First Report of the Pathogenicity of Colletotrichum gloeosporioides on Invasive Ferns, Lygodium microphyllum and L. japonicum, in Florida

K. A. Jones; M. B. Rayamajhi; P. D. Pratt; T. K. Van

doi:10.1094/pdis.2003.87.1.101b

First Report of the Pathogenicity of Colletotrichum gloeosporioides on Invasive Ferns, Lygodium microphyllum and L. japonicum, in Florida

Plant Disease ◽

10.1094/pdis.2003.87.1.101b ◽

2003 ◽

Vol 87 (1) ◽

pp. 101-101 ◽

Cited By ~ 2

Author(s):

K. A. Jones ◽

M. B. Rayamajhi ◽

P. D. Pratt ◽

T. K. Van

Keyword(s):

Colletotrichum Gloeosporioides ◽

First Record ◽

South Florida ◽

Growth Chamber ◽

Fluorescent Light ◽

Distilled Water ◽

Conidial Suspension ◽

Potted Plants ◽

Plastic Bags ◽

Fern Species

Lygodium microphyllum (Cav.) R.Br. (Old World climbing fern) and L. japonicum (Thunb.) Sw. (Japanese climbing fern), in the family Schizaeaceae, are among the most invasive weeds in Florida (1). L. microphyllum invades fresh water and moist habitats in south Florida, while L. japonicum has spread in relatively well-drained habitats from Texas to North Carolina and central Florida. Some potted plants of both Lygodium spp. grown in shadehouse as well as in full sunlight developed discolored spots on pinnules (foliage), which coalesced and resulted in browning and dieback of severely infected vines. Symptomatic foliage obtained from these plants was surface-sterilized by immersing in a 15% solution of commercial bleach for 90 s, followed by a series of four rinses with sterile deionized distilled water. Disks (4 mm in diameter) of pinnules were cut from the junction of discolored and healthy tissues and placed on potato dextrose agar (PDA). A fungus, Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. was consistently isolated from these disks. Fungal colonies produced abundant conidia on PDA. Conidia were hyaline, straight, cylindrical, averaging 14.7 μm (range 12.5 to 17.5 μm) × 5.0 μm (range 3.8 to 7.5 μm), and similar to those described for C. gloeosporioides (2). To confirm the pathogenicity of C. gloeosporioides on L. microphyllum and L. japonicum, Koch's postulates were performed. A fungal isolate was grown on PDA for 3 weeks, after which 10 ml of sterile deionized distilled water was added to the culture and agitated to dislodge conidia. The conidial suspension was strained through three layers of cheesecloth to remove hyphal fragments, and its concentration was adjusted to 1.7 × 106 conidia/ml. Foliage of healthy L. microphyllum and L. japonicum plants grown in 500-ml containers was sprayed with the conidial suspension until runoff. Plants were covered with plastic bags whose inner sides were misted with water to maintain high humidity and placed in a growth chamber under 12 h of fluorescent light per day. Temperature and relative humidity in the chamber ranged from 26 to 29°C and 44 to 73%, respectively. Plastic bags were removed after 3 days, and plants were further incubated for 3 weeks in the same growth chamber. Control plants were sprayed with sterile water, covered with plastic bags, and exposed to the same temperature, light, and humidity regime as those of the fungus-inoculated plants. Small, discolored foliar spots appeared 3 days after fungus inoculation. These spots were similar to those observed on pinnules of potted plants that originated from shadehouse and outdoor environments. Within 3 weeks after inoculation, the foliage of L. japonicum developed abundant discolored spots that led to edge browning and wilting of the pinnules. L. microphyllum had similar but more severe symptoms, with plants suffering as much as 50% dieback. C. gloeosporioides was consistently reisolated from the symptomatic tissues of both fern species. No symptoms appeared on the water-inoculated plants. To our knowledge, this is the first record of C. gloeosporioides pathogenicity on L. microphyllum and L. japonicum. References: (1) R. W. Pemberton and A. P. Ferriter. Am. Fern J. 88:165, 1998. (2) B. C. Sutton. Colletotrichum: Biology, Pathology and Control. CAB International, Wallingford, Oxon, UK, 1992.

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First Report of Brown Blight Disease Caused by Colletotrichum gloeosporioides on Camellia sinensis in Anhui Province, China

Plant Disease ◽

10.1094/pdis-08-13-0896-pdn ◽

2014 ◽

Vol 98 (2) ◽

pp. 284-284 ◽

Cited By ~ 16

Author(s):

M. Guo ◽

Y. M. Pan ◽

Y. L. Dai ◽

Z. M. Gao

Keyword(s):

