First Report of Colletotrichum acutatum in Strawberry in Norway

Anthracnose caused by Colletotrichum acutatum J. H. Simmonds was detected in strawberry (Fragaria × ananassa Duch.) for the first time in Norway in 1999. Symptoms were found in greenhouse grown strawberries in the cultivar Korona. Symptoms were typical of strawberry anthracnose: sunken, brown, and firm lesions appeared on maturing fruits. Masses of conidia were produced in acervuli in the center of lesions. The fungus was isolated on acidified potato dextrose agar. Colonies grown on potato dextrose agar (PDA) were pale to mouse gray and became dark greenish to blackish in reverse. Conidia were formed in orange to salmon pink masses in the center of the culture. Conidia in cultures were 16.5 (13.8 to 18.8) × 4.5 (3.8 to 5) μm, and were hyaline, cylindrical, with pointed ends, and aseptate. Setae were never observed in culture or on fruits. The fungus did not form an ascigerous stage in culture. Mycelial growth rate at 25 to 26°C on PDA was 8.1 to 8.4 mm per day. Morphological characters and growth rate were in accordance with previous reports on C. acutatum (1,2). The isolated fungus was confirmed to be C. acutatum by both the International Mycological Institute, Egham, England, and Centraalbureau voor Schimmelcultures, Baarn, the Netherlands. Koch's postulates were fulfilled by inoculating ripe and unripe fruits on strawberry plants with the isolated fungus. Fruits were either sprayed with a conidial suspension (106 conidia per ml) or slightly wounded with a needle that had been dipped in a conidial mass from a pure culture of C. acutatum. Symptoms appeared after 4 days at 20°C, and after 5 days, brown, sunken, circular lesions reached a size of 1 cm in diameter on wounded, ripe fruits. In unripe fruits the lesions developed more slowly, and in unwounded fruits sprayed with a conidial suspension, large, irregular spots developed. Leaves were inoculated by placing a small block of agar at the base of petioles on intact strawberry plants. The tissue underneath the agar was either unwounded or slightly wounded with a needle. After 20 days (at 20 to 25°C) some necrosis developed on both unwounded and wounded petioles. No symptoms were observed in the crown tissue where the inoculated petioles were attached. The fungus was readily reisolated from both fruits and petioles, after which typical morphological characters developed in culture as described above. References: (1) P. S. Gunnell and W. D. Gubler. Mycologia 84:157, 1992. (2) B. J. Smith and L. L. Black. Plant Dis. 74:69, 1990.

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First Report of Strawberry Anthracnose (Colletotrichum acutatum) in Strawberry Fields in New York

Plant Disease ◽

10.1094/pdis.2002.86.8.922d ◽

2002 ◽

Vol 86 (8) ◽

pp. 922-922 ◽

Cited By ~ 1

Author(s):

W. W. Turechek ◽

C. Heidenreich ◽

M. P. Pritts

Keyword(s):

New York ◽

Potato Dextrose Agar ◽

Colletotrichum Acutatum ◽

First Year ◽

Conidial Suspension ◽

Northeastern United States ◽

First Report ◽

Strawberry Anthracnose ◽

Spore Mass ◽

Average Size

Strawberry plants with red to black, sunken, fusoid lesions on runners and leaf petioles were found in several first-year plantings in grower's fields in western New York in 2000. Affected cultivars included Honeoye, Jewel, and Primetime. Sections of petiole were excised from lesion margins and plated on potato dextrose agar (PDA) amended with chloramphenicol, streptomycin sulfate, and tetracycline hydrochloride at 100 μg/ml. The fungus, Colletotrichum acutatum (J.H. Simmonds), was consistently isolated and identified based on conidia morphology and its growth rate in culture relative to reference cultures of C. acutatum, C. gloeosporoides, and C. fragariae (1,2). The average size of conidia produced on PDA was 15.2 × 5 μm. For each of six isolates, three plants each of six-week-old Honeoye and Kent were spray inoculated with a conidial suspension (106 conidia per ml), and petioles, leaves, and crowns were stabbed with a sterile pin following inoculation. After 14 days at 20 to 25°C, petioles and leaves on all inoculated plants developed lesions consistent with those seen in the field. The fungus was readily reisolated from leaf and petiole lesions. Subsequent inoculations on detached fruit under the same conditions yielded circular, sunken, dry lesions that produced a salmon-colored, slimy, spore mass typical of C. acutatum. This is the second report of strawberry anthracnose in the northeastern United States (3) and to our knowledge, the first report in New York. References: (1) J. A. García Muñoz et al. Mycologia 92:288, 2000. (2) P. S. Gunnel and W. D. Gubler. Mycologia 84:157, 1992. (3) J. A. LaMondia. Plant Dis. 75:1286, 1991.

