scholarly journals First Report of Downy Mildew on Basil (Ocimum basilicum) in Italy

Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 312-312 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
G. Minuto ◽  
M. L. Gullino
Keyword(s):  
Relative Humidity ◽  
Downy Mildew ◽  
Morphological Characteristics ◽  
Ocimum Basilicum ◽  
Central Vein ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
First Report ◽  
Sweet Basil ◽  
Mediterranean Countries

Sweet basil (Ocimum basilicum) is an economically important herb in several Mediterranean countries. Approximately 80 ha are grown annually in Italy for fresh and processed consumption. In 2003, a damaging foliar disease was observed in several greenhouses located in the Liguria Region of northern Italy. More that 50% of the plants were affected. Leaves of infected plants were initially slightly chlorotic, especially near the central vein. Within 2 to 3 days, a characteristic gray, furry growth was evident on the lower surface of infected leaves. These symptoms sometimes occurred on the top sides of leaves. Although the distribution of the disease was generally uniform, symptoms appeared first in a patchy pattern in the central part of the greenhouses where air temperature and relative humidity were highest. Where air circulation was apparently poor, bottom leaves were severely affected by the disease. Microscopic observations revealed conidiophores branching two to seven times. Conidiophores with a length of 250 to 500 μm (average 350 μm) ended with sterigmata bearing single conidia. Conidia measured 15 to 25 × 20 to 35 μm (average 22 × 28 μm) and were elliptical and grayish in mass. The pathogen was identified as a Peronospora sp. based on its morphological characteristics (3). Pathogenicity was confirmed by inoculating leaves of 40-day-old healthy plants with a conidial suspension (1 × 105 conidia per ml). Three containers containing 150 plants each of O. basilicum cv. Genovese gigante were used as replicates. Noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a growth chamber at 20°C (12 h of light per day) and 90 to 95% relative humidity. The pathogenicity test was carried out twice. After 6 days, typical symptoms of downy mildew developed on the inoculated plants and a Peronospora sp. was observed on the leaves. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of a Peronospora sp. on basil in Italy. Peronospora sp. and P. lamii were previously reported on sweet basil in Uganda (1,2). References: (1) C. G. Hansford. Rev. Appl. Mycol. 12:421, 1933. (2) C. G. Hansford. Rev. Appl. Mycol. 17:345, 1938. (3) D. M. Spencer. The Downy Mildews. Academic Press, N.Y., 1978.

scholarly journals First Report of Downy Mildew Caused by Peronospora sp. on Basil (Ocimum basilicum) in France

Plant Disease ◽  
2005 ◽  
Vol 89 (6) ◽  
pp. 683-683 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
Downy Mildew ◽  
Leaf Surface ◽  
Morphological Characteristics ◽  
Sprinkler Irrigation ◽  
Ocimum Basilicum ◽  
Central Vein ◽  
Pathogenicity Test ◽  
First Report ◽  
Sweet Basil ◽  
Mediterranean Countries

Sweet basil (Ocimum basilicum) is an economically important herb in several Mediterranean countries. Approximately 30 ha are grown annually in France for fresh and processed consumption. During the spring and fall of 2004, a damaging foliar disease was observed in some crops near Saint Tropez in the French Riviera Region. More than 50% of plants were affected in an organically produced field-grown crop at an altitude of 250 m. Leaves of infected plants were initially slightly chlorotic, especially near the central vein. Within 2 to 3 days, a characteristic gray, furry growth was evident on the lower leaf surface and sometimes on the upper leaf surface. The appearance and severity of the disease was affected by overhead sprinkler irrigation. Basal leaves were severely affected. Microscopic observations revealed sporangiophores branching two to seven times. Sporangiophores, with a length of 250 to 500 μm (average 350 μm), ended with sterigmata bearing single sporangia. Sporangia measured 15 to 25 × 20 to 35 μm (average 22 × 28 μm), were elliptical and grayish in mass. The pathogen was identified as Peronospora sp. on the basis of its morphological characteristics (4). Pathogenicity was confirmed by inoculating leaves of 40-day-old healthy plants with a sporangial suspension (1 × 105 conidia/ml). Three containers with 150 plants each of O. basilicum cv Genovese gigante were used as replicates. Noninoculated plants served as controls. Plants were maintained in a growth chamber at 20°C (12 h of light per day) and 90 to 95% relative humidity. The pathogenicity test was carried out twice. After 6 days, typical symptoms of downy mildew developed on the inoculated plants, and Peronospora sp. was observed on the leaves. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of Peronospora sp. on basil in France. Peronospora sp. was previously reported on sweet basil in Italy (1) and P. lamii on sweet basil in Uganda (3). Seed transmission (2) is suspected as the reason for recent outbreaks in Europe. References: (1) A. Garibaldi et al. Plant Dis. 88:312, 2004. (2) A. Garibaldi et al. Z. Pflanzenkr. Pflanzenschutz 111:465, 2004 (3) C. G. Hansford. Rev. Appl. Mycol. 12:421, 1933. (4) D. M. Spencer. The Downy Mildews. Academic Press, NY, 1981.