Camellia Sinensis ◽

Colletotrichum Gloeosporioides ◽

Tea Plant ◽

Anhui Province ◽

Molecular Characteristics ◽

Fluorescent Light ◽

Distilled Water ◽

Conidial Suspension ◽

First Report ◽

Twig Blight

Yellow Mountain fuzz tip, a cultivar of Camellia sinensis (L.) Kuntze, is commonly grown in the Yellow Mountain region in Anhui Province of China. During 2011 to 2012, leaf and twig blight on tea plants occurred from July to September in growing regions. Symptoms of blight on leaves of infected plants were detected in 30 to 60% of the fields visited and up to 500 ha were affected each year. Symptoms began as small, water-soaked lesions on young leaves and twigs and later became larger, dark brown, necrotic lesions, 1 to 3 mm in diameter on leaves and 2 to 5 mm long on twigs. To determine the causal agent, symptomatic leaf tissue was collected from plants in Gantang and Tangkou townships in September 2012. Small pieces of diseased tea leaves and twigs were surface-disinfested in 2% NaClO for 3 min, rinsed twice in distilled water, plated on potato dextrose agar, and incubated at 28°C for 5 days. Eleven isolates were recovered and all cultures produced white-to-gray fluffy aerial hyphae and were dark on the reverse of the plate. The hyphae were hyaline, branching, and septate. Setae were 2- to 3-septate, dark brown, acicular, and 78.0 to 115.0 μm. Conidiogenous cells were hyaline, short, branchless, cylindrical, and 11.3 to 21.5 × 4.2 to 5.3 μm. Conidia were hyaline, aseptate, guttulate, cylindrical, and 12.5 to 17.3 × 3.9 to 5.8 μm. Appresoria were ovate to obovate, dark brown, and 8.4 to 15.2 × 7.8 to 12.9 μm. DNA was amplified using the rDNA-ITS primer pair ITS4/ITS5 (3), glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH) primer pair GDF/GDR (2) and beta-tubulin 2 gene (Tub2) primer pair Btub2Fd/Btub4Rd (4). Sequences (GenBank Accession Nos. KC913203, KC913204, and KC913205) of the 11 isolates were identical and revealed 100% similarity to the ITS sequence of strain P042 of Colletotrichum gloeosporioides (EF423527), 100% identity to the GAPDH of isolate C07009 of C. gloeosporioides (GU935860), and 99% similarity to Tub2 of isolate 85 of C. gloeosporioides (AJ409292), respectively. Based on the above data, the 11 isolates were identified as C. gloeosporioides (Penz.) Penz. & Sacc. To confirm pathogenicity, Koch's postulate was performed and 4 ml of conidial suspension (1 × 105 conidia/ml) of each of the 11 isolates was sprayed on five leaves and five twigs per plant on four 12-month-old Yellow Mountain fuzz tip plants. Control plants were sprayed with distilled water. The inoculated plants were maintained at 28°C in a greenhouse with constant relative humidity of 90% and a 12-h photoperiod of fluorescent light. Brown necrotic lesions appeared on leaves and twigs after 7 days, while the control plants remained healthy. The experiments were conducted three times and the fungus was recovered and identified as C. gloeosporioides by both morphology and molecular characteristics. Tea plant blight caused by C. gloeosporioides was identified in Brazil (1), but to our knowledge, this is the first report of C. gloeosporioides causing tea leaf and twig blight on Yellow Mountain fuzz tip plants in Anhui Province of China. References: (1) M. A. S. Mendes et al. Page 555 in: Embrapa-SPI/Embrapa-Cenargen, Brasilia, 1998. (2) M. D. Templeton et al. Gene 122:225, 1992. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (4) J. H. C. Woudenberg et al. Persoonia 22:56, 2009.

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Brown leaf spot of Cycas debaoensis Caused by Colletotrichum siamense in Sichuan, China

Plant Disease ◽

10.1094/pdis-10-20-2149-pdn ◽

2021 ◽

Author(s):

Shan Han ◽

Jimin Ma ◽

Yanyue Li ◽

Shujiang Li ◽

yinggao Liu ◽

...