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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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Occurrence of Colletotrichum acutatum, Causal Organism of Strawberry Anthracnose in Southwestern Spain

Plant Disease ◽

10.1094/pdis.1999.83.3.301c ◽

1999 ◽

Vol 83 (3) ◽

pp. 301-301 ◽

Cited By ~ 7

Author(s):

B. de los Santos G de Paredes ◽

F. Romero Muñoz

Keyword(s):

Immunosorbent Assay ◽

Morphological Characteristics ◽

Potato Dextrose Agar ◽

Colletotrichum Acutatum ◽

Enzyme Linked Immunosorbent Assay ◽

Fluorescent Light ◽

Fragaria Ananassa ◽

Causal Organism ◽

Strawberry Anthracnose ◽

Different Tissues

A wilting disease of strawberry (Fragaria × ananassa Duchesne ‘Oso Grande’) was observed in production fields in Huelva, southwestern Andalucía, Spain. Crowns of wilted plants developed a reddish brown, firm rot. Longitudinal sections of roots of diseased plants showed a black coloration of the cortex. Symptons also included blighting of flowers due to floral infection and rotting of green and ripening fruits. On the fruit, the round, firm sunken lesions were covered with masses of salmon-colored spores. Lesions on the leaves were round, ranged in diameter from 5 to 10 mm, and were light brown with purple edges. Infected tissues were surface disinfected in 20% sodium hypoclorite, blotted dry, and plated on water agar. Dishes were incubated at 25°C; hyphal tips made of fungi growing from lesions were transferred to potato dextrose agar (PDA) and incubated under cool-white fluorescent light at 25°C. One fungus was isolated consistently from lesions on different tissues. It was identified as Colletotrichum acutatum by morphological characteristics (2) and enzyme-linked immunosorbent assay (1). On PDA, the mycelium of the fungus was white to gray and covered with salmon spore masses. Colony diameters on PDA averaged 45 mm after 7 days at 25°C. Hyaline, aseptate conidia were cylindrical, fusiform, and intermediate in shape and averaged 12.8 × 4.2 μm in size. The fungus produced setae on infected fruit. Inoculations of strawberry cvs. Oso Grande and Chandler with conidial suspensions (106 conidia per ml) of C. acutatum produced lesions on the fruit, petioles, and crowns, and caused wilt. The pathogen was reisolated from lesions on the inoculated plants. This is the first report of C. acutatum causing strawberry anthracnose in Huelva. References: (1) T. A. Cooke et al. EPPO Bulletin 25:57, 1995. (2) B. C. Sutton. The Coelomycetes. CMI, Kew, England, 1980.

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First Report of Anthracnose Fruit Rot of Strawberry Caused by Colletotrichum acutatum in Montenegro

Plant Disease ◽

10.1094/pdis-02-12-0108-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1066-1066 ◽

Cited By ~ 1

Author(s):

J. Latinovic ◽

N. Latinovic ◽

J. Tiodorovic ◽

A. Odalovic

Keyword(s):

