both Kalmia cultivars. Additional isolations from this material were characterized as C. acutatum. Identification of representative isolates was confirmed by CABI Bioscience, Egham, UK, where a reference culture (accession number IMI 384569) has been deposited. As advanced symptoms were observed immediately on arrival of this consignment in the UK, original infection is thought to have occurred prior to importation. This is the first report of C. acutatum infecting K. latifolia. References: (1) I. Barker et al. 1994. Pages 179-182 in: Assays for Plant Pathogenic Fungi: Identification, Detection and Quantification. A. Schots, F. M. Dewey, and R. Oliver, eds. CABI International, Wallingford, UK. (2) B. J. Dyko and J. E. M. Mordue. CMI Descriptions of Pathogenic Fungi and Bacteria. No. 630, 1979.

Download Full-text

First Report of Apple Bitter Rot Caused by Colletotrichum godetiae in the United Kingdom

Plant Disease ◽

10.1094/pdis-11-13-1177-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 1000-1000 ◽

Cited By ~ 16

Author(s):

R. Baroncelli ◽

S. Sreenivasaprasad ◽

M. R. Thon ◽

S. A. Sukno

Keyword(s):

United Kingdom ◽

Phylogenetic Tree ◽

Management Practices ◽

Morphological Characteristics ◽

Colletotrichum Acutatum ◽

Total Production ◽

First Report ◽

The United Kingdom ◽

Bitter Rot ◽

Apple Bitter Rot

Apple is an important crop in United Kingdom, with a total production of 233,750 tonnes in 2011. Symptoms of apple bitter rot were observed on apple fruits (Malus domestica L.) in the Newcastle area, United Kingdom, in October 2008. Lesions were round, 1 to 5 cm in diameter, brown and dry, with acervuli producing yellowish spore masses in concentric bands. Infected material was sent to the W-HRI (University of Warwick) for identification of the causal agent. Fungal isolates with morphological characteristics similar to those of Colletotrichum acutatum sensu lato were isolated from diseased fruits. Monoconidial isolates were grown on PDA at 25°C with a 12-h light period. The cultures were light gray, with cottony aerial mycelium getting darker with age and with color ranging from whitish to dark gray on the reverse side of the colony. The cultures have yellowish spores masses and dark melanized structures similar to acervuli. Colletotrichum spp. are difficult to identify solely on morphology; therefore, representative isolates were used for multi-locus gene sequencing and characterization (1). Genomic DNA was extracted using a modified Chelex100 protocol. Three loci were amplified and sequenced: the ITS region was amplified and sequenced using the universal primers ITS4 and ITS5. Primers TB5 and TB6 were used for the amplification and sequencing of the variable region of the TUB gene. Primers GDF1 and GDR1 were used to amplify a 200-bp intron region of the GAPDH gene. No differences were found among the strains at any of the loci. One sequence for each locus has been deposited in GenBank under accessions KF834206 (ITS), KF834207 (TUB), and KF834208 (GAPDH). In GenBank, ITS sequences matched with 100% identity to C. higginsianum (EU400147) and to C. gloeosporioides (AJ301931 to 972); and with identity between 99.6 and 99.8% with sequences belonging to C. godetiae (part of C. acutatum species complex). The TUB sequences match with 100% identity to more than 25 sequences belonging to C. godetiae. The GAPDH sequences match with 100% identity to JQ948739 and 35 belonging to C. godetiae strains IMI 381927 and CBS 131331. A multilocus phylogenetic tree (ITS, TUB, and GAPDH) was reconstructed using sequences of reference strains belonging to C. higginsianum, C. gloeosporioides, C. godetiae, and related species. The phylogenetic tree confirmed the identity of the strains isolated from apple as C. godetiae. Koch's postulates were tested with representative isolate by artificial inoculation of 12 healthy fruits of the cv. Golden Delicious. Fruit surfaces were sterilized with 70% ethanol, wounded with a sterile needle, and then inoculated with a plug of actively growing mycelium prepared from a 10-day-old culture grown on PDA. Inoculated fruits were incubated in sterile conditions at 25°C with a 12-h photoperiod. In 83% of fruits, symptoms appeared between 7 and 15 days later. The rot begins as light brown, circular lesion getting darker with orange spore masses. Fungal colonies isolated from the lesions and cultured on PDA have identical morphological characteristics of the isolate used for the pathogenicity assay. To the best of our knowledge, this is the first report of apple bitter rot caused by C. godetiae in the United Kingdom. Apple bitter rot is spread worldwide and in moist, temperate regions it is considered one of the most important diseases causing considerable crop losses. Since the losses are more severe under prolonged warm and wet weather conditions, bitter rot caused by C. acutatum species may become an emerging problem in the United Kingdom in the near future, and may require investigation of management practices to control this new disease. References: (1) R. Baroncelli. Colletotrichum acutatum sensu lato: From diversity study to genome analysis. Coventry, United Kingdom, PhD thesis, 2012. (2) U. Damm et al. Stud. Mycol. 73:37, 2012.

Download Full-text

Evaluation of fungicides for control of bitter and sprinkler rots on apple fruit

New Zealand Plant Protection ◽

10.30843/nzpp.2015.68.5801 ◽

2015 ◽

Vol 68 ◽

pp. 264-274 ◽

Cited By ~ 2

Author(s):

K.R. Everett ◽

I.P.S. Pushparajah ◽

J.T. Taylor ◽

O.E. Timudo-Torrevilla ◽

T.M. Spiers ◽

...

Keyword(s):

Bacillus Subtilis ◽

New Zealand ◽

Calcium Chloride ◽

Apple Fruit ◽

Colletotrichum Acutatum ◽

Phytophthora Cactorum ◽

Copper Oxychloride ◽

Bitter Rot ◽

Fruit Disease

Bitter rot is an apple fruit disease most commonly caused in New Zealand by the fungus Colletotrichum acutatum The timing of fungicide applications to manage this disease was investigated during two seasons Fungicides applied during October (carbendazim) or November and December (tolyfluanid captan and mancozeb) reduced incidence of rots expressing on trees in the orchard Fungicides (halfstrength copper oxychloride Bacillus subtilis QST 713 and tolyfluanid) applied during January and February reduced the incidence of postharvest rots Bacillus subtilis QST 713 applied regularly throughout the season reduced incidence of field rots but was not effective when the number of applications was reduced Calcium chloride (CaCl2) or copper oxychloride applied during November and December reduced the incidence of sprinkler rots caused by Phytophthora cactorum

Download Full-text