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

Negative Control ◽

Wild Plants ◽

Pathogenicity Test ◽

Distilled Water ◽

Conidial Suspension ◽

Potted Plants ◽

Brown Leaf Spot ◽

Brown Leaf

Cycas debaoensis Y. C. Zhong et C. J. Chen is an endemic species in China that is listed among China’s national key preserved wild plants (Class I) (Xie et al. 2005). It is mainly distributed in south China (Guangxi, Guizhou, and other regions). In April 2017, a new leaf disease of C. debaoensis was found in Chengdu (30°35′32″ N; 104°05′11″E) in China with an incidence over 40%. Symptoms on C. debaoensis initially appeared as brown necrotic lesions on the margin or in the center of leaves. The lesions then enlarged gradually and developed into brown spots, necrotic lesions with dark brown margins. Many small and black dots were observed on necrotic lesions. Eventually, the diseased leaves withered and died. Ten samples were collected and surface-sterilized by 3% NaClO and 75% ehanol respectively for 60s and 90s, rinsed with autoclaved distilled water and then blot-dried with autoclaved paper towels. Five isolates from diseased leaves with similar morphology were isolated from single spores. Morphological characteristics were recorded from pure cultures grown on potato dextrose agar (PDA) incubated at 25°C for 3-9 days. Initially, the colonies grown on PDA were white, then, became pale gray with concentric zones and greenish black beneath. Conidia were single-celled, smooth-walled, straight, colorless, cylindrical with both ends bluntly rounded,13.0-16.5 × 4.7-5.8 μm in size (n = 100 spores). For molecular identification, the genomic DNA of the isolates was extracted using a DNeasyTM Plant Mini Kit (Qiagen). The internal transcribed spacer (ITS) (ITS1/ITS4 White et al., 1990), β-tubulin (TUB2) (BT2A/BT2B (O’Donnell et al., 1997)), actin (ACT) (ACT512F/ACT (Carbone & Kohn, 1999)), calmodulin (CAL) (CL1C/CL2C (Weir et al., 2012)), mating type protein and chitin synthase (CHS-1) (CHS-1) (CHS-9 79F/CHS-345R (Carbone & Kohn, 1999)) were amplified. BLAST results indicated that the ITS, TUB2, ACT, CAL, CHS-1 sequences (GenBank MN305712, MN605072, MT478663, MT465591 and MT478664) showed 99-100% identity with C. siamense sequences at NCBI (GenBank JF710564, MK341542, MK855094, MH351155 and MK471373). The Phylogenetic tree inferred from the combined dataesets (TEF, TUB and ACT) show that the isolate belongs to C. siamense clade with a credibility value of 99%. Two-year-old potted plants of C. debaoensis (10 plants) were used for pathogenicity test. On each plant, 5 leaves were sprayed with a conidial suspension (1 × 106 conidia/ml) on both sides of the leaves. Autoclaved distilled water was used as negative control (10 plants). Plants were kept in the greenhouse at 25 °C under 16h/8h photoperiod and 70-75% relative humidity (RH). The symptoms observed on the inoculated plants were similar to those observed in the field, while the controls remained asymptomatic. C. siamense was re-isolated from all diseased inoculated plants, and the culture and fungus characteristics were the same as the original isolate. The morphological characteristics and molecular analyses of the isolate matched the description of C. siamense (Prihastuti et al., 2009). C. siamense was previously reported infecting Citrus reticulata (Cheng et al. 2013), but this is the first report of brown leaf spot on C. debaoensis caused by C. siamense in China. This finding provides important basis for further research on the control of the disease.

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First Report of Target Spot of Broadleaf Tobacco Caused by Rhizoctonia solani (AG-3) in Connecticut

Plant Disease ◽

10.1094/pdis-04-12-0335-pdn ◽

2012 ◽

Vol 96 (9) ◽

pp. 1378-1378 ◽

Cited By ~ 1

Author(s):

J. A. LaMondia ◽

C. R. Vossbrinck

Keyword(s):

Rhizoctonia Solani ◽

Sequence Data ◽

Its Region ◽

Anastomosis Group ◽

Growth Chamber ◽

First Report ◽

Potted Plants ◽

Plastic Bags ◽

Target Spot ◽

Half Strength

In June 2011, 15 transplant beds of broadleaf cigar wrapper tobacco (Nicotiana tabacum L., cv. C9) plants in Hartford County, Connecticut, were observed with almost every plant diseased. Leaf lesion symptoms ranged from small (2 to 3 mm) water-soaked spots to larger (2 to 3 cm) lesions. Disease was subsequently observed, also at nearly 100% incidence in a 10-hectare field on that farm and at additional broadleaf tobacco farms from two other towns in Hartford County and one town in Tolland County. Lesions exhibited a pattern of concentric rings, necrotic centers and tears in the centers, and margins that often resulted in a shot-hole appearance. Some lesions had chlorotic halos. Rhizoctonia solani Kuhn (Thanatephorus cucumeris A. B. Frank) was isolated from the margins of lesions that had been surface sterilized in 0.5% NaOCl for 30 s and then rinsed in sterile distilled water and placed on the surface of half-strength potato dextrose agar (PDA). Multiple isolations were made and the pathogen was identified on the basis of mycelial characteristics including multinucleate cells, septate hyphae wider than 7 μm, and hyphal branches occurring at approximately right angles, constricted at the base (4). Eight-week-old potted tobacco plants were each inoculated by spraying with a mycelial suspension (1 × 105 CFU) of an isolate of R. solani recovered from tobacco onto leaves, or with water alone (five plants each). The plants were placed in plastic bags in a 24°C growth chamber and misted. After 2 days, the bags were removed and the potted plants placed in trays filled to a depth of 1 cm with water in the growth chamber. After 8 days, the pathogen was reisolated from all inoculated plants exhibiting water-soaked spots as disease symptoms. Leaves inoculated with water or half-strength PDA plugs alone were asymptomatic. DNA was liberated from hyphae of the R. solani isolate by bead beating in STE buffer using 0.15 mm zirconium beads. Two microliters of the eluate was used to amplify the ITS region. Amplified DNA was purified in a Qiagen QIAquick PCR purification kit and submitted to the Yale science hill genomic facility for standard Sanger dideoxy sequencing. The sequence was exactly the same as an isolate from Massachusetts that we sequenced in 2010 (GenBank Accession No. HQ241274). The ITS sequence confirmed our identification of this new isolate as R. solani anastomosis group (AG) 3. This disease has been previously reported on tobacco from South America, South Africa, and the southern United States (1), Canada (3), and Massachusetts (2). Conditions were very conducive for disease because 2011 was a very wet year in Connecticut. To our knowledge, this is the first report of this disease in broadleaf cigar wrapper tobacco in Connecticut. The sequence data suggested that it may have been introduced to Connecticut from Massachusetts. We have found the target spot pathogen distributed across the tobacco producing area of Connecticut. This constitutes a serious threat as there are no systemic fungicides currently registered for control of this disease in broadleaf tobacco. References: (1) J. S. Johnk et al. Phytopathology 83:854, 1993. (2) J. A. LaMondia and C. R. Vossbrinck, Plant Dis. 95:496, 2010. (3) R. D. Reeleder et al., Plant Dis., 80:712. (4) B. Sneh et al. Identification of Rhizoctonia species. The American Phytopathological Society, St. Paul, MN, 1991.