Morphological Characteristics ◽

Its Region ◽

Fruit Rot ◽

Colletotrichum Acutatum ◽

Pathogenicity Test ◽

Centraalbureau Voor ◽

First Report ◽

Strawberry Anthracnose ◽

Production Area ◽

Ascigerous Stage

Strawberries (Fragaria × ananassa) in Montenegro have become an increasingly important economic crop in recent years. During May 2011, severe fruit damage in strawberry cv. Clery was observed in two fields in the Podgorica region. Fruit symptoms were typical for strawberry anthracnose: sunken, dark brown to black circular lesions appeared on maturing fruits. However, no stem, crown, or foliar symptoms were observed. Under wet conditions, orange masses of conidia were produced in acervuli in the center of lesions. Conidia were hyaline, aseptate, cylindrical, with pointed ends, measuring 9.8 to 17.2 (mean 14.3) × 2.5 to 6.1 (mean 4.4) μm. Colonies on potato dextrose agar (PDA) were initially white, then turned gray as conidia formed in orange to salmon pink masses around the center of the culture. Setae or an ascigerous stage were never observed in culture or on the host. Koch's postulates were fulfilled by inoculating ripe and unripe asymptomatic fruits (20 of each, removed from strawberry plants cv. Clery) with the isolated fungus. Fruits were sprayinoculated (106 conidia/ml). An equal number of noninoculated fruits were used as a control. After incubation time of 2 to 3 days at 25°C in a moist chamber, symptoms appeared on inoculated ripe fruits. On unripe fruits, the lesions developed only 3 to 4 days after the inoculation. No symptoms were found on control fruits. The fungus was reisolated from fruits, after which typical morphological characteristics developed in culture as described above. On the basis of the symptoms, the morphological and cultural characteristics of the fungus, and the pathogenicity test, the disease was identified as strawberry anthracnose caused by Colletotrichum acutatum, which is in accordance with previous reports (1,2,3,4). The isolate was submitted to the Centraalbureau voor Schimmelcultures in the Netherlands (CBS 131813). The internal transcribed spacer (ITS) region of the fungal DNA was amplified with ITS1F and ITS4 primers, sequenced, and submitted to NCBI GenBank (Accession No. JQ424934). BLASTn searches of GenBank using the ITS sequence revealed 99% similarity with database sequences of C. acutatum. Since the pathogen was found in the main Montenegrin strawberry production area, it poses a threat to strawberry production in Montenegro. To our knowledge, this is the first report of anthracnose fruit rot of strawberry in Montenegro. References: (1) S. G. Bobev et al. Plant Dis. 86:1178, 2002. (2) F. M. Dai et al. Plant Dis. 90:1460, 2006. (3) U. Nilsson et al. Plant Dis. 89:1242, 2005. (4) A. Stensvand et al. Plant Dis. 85:558, 2001.

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First Report of Anthracnose Fruit Rot Caused by Colletotrichum acutatum on Strawberry in Korea

Plant Disease ◽

10.1094/pdis-92-8-1247c ◽

2008 ◽

Vol 92 (8) ◽

pp. 1247-1247 ◽

Cited By ~ 1

Author(s):

M. H. Nam ◽

T. I. Kim ◽

M. L. Gleason ◽

J. Y. Song ◽

H. G. Kim

Keyword(s):

Pcr Amplification ◽

Morphological Characters ◽

Fruit Rot ◽

Colletotrichum Acutatum ◽

Pathogenicity Test ◽

First Report ◽

Strawberry Anthracnose ◽

Dark Green ◽

Average Size ◽

Species Specific

Symptoms typical of anthracnose fruit rot; sunken, dark brown lesions on maturing fruits, were found in a commercial field of strawberry (Fragaria × ananassa) cv. Cal Giant in Yangyang County, Korea in May 2007. Masses of conidia were produced in acervuli in the center of lesions. The fungus was isolated on potato dextrose agar (PDA). Colonies grown on PDA were pale to mouse gray and became dark green to black in reverse. Conidia were formed in orange-to-salmon pink masses in the center of the culture. The average size of conidia on PDA was 15.2 × 4.6 μm, and they were hyaline, straight, cylindrical, with pointed ends, and aseptate (1). The fungus did not form an ascigerous stage in culture. Mycelial growth rate was 7.5 mm per day at 25°C on PDA. The identity of two isolates was confirmed as Colletotrichum acutatum J.H. Simmonds by PCR amplification using species-specific primers TBCA and TB5 (2), resulting in a characteristic 330-bp band on agarose gel. Morphological characters were in accordance with previous reports on C. acutatum. A pathogenicity test was conducted with five healthy plants of cvs. Cal Giant, Maehyang, Seolhyang, Kumhyang, Akihime, and Redpearl. After fruits and flowers were sprayed with a conidia suspension (105 conidia per ml), the plants were maintained at 10 to 25°C and 100% relative humidity in a greenhouse. As a control, five healthy plants were sprayed with sterile distilled water and incubated under the same conditions. Dark brown, water-soaked spots appeared on mature fruits of all cultivars after 5 days, and lesions on green fruits appeared on individual achenes. Flowers developed dark lesions, dried out, and died. No symptoms were found on the control plants. After the pathogen was reisolated from fruits and flowers lesions, the morphological characters developed in culture as described above. To our knowledge, this is the first report of C. acutatum causing strawberry anthracnose in Korea. References: (1) B. J. Smith and L. L. Black. Plant Dis. 74:69, 1990. (2) P. Talhinhas et al. Appl. Environ. Microbiol. 71:2987, 2005.