scholarly journals First Report of Downy Mildew Caused by Peronospora belbahrii on Sweet Basil (Ocimum basilicum) in Cyprus

Plant Disease ◽  
2014 ◽  
Vol 98 (2) ◽  
pp. 283-283 ◽  
Author(s):  
L. Kanetis ◽  
A. Vasiliou ◽  
G. Neophytou ◽  
S. Samouel ◽  
D. Tsaltas
Keyword(s):  
Downy Mildew ◽  
Disease Incidence ◽  
Infected Plant ◽  
Morphological Characteristics ◽  
Ocimum Basilicum ◽  
First Report ◽  
Consensus Sequences ◽  
Sweet Basil ◽  
Plastic Bags ◽  
Necrotic Spots

Sweet basil (Ocimum basilicum L.) is an economically important annual aromatic plant, grown mostly for culinary use for both fresh and dry consumption and as a source of essential oil. In Cyprus, approximately 4 ha are grown annually, either in greenhouses as a year-round crop or in open fields from April to November, and the majority of the production is exported to the European market. During May 2012, a sweet basil cv. Genovese Gigante greenhouse operation in the area of Limassol was severely affected by a foliar disease, causing almost 100% crop losses. Within a few days, a similar, heavy disease incidence was also reported from a nearby greenhouse facility on the Genovese-type cultivars Superbo, Aroma 2, and Bonazza, as well as on Thai basil (O. basilicum var. thyrsiflorum). Successively, destructive hits of similar symptomatology have been reported from other areas and since then the disease appears to have been well-established in the country, causing major economic damages. It is also noteworthy to mention that in greenhouse infections the disease remains active even during winter, considering the mild environmental conditions and the monoculture fashion followed. Symptoms appeared on the leaves initially as interveinal, zonal, chlorotic lesions, followed by the appearance of a fuzzy, purplish sporulation on the abaxial side. Progressively, infected leaves curled and sporadic necrotic spots were evident and finally abscised. Light microscopic examination of infected samples revealed the presence of straight, hyaline sporangiophores (n = 15) typical of downy mildew, 210 to 590 μm long (mean = 350.7 μm; SD ± 117.5 μm) × 12 to 15 μm wide (mean = 13.1 μm; SD ± 1.4 μm). Sporangiophores were monopodially branched three to five times, terminating with curved branchlets bearing single sporangia at their tips. The sporangia (n = 25) were purplish-grey, ovoid to subglobose, and measured 32 to 22 μm in length (mean = 27.2 μm; SD ± 2.8 μm) and 30 to 10 μm in breadth (mean = 21.7 μm; SD ± 4.8 μm). Based on these morphological characteristics, the causal agent was identified as Peronospora belbahrii Thines (1,4). Furthermore, genomic DNA was extracted from infected plant tissue from eight different samples according to Dellaporta et al. (2). The complete ITS rDNA region was amplified and sequenced using primers ITS5 and ITS4 (3). Two of the consensus sequences were deposited in GenBank (Accession Nos. KF419289 and KF419290) and a BLAST analysis in the NCBI database revealed 99% similarity to all of the P. belbahrii sequences and other Peronospora sp. previously reported on sweet basil (Accession Nos. AY831719, DQ479408, FJ394336, and FJ436024). In a pathogenicity trial, five 40-day-old potted sweet basil plants were spray-inoculated with a sporangial suspension (1 × 105 sporangia/ml) until runoff, bagged for 24 h, and placed in a growth chamber at 18°C. Subsequently, the plastic bags were removed and the plants were kept at 22°C with a 16-h photoperiod and 80% relative humidity. Additionally, five plants were water-sprayed and served as controls. Typical downy mildew symptoms appeared 6 to 8 days after inoculation, while the uninoculated plants remained disease-free. To our knowledge, this is first report of downy mildew on sweet basil in Cyprus. References: (1) L. Belbahri et al. Mycol. Res. 109:1276, 2005. (2) S. L. Dellaporta et al. Plant Mol. Biol. Rep., 1:19, 1983. (3) G. Nagy and A. Horvat, Plant Dis. 93:1999, 2009. (4) M. Thines et al. Mycol. Res. 113:532, 2009.

