scholarly journals First Report of Cylindrocladium Black Rot of Peanut Caused by Cylindrocladium parasiticum (Teleomorph Calonectria ilicicola) in Jiangxi Province, China

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 586-586 ◽  
Author(s):  
Y. Gai ◽  
Q. Deng ◽  
R. Pan ◽  
X. Chen ◽  
M. Deng
Keyword(s):  
Southern China ◽  
Disease Incidence ◽  
Jiangxi Province ◽  
Black Rot ◽  
Brown Pigment ◽  
Fruiting Bodies ◽  
Calonectria Ilicicola ◽  
Cylindrocladium Parasiticum ◽  
Stem Lesions ◽  
Reddish Orange

In July 2010, a serious disease of peanut (Arachis hypogaea) resembling Cylindrocladium black rot (CBR) was found in Longnan County, Jiangxi Province, China. Symptoms included chlorotic, yellowish and blighted leaves, and wilting of the plants. Taproots and hypocotyls were blackened and rotted. Clusters of reddish orange spherical fruiting bodies appeared in the lesions present on basal stems, pegs, pods, and roots of peanut. Disease incidence reached as much as 50% in some patches of the field. Plants with symptoms were sampled from fields. Microscopic examination revealed that the reddish orange, spherical fruiting bodies were the perithecia and measured 461.6 (337.5 to 609.4) × 395.5 (309.4 to 496.9) μm. With gentle pressure, asci and ascospores were exuded from perithecia. The asci were hyaline, thin walled, and long stalked. Ascospores were hyaline, falcate with one septum, and measured 43.5 (27.3 to 54.5) × 5.6 (4.1 to 6.8) μm with a length/width (L/W) ratio of 7.8 ± 1.3. A fungus with white-to-pale buff border mycelia and yellowish brown pigment was consistently isolated from the edge of basal stem lesions on potato dextrose agar at 25°C. Mycelia grew at temperatures ranging from 8 to 32°C and the optimum was 25 to 26°C. To determine the species, single-conidial isolates of the fungus were cultured on carnation leaf agar for 7 days at 25°C and 12 h of light/dark conditions. Conidia were hyaline, cylindrical with one to three septa (mostly three septa), and measured 49.3 (27.3 to 70.9) × 5.9 (4.1 to 6.8) μm with L/W ratio of 8.4 ± 1.6. Vesicles were globose and measured 5.5 to 10.9 μm in diameter. The fungus was identified as Cylindrocladium parasiticum (teleomorph Calonectria ilicicola) (1,2). A PCR assay was conducted on one representative isolate (JXLN32) by analyzing multilocus sequences of the TUB2 (coding β-tubulin protein), ACT (coding actin), and CaM gene (coding calmodulin protein) and were amplified and sequenced using the primers reported by Crous et al. (3). Sequences of the studied DNA regions were submitted to GenBank (Accession Nos. TUB2: JF429649; ACT: JQ070809; and CaM: JQ070808). BLAST searches with the existing sequences in GenBank showed that there was 99 to 100% identity with the existing sequences of C. ilicicola (GenBank Accession Nos. TUB2: AY725643; ACT: GQ280446; and CaM: GQ267402). To complete Koch's postulates, inoculum was prepared by mixing the microsclerotia (MS) suspension of the isolate (JXLN32) with soil at a proportion of 10 MS per g of soil. Ten replicate plastic pots containing five peanut seeds (cv. Yueyou 7) each were planted and placed in a glasshouse at 25 ± 2°C. The same number of peanut seeds was used as an uninoculated control. Typical basal stem and roots rot symptoms of CBR were observed in 2 months and C. parasiticum was reisolated from these inoculated diseased plants. No symptoms were detected on the control plants. To our knowledge, this is the first finding of Cylindrocladium black rot in Jiangxi Province, which is the main peanut-producing area in China. The disease has been previously reported in Guangdong Province in southern China but is not known elsewhere (4). Because of its ability to spread through seed and soil and its destructive potential, this pathogen may pose a serious threat to peanut production in China. References: (1) D. K. Bell and E. K. Sobers. Phytopathology 56:1361, 1966. (2) P. W. Crous et al. Mycol. Res. 97:889, 1993. (3) P. W. Crous et al. Stud. Mycol. 50:415, 2004. (4) R. Pan et al. Plant Pathol. 58:1176, 2009.

scholarly journals First Report of Peanut Cylindrocladium Black Rot Caused by Cylindrocladium parasiticum in Fujian Province, Eastern China

Plant Disease ◽  
2012 ◽  
Vol 96 (4) ◽  
pp. 583-583 ◽  
Author(s):  
R. Pan ◽  
Q. Deng ◽  
D. Xu ◽  
C. Ji ◽  
M. Deng ◽  
...  
Keyword(s):  
Southern China ◽  
Disease Incidence ◽  
Eastern China ◽  
Black Rot ◽  
Brown Pigment ◽  
Fujian Province ◽  
First Report ◽  
Calonectria Ilicicola ◽  
Cylindrocladium Parasiticum ◽  
Wheat Kernels