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First Report of Colletotrichum gloeosporioides on Chinese Rose in Argentina

Plant Disease ◽

10.1094/pdis.2000.84.12.1345b ◽

2000 ◽

Vol 84 (12) ◽

pp. 1345-1345 ◽

Cited By ~ 1

Author(s):

M. C. Rivera ◽

E. R. Wright ◽

S. Carballo

Keyword(s):

Colletotrichum Gloeosporioides ◽

Buenos Aires ◽

Morphological Characteristics ◽

Disease Prevalence ◽

Potato Dextrose Agar ◽

Conidial Suspension ◽

First Report ◽

Hibiscus Rosa Sinensis ◽

Leaf Drop ◽

Stems And Leaves

Chinese rose (Hibiscus rosa-sinensis L.) is a shrub frequently planted in Argentina. In November 1999, dieback and anthracnose symptoms were detected on stems and leaves of plants cv. Hawaii cultivated in Buenos Aires. Disease prevalence was 50%. Pieces of infected tissues were surface-sterilized for 1 min in 2% NaOCl, plated on potato-dextrose agar and incubated at 24 ± 2°C. The isolate that was consistently recovered from diseased tissues was identified as Colletotrichum gloeosporioides (Penz.) Penz. and Sacc., based on morphological characteristics (1,2). Teleomorph stage was not observed. Inoculation for pathogenicity testing was carried out by spraying a conidial suspension (6.5 × 106 conidia per ml) on plants with previously punctured leaves and pruned stems. Inoculated plants with unwounded tissues, as well as noninoculated controls, were included. Five replications of each treatment were done. Plants were incubated in moist chambers at 24°C. Whitish areas of 0.3 to 0.5 cm diameter surrounded by a purple halo developed on all punctured leaves within 10 days. Stem blight and leaf drop were observed. The center of the lesions was covered by black acervuli 14 days after inoculation. Unwounded and noninoculated controls remained symptomless. The pathogen was reisolated from inoculated leaves, completing Koch's postulates. This is the first report of C. gloeosporioides causing disease on Chinese rose in Argentina. References: (1) J. A. Bailey and M. J. Jeger, eds. 1992. Colletotrichum. CAB International, Surrey, England. (2) B. C. Sutton. 1980. The Coelomycetes. CMI, Kew.

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Isozyme variation, morphology, and growth response to temperature in Pythium irregulare

Canadian Journal of Botany ◽

10.1139/b97-918 ◽

1997 ◽

Vol 75 (12) ◽

pp. 2073-2081 ◽

Cited By ~ 23

Author(s):

D. J. S. Barr ◽

S. I. Warwick ◽

N. L. Desaulniers

Keyword(s):

Growth Rate ◽

Pythium Ultimum ◽

Morphological Characters ◽

Published Data ◽

Pythium Irregulare ◽

Analysis Group ◽

Wide Range ◽

Pythium Sylvaticum ◽

Group A ◽

Group B

Isozyme-based genetic diversity, morphological characters, and growth rate at different temperatures were compared in a worldwide collection of 125 isolates presumed to be Pythium irregulare Buisman. The isozyme data was analysed with previously published data for Pythium ultimum Trow and Pythium sylvaticum Campbell & Hendrix. UPGMA cluster analysis yielded a dendrogram with four distinct groups: P. ultimum, P. sylvaticum, and two for P. irregulare. Putative P. irregulare isolates were separated into 33 multilocus genotypes defined by 11 isozyme loci: group A contained 116 isolates in 25 genotypes, and group B, 8 isolates in 7 genotypes. One genotype with a single isolate was determined as P. sylvaticum. Based on the isozyme analysis, group B was considered a distinct taxonomic entity from group A, but lacked any unique morphological character. There was a wide range in oogonium and oospore sizes among different isolates of P. irregulare, with those in group B generally being larger. Some isolates in group A had well developed oogonial spines, but others were essentially spineless, whereas all those in group B were spineless. Both groups A and B contained isolates with distinctly aplerotic oospores and others with essentially plerotic oospores. Antheridial number and shape were highly variable both within and among isolates in the two groups. Growth rate over a range of temperatures varied among isolates in both groups and was not a reliable taxonomic criterion. The irregular shape of oogonia and, when present, oogonial spines were the only reliable characters for distinguishing P. irregulare isolates from other taxa. Key words: taxonomy, Oomycetes, Pythiaceae, Pythium ultimum, Pythium sylvaticum.