scholarly journals First Report of White Mold Caused by Sclerotinia sclerotiorum on Sweet Basil in Turkey

Plant Disease ◽  
2008 ◽  
Vol 92 (10) ◽  
pp. 1471-1471 ◽  
Author(s):  
F. M. Tok
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Morphological Characteristics ◽  
The United States ◽  
Ocimum Basilicum ◽  
Pathogenicity Test ◽  
Distilled Water ◽  
First Report ◽  
Sweet Basil ◽  
Pathogenicity Tests ◽  
Filter Papers

In February of 2008, wilt and collapse of sweet basil (Ocimum basilicum L.) was observed on approximately 20% of the plants in a commercial greenhouse in Demre, Antalya, Turkey. Crown and stems of infected plants were necrotic; leaves turned brown and wilted. Profuse, white mycelia and occasionally black sclerotia were found inside and outside of affected stems. Sclerotinia sclerotiorum (Lib). de Bary, identified based on morphological characteristics was isolated from sclerotia and symptomatic stems on potato dextrose agar amended with tetracycline. To conduct pathogenicity tests, sclerotia produced on carrot discs were surface disinfested in 70% ethanol and dried on sterilized filter papers. Ten sclerotia were placed in 9-cm-diameter glass petri plates containing 15 ml of sterilized distilled water. Plates were wrapped with Parafilm and incubated at 4°C for 5 to 6 weeks in the dark. Plates were then incubated at 15°C in 12 h of dark and 12 h of light. Apothecia developed after 2 weeks. Ascospores were harvested from apothecia with distilled water by crushing and shaking the apothecia in centrifuge tubes. Thirty basil plants sprayed with ascospores (106 spores per ml) were maintained in a growth chamber at 22°C and 90% humidity. After 2 weeks, necrotic leaves and stems were observed on all inoculated plants. S. sclerotiorum was recovered from symptomatic tissues. No symptoms developed on the 30 basil plants sprayed with sterile distilled water. The pathogenicity test was repeated with similar results. S. sclerotiorum on basil has been reported in Canada (4), the United States, (2,3), and Italy (1). To our knowledge, this is the first report of S. sclerotiorum on basil in Turkey. References: (1) A. Garibaldi et al. Plant Dis. 81:124, 1997. (2) G. E. Holcomb and M. J. Reed. Plant Dis. 78:924, 1994. (3) S. T. Koike. Plant Dis. 84:1342, 2000. (4) T. C. Paulitz. Plant Dis. 81:229, 1997.

scholarly journals First Report of Leaf Spot Caused by Corynespora cassiicola on Basil (Ocimum basilicum) in Italy

Plant Disease ◽  
2007 ◽  
Vol 91 (10) ◽  
pp. 1361-1361 ◽  
Author(s):  
A. Garibaldi ◽  
S. Rapetti ◽  
J. Rossi ◽  
M. L. Gullino
Keyword(s):  
Disease Incidence ◽  
Aqueous Suspension ◽  
Its Region ◽  
Ocimum Basilicum ◽  
Pathogenicity Test ◽  
Corynespora Cassiicola ◽  
First Report ◽  
Sweet Basil ◽  
Mediterranean Countries ◽  
Stem Lesions