During late July and early August of 2010, a serious disease of peanut (Arachis hypogaea L.) resembling Cylindrocladium black rot (CBR) was found in Longyan City, Fujian Province of Eastern China. Aboveground symptoms were chlorosis and yellowing of leaves, a black rot of the basal stem and pegs, and wilting of the vines. Underground plant parts (including pods, pegs, taproots, and hypocotyls) were blackened and rotted. Orange-to-reddish spherical fruiting bodies appeared on the lesions of the basal stems and pegs of peanut. Disease incidence was approximately 20%. A fungus was consistently isolated from the edge of lesions on potato dextrose agar (PDA) amended with streptomycin and incubated at 25°C. The fungus produced white-to-pale buff mycelia with a yellowish brown pigment. Optimum growth of the fungus on PDA was at 25 to 30°C. Conidiophores were borne laterally on a stipe that terminated in a hyaline, globose vesicle measuring 5.5 × 10.9 μm in diameter. Conidia were hyaline, cylindrical, rounded at both ends, slightly wider at the base than at the apex, with one to three septa (mostly one septa), and measured 27.3 to 70.9 × 4.1 to 8.2 μm. Orange-to-reddish perithecia were readily formed in old cultures. The perithecia were subglobose to oval or obovate and measured 215.6 to 609.4 × 309.4 to 496.9 μm. The asci were hyaline, clavate, thin walled, long stalked, with each containing eight ascospores. Ascospores were hyaline, falcate, had one septum, and measured 27.3 to 54.5 × 4.1 to 6.8 μm. The fungus was identified as Cylindrocladium parasiticum Crous, M.J. Wingfield, & Alfenas (teleomorph Calonectria ilicicola) (1,2). The beta-tubulin gene fragment was amplified using the T1/Bt2b primers (3) and sequenced. The sequences of three isolates (GenBank Accession Nos. JF343965, JF429656, and JF429657), when compared with existing sequences in GenBank, had 95 to 99% sequence identity with Calonectria ilicicola (GenBank Accession Nos. AY725643 and AY725639). Pathogenicity tests were conducted by first culturing the fungus on wheat kernels for 2 weeks. Inoculated kernels were then used as inoculum and mixed with sterilized soil in a proportion of 1:20 by weight in plastic pots (10 × 9 cm). Noninoculated wheat kernels were mixed with sterilized soil in the same proportion and served as the control. Two-week-old peanut seedlings (cv. Yueyou No. 7) were transplanted into inoculated or noninoculated pots. There were five plants per pot and each treatment was replicated four times. The plants were incubated in a greenhouse at 25 ± 2°C. All of the treated plants exhibited typical basal stem and root rot symptoms of CBR 2 weeks after inoculation, while all of the control plants remained healthy. C. parasiticum was reisolated from the diseased plants. To our knowledge, this is the first report of CBR on peanut in Fujian Province in Eastern China. The disease has been previously reported in Guangdong Province in Southern China but is not known elsewhere (4). This pathogen may pose a serious threat to peanut production in China, where peanut is an important crop. References: (1) D. K. Bell and E. K. Sobers. Phytopathology 56:1361, 1966. (2) P. W. Crous et al. Mycol. Res. 97:889, 1993. (3) P. W. Crous et al. Can. J. Bot. 77:1813, 1999. (4) R. Pan et al. Plant Pathol. 58:1176, 2009.

scholarly journals First Report of Red Crown Rot Caused by Cylindrocladium parasiticum on Soybean in Guangdong, Southern China

Plant Disease ◽  
2010 ◽  
Vol 94 (4) ◽  
pp. 485-485 ◽  
Author(s):  
M. Guan ◽  
R. Pan ◽  
X. Gao ◽  
D. Xu ◽  
Q. Deng ◽  
...  
Keyword(s):  
Southern China ◽  
Disease Incidence ◽  
Eastern China ◽  
Guangdong Province ◽  
Crown Rot ◽  
Western China ◽  
Calonectria Ilicicola ◽  
Cylindrocladium Parasiticum ◽  
Red Crown Rot ◽  
Whole Plants