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First Report of Botrytis Blight Caused by Botrytis cinerea on Sweet Basil in Hungary

Plant Disease ◽

10.1094/pdis-91-8-1052c ◽

2007 ◽

Vol 91 (8) ◽

pp. 1052-1052

Author(s):

G. Nagy

Keyword(s):

Botrytis Cinerea ◽

Northern Region ◽

Conidial Suspension ◽

Large Area ◽

Field Surveys ◽

First Report ◽

Sweet Basil ◽

Potted Plants ◽

Plastic Bags ◽

Disease Occurrence

In Hungary, sweet basil (Ocimum basilicum L.) is an important medicinal and aromatic plant cultivated over a large area. During field surveys conducted in August and September of 2001 and 2002, significant blossom and leaf blight were observed in plant stands located near Budapest and in the northern region of Hungary at Herencsény. Incidence of disease occurrence ranged between 49 and 92%. Abundant grayish-brown mold consisting of mycelia and conidiophores was observed on necrotic flowers and upper leaves. The fungus was identified as Botrytis cinerea Pers.:Fr.. Conidia were one-celled, ovoid to elliptical, and measured 11.2 × 7.4 μm (7.5 to 15.0 × 5.0 to 10.0 μm). The fungus was isolated on Leonian malt media. In culture, small and large irregular sclerotia, as well as conidiophores, were produced abundantly. Size of large sclerotia ranged between 45 and 95 mm. Sclerotia were produced only in culture. Pathogenicity of two isolates originating from Herencsény was confirmed by spraying eight sweet basil potted plants with a conidial suspension (6.3 × 105 conidia/ml) made from a pure culture. Two noninoculated plants served as controls. Half of the plants were wounded with needles to make incisions on the leaves and flower axes prior to the inoculation, while the remaining plants were directly sprayed. After inoculation, plants were kept in plastic bags in a greenhouse to maintain 90 to 100% relative humidity at 15 to 40°C. After 5 days, water-soaked chlorotic lesions appeared on the wounded leaves of the inoculated plants. After day 12, brown necrosis developed on the flowers of all inoculated plants. Flower axes often broke. Sporulation of the fungus was abundant. Wounding contributed to earlier appearance of the symptoms and more intensive disease development. To our knowledge, this is the first report of botrytis blight on sweet basil in Hungary. In Europe, the disease has been observed in Italy (1) and Greece (2). References: (1) A. Garibaldi et al. Plant Dis. 81:124, 1997. (2) C. D. Holevas et al. Benaki Phytopathol. Inst. Kiphissia, Athens 19:1, 2000.

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First Report of Alternaria Blight of Potato Caused by Alternaria tenuissima in China

Plant Disease ◽

10.1094/pdis-08-12-0763-pdn ◽

2013 ◽

Vol 97 (9) ◽

pp. 1246-1246 ◽

Cited By ~ 7

Author(s):

H. H. Zheng ◽

X. H. Wu

Keyword(s):

