scholarly journals First Report of Pythium aphanidermatum Causing Stalk Rot on Abelmoschus manihot (L. ) Medic in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Qing Qu ◽  
Liu Shiwei ◽  
Ning Liu ◽  
Yunxia Liu ◽  
Jia Hui ◽  
...  
Keyword(s):  
Management Practices ◽  
Vascular System ◽  
Morphological Characteristics ◽  
Pythium Aphanidermatum ◽  
Negative Control ◽  
Perennial Herb ◽  
Universal Primers ◽  
First Report ◽  
Stalk Rot ◽  
Aerial Hyphae

Abelmoschus manihot (Linn. ) Medicus (A. manihot) is an annual to perennial herb of the Malvaceae okra, mainly distributed in Guangdong, Guangxi, Fujian, Hunan, Hubei provinces. It can not only be used as an ornamental flower, but also has important economic and medicinal value. Last year, 10% A. manihot in 1,000 acres were observed with stalk rot in the Zhongshang Agricultural Industrial Park, 50 meters east of Provincial Highway 235 in Gaoyang County of Hebei province. Internal discoloration of the stem began brown to black discoloration of the vascular system and became hollow, with the mycelium growing on the surface. Stems from symptomatic plants (approximately 5 mm2) were dissected, washed free of soil, then soaked in 75% ethanol for 16 s to surface-sterilize, and 40 s in HgCl2, then rinsed three times in sterile water. After being dried with blotting paper, five pieces were placed on potato dextrose agar (PDA). After cultured 2 or 3 days, five isolates were purified and re-cultured on PDA in the dark at 25°C. The color of the colony was white. The hyphae were radial in PDA, and the aerial hyphae were flocculent, well-developed with luxuriant branches. The colonies were white and floccus, and the aerial hyphae were well developed, branched and without septum on corn meal agar (CMA). The sporangia were large or petal shaped, composed of irregular hyphae, terminal or intermediate , with the size of (31.6-88.4) μm ×(12.7- 14.6) μm. Vesicles were spherical, terminal or intermediate, ranging from 14.6 to 18.5μm. Oogonia were globose, terminal and smooth which stipe was straight. Antheridia were clavate or baggy and mostly intercalary, sometimes terminal. Oospores were aplerotic, 21.5 to 30.0 μm in diameter, 1.6 to 3.1 μm in wall thickness. The isolates morphological characteristics were consistent with P. aphanidermatum (van der Plaats-Niterink 1981, Wu et al. 2021 ). To identify the isolates, universal primers ITS1/ITS4 (White et al. 1993) were used for polymerase chain reaction–based molecular identification. The amplification region was sequenced by Sangon Biotech (Shanghai, China) and submitted to GenBank (MW819983). BLAST analysis showed that the sequence was 100% identical to Pythium aphanidermatum. Pathogenicity tests were conducted 3 times, with 4 treatments and 2 controls each time. The plants treated were 6 months old. Then the hyphae growing on PDA for 7 days were cut into four pieces. Next, they were inoculated into the soil of the A. manihot. Negative control was inoculated only with PDA for 7 days ( Zhang et al. 2000). The plants were then placed in a greenhouse under 28°C, 90% relative humidity. After inoculated 20 to 30 days, the infected plants showed stalk rot, the same symptoms as observed on the original plants. The control plants didn’t display symptoms. Pythium aphanidermatum was re-isolated from infected stems and showed the same characteristics as described above and was identical in appearance to the isolates used to inoculate the plants. To our knowledge, this is the first report of Pythium aphanidermatum infecting A. manihot stem and causing stalk rot in China. It may become a significant problem for A. manihot. Preliminary management practices are needed for reducing the cost and losses of production.

scholarly journals First Report of Wilt of European hornbeam (Carpinus betulus L.) Caused by Fusarium oxysporum in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yun-fei Mao ◽  
Huiyue Chen ◽  
Li Jin ◽  
Minjia Wang ◽  
Xiang-rong Zheng ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Vascular System ◽  
Morphological Characteristics ◽  
Soil Surface ◽  
Negative Control ◽  
Bootstrap Support ◽  
Conidial Suspension ◽  
Carpinus Betulus ◽  
First Report ◽  
Vascular Tissues