Sweet basil (Ocimum basilicum) is an economically important herb in several Mediterranean countries. Approximately 80 ha are grown annually in Italy for fresh consumption and processing. In 2006, a damaging foliar disease of sweet basil cv. Genovese gigante was observed in several greenhouses located in the Liguria Region of northern Italy. A disease incidence of more than 50% was observed. Leaves of infected plants initially showed dark brown-to-black, 1 to 3 × 1.5 to 5.3 mm in diameter, circular spots surrounded by a chlorotic halo. Within 2 to 3 days, the spots coalesced, leading to extensive leaf necrosis with occasional shot holes. Stem lesions were brown, elongated, and irregularly dispersed. Although the distribution of the disease generally became uniform, it usually appeared originally in a patchy pattern at the central areas of the greenhouses, where temperatures and relative humidity were highest. Basal leaves were most severely affected by the disease when air circulation was apparently poor. Microscopic observations revealed light brown conidiophores, ending in sterigmata with conidia borne singly or in chains. Conidia were 31.9 to 212.2 μm (average 68.1 μm) long and 4.3 to 11.6 μm (average 7.8 μm) wide, with longitudinal cross walls. Such morphology is typical of Corynespora cassiicola (3). The fungus was consistently isolated from symptomatic leaves onto potato dextrose agar. The ITS region (internal transcribed spacer) of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 215 bp obtained showed an E-value of 0.0 with C. cassiicola and the nucleotide sequence has been assigned GenBank Accession No. EF 545008. Pathogenicity tests were performed by spraying leaves of 10 healthy 30-day-old potted O. basilicum plants cv. Genovese gigante with a 105 conidia per ml aqueous suspension. Plants in 10 pots sprayed with water only served as controls. Plants were covered with plastic bags for 24 h after inoculation and maintained at 20 to 25°C. The first foliar lesions developed on leaves 3 to 4 days after inoculation, whereas control plants remained healthy. C. cassiicola was consistently reisolated from these lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of C. cassiicola on O. basilicum in Italy. Other previous records of this disease were from India (2) and Brunei (4). References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) L. R. Devi et al. Indian Phytopathol. 32:150, 1979. (3) M. B. Ellis. CMI Mycol. Pap. No. 65, 1957. (4) W. T. H. Peregrine and K. B. Ahmad. Phytopathol. Pap. 27:1, 1982.

scholarly journals First Report of Ramularia coleosporii causing Leaf Spot on Perilla frutescens in Korea

Plant Disease ◽  
2021 ◽  
Author(s):  
Md Aktaruzzaman ◽  
Tania Afroz ◽  
Hyo-Won Choi ◽  
Byung Sup Kim
Keyword(s):  
Leaf Spot ◽  
Ipomoea Batatas ◽  
Rust Fungus ◽  
Morphological Characteristics ◽  
Perilla Frutescens ◽  
Herbaceous Plant ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report

Perilla (Perilla frutescens var. japonica), a member of the family Labiatae, is an annual herbaceous plant native to Asia. Its fresh leaves are directly consumed and its seeds are used for cooking oil. In July 2018, leaf spots symptoms were observed in an experimental field at Gangneung-Wonju National University, Gangneung, Gangwon province, Korea. Approximately 30% of the perilla plants growing in an area of about 0.1 ha were affected. Small, circular to oval, necrotic spots with yellow borders were scattered across upper leaves. Masses of white spores were observed on the leaf underside. Ten small pieces of tissue were removed from the lesion margins of the lesions, surface disinfected with NaOCl (1% v/v) for 30 s, and then rinsed three times with distilled water for 60 s. The tissue pieces were then placed on potato dextrose agar (PDA) and incubated at 25°C for 7 days. Five single spore isolates were obtained and cultured on PDA. The fungus was slow-growing and produced 30-50 mm diameter, whitish colonies on PDA when incubated at 25ºC for 15 days. Conidia (n= 50) ranged from 5.5 to 21.3 × 3.5 to 5.8 μm, were catenate, in simple or branched chains, ellipsoid-ovoid, fusiform, and old conidia sometimes had 1 to 3 conspicuous hila. Conidiophores (n= 10) were 21.3 to 125.8 × 1.3 to 3.6 μm in size, unbranched, straight or flexuous, and hyaline. The morphological characteristics of five isolates were similar. Morphological characteristics were consistent with those described for Ramularia coleosporii (Braun, 1998). Two representative isolates (PLS 001 & PLS003) were deposited in the Korean Agricultural Culture Collection (KACC48670 & KACC 48671). For molecular identification, a multi-locus sequence analysis was conducted. The internal transcribed spacer (ITS) regions of the rDNA, partial actin (ACT) gene and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene were amplified using primer sets ITS1/4, ACT-512F/ACT-783R and gpd1/gpd2, respectively (Videira et al. 2016). Sequences obtained from each of the three loci for isolate PLS001 and PLS003 were deposited in GenBank with accession numbers MH974744, MW470869 (ITS); MW470867, MW470870 (ACT); and MW470868, MW470871 (GAPDH), respectively. Sequences for all three genes exhibited 100% identity with R. coleosporii, GenBank accession nos. GU214692 (ITS), KX287643 (ACT), and 288200 (GAPDH) for both isolates. A multi-locus phylogenetic tree, constructed by the neighbor-joining method with closely related reference sequences downloaded from the GenBank database and these two isolates demonstrated alignment with R. coleosporii. To confirm pathogenicity, 150 mL of a conidial suspension (2 × 105 spores per mL) was sprayed on five, 45 days old perilla plants. An additional five plants, to serve as controls, were sprayed with sterile water. All plants were placed in a humidity chamber (>90% relative humidity) at 25°C for 48 h after inoculation and then placed in a greenhouse at 22/28°C (night/day). After 15 days leaf spot symptoms, similar to the original symptoms, developed on the leaves of the inoculated plants, whereas the control plants remained symptomless. The pathogenicity test was repeated twice with similar results. A fungus was re-isolated from the leaf lesions on the inoculated plants which exhibited the same morphological characteristics as the original isolates, fulfilling Koch’s postulates. R. coleosporii has been reported as a hyperparasite on the rust fungus Coleosporium plumeriae in India & Thailand and also as a pathogen infecting leaves of Campanula rapunculoides in Armenia, Clematis gouriana in Taiwan, Ipomoea batatas in Puerto Rico, and Perilla frutescens var. acuta in China (Baiswar et al. 2015; Farr and Rossman 2021). To the best of our knowledge, this is the first report of R. coleosporii causing leaf spot on P. frutescens var. japonica in Korea. This disease poses a threat to production and management strategies to minimize leaf spot should be developed.