Solanum Tuberosum L ◽

Histone Gene ◽

Gansu Province ◽

Molecular Characteristics ◽

Fluorescent Light ◽

Distilled Water ◽

Conidial Suspension ◽

Species Identity ◽

First Report ◽

Alternaria Blight

Potato (Solanum tuberosum L.) is grown worldwide as a major food crop. Potato early blight is an important disease caused by Alternaria solani (4). In 2011, diseased potato leaves with blight symptoms were collected from 21 sites (incidence averaged 60% for about 2,000 ha of potato fields examined) in Gansu Province, northwest China. Small pieces of tissue taken from the margin between healthy and diseased tissues were surface-disinfected in 0.3% NaOCl for 2 min, rinsed with sterilized, distilled water, then placed on potato dextrose agar (PDA) at 25°C in the dark. Two of 24 Alternaria isolates from single-spore cultures were identified preliminarily as A. tenuissima, and the remaining isolates as A. solani or A. alternata, based on morphological traits. Colony appearance on potato carrot agar (PCA) was loosely cottony under a day/night cycle of 8 h fluorescent light/16 h dark at 22°C for 7 days (3). The isolates were characterized by formation of unbranched conidial chains up to 12 conidia in length, with one or two lateral branches forming occasionally. Conidia were typically ovoid to obclavate, and ranged from 20.4 to 42.4 × 7.7 to 13.2 μm. Transverse septa and longitudinal septa of conidia varied from 1 to 6 and 0 to 2, respectively. Short conidiophores arose singly and were 15.1 to 76.8 μm long by 2.4 to 6.2 μm wide. The internal transcribed spacer (ITS) region of rDNA and partial coding sequence of a histone gene were amplified from genomic DNA of the two A. tenuissima isolates using the ITS1/ITS4 and H3-1a/H3-1b primers (2), respectively. The ITS sequences of the two isolates (GenBank Accession Nos. JX495165 and JX495166) were 100% identical to those of A. tenuissima strains sdau 07-100 and BL08-3 (GQ871507 and AB470887), as well as to other Alternaria species, but the partial histone gene sequences (JX495167 and JX495168) were 99% identical to those of A. tenuissima isolates CR27, MA1, MA6, and CN-L-01 (AF404622, AF404633, AF404634, and EF371552, respectively) with less similarity to those of other Alternaria spp. Therefore, the isolates were identified as A. tenuissima based on morphological and molecular characteristics. Pathogenicity tests were conducted by inoculating detached leaves (30 per isolate) from 45-day-old plants of potato cv. Favorita with 20 μl drops (one drop per leaf) of a conidial suspension containing 106 conidia/ml in sterilized, distilled water. Thirty control leaves were inoculated similarly with sterilized, distilled water. Inoculated leaves were incubated in chambers at 25°C and 90% RH with a 12-h photoperiod/day. After 7 days, symptoms on the inoculated leaves were similar to those naturally occurring on the original plants, and the two cultures were reisolated consistently from those leaves, and the species identity was confirmed by morphological and molecular characteristics, fulfilling Koch's postulates. The control leaves remained asymptomatic and Alternaria was not isolated from those leaves. Alternaria blight of potato caused by A. tenuissima was previously detected in Iran (1). To our knowledge, this is the first report of A. tenuissima causing blight on potatoes in China. References: (1) S. T. Ardestani et al. Iran. J. Plant Pathol. 45:83, 2010. (2) N. L. Glass and G. C. Donaldson. Appl. Environ. Microbiol. 61:1323, 1995. (3) E. G. Simmons. Alternaria. An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, the Netherlands, 2007. (4) J. E. van der Waals et al. Plant Dis. 88:959, 2004.

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First Report of Alternaria tenuissima as a Leaf Pathogen of Amaranthus hybridus

Plant Disease ◽

10.1094/pdis.1999.83.9.878a ◽

1999 ◽

Vol 83 (9) ◽

pp. 878-878 ◽

Cited By ~ 3

Author(s):

J. T. Blodgett ◽

W. J. Swart ◽

Weiqun Chen

Keyword(s):

Leafy Vegetable ◽

Growth Chamber ◽

Minimal Amount ◽

Distilled Water ◽

Conidial Suspension ◽

Vegetable Crop ◽

Single Spore ◽

Amaranthus Hybridus ◽

Alternaria Tenuissima ◽

Agar Plug

Amaranthus hybridus is an important alternative leafy-vegetable crop with the potential for increased commercial production in southern Africa and other semi-arid regions of the world (2). In May 1998, extensive leaf spotting was observed on A. hybridus at Potchefstroom, South Africa. Many of the leaves had symptoms and most were severe. Symptoms were dark brown to black, circular to oval, necrotic lesions with a diameter ranging from <1 mm up to 7 mm. Larger lesions had tan centers. Tissues adjacent to the leaf spots remained green. Alternaria tenuissima was isolated from 43% of 40 lesions sampled making up 89% of the isolates recovered. A. tenuissima was isolated from asymptomatic leaves of 5-month-old A. hybridus plants sampled from the same site in April 1997 (1). The foliar symptoms observed on A. hybridus in Potchefstroom were reproduced by inoculating wounded leaves of A. hybridus with single-spore A. tenuissima isolates obtained from asymptomatic leaves collected at Potchefstroom. Eight isolates were selected for pathogenicity tests conducted in a growth chamber. A. hybridus leaves grown from seed in a greenhouse were placed in moist chambers and wounded with a needle (0.5 mm) at leaf center; one 5-mm-diameter, colonized potato dextrose agar plug of each of the isolates was placed on the center of each leaf. A sterile plug was used as a control. Moist chambers were placed in a growth chamber set at 25°C day and 20°C night and provided artificial light for 16 h per day. In a greenhouse (average temperature 25°C day, 17°C night), a conidial suspension (105 conidia per ml of sterile, distilled water) was applied to an individual leaf of each of 14 plants with an atomizer. Sterile, distilled water was applied to control leaves. Leaves were then wounded with a needle (0.5 mm) at leaf center. Treatments were assigned randomly and the experiments were repeated. Symptoms were first observed at 14 and 18 days (growth chamber and greenhouse, respectively). Seven of the eight isolates caused necrotic lesions with an average diameter of 3 mm (both growth chamber and greenhouse). Symptoms were observed on an average of 56 and 82% of the inoculated leaves (growth chamber and greenhouse, respectively). The range of symptoms was the same as that observed in the field, but symptoms were only observed at the wounds. Controls remained green and showed no symptoms. A. tenuissima was recovered from necrotic lesions of surface-disinfested, inoculated leaves (average 93 and 68%; growth chamber and greenhouse, respectively), never recovered from growth chamber controls, and seldom recovered from greenhouse controls (5%). These results suggest that A. tenuissima is a leaf-spot pathogen of A. hybridus and wounding might trigger disease expression. A minimal amount of leaf spotting of this leafy-vegetable crop can cause total crop loss. References: (1) J. T. Blodgett et al. S. Afr. J. Sci. 94:xviii, 1998. (2) W. J. Swart et al. S. Afr. J. Sci. 93:xxii, 1997.