European hornbeam (Carpinus betulus L.) has been used as an important ornamental species for urban landscaping since the Italian Renaissance (Rocchi et al. 2010). In May 2019, 15% of 3000 C. betulus trees with wilted leaves and root rot were observed in a field (about 26 ha) in Pizhou, Jiangsu Province, China. Internal discoloration of the stem began with brown to black discoloration of the vascular system and gradually spread to inward areas. Roots and stems from symptomatic plants were washed free of soil, surface sterilized with 0.8% NaOCl, rinsed three times in sterile H2O, and blotted dry with a paper towel. Small segments (0.5-cm-long) were cut from the discolored vascular tissues, and then put on potato dextrose agar (PDA) at 25°C in darkness. After 4 days, fungal colonies were observed on the PDA. Pure cultures were obtained by monosporic isolation, and 9 morphologically similar fungal isolates (EJ-1 to EJ-9) were obtained. All purified cultures were incubated on PDA at 25°C in darkness as the initial isolation. Colonies of the 9 isolates on PDA displayed entire margins and showed abundant pink aerial mycelia initially and turned to light violet with age. Microconidia were elliptical or oval in shape, 0 septate, (5.2–)8.7(–12.5) × (3.5–)3.6(–5.5) µm. Macroconidia were falciform, 0-4 septate, and straight to slightly curved with a notched foot cell, (17.1–)20.5(–28.4) × (3.8–)4.1(–4.6) µm. These morphological characteristics resemble Fusarium oxysporum (Leslie and Summerell 2006). Genomic DNA of each isolate was extracted from mycelia using a CTAB method (Mo¨ller et al. 1992). The RPB2, TEF1 and cmdA genes were amplified and sequenced with the primers 5f2/7c (Liu et al. 2000), EF-1Ha/EF-2Tb (Carbone and Kohn 1999) and Cal228F/CAL2Rd (Groenewald et al. 2013), respectively. The sequences were deposited in GenBank (Table 1). A maximum likelihood phylogenetic analysis based on RPB2, TEF1 and cmdA sequences using MEGA7 revealed that the isolates were placed in the F. oxysporum species complex with 98% bootstrap support. Based on the morphological and molecular characters, all 9 isolates were identified as F. oxysporum. A pathogenicity experiment was conducted using 30 2-year-old C. betulus seedlings potted in sterile peat, 27 for inoculation (3 replicate plants per isolate) and 3 for a negative control. The treated plants were planted in the peat mixed with 50 ml of a conidial suspension of each isolate respectively. The negative control was inoculated with sterilized water. Conidia were harvested from colonized plates of PDA using sterilized water and adjusted to a concentration of 1×107 conidia/ml. All 30 seedlings were incubated in a greenhouse at 25°C with a relative humidity of 80% and a 12-h photoperiod. The inoculated seedlings displayed wilt symptoms within 30 to 40 days, and eventually died within 75 to 85 days after inoculation. Control plants remained symptomless. F. oxysporum was successfully reisolated from the vascular tissues of symptomatic plants, and sequences of RPB2, TEF1 and cmdA of re-isolates matched those of the original isolates. No pathogen was isolated from the tissues of control plants. The experiment was repeat twice with the similar results, fulfilling Koch's postulates. F. oxysporum is an important soil-borne pathogen and can cause disease in many economic plants, such as yellowwood (Graney et al. 2016), hickory (Zhang et al. 2015) and larch (Rolim et al. 2020). To our knowledge, this is the first report of wilt on C. betulus caused by F. oxysporum in China.

scholarly journals First Report of Stem and Foliage Blight of Chrysanthemum Caused by Phytophthora drechsleri in the United States

Plant Disease ◽  
2021 ◽  
Author(s):  
Charles Krasnow ◽  
Nancy Rechcigl ◽  
Jennifer Olson ◽  
Linus Schmitz ◽  
Steven N. Jeffers
Keyword(s):  
United States ◽  
South Carolina ◽  
Sequence Similarity ◽  
Morphological Characteristics ◽  
The United States ◽  
Universal Primers ◽  
Broad Host Range ◽  
Pathogenicity Test ◽  
First Report ◽  
Foliage Blight

Chrysanthemum (Chrysanthemum × morifolium) plants exhibiting stem and foliage blight were observed in a commercial nursery in eastern Oklahoma in June 2019. Disease symptoms were observed on ~10% of plants during a period of frequent rain and high temperatures (26-36°C). Dark brown lesions girdled the stems of symptomatic plants and leaves were wilted and necrotic. The crown and roots were asymptomatic and not discolored. A species of Phytophthora was consistently isolated from the stems of diseased plants on selective V8 agar (Lamour and Hausbeck 2000). The Phytophthora sp. produced ellipsoid to obpyriform sporangia that were non-papillate and persistent on V8 agar plugs submerged in distilled water for 8 h. Sporangia formed on long sporangiophores and measured 50.5 (45-60) × 29.8 (25-35) µm. Oospores and chlamydospores were not formed by individual isolates. Mycelium growth was present at 35°C. Isolates were tentatively identified as P. drechsleri using morphological characteristics and growth at 35°C (Erwin and Ribeiro 1996). DNA was extracted from mycelium of four isolates, and the internal transcribed spacer (ITS) region was amplified using universal primers ITS 4 and ITS 6. The PCR product was sequenced and a BLASTn search showed 100% sequence similarity to P. drechsleri (GenBank Accession Nos. KJ755118 and GU111625), a common species of Phytophthora that has been observed on ornamental and vegetable crops in the U.S. (Erwin and Ribeiro 1996). The gene sequences for each isolate were deposited in GenBank (accession Nos. MW315961, MW315962, MW315963, and MW315964). These four isolates were paired with known A1 and A2 isolates on super clarified V8 agar (Jeffers 2015), and all four were mating type A1. They also were sensitive to the fungicide mefenoxam at 100 ppm (Olson et al. 2013). To confirm pathogenicity, 4-week-old ‘Brandi Burgundy’ chrysanthemum plants were grown in 10-cm pots containing a peat potting medium. Plants (n = 7) were atomized with 1 ml of zoospore suspension containing 5 × 103 zoospores of each isolate. Control plants received sterile water. Plants were maintained at 100% RH for 24 h and then placed in a protected shade-structure where temperatures ranged from 19-32°C. All plants displayed symptoms of stem and foliage blight in 2-3 days. Symptoms that developed on infected plants were similar to those observed in the nursery. Several inoculated plants died, but stem blight, dieback, and foliar wilt were primarily observed. Disease severity averaged 50-60% on inoculated plants 15 days after inoculation. Control plants did not develop symptoms. The pathogen was consistently isolated from stems of symptomatic plants and verified as P. drechsleri based on morphology. The pathogenicity test was repeated with similar results. P. drechsleri has a broad host range (Erwin and Ribeiro 1996; Farr et al. 2021), including green beans (Phaseolus vulgaris), which are susceptible to seedling blight and pod rot in eastern Oklahoma. Previously, P. drechsleri has been reported on chrysanthemums in Argentina (Frezzi 1950), Pennsylvania (Molnar et al. 2020), and South Carolina (Camacho 2009). Chrysanthemums are widely grown in nurseries in the Midwest and other regions of the USA for local and national markets. This is the first report of P. drechsleri causing stem and foliage blight on chrysanthemum species in the United States. Identifying sources of primary inoculum may be necessary to limit economic loss from P. drechsleri.