In October 2006, occurrence of a disease on soybean (Glycine max) was observed in Guangdong Province of southern China with symptoms resembling red crown rot (3,4). Reddish brown lesions girdled the basal stems with numerous reddish orange perithecia on the lesion surface. Roots became black and rotted and whole plants wilted and died. More recently, outbreaks of this disease were observed in several counties in Guangdong. Disease incidence reached as much as 80% on cv. Huaxia 3 in some fields, causing severe yield losses. Isolation was made from the edge of lesions on potato dextrose agar at 25°C. The fungus produced white, aerial mycelia and a burnt orange-to-dark brown submerged growth. Conidiophores were borne laterally on a stipe, terminating in a hyaline, globose vesicle measuring 4.0 to 13.0 μm in diameter. After branching from the stipe, the conidiophore continued to develop by forming two to three single-celled branches. These cells might give rise to two or three shorter branches (14.8 to 36.9 μm long) and phialides. The phialides were doliform, nonseptate, and measured 7.4 to 19.7 × 3.7 to 4.9 μm. Conidia were hyaline, cylindrical with one to three septa (mostly three septa), and measured 54.1 to 76.3 × 4.9 to 7.4 μm. Perithecia were orange to red, subglobose to oval or globose, 212.1 to 454.5 μm high, and 111.1 to 333.3 μm wide. Asci were hyaline, clavate, thin walled, long stalked, measured 121.0 to 200.8 × 11.5 to 25.6 μm, and each contained eight ascospores that became aggregated in the upper half of the ascus at maturity. The ascospores were hyaline, fusoid to falcate with one to three septa (mostly with one septum), constricted slightly at the septum, and measured 29.5 to 73.8 × 4.9 to 9.8 μm. The fungus was identified as Cylindrocladium parasiticum (teleomorph Calonectria ilicicola) (1,2). The beta-tubulin gene fragment sequences of three isolates were obtained (one sequence being GenBank Accession No. GU073284) and comparisons with GenBank showed 99 to 100% similarity with Calonectria ilicicola (EF159730 and AY725643). Pathogenicity was confirmed by inoculation of 2-week-old seedlings of cv. Huaxia 3 in plastic pots (10 × 9 cm) by drenching with a conidia suspension (105 conidia per ml). All inoculated plants showed similar red crown rot symptoms on stem bases and roots 1 week after inoculation. C. parasiticum was reisolated from the diseased plants, and many orange-to-red perithecia of Calonectria ilicicola were formed on the lesions 3 weeks after inoculation. This pathogen may pose a serious threat to >300,000 ha of soybean production as well as >300,000 ha of peanut production in Guangdong Province. It has been previously reported in Jiangsu Province in eastern China (3) and Yunnan Province in western China (4). References: (1) D. K. Bell, and E. K. Sobers. Phytopathology 56:1361, 1966. (2) P. W. Crous et al. Mycol. Res. 97:889, 1993. (3) J. Y. Gai et al. Soybean Sci. (in Chinese) 11:113, 1992. (4) Z. H. Ma et al. Plant Pathol. 53:537, 2004.

Screening of Virginia-Type Peanut Breeding Lines for Resistance to Cylindrocladium Black Rot and Sclerotinia Blight in the Greenhouse

2008 ◽  
Vol 35 (1) ◽  
pp. 18-24 ◽  
Author(s):  
J. E. Hollowell ◽  
T. G. Isleib ◽  
S. P. Tallury ◽  
S. C. Copeland ◽  
B. B. Shew
Keyword(s):  
Disease Incidence ◽  
Field Performance ◽  
Black Rot ◽  
Block Designs ◽  
Breeding Lines ◽  
Sclerotinia Blight ◽  
Cylindrocladium Parasiticum ◽  
Production Area ◽  
Mist Chamber ◽  
Greenhouse Assay

Abstract Cylindrocladium black rot (CBR) caused by Cylindrocladium parasiticum and Sclerotinia blight caused by Sclerotinia minor are two economically important diseases of peanut (Arachis hypogaea) in the Virginia-Carolina production area. Developing cultivars with resistance to both diseases requires screening of new peanut breeding lines for resistance. Because field evaluations of resistance to these diseases often fail to produce usable results, greenhouse protocols were used to screen breeding lines and cultivars for resistance. For CBR, two seeds of a genotype were planted in a “cone-tainer” filled with a planting medium artificially infested with 25 microsclerotia of C. parasiticum per g of medium. After approximately 8 wk, the roots were washed and rated for degree of decay on a 0–5 proportional scale (0  =  no decay to 5  =  completely decayed). For Sclerotinia blight, plants were inoculated at 6 wk after planting by pushing a plug of potato dextrose agar (PDA) colonized by S. minor and protected from desiccation in a BEEM embedding capsule onto a freshly cut petiole on the main stem of the plant. Inoculated plants were placed in a mist chamber to maintain the high humidity necessary for infection. Lesion lengths were measured 4, 5, 6, and 7 days after inoculation, and areas under the disease progress curves (AUDPC) were calculated. All tests were conducted as incomplete block designs with six replications for CBR tests and four replications for Sclerotinia blight tests. Adjusted entry means were computed from each year's tests and used in summary analyses. Of the 125 breeding lines and checks tested at least once from 2003 through 2006, 51 were tested in at least two years, 34 in at least three years, and 15 lines were tested in all four years. Of the 15 lines tested in all four years, registered germplasm line N96076L had the lowest AUDPC for Sclerotinia blight (58 mm days), but had the greatest CBR root decay score (4.1 decay rating units). Several closely related breeding lines descended from a cross of N96076L and NC 12C were not significantly different from the most resistant line for either disease with scores ranging from 2.2–3.0 decay rating units for CBR and 63–99 mm days for Sclerotinia blight. Correlations of multiple-year greenhouse assay means with field disease incidence means were 0.83 for CBR and 0.35 for Sclerotinia blight. The greenhouse assay for CBR was a reasonably good predictor of field performance, but the assay for Sclerotinia blight was less reliable as a predictor.

Phylogenetic diversity of Calonectria ilicicola causing