scholarly journals First Report of Nigrospora osmanthi Causing Leaf Spot on Tartary Buckwheat in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Quan Shen ◽  
Xixu Peng ◽  
Feng He ◽  
Shaoqing Li ◽  
Zuyin Xiao ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Leaf Spot ◽  
Plant Pathogens ◽  
Hunan Province ◽  
Tartary Buckwheat ◽  
Tween 20 ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Sterile Water ◽  
First Report

Buckwheat (Fagopyrum tataricum) is a traditional short-season pseudocereal crop originating in southwest China and is cultivated around the world. Antioxidative substances in buckwheat have been shown to provide many potential cardiovascular health benefits. Between August and November in 2019, a leaf spot was found in several Tartary buckwheat cv. Pinku1 fields in Xiangxiang County, Hunan Province, China. The disease occurred throughout the growth cycle of buckwheat after leaves emerged, and disease incidence was approximately 50 to 60%. Initially infected leaves developed a few round lesions, light yellow to light brown spots. Several days later, lesions began to enlarge with reddish brown borders, and eventually withered and fell off. Thirty lesions (2×2 mm) collected from three locations with ten leaves in each location were sterilized in 70% ethanol for 10 sec, in 2% sodium hypochlorite for 30 sec, rinsed in sterile water for three times, dried on sterilized filter paper, and placed on a potato dextrose PDA with lactic acid (3 ml/L), and incubated at 28°C in the dark for 3 to 5 days. Fungal colonies were initially white and later turned black with the onset ofsporulation. Conidia were single-celled, black, smooth, spherical to subspherical, and measured 9.2 to 15.6 µm long, and 7.1 to 11.6 µm wide (n=30). Each conidium was terminal and borne on a hyaline vesicle at the tip of conidiophores. Morphologically, the fungus was identified as Nigrospora osmanthi (Wang et al. 2017). Identification was confirmed by amplifying and sequencing the ITS region, and translation elongation factor 1-alpha (TEF1-α) and partial beta-tublin (TUB2) genes using primers ITS1/ITS4 (Mills et al. 1992), EF1-728F/EF-2 (Carbone and Kohn 1999; O’Donnell et al. 1998) and Bt-2a/Bt-2b (Glass et al. 1995), respectively. BLAST searches in GenBank indicated the ITS (MT860338), TUB2 (MT882054) and TEF1-α (MT882055) sequences had 99.80%, 99% and 100% similarity to sequences KX986010.1, KY019461.1 and KY019421.1 of Nigrospora osmanthi ex-type strain CGMCC 3.18126, respectively. A neighbor-joining phylogenetic tree constructed using MEGA7.0 with 1,000 bootstraps based on the concatenated nucleotide sequences of the three genes indicated that our isolate was closely related to N. osmanthi. Pathogenicity test was performed using leaves of healthy F. tataricum plants. The conidial suspension (1 × 106 conidia/ml) collected from PDA cultures with 0.05% Tween 20 buffer was used for inoculation by spraying leaves of potted 20-day-old Tartary buckwheat cv. Pinku1. Five leaves of each plant were inoculated with spore suspensions (1 ml per leaf). An equal number of control leaves were sprayed with sterile water to serve as a control. The treated plants were kept in a greenhouse at 28°C and 80% relative humidity for 24 h, and then transferred to natural conditions with temperature ranging from 22 to 30°C and relative humidity ranging from 50 to 60%. Five days later, all N. osmanthi-inoculated leaves developed leaf spot symptoms similar to those observed in the field, whereas control leaves remained healthy. N. osmanthi was re-isolated from twelve infected leaves with frequency of 100%, fulfilling Koch’s postulates. The genus Nigrospora has been regarded by many scholars as plant pathogens (Fukushima et al. 1998) and N. osmanthi is a known leaf blight pathogen for Stenotaphrum secundatum (Mei et al. 2019) and Ficus pandurata (Liu et al. 2019) but has not been reported on F. tataricum. Nigrospora sphaerica was also detected in vegetative buds of healthy Fagopyrum esculentum Moench (Jain et al. 2012). To our knowledge, this is the first report of N. osmanthi causing leaf spot on F. tataricum in China and worldwide. Appropriate strategies should be developed to manage this disease.