scholarly journals First report of banana (Musa acuminate L. AAA Cavendish, cv. Formosana) leaf spot disease caused by Curvularia geniculata in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Yanxiang Qi ◽  
Yanping Fu ◽  
Jun Peng ◽  
Fanyun Zeng ◽  
Yanwei Wang ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Universal Primers ◽  
Leaf Spot Disease ◽  
Leaf Margin ◽  
Conidial Suspension ◽  
Tropical Fruit ◽  
First Report ◽  
Spot Disease

Banana (Musa acuminate L.) is an important tropical fruit in China. During 2019-2020, a new leaf spot disease was observed on banana (M. acuminate L. AAA Cavendish, cv. Formosana) at two orchards of Chengmai county (19°48ʹ41.79″ N, 109°58ʹ44.95″ E), Hainan province, China. In total, the disease incidence was about 5% of banana trees (6 000 trees). The leaf spots occurred sporadically and were mostly confined to the leaf margin, and the percentage of the leaf area covered by lesions was less than 1%. Symptoms on the leaves were initially reddish brown spots that gradually expanded to ovoid-shaped lesions and eventually become necrotic, dry, and gray with a yellow halo. The conidia obtained from leaf lesions were brown, erect or curved, fusiform or elliptical, 3 to 4 septa with dimensions of 13.75 to 31.39 µm × 5.91 to 13.35 µm (avg. 22.39 × 8.83 µm). The cells of both ends were small and hyaline while the middle cells were larger and darker (Zhang et al. 2010). Morphological characteristics of the conidia matched the description of Curvularia geniculata (Tracy & Earle) Boedijn. To acquire the pathogen, tissue pieces (15 mm2) of symptomatic leaves were surface disinfected in 70% ethanol (10 s) and 0.8% NaClO (2 min), rinsed in sterile water three times, and transferred to potato dextrose agar (PDA) for three days at 28°C. Grayish green fungal colonies appeared, and then turned fluffy with grey and white aerial mycelium with age. Two representative isolates (CATAS-CG01 and CATAS-CG92) of single-spore cultures were selected for molecular identification. Genomic DNA was extracted from the two isolates, the internal transcribed spacer (ITS), large subunit ribosomal DNA (LSU rDNA), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), translation elongation factor 1-alpha (TEF1-α) and RNA polymerase II second largest subunit (RPB2) were amplified and sequenced with universal primers ITS1/ITS4, LROR/LR5, GPD1/GPD2, EF1-983F/EF1-2218R and 5F2/7cR, respectively (Huang et al. 2017; Raza et al. 2019). The sequences were deposited in GenBank (MW186196, MW186197, OK091651, OK721009 and OK491081 for CATAS-CG01; MZ734453, MZ734465, OK091652, OK721100 and OK642748 for CATAS-CG92, respectively). For phylogenetic analysis, MEGA7.0 (Kumar et al. 2016) was used to construct a Maximum Likelihood (ML) tree with 1 000 bootstrap replicates, based on a concatenation alignment of five gene sequences of the two isolates in this study as well as sequences of other Curvularia species obtained from GenBank. The cluster analysis revealed that isolates CATAS-CG01 and CATAS-CG92 were C. geniculata. Pathogenicity assays were conducted on 7-leaf-old banana seedlings. Two leaves from potted plants were stab inoculated by puncturing into 1-mm using a sterilized needle and placing 10 μl conidial suspension (2×106 conidia/ml) on the surface of wounded leaves and equal number of leaves were inoculated with sterile distilled water serving as control (three replicates). Inoculated plants were grown in the greenhouse (12 h/12 h light/dark, 28°C, 90% relative humidity). Necrotic lesions on inoculated leaves appeared seven days after inoculation, whereas control leaves remained healthy. The fungus was recovered from inoculated leaves, and its taxonomy was confirmed morphologically and molecularly, fulfilling Koch’s postulates. C. geniculata has been reported to cause leaf spot on banana in Jamaica (Meredith, 1963). To our knowledge, this is the first report of C. geniculata on banana in China.