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First Report of Botrytis Blight Caused by Botrytis cinerea on Gaura lindheimeri in Italy

Plant Disease ◽

10.1094/pdis-93-1-0107c ◽

2009 ◽

Vol 93 (1) ◽

pp. 107-107

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

P. Pensa ◽

M. L. Gullino

Keyword(s):

Botrytis Cinerea ◽

Leaf Tissue ◽

Fluorescent Light ◽

Pathogenicity Test ◽

First Report ◽

Perennial Plant ◽

Potted Plants ◽

Plastic Bags ◽

Pathogenicity Tests ◽

Basal Portion

Gaura lindheimeri (wand flower) is a perennial plant belonging to the Onagraceae family that is used for perennial borders in xeric and mesic landscapes. It produces flowers floating above the plant like small, dancing butterflies. This plant is becoming popular in the Albenga Region (northern Italy) where white and rose varieties are grown as potted plants. In January of 2008, 5-month-old ‘Whirling Butterflies’ plants grown in plastic pots (14 cm in diameter) in the open field started showing symptoms of a previously unknown blight. When the disease developed, temperatures ranged between 3 and 17°C (average 9°C) and average relative humidity was 64%. Small, brown spots appeared on the basal portion of leaves first, eventually spreading to cover entire leaves. Subsequently, the pathogen developed abundant, soft gray mycelium on affected leaf tissue. Severely infected leaves eventually became completely rotten and desiccated. Sixty percent of plants were affected by the disease. Tissues were excised from diseased leaves, immersed in a solution containing 1% sodium hypochlorite for 10 s, and then cultured on potato dextrose agar (PDA) medium. The fungus produced abundant mycelium on PDA medium when incubated under constant fluorescent light at 22 ± 1°C. The conidia were smooth, hyaline, globoid, measuring 11.8 to 9.4 × 8.3 to 6.6 (average 10.7 × 7.4) μm, and are similar to those described for Botrytis cinerea. The identity of the pathogen was also confirmed by the production of numerous sclerotia on PDA plates incubated for 20 days at 8 ± 1°C. Sclerotia were dark, irregular, and measured 3 to 4 × 2 to 3 mm. The fungus was identified as B. cinerea on the basis of these characters (1). Pathogenicity tests were performed by spraying leaves of healthy, potted 8-month-old G. lindheimeri ‘Whirling Butterflies’ plants with a 105 conidia/ml suspension. Plants sprayed with water only served as controls. Five plants per treatment were used. Plants were covered with plastic bags for 6 days after inoculation and maintained in a growth chamber at 20 ± 1°C. The first foliar lesions developed on leaves 5 days after inoculation, whereas control plants remained healthy. B. cinerea was consistently reisolated from these lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of B. cinerea on G. lindheimeri in Italy. The economic importance of this disease will increase with the increased cultivation of this species. Reference: (1) H. L. Barnett and B. B. Hunter. Illustrated Genera of Imperfect Fungi. Burgess Publishing Company, Minneapolis, MN, 1972.

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First Report of Black Spot Caused by Colletotrichum gloeosporioides on Paper Mulberry in China

Plant Disease ◽

10.1094/pdis-03-11-0186 ◽

2011 ◽

Vol 95 (7) ◽

pp. 880-880 ◽

Cited By ~ 15

Author(s):

J. Yan ◽

P. S. Wu ◽

H. Z. Du ◽

Q. E. Zhang

Keyword(s):