scholarly journals First Report of Passalora Leaf Spot Caused by Passalora bougainvilleae on Bougainvillea in Mexico

Plant Disease ◽  
2011 ◽  
Vol 95 (6) ◽  
pp. 775-775 ◽  
Author(s):  
V. Ayala-Escobar ◽  
V. Santiago-Santiago ◽  
A. Madariaga-Navarrete ◽  
A. Castañeda-Vildozola ◽  
C. Nava-Diaz
Keyword(s):  
Uv Light ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
The United States ◽  
Pathogenicity Test ◽  
Commonwealth Mycological Institute ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report ◽  
Bougainvillea Spectabilis

Bougainvillea (Bougainvillea spectabilis Willd) growing in 28 gardens during 2009 showed 100% disease incidence and 3 to 7% disease severity. Bougainvilleas with white flowers were the most affected. Symptoms consisted of light brown spots with dark brown margins visible on adaxial and abaxial sides of the leaves. Spots were circular, 2 to 7 mm in diameter, often surrounded by a chlorotic halo, and delimited by major leaf veins. Single-spore cultures were incubated at 24°C under near UV light for 7 days to obtain conidia. Pathogenicity was confirmed by spraying a conidial suspension (1 × 104 spores/ml) on leaves of potted bougainvillea plants (white, red, yellow, and purple flowers), incubating the plants in a dew chamber for 48 h and maintaining them in a greenhouse (20 to 24°C). Identical symptoms to those observed at the residential gardens appeared on inoculated plants after 45 to 60 days. The fungus was reisolated from inoculated plants that showed typical symptoms. No symptoms developed on control plants treated with sterile distilled water. The fungus produced distinct stromata that were dark brown, spherical to irregular, and 20 to 24 μm in diameter. Conidiophores were simple, born from the stromata, loose to dense fascicles, brown, straight to curved, not branched, zero to two septate, 14 × 2 μm, with two to four conspicuous and darkened scars. The conidia formed singly, were brown, broad, ellipsoid, obclavate, straight to curved with three to four septa, 40 × 4 μm, and finely verrucous with thick hilum at the end. Fungal DNA from the single-spore cultures was obtained using a commercial DNA Extraction Kit (Qiagen, Valencia, CA); ribosomal DNA was amplified with ITS5 and ITS4 primers and sequenced. The sequence was deposited at the National Center for Biotechnology Information Database (GenBank Accession Nos. HQ231216 and HQ231217). The symptoms (4), morphological characteristics (1,2,4), and pathogenicity test confirm the identity of the fungus as Passalora bougainvilleae (Muntañola) Castañeda & Braun (= Cercosporidium bougainvilleae Muntañola). This pathogen has been reported from Argentina, Brazil, Brunei, China, Cuba, El Salvador, India, Indonesia, Jamaica, Japan, Thailand, the United States, and Venezuela (3). To our knowledge, this is the first report of this disease on B. spectabilis Willd in Mexico. P. bougainvilleae may become an important disease of bougainvillea plants in tropical and subtropical areas of Mexico. References: (1) U. Braun and R. R. Castañeda. Cryptogam. Bot. 2/3:289, 1991. (2) M. B. Ellis. More Dematiaceous Hypomycetes. Commonwealth Mycological Institute, Kew, Surrey, UK, 1976. (3) C. Nakashima et al. Fungal Divers. 26:257, 2007. (4) K. L. Nechet and B. A. Halfeld-Vieira. Acta Amazonica 38:585, 2008.