scholarly journals First Report of Powdery Mildew Caused by Golovinomyces cichoracearum on Crotalaria juncea (‘Tropic Sun’ Sunn hemp)

Plant Disease ◽  
2009 ◽  
Vol 93 (4) ◽  
pp. 427-427 ◽  
Author(s):  
A. J. Gevens ◽  
G. Maia ◽  
S. A. Jordan
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Cover Crop ◽  
Morphological Characteristics ◽  
The United States ◽  
Universal Primers ◽  
Crotalaria Juncea ◽  
First Report ◽  
Golovinomyces Cichoracearum ◽  
Sunn Hemp

Crotalaria juncea L. (Fabaceae), commonly known as sunn hemp, is a subtropical annual legume grown in the United States as a cover crop that improves soil quality, provides nitrogen, suppresses weeds and nematodes, and adds organic matter to soils. In Florida, sunn hemp is a warm- and short-season cover crop that is typically planted in June and cut and incorporated into soil in September. In 2008, powdery mildew was observed on sunn hemp in a research field in Hastings, FL. This disease is important because it has the potential to impact the health and quality of sunn hemp, and this particular powdery mildew can infect cucurbits that are grown in north Florida from late summer to fall. Fungal growth appeared as typical white, powdery mildew colonies initially seen on upper leaf surfaces, especially along the midvein of infected leaves, but moving to undersides as disease progressed; petioles and floral parts were disease free. As disease progressed, colonies enlarged and coalesced to cover the entire leaf surface; heavily infected leaves senesced and abscised. Infection was primarily seen on the lower, more mature leaves of plants and not on the top 0.6 m (2 feet) of the plant. Mycelia produced white accumulations of conidiophores and conidia. Hyphae were superficial with papillate appressoria and produced conidiophores with cylindrical foot cells that measured 48.5 × 10.0 μm (mean of 100 foot cell measurements) and short chains of conidia. Conidia were hyaline, short-cylindrical to ovoid, lacked fibrosin bodies, borne in chains, had sinuate edge lines with other immature conidia, and measured 22.5 to 40.0 (mean = 29.85 μm) × 12.5 to 20.0 μm (mean = 15.55 μm). The teleomorph was not observed. The nuclear rDNA internal transcribed spacer (ITS) regions were amplified by PCR, using universal primers ITS1 and ITS4, and sequenced (GenBank Accession No. FJ479803). On the basis of morphological characteristics of the asexual, imperfect state that are consistent with published reports of Golovinomyces cichoracearum (2) and ITS sequence data that indicated 100% homology with G. cichoracearum from Helianthus annus (GenBank Accession No. AB077679), this powdery mildew was identified as caused by G. cichoracearum of the classification Golovinomyces Clade III (3). Pathogenicity was confirmed by gently pressing disease leaves onto leaves of healthy C. juncea plants. Inoculated plants were placed into plastic bags containing moist paper towels to maintain high humidity. The temperature was maintained at 24°C, and after 2 days, powdery mildew colonies developed in a manner consistent with symptoms observed under field conditions. A powdery mildew on Crotalaria was previously identified as caused by Microsphaera diffusa Cooke & Peck (1). To our knowledge, this is the first report of G. cichoracearum causing powdery mildew on C. juncea. References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (2) D. A. Glawe et al. Online publication. doi: 10.1094/PHP-2006-0405-01-BR. Plant Health Progress, 2006. (3) S. Takamatsu et al. Mycol. Res. 110:1093, 2006.

scholarly journals First report of Fusarium cf. longipes associated with maize stalk rot in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Shengbo Han ◽  
Yanyong Cao ◽  
Jie Zhang ◽  
Jie Wang ◽  
Lili Zhang ◽  
...  
Keyword(s):  
Sequence Data ◽  
Fusarium Species ◽  
Apical Cell ◽  
Morphological Characteristics ◽  
Liaoning Province ◽  
Bootstrap Support ◽  
Flowering Stage ◽  
Single Spore ◽  
First Report ◽  
Stalk Rot