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First Report of Stem Blight Caused by Calonectria colhounii (Anamorph Cylindrocladium colhounii) on Greenhouse-Grown Blueberries in the United States

Plant Disease ◽

10.1094/pdis-02-11-0117 ◽

2011 ◽

Vol 95 (9) ◽

pp. 1187-1187

Author(s):

J. J. Sadowsky ◽

T. D. Miles ◽

A. M. C. Schilder

Keyword(s):

United States ◽

North Carolina ◽

Root Rot ◽

The United States ◽

Vaccinium Corymbosum ◽

Conidial Suspension ◽

Centraalbureau Voor ◽

First Report ◽

Stem Lesions ◽

Β Tubulin

Necrotic stems and leaves were observed on 2- to 4-month-old, rooted microshoot plants (Vaccinium corymbosum L. ‘Liberty’ and ‘Bluecrop’, V. angustifolium Aiton ‘Putte’, and V. corymbosum × V. angustifolium ‘Polaris’) in a Michigan greenhouse in 2008 and 2009. As the disease progressed, leaves fell off and 80 to 100% of the plants died in some cases. Root rot symptoms were also observed. A fungus was isolated from stem lesions. On potato dextrose agar (PDA), cultures first appeared light tan to orange, then rusty brown and zonate with irregular margins. Chains of orange-brown chlamydospores were abundant in the medium. Macroconidiophores were penicillately branched and had a stipe extension of 220 to 275 × 2.5 μm with a narrowly clavate vesicle, 3 to 4 μm wide at the tip. Conidia were hyaline and cylindrical with rounded ends, (1-)3-septate, 48 to 73 × 5 to 7 (average 60 × 5.5) μm and were held together in parallel clusters. Perithecia were globose to subglobose, yellow, 290 to 320 μm high, and 255 to 295 μm in diameter. Ascospores were hyaline, 2- to 3-septate, guttulate, fusoid with rounded ends, slightly curved, and 30 to 88 × 5 to 7.5 (average 57 × 5.3) μm. On the basis of morphology, the fungus was identified as Calonectria colhounii Peerally (anamorph Cylindrocladium colhounii Peerally) (1,2). The internal transcribed spacer region (ITS1 and ITS2) of the ribosomal DNA and the β-tubulin gene were sequenced (GenBank Accession Nos. HQ909028 and JF826867, respectively) and compared with existing sequences using BLASTn. The ITS sequence shared 99% maximum identity with that of Ca. colhounii CBS 293.79 (GQ280565) from Java, Indonesia, and the β-tubulin sequence shared 97% maximum identity with that of Ca. colhounii CBS 114036 (DQ190560) isolated from leaf spots on Rhododendron sp. in North Carolina. The isolate was submitted to the Centraalbureau voor Schimmelcultures in the Netherlands (CBS 129628). To confirm pathogenicity, 5 ml of a conidial suspension (1 × 105/ml) were applied as a foliar spray or soil drench to four healthy ‘Bluecrop’ plants each in 10-cm plastic pots. Two water-sprayed and two water-drenched plants served as controls. Plants were misted intermittently for 2 days after inoculation. After 7 days at 25 ± 3°C, drench-inoculated plants developed necrotic, sporulating stem lesions at the soil line, while spray-inoculated plants showed reddish brown leaf and stem lesions. At 28 days, three drench-inoculated and one spray-inoculated plant had died, while others showed stem necrosis and wilting. No symptoms were observed on control plants. Fungal colonies reisolated from surface-disinfested symptomatic stem, leaf, and root segments appeared identical to the original isolate. Cy. colhounii was reported to cause a leaf spot on blueberry plants in nurseries in China (3), while Ca. crotalariae (Loos) D.K. Bell & Sobers (= Ca. ilicicola Boedijn & Reitsma) causes stem and root rot of blueberries in North Carolina (4). To our knowledge, this is the first report of Ca. colhounii causing a disease of blueberry in Michigan or the United States. Because of its destructive potential, this pathogen may pose a significant threat in blueberry nurseries. References: (1) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. The American Phytopathological Society, St. Paul, MN, 2002. (2) L. Lombard et al. Stud. Mycol. 66:31, 2010. (3) Y. S. Luan et al. Plant Dis. 90:1553, 2006. (4) R. D. Milholland. Phytopathology 64:831, 1974.