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

Plant Disease ◽  
2012 ◽  
Vol 96 (7) ◽  
pp. 1070-1070 ◽  
Author(s):  
J. H. Park ◽  
K. S. Han ◽  
Y. D. Kwon ◽  
H. D. Shin
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Morphological Characteristics ◽  
Its Region ◽  
Culture Collection ◽  
Perennial Herb ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Natural Habitats ◽  
First Report ◽  
Small Water

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

scholarly journals First Report of Leaf Spot of Lettuce (Lactuca sativa L.) Caused by Phoma tropica in Italy

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1380-1380 ◽  
Author(s):  
A. Garibaldi ◽  
G. Gilardi ◽  
G. Ortu ◽  
M. L. Gullino
Keyword(s):  
Relative Humidity ◽  
Lactuca Sativa ◽  
Leaf Spot ◽  
Morphological Characteristics ◽  
The United States ◽  
Fluorescent Light ◽  
Malt Extract ◽  
Pathogenicity Test ◽  
First Report ◽  
Lactuca Sativa L

Lettuce (Lactuca sativa L.) is widely grown in Italy, with the production for the preparation of ready-to-eat salads becoming increasingly important. During the spring of 2011, a previously unknown leaf spot was observed on L. sativa plants, cv Rubia, grown in several plastic tunnels in Lumbardy (northern Italy), 20 to 25 days after sowing. Thirty to forty per cent of leaves of the plants growing in the part of the tunnel with the highest relative humidity were affected. Leaves of infected plants showed extensive, irregular, dark brown, necrotic lesions with a chlorotic halo. Lesions initially ranged from 0.5 to 3 mm, then eventually coalesced, reaching 2 to 3 cm, showing a well-defined, dark brown border. Affected leaves senesced and withered. The crown was not affected by the disease. Diseased tissue was excised, immersed in a solution containing 1% sodium hypochlorite for 60 s, rinsed in water, then cultured on potato dextrose agar (PDA), amended with 25 mg/l of streptomycin sulphate. After 5 days, a fungus developed, producing a greenish grey mycelium with a white border when incubated under 12 h/day of fluorescent light at 21 to 23°C. In order to favor the production of conidia, the fungus was transferred on malt extract agar (MA) and maintained under 12 h/day of fluorescent light at 22°C. After 15 days, black pycnidia, 175 to 225 μm, developed, with hyaline, elliptical, unicellular conidia, measuring 3.21 to 6.7 × 1.08 to 3.2 (average 5.5 × 1.9) μm. On the basis of these morphological characteristics, the fungal causal agent of the disease could be related to the genus Phoma (2). The internal transcribed spacer (ITS) region of rDNA of the isolate PHT30 was amplified using the primers ITS1/ITS4 and sequenced. BLAST analysis (1) of the 466-bp segment showed a 99% similarity with the sequence of Phoma tropica (GenBank Accession No. JF923820.1). The nucleotide sequence has been assigned the GenBank Accession No. JQ954396. Pathogenicity tests were performed by spraying healthy 20-day-old lettuce plants, cv Rubia, with a spore suspension (1 × 105 conidia/ml) prepared from 14-day-old colonies of the strain PHT30 grown on MA cultures. Plants inoculated with water alone served as controls. Ten plants per isolate were used. Plants were covered with plastic bags for 5 days after inoculation and maintained in a growth chamber at 20°C and 80% relative humidity. The first foliar lesions, similar to those occurring on the naturally infected plants, developed on leaves 12 days after inoculation. Control plants remained healthy. The pathogen was consistently reisolated from leaf lesions. The pathogenicity test was completed twice. To our knowledge, this is the first report of the presence of P. tropica on lettuce in Italy as well as worldwide. In the United States, the presence of P. exigua was reported in 2006 (3). The economic importance of the disease at present is limited, probably also because symptoms can be confused with those caused by Botrytis cinerea. However, P. tropica could become a more significant problem because of the importance of the crop. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) G. H. Boerema. Trans. Br. Mycol. Soc. 67:289, 1976. (3) S. Y. Koike. Plant Dis. 90:1268, 2006.