In a field survey from 2017 to 2019, Fusarium stalk rot symptoms including discolored, disintegrated stalk pith tissues and lodged plants were observed in maize hybrid lines Fuyu1611, Jidan66, and Danyu8439 grown in fields in Anshan (40o49′39′′N, 122 o34′6′′E), Liaoning province. Its incidence ranged from 15% to 20% and caused a yield loss of up to 30%. Infected pieces of stem tissues were dissected and then sterilized with 1% NaOCl for 1 min, 70% ethanol for 1 min, rinsed 3 times with sterilized ddH2O, and dried with filter paper in hood. Three pieces were placed onto Potato dextrose agar (PDA) and incubated at 25 °C for 5 days. The colonies were single-spore subcultured on PDA at 25 °C for 2 weeks (Leslie and Summerell 2006). Morphological features were observed on PDA and carnation leaf agar (CLA). The average mycelial growth rate was 4.5 to 10.3 mm/day at 25 °C on PDA. The colonies produced aerial mycelia, varying from dense white to grayish-rose, and secreted red pigments in the agar (Fig. 1A; 1B). Macroconidia produced on CLA were long and relatively slender, commonly 4- to 7-septate, averaging 85.6 × 5.2 μm, with thick walls and pronounced dorsiventral curvature with a distinctly foot-shaped and elongated basal cell and an apical cell that was whip-like (Fig. 1C). Microconidia were rarely observed on PDA or CLA. Morphological characteristics of the isolates were similar to the features of Fusarium longipes as previously described (Leslie and Summerell 2006). The portions of three phylogenic loci (EF1-α, RPB1, RPB2) were PCR amplified using the primer pairs EF1/EF2 (O'Donnell et al, 1998), lonR1F/lonR1R (5-TTTTCCTCACCAAGGAGCAGATCATG-3 and 5-CCAATGGACTGGGCAGCCAAAACGCC-3) and lonR2F/lonR2R (5-TATACATTTGCCTCCACTCTTTCCCAT-3 and 5-CGGAGCTTGCGTCCGGTGTGGCCGTTG-3) and sequenced. The consensus sequences were submitted to GenBank (MT513215 and MT997083 for TEF, MT513213 and MT997088 for RPB1; MT513214 and MW020572 for RPB2). BLASTn searches indicated that the nucleotide sequences of the three loci of the two isolates shared 94.52% to 99.69% identity with sequences of F. longipes strains deposited in the GenBank, Fusarium-ID and Fusarium MLST databases (Supplementary Table 1, 3, 4). A phylogram inferred via maximum likelihood analysis of the combined EF-1α, RPB1, RPB2 partial sequence data of Fusarium species (Supplementary Table 2) was inferred using the CIPRIES website (https://www.phylo.org). Isolates LNAS-05-A and LNAS-09-A clustered with F. longipes, with 98% bootstrap support (Fig. 2). Pathogenicity tests were conducted on three-leaf-stage seedlings and flowering-stage c.v. Zhengdan958 and B104 plants according to previously described methods (Ye et al., 2013; Zhang et al. 2016) with minor modifications. Three days after the roots of the seedlings were inoculated with 1 × 106 macroconidia solution, the leaves and stems exhibited typical wilt symptoms (Fig. 1D). Twenty flowering-stage maize plants were drilled individually at the second or third node above the soil using an electric drill (Bosch TSR1080-2-Li) to create a hole (8 mm in diameter). An approximately 0.5 mL mycelia plug (125 mL homogenized hyphal mats + 75 mL sterilized ddH2O) was injected into the hole and covered with Vaseline. Sterilized PDA plugs were used as a control. The stalk tissue of the split internodes turned dark brown and the brown area expanded above and below the injection site by 14 dpi. All of the inoculated plants developed characteristic stalk rot symptoms, whereas no symptoms were observed in the controls (Fig. 1E). The pathogen was re-isolated, and its identity was confirmed by sequencing the above mentioned loci. F. longipes was generally regarded as a tropical Fusarium species (Leslie and Summerell 2006). This is the first report that F. cf. longipes can cause stalk rot of maize under filed condition in a temperate, typical corn belt region of China.

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 Blight in Chinese Hickory (Carya cathayensis) Caused by Alternaria petroselini in China

Plant Disease ◽  
2013 ◽  
Vol 97 (9) ◽  
pp. 1253-1253 ◽  
Author(s):  
Y. H. Liu ◽  
C. Q. Zhang ◽  
B. C. Xu
Keyword(s):  
Management Practices ◽  
Morphological Characteristics ◽  
Morphological Characterization ◽  
Leaf Blight ◽  
Internal Transcribed Spacers ◽  
Infected Leaf ◽  
First Report ◽  
Plastic Bags ◽  
Initial Symptoms ◽  
Carya Cathayensis