Colletotrichum Gloeosporioides ◽

Black Spot ◽

Pathogenic Fungi ◽

Conidial Suspension ◽

Stem Cuttings ◽

Sterile Water ◽

First Report ◽

Forest Park ◽

Plastic Bags ◽

Black Spots

Paper mulberry, Broussonetia papyrifera (L.) Venten. (family Moraceae), is a fast-growing tree with luxuriant branches and leaves. Because of strong adaptability and tolerance to unfavorable environmental conditions, it is an important tree species for shade or shelter and reforestation in mined areas and on hillsides. During the summer of 2010, brown-to-black spots were observed on leaves of paper mulberry in Baiwangshan Forest Park in Beijing, China. Early symptoms were round or elliptic, light brown, small lesions that later extended to round or irregular spots (4 to 6 × 4 to 8 mm) that were dark brown or black in the center with brown or light brown margins. Several dozen spots were found on severely infected leaves. Leaf tissues (2 × 2 mm), cut from the margins of lesions, were surface disinfected in 0.5% NaOCl solution for 3 min, rinsed three times with sterile water, plated on potato dextrose agar (PDA) and incubated at 25°C with a 12-h light and 12-h dark period. Numerous waxy subepidermal acervuli with setae were observed after 3 days. Acervuli were brown or black, round or elongate, and 100 to 250 μm in diameter. Setae were dark brown, erect straight or slightly curved, and 60 to 74 × 4 to 8 μm with one to two septa. Conidiophores were hyaline or light brown, short with no branches, and cylindrical with dimensions of 12 to 21 × 4 to 5 μm. Conidia were 11 to 21 × 3 to 6 μm, hyaline, aseptate, and cylindrical. Mycelia on PDA were off white-to-dark gray on the reverse side of the colony. Six isolates (BP21-1 to BP21-6) were obtained from different infected leaves and identified as Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. (teleomorph Glomerella cingulata (Stonem.) Spaulding & Schrenk) on the basis of reverse colony color, dimensions and colors of acervuli, conidiophores, and conidia (3). ITS1-5.8S-ITS2 rDNA sequence analysis was performed on all six isolates. The resultant sequences were identical (GenBank Accession No. HQ 654780) and revealed 99% similarity (100% coverage) with C. gloeosporioides isolates in the GenBank (Accession Nos. EU371022.1 and AY376532.1) (2). Pathogenicity was demonstrated using six potted 3-month-old paper mulberry trees. Isolate BP21-2 was grown on PDA for 14 days and conidia were harvested to prepare a suspension of 106 conidia/ml. Three plants were sprayed with the conidial suspension and three were sprayed with sterile water. All trees were covered with plastic bags for 24 h to maintain high humidity and incubated at 25°C for 6 days. All conidia-inoculated trees showed identical symptoms as the infected leaves in the park, while the control trees remained symptom free. Reisolation of the fungus confirmed that the causal agent was C. gloeosporioides. C. gloeosporioides is distributed worldwide causing anthracnose on a wide variety of plants including members of mulberry family Moraceae, e.g., mortality of stem cuttings and death of saplings on mulberry (Morus alba L.) in India (1). To our knowledge, this is the first report of C. gloeosporioides causing black spots on paper mulberry in China. References: (1) V. P. Gupta et al. Indian Phytopathol. 50:402, 1997. (2) K. D. Hyde et al. Fungal Divers. 39:147, 2009. (3) J. E. M. Mordue. No. 315 in: Descriptions of Pathogenic Fungi and Bacteria. CMI. Kew, Surrey, UK, 1971.

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First Report of Alternaria japonica Causing Black Spot of Turnip in Spain

Plant Disease ◽

10.1094/pdis-01-13-0090-pdn ◽

2013 ◽

Vol 97 (11) ◽

pp. 1505-1505 ◽

Cited By ~ 7

Author(s):

D. D. M. Bassimba ◽

J. L. Mira ◽

A. Vicent

Keyword(s):

Disease Incidence ◽

Black Spot ◽

Fluorescent Light ◽

Conidial Suspension ◽

Morphological Examination ◽

Leaf Spots ◽

Plastic Bags ◽

Manual Pressure ◽

Leaves And Roots ◽

Turnip Leaves

Turnip (Brassica rapa subsp. rapa L.) is an annual vegetable crop cultivated for consumption of its succulent root. In July 2011, symptoms consisting of leaf spots 1 to 8 mm in diameter with a dark brown color surrounded by a yellow halo and black sunken lesions in the swollen storage root were observed in production areas in Alicante Province in east-central Spain. Disease incidence was approximately 20% in fields of about 3 ha where infection was highest. Symptomatic leaves and roots collected from turnip cv. Virtudes-Martillo in three affected fields were surface disinfected with 0.5% NaOCl for 2 min, and small fragments from necrotic lesions were plated on potato dextrose agar (PDA) amended with 0.5 g streptomycin sulfate per liter. Alternaria colonies were consistently isolated from affected leaves and roots after 7 days of incubation at 24°C, and were transferred to V-8 with autoclaved turnip cv. Virtudes-Martillo leaves. Two isolates from leaves and two isolates from roots were included in the study. Plates were incubated for 15 days at 24°C with an 8-h fluorescent light period and a 12-h dark period for morphological examination. Conidia produced in culture were mostly solitary or in short chains of 2 to 3 spores, beakless, ovoid to ellipsoid, and light brown. Conidia were 32 to 78 × 13 to 24 μm, with 3 to 7 transverse septa and 1 to 2 longisepta. Aggregated hyphal chains of dark, thick-walled ornamented cells distinctive of Alternaria japonica Yoshii (3) were observed. The 5.8S, ITS2, and 28S ribosomal RNA (rRNA) regions were amplified using the primers ITS3 and ITS4 (4) and sequenced from DNA extracted from the isolate designated as IVIA-A070, obtained from turnip leaves cv. Virtudes-Martillo in Alicante Province (GenBank Accession No. JX983044). The sequence had 100% identity (total score 302, 73% coverage) with that of A. japonica strain ATCC 13618 (2) (AY376639). Pathogenicity tests were performed twice on two 3-month-old plants of turnip cv. Virtudes-Martillo and cv. Blanco-Globo, and cabbage (B. oleracea var. capitata L.) cv. Brunswick. Plants were inoculated by spraying a conidial suspension of the isolate IVIA-A070 (10 ml/plant, 104 conidia/ml water) using manual pressure sprayer. Two plants of each host sprayed with sterile distilled water were used as controls in each experiment. Plants were covered with black plastic bags and incubated in a growth chamber for 48 h at 25°C. Leaf spots similar to those observed in affected plants in the field were visible on all turnip and cabbage plants 4 days after inoculation with the fungus. No symptoms were observed on control plants. Fungal colonies morphologically identified as A. japonica were reisolated from leaf lesions on inoculated turnip and cabbage plants, but not from asymptomatic leaves of control plants. Based on these results, the disease was identified as black spot of turnip caused by A. japonica. In Spain, black spot of brassicas was previously associated only with A. brassicae (Berkeley) Saccardo and A. brassicicola (Schw.) Wiltshire (1). References: (1) P. Melgarejo et al. Patógenos de Plantas Descritos en España. MARM-SEF, Madrid, 2010. (2) B. M. Pryor and R. L. Gilbertson. Mycol. Res. 104:1312, 2000. (3) E. G. Simmons. Alternaria: An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, 2007. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