scholarly journals First report of Cercospora cf. citrulina causing leaf spot of Ipomoea pes-caprae in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Min Li ◽  
Meijiao Hu ◽  
Zhaoyin Gao ◽  
Xiaoyu Hong ◽  
Chao Zhao ◽  
...  
Keyword(s):  
Molecular Identification ◽  
Leaf Spot ◽  
Plant Protection ◽  
Morphological Characteristics ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Xisha Islands ◽  
First Report ◽  
Initial Symptoms ◽  
Leaf Surfaces

Ipomoea pes-caprae plays an important role in protecting the tropical and subtropical coastal beach of the world. In 2018, a leaf spot was observed on I. pes-caprae in Xisha islands of China, 13.2–25.8% of leaves were infected. The initial symptoms were small (1–3 mm diameter), single, circular, dark gray spots with a light-yellow center on the leaves. The lesions enlarged and were scattered or confluent, distinct and circular, subcircular or irregular, occasionally vein-limited, pale to dark gray-brown, with a narrow dark brown border surrounded by a diffuse yellow margin. Microscopic observations of the spots revealed that caespituli were dark brown and amphigenous, but abundant on the underside of the leaves. Mycelia were internal. Conidiophores were fasciculate, occasionally solitary, pale olivaceous-brown throughout, 0- to 3-septate, 27.9–115.8 (63.4±22.5) µm × 3.2–5.3 (4.3±0.87) µm (n=100). Conidial scars were conspicuously thickened. Conidia were solitary, hyaline, filiform, acicular to obclavate, straight to slightly curved, subacute to obtuse at the apex, truncate at the base, multi-septate, 21.0–125.5 (60.2±20.1) µm × 2.0–5.0 (3.8±0.83) µm (n=100). Single-conidium isolates were obtained from representative colonies grown on potato dextrose agar (PDA) incubated at 25℃ in the dark. The colonies grew slowly and were dense, white to gray and flat with aerial mycelium. Mycelia were initially white, and then became gray. Conidia were borne on the conidiophores directly. The pure isolate HTW-1 was selected for molecular identification and pathogenicity test, which were deposited in Microbiological Culture Collection Center of Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences. The internal transcribed spacer (ITS) region of rDNA, translation elongation factor 1-alpha (tef1) and histone H3 (his3) genes were amplified with ITS1/ITS4, EF-1 / EF-2, and CYLH3F / CYLH3R primers, respectively (Groenewald et al. 2013). The obtained sequences of HTW-1 were all deposited in GenBank with accession numbers MT410467 for ITS, MT418903 for tef1 and MT418904 for his3. The ITS, tef1 and his3 genes all showed 100% similarity for ITS (JX143582), tef1 (JX143340) and his3 (JX142602) with C. cf. citrulina (MUCC 588; MAFF 239409) from I. pes-caprae in Japan. Based on the morphological characteristics and molecular identification, the pathogen was identified as Cercospora cf. citrulina (Groenewald et al. 2013). The pathogenicity test was conducted by spraying conidial suspension (1×104 conidia/mL) on wounded and unwounded leaves for seedling of I. pes-caprae in greenhouse and in sterile vitro condition. The conidial suspension was prepared using conidia from 30-day-old culture grown on PDA at 25℃ in the dark. Leaf surfaces of seedling in greenhouse were wounded by lightly rubbing with a steel sponge and detached leaf surfaces were wounded by sterile needles. the treatments were sprayed with conidial suspensions on wounded and unwounded leaf surfaces. The control was sprayed with sterile water. After eight days, the typical symptoms of spots which were small, single, circular and dark gray appeared on the inoculated wounded leaves, while the inoculated unwounded leaves and the control leaves were symptomless. The pathogen was only re-isolated from the inoculated wounded leaves. The pathogen may be infected by wound. A total of 20 Cercospora and related species was found on Ipomoea spp. (García et al. 1996). Cercospora cf. citrulina has been reported on I. pes-caprae in Japan, although it was unclear if it was a pathogen or saprophyte (Groenewald et al. 2013). To our knowledge, this is the first report of C. cf. citrulina causing leaf spot of I. pes-caprae in China. This disease could threat the cultivation of I. pes-caprae in China.

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