Chinese hickory (Carya cathayensis) is one of the important economic forest crops in Zhejiang and Anhui Provinces, China. In 2012, nearly 40% of hickory orchards and 6.8% of hickory trees were affected by leaf blight in Zhejiang. Initial symptoms consisted of small, brown, water-soaked lesions, which subsequently enlarged and developed a black sporulating necrotic center surrounded by a chlorotic halo. Infected leaf samples collected from 25 different orchards in Lin'an and 13 different orchards in Chun'an were surface sterilized with 1.5% sodium hypochlorite for 1.5 min, rinsed in water, plated on 2% potato dextrose agar (PDA), and incubated at 25°C in the dark for 1 week. Single conidium cultures were consistently isolated and cultured on PDA and V8 agar for morphological characterization (1,3). On both agar media, colonies were dark olive brown with smooth margins and concentric rings of sporulation. Conidia were solitary, darkly pigmented, predominantly ovoid-subsphaeroid, and 23 to 52 × 13 to 23 μm with up to six or seven transepta and one to three longisepta. The ribosomal internal transcribed spacers ITS1 and ITS2 of 10 isolates were amplified using primers ITS1/ITS4 on DNA extracted from mycelium and nucleotide sequences showed 100% similarity to that of A. petroselini (GenBank Accession Nos. AY154685.1 and EU807868.1). To confirm pathogenicity, 10 uninfected leaves from each of 10 C. cathayensis trees were sprayed either with a conidia suspension (105 conidia per ml) or with distilled water only to serve as an un-inoculated control. Leaves were subsequently wrapped in plastic bags to retain moisture, and incubated for 48 h. After 1 week, 8 of 10 isolates caused lesions identical to those initially described whereas no symptoms developed on water inoculated leaves. Cultures reisolated from lesions and cultured on PDA exhibited morphological characteristics identical to A. petroselini (1,2,3), confirming Koch's postulates. To our knowledge, this is the first report of leaf blight in C. cathayensis, and this identification would allow producers to identify for appropriate management practices. References: (1) P. M. Kirk et al. The Dictionary of the Fungi, 10th edition, page 159. CABI Bioscience, UK, 2008. (2) B. M. Pryor et al. Mycologia 94:49, 2002. (3) E. G. Simmons. Alternaria: An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, The Netherlands, 2007.

scholarly journals First Report of Damping-off of Ovate-leaf Atractylodes Caused by Pythium aphanidermatum in South Korea

Plant Disease ◽  
2020 ◽  
Author(s):  
Oliul Hassan ◽  
Taehyun Chang
Keyword(s):  
South Korea ◽  
Cytochrome Oxidase ◽  
Tap Water ◽  
Morphological Characteristics ◽  
Pythium Aphanidermatum ◽  
Causal Agent ◽  
Effective Control ◽  
Root Extract ◽  
Damping Off ◽  
First Report

Ovate-leaf Atractylodes (Atractylodes ovata) is a well-known medicinal plant in Korea, where the dried rhizome and the root extract are used in herbal medicines. In 2019, severe damping-off of ovate-leaf Atractylodes at the early seedling stage was observed in a commercial planting in Sangju, South Korea. Approximately 35% of young seedlings suddenly wilted and then died despite adequate soil moisture. Putative causal agents were isolated from roots of diseased plants. Roots were washed thoroughly wih tap water, cut into 1-cm-long pieces and then split in half longitudinally. Root pieces were surface disinfected in 0.1% NaOCl solution for 1 min, washed three times with sterilized distilled water, and finally blotted dry. Root tissue was placed on potato dextrose agar (PDA, Difco, and Becton Dickinson) amended with tetracycline (0.05 g/L) and incubated at 25°C in the dark. Twelve pure culture of the potential causal agent were obtained by hyphal tipping twice. Mycelia of the seven-day-cultures were white and the colony produced numerous oogonia. The oogonia were smooth, globose, terminal and rarely intercalary, and 17.3 to 27.1 µm (mean ± SD 24.3 ± 2.25 µm) in diameter. Antheridia were diclinous or monoclinous (rare) with clavate cells that were 17.9 to 31.6 × 7.1 to 8.8 µm (mean 26.8 × 7.5 µm). The stalks of the antheridia were unbranched. Oospores were plerotic or nearly plerotic and 16.3 to 25.4 µm (mean ± SD = 20.1 µm ± 3.2) in diameter. The morphological characteristics of the isolates were comparable to those of Pythium spp. including P. aphanidermatum (Van der Plaats-Niterink,1981). The internal transcribed spacers (ITS), cytochrome oxidase 1 (cox1), and cytochrome oxidase 2 (cox2) regions of genomic DNA from SRRS1, SRRS2, and SRRS4 were amplified using primer sets ITS5 + ITS4, FM52R + FM55, and FM58 + FM66 respectively (Ueta and Tojo 2016) and sequenced. Resulting sequences were deposited in GenBank under accession numbers LC569777 to LC569779 and LC569785 to LC569790. The concatenated sequence data contained 46 taxa for the ITS–cox2 phylogenetic analysis and 17 taxa for cox1. The maximum likelihood estimation and Bayesian inference consensus tree showed that the present isolates formed a clade with P. aphanidermatum (strain NBRC 100101, P36-3, and 1987-61). The pathogenicity of three isolates was tested using the procedure described by Herrero et al. (2003) with some modification. Five surface disinfected seeds were sown in a plastic pot containing autoclaved peat soil. There was a total of twelve pots. After emergence seedlings were thinned to three similar sized seedlings per pot and grown for 25 days at 25°C in the 16‐h light. Seedling were then inoculated with mycelial plugs (10 mm diam.) from four day old cultures on PDA. Three plugs per pot were placed 1 cm apart from the seedlings (one plug per seedling). Three pots per isolates were inoculated and three pot with non‐inoculated seedlings were used as control. All plants were grown in a growth chamber at 25°C with 16‐h light and 80% relative humidity and irrigated twice per week with sterile water. All inoculated seedlings (100%) suddenly collapsed 10 days after inoculation while the control plants remained healthy and vigorous. Pythium aphanidermatum was re-isolated from the inoculated seedlings and identified following the procedures previously described thus completing Koch’s postulates. This pathogen has also reported as the causal agent of damping-off of common bean, cucumber, wheat, tomato and tobacco (Al-Saadi et al. 2007; Herrero et al. 2003; and Gilardi et al. 2018). To our knowledge, this is the first report of Pythium aphanidermatum causing damping-off disease on ovate-leaf Atractylodes in South Korea, and this pathogen could threaten production. Outcomes of present study will help manage this disease with effective control measures.