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First Report of Colletotrichum acutatum sensu lato Causing Leaf Curling and Petiole Anthracnose on Celery (Apium graveolens) in Michigan

Plant Disease ◽

10.1094/pdis-05-12-0456-pdn ◽

2012 ◽

Vol 96 (9) ◽

pp. 1383-1383 ◽

Cited By ~ 2

Author(s):

L. M. Rodriguez-Salamanca ◽

T. B. Enzenbacher ◽

J. M. Byrne ◽

C. Feng ◽

J. C. Correll ◽

...

Keyword(s):

Its Region ◽

Apium Graveolens ◽

Colletotrichum Acutatum ◽

Fluorescent Light ◽

Post Inoculation ◽

Malt Extract ◽

Distilled Water ◽

Conidial Suspension ◽

First Report ◽

Leaf Curling

In September 2010, celery plants with leaf cupping and petiole twisting were observed in commercial production fields located in Barry, Kent, Newago, and Van Buren Counties in Michigan. Long, elliptical lesions were observed on petioles but signs (mycelia, conidia, or acervuli) were not readily observed. Celery petioles were incubated in humid chambers (acrylic boxes with wet paper towels). After 24 h, conidia corresponding to the genus Colletotrichum were observed. Isolations were performed by excising pieces of celery tissue from the lesion margin and placing them on potato dextrose agar (PDA) amended with 30 ppm of rifampicin and 100 ppm of ampicillin. Plates were incubated at 21 ± 2°C under fluorescent light for 5 days. Fungal colony morphology was gray with salmon-colored masses of spores when viewed from above, and carmine when viewed from below. Isolates were single-spored and placed on 30% glycerol in –20°C, and cryoconservation media (20% glycerol, 0.04% yeast extract, 0.1% malt extract, 0.04% glucose, 0.02% K2HPO4) at –80°C. Conidia were 8.5 to 12.0 × 2.8 to 4.0 μm and straight fusiform in shape. Three isolates were confirmed as C. acutatum sensu lato based on sequences of the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA and the 1-kb intron of the glutamine synthase gene (3), both with 100% similarity with Glomerella acutata sequences. Sequences were submitted to GenBank (Accession Nos. JQ951599 and JQ951600 for ITS and GS, respectively). Additionally, C. acutatum specific primer CaIntg was used in combination with the primer ITS4 on 54 isolates from symptomatic celery plants, obtaining the expected 490-pb fragment (1). Koch's postulates were completed by inoculating 4-week-old celery seedlings of cultivars Sabroso, Green Bay, and Dutchess using three plants per cultivar. Prior to inoculation, seedlings were incubated for 16 h in high relative humidity (≥95%) by enclosing the plants in humid chambers. Seven-day-old C. acutatum s. l. colonies were used to prepare the inoculum. Seedlings were spray-inoculated with a C. acutatum s. l. conidial suspension of 1 × 106 conidia/ml in double-distilled water plus Tween 0.01%. Two control seedlings per cultivar were sprayed with sterile, double-distilled water plus 0.01% Tween. Plants were enclosed in bags for 96 h post inoculation and incubated in a greenhouse at 27°C by day/20°C by night with a 16-h photoperiod. Leaf curling was observed on all inoculated plants of the three cultivars 4 days after inoculation (DAI). Petiole lesions were observed 14 to 21 DAI. Conidia were observed in lesions after incubation in high humidity at 21 ± 2°C for 24 to 72 h. Symptomatic tissue was excised and cultured onto PDA and resulted in C. acutatum colonies. Control plants remained symptomless. C. acutatum (4) and C. orbiculare (2) were reported to cause celery leaf curl in Australia in 1966 (2,4). To our knowledge, this is the first report of C. acutatum s. l. infecting celery in Michigan. References: (1) A. E. Brown et al. Phytopathology 86:523, 1996. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., USDA-ARS. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , 10 September 2010. (3) J. C. Guerber et al. Mycologia 95:872, 2003. (4) D. G. Wright and J. B. Heaton. Austral. Plant Pathol. 20:155, 1991.

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