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Characterization of Colletotrichum acutatum Isolates Causing Anthracnose of Almond and Peach in California

Phytopathology ◽

10.1094/phyto.1997.87.9.979 ◽

1997 ◽

Vol 87 (9) ◽

pp. 979-987 ◽

Cited By ~ 106

Author(s):

J. E. Adaskaveg ◽

R. J. Hartin

Keyword(s):

Growth Rate ◽

South Carolina ◽

Dna Sequences ◽

Optimal Growth ◽

Colletotrichum Acutatum ◽

Similar Response ◽

Mature Fruit ◽

Causal Organism ◽

Conidial Morphology ◽

Optimal Growth Rate

The causal organism responsible for the recent outbreak of almond and peach anthracnose in California was identified and characterized as Colletotrichum acutatum. Isolates of C. acutatum from almond were found to be similar to California strawberry isolates and South Carolina peach and apple isolates of C. acutatum based on conidial morphology, temperature relationships, fungicide sensitivity, and polymerase chain reaction (PCR) methods using DNA species-specific primers. On almond, blossoms and immature or mature fruit were affected by the disease, causing direct losses of crop. On peach, the disease was observed only on mature fruit. Pathogenicity of almond and peach isolates of C. acutatum was demonstrated on wound- and nonwound-inoculated almond or peach fruit by fulfilling Koch's postulates. Conidial morphology of isolates was variable, depending on the medium or substrate used to culture the isolates. Isolates of C. acutatum from strawberry, almond, and peach were grouped together based on a similar response to temperature, with an optimal growth rate at 25°C (generally less than 10 mm/day), whereas isolates of C. gloeosporioides from citrus and papaya had an optimal growth rate at 30°C (generally greater than 10 mm/day). In fungicide disk assays, isolates of C. acutatum from strawberry, peach, and apple, as well as almond and peach isolates from California, were less sensitive to benomyl at 300, 600, or 1,200 μg/ml. In contrast, C. gloeosporioides isolates from citrus and papaya were very sensitive to benomyl at all concentrations evaluated. All isolates of both species were sensitive to captan (300, 600, or 1,200 μg/ml). Oligonucleotide primers were synthesized for C. acutatum, C. fragariae, or C. gloeosporioides using published DNA sequences from the internal transcribed spacer 1 region of ribosomal DNA. Thirty-two Colletotrichum isolates from almond fruit produced DNA products with a C. acutatum primer (CaInt-2) that matched products and approximate molecular weight of known C. acutatum isolates. No PCR products were produced with primers for C. gloeosporioides or C. fragariae. Isolates from citrus and papaya produced DNA products only with primers from C. gloeosporioides or C. fragariae. Thus, worldwide, anthracnose of almonds may be caused by either C. gloeosporioides, as previously reported, or by C. acutatum, as indicated in this study.

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Strawberry Anthracnose: Histopathology of Colletotrichum acutatum and C. fragariae

Phytopathology ◽

10.1094/phyto.2002.92.10.1055 ◽

2002 ◽

Vol 92 (10) ◽

pp. 1055-1063 ◽

Cited By ~ 48

Author(s):

Kenneth J. Curry ◽

Maritza Abril ◽

Jana B. Avant ◽

Barbara J. Smith

Keyword(s):

Vascular Tissue ◽

Light And Electron Microscopy ◽

Hyphal Growth ◽

Fungal Species ◽

Colletotrichum Acutatum ◽

Cortical Tissue ◽

In Planta ◽

Strawberry Anthracnose ◽

Strawberry Cultivar ◽

Germ Tubes

Ontogeny of the invasion process by Colletotrichum acutatum and C. fragariae was studied on petioles and stolons of the strawberry cultivar Chandler using light and electron microscopy. The invasion of host tissue by each fungal species was similar; however, each invasion event occurred more rapidly with C. fragariae than with C. acutatum. Following cuticular penetration via an appressorium, subsequent steps of invasion involved hyphal growth within the cuticle and within the cell walls of epidermal, subepidermal, and subtending cells. Both species of fungi began invasion with a brief biotrophic phase before entering an extended necrotrophic phase. Acervuli formed once the cortical tissue had been moderately disrupted and began with the development of a stroma just beneath the outer periclinal epidermal walls. Acervuli erupted through the cuticle and released conidia. Invasion of the vascular tissue typically occurred after acervulus maturation and remained minimal. Chitin distribution in walls of C. fragariae was visualized with gold-labeled wheat germ agglutinin. The outer layer of bilayered walls of conidia, germ tubes, and appressoria contained less chitin than unilayered hyphae in planta.

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