scholarly journals First Report of Penicillium digitatum causing Postharvest rot of Citron Fruit in Kunming, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Huan Ren ◽  
Gao Yang ◽  
Xue Li ◽  
Shijun Xing ◽  
Yating Gao ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Penicillium Digitatum ◽  
Green Water ◽  
Universal Primers ◽  
Single Strain ◽  
First Report ◽  
Rdna Its ◽  
Its Sequence Analysis ◽  
Initial Symptoms ◽  
Citrus Medica

Citron (Citrus medica L.) is a perennial evergreen woody tree of Rutaceae family and Genus of Citrus. The citron is cultivated for its economic, medicinal and ornamental values in the south of China. (Yang et al., 2015). The shapes range from spherical to ovate and the sizes range from 3 to 5 kg (Klein et al., 2016). In June 2021, some postharvest citron fruits (Citrus medica var. medica) were found to have decay with a green or greyish mycelium on part or whole citron in 2 farmer’s markets in Kunming city, Yunnan Province (N 25°02′; E 102°42′), southwest China. Initial symptoms appeared as white, brown, and irregular necrotic spots in the pericarp. The lesions enlarged gradually and developed into green, water-soaked areas which extend rapidly. Eventually, the diseased fruits were rotten, soften, and the green spore masses confined to the surface (Fig. 1A). The incidence of this disease in postharvest citron fruits ranges from 15 % to 35 %, which is extremely destructive to the fruit of Rutaceae family plants (Chen et al., 2019). Small pieces (5 mm2) of symptomatic citron fruits were surface disinfected in 75 % ethanol and 0.3 % NaClO for 30 s and 2 min respectively, rinsed with distilled water for three times, blotted dry, placed onto potato dextrose agar (PDA) medium aseptically and incubated in a growth chamber at 25 ± 1 ℃, after 7 days, different colonies grew on PDA plates that were isolated and purified on new PDA medium at 25 ± 1 ℃ for 7 days. Inoculating repeatedly until six single-strain (XY01 to XY06) were obtained, and these isolates were stored in 15 % glycerol at –80 ℃ in a refrigerator in the State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan Agricultural University. The selected pathogens (XY01 to XY06) were inoculated on PDA medium, incubated at 25 ± 1 ℃. After 7 days, colonies of the isolate obverse are olive green, the white margin and greyish-green spores on the surface, and the reverse colorless to cream yellow or pale dull brown. Colonies texture was velutinous, with a special fragrance. The conidia structure was very fragile and break up easily into many cellular elements. Conidiophores were terverticillate, produced by subsurface or aerial hyphae, irregularly branched and composed of short stipes with few metulae and branches that terminate in whorls of three to six phialides, which are often solitary, cylindrical with a short neck. Conidia are hyaline to pale green, smooth-walled, without septate, partially ellipsoidal, or obovate (4.9 to11.9× 4.3 to 8.9 μm). Partial cylindrical (8.2 to 10.5× 2.7 to 5.3 μm), there are some small conidia, which were ellipsoidal or spherical (3.9 to 5.2× 2.7 to 5.2 μm). According to morphological characteristics, the fungus was identified as Penicillium digitatum (Pers.) Sacc. Isolate XY01 and XY02 were used for molecular identification and genomic DNA was extracted using the CTAB method (Aboul-Maaty & Oraby, 2019). The universal primers ITS1 and ITS4 were used to amplify and sequence the ITS1, 5.8S, and ITS2 rDNA region. Using NCBI’s BLASTn tools, the nucleotide sequences of XY01 and XY02 (Gen-Bank accessions MZ976843 and OK513274) show 100 % identity to MK450692 (P. digitatum strain CMV010G4). Pathogenicity tests have used the fruits (Citrus medica), which maturity was more than 80%. The pathogens (XY01, XY02) were cultured for 7 days on PDA medium, washed with sterilized water the resulting spore suspensions diluted to 1.0 × 106 spores/ml. Wounds (0.5 × 0.5 cm) were made on the surface of citron fruits by scraping with a sterile scalpel and then treated with 200 µl of spore suspension (Wild, 1994). Control citron fruits were treated with sterile water. citron fruits were incubated at 24-26 °C. Each treatment was performed in triplicate with 6 citron fruits. After 3 days, all fruits had developed lesions, in a water-stained, pale brown, and rapidly formed white hyphae, white mold layer was observed with a length of 1.5-2.5 cm and a width of 1-2 cm (Fig.1C), but control did induce infection. After 7 days, decay developed more quickly, the hyphae rapidly expanded on the surface of the pericarp, with vague and irregular edges, then a green mold layer was formed, the whole fruit was observed to rot and soften, When the citron was cut, the white flesh inside turned black and rotted (Fig.1B). P. digitatum was consistently reisolated from the inoculated plants but not from the controls. No symptoms developed on the control (Fig.1D). According to Koch’s postulates, the inoculated strains of XY01 and XY02 were the isolates causing citron decay disease. Based on symptoms, morphological characteristics, rDNA-ITS sequence analysis, and pathogenicity, this fungus was identified as P. digitatum. To our knowledge, this is the first report of the distribution of P. digitatum on Citron (Citrus medica) in China.

scholarly journals First Report of Fusarium solani Causing Root Rot of Juglans sigllata Dode in China

Plant Disease ◽  
2015 ◽  
Vol 99 (1) ◽  
pp. 159-159 ◽  
Author(s):  
L. Zheng ◽  
Y. Peng ◽  
J. Zhang ◽  
W. J. Ma ◽  
S. J. Li ◽  
...  
Keyword(s):  
Fusarium Solani ◽  
Root Rot ◽  
Industrial Development ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Colony Growth ◽  
Universal Primers ◽  
Laboratory Manual ◽  
First Report ◽  
Stem Cankers

Juglans sigllata Dode, known as the iron walnut, is widely planted in Liangshan prefecture of southwest China for its nuts and wood. Liangshan prefecture is a major traditional growing area of J. sigllata and has unique advantages for walnut industrial development because of its good soil, climate, and availability of water. Currently there are 2.7 million hectares of walnut, contributing important incomes for farmers. In April 2013, numerous J. sigllata were found infected with root rot in the Muli county of Liangshan prefecture. Symptoms included dried leaves, dead branchcs, and even death. Rotted roots were collected and surface-sterilized in 2% NaOCl and 70% ethanol. The junction (1 cm) between infected and healthy regions was removed, plated on rose bengal-glycerin-urea medium, and incubated at 20°C for 12 h. A fungus was found and purified successively by transferring hyphal tips from the margin of a thinly growing colony on 2% water agar (3). Morphological characteristics were identified both on potato dextrose agar (PDA) and carnation leaf-piece agar. Evaluation of pigmentation and colony growth rate were also measured using PDA. Ovoid microconidia (average dimensions 10.6 × 9.1 μm) were observed after 2 to 3 days, and most of them had no septa or only one septum. Macroconidia (average dimensions 47.4 × 5.3 μm), with one to three septate sickle shapes, were found after 3 to 6 days. Single or paired chlamydospores (average dimensions 10.3 × 9.2 μm), which were circular to ovate, smooth or not smooth, were observed after 7 days of incubation in clean water. According to the cultural characteristics, the fungus was primarily identified as Fusarium solani (1). To better determine the species, universal primers ITS1/ITS4 for the ribosomal internal transcribed spacer (ITS) coupled with translation elongation factor (EF-1α) primers EF1/EF2 were used for PCR-based molecular identification. Against GenBank and the FUSARIUM-ID databases, our sequences shared 99 and 98% identities with ITS (FJ459973.1) and EF-1α (JX677562.1) of F. solani, respectively. Both sequences produced in this study have been deposited in GenBank under accession numbers KJ528277 for ITS and KJ528278 for EF-1α. Pathogenicity tests were conducted by drop inoculating 20 ml of microconidia suspension (106 spores/ml) on the roots of 1-year-old healthy potted J.sigllata, Mianyang walnut, and Xinjiang walnut. Controls were not treated with F. solani. Fifteen plants were in each group. All materials, including pots and soil, were disinfected. After 12 days, all J. sigllata inoculated with F. solani exhibited dried leaves, and after 17 days, Mianyang walnut and Xinjiang walnut infected with F. solani also developed the same symptoms. After 24 days, the inoculated J. sigllata died. However, control plants remained asymptomatic. The fungus re-isolated from infected roots showed the same characteristics as described above and was totally identical in appearance to the isolates used to inoculate the plants. No colonies of F. solani were isolated from untreated plants. At present, F. solani has been reported in stem cankers on English walnut in South Africa (2). To our knowledge, this is the first report of root rot caused by F. solani in J. sigllata in China. References: (1) C. Booth. Fusarium Laboratory Guide to the Identification of the Major Species. CMI, Kew, England, 1977. (2) W. Chen and W. J. Swart. Plant Dis. 84:592, 2000. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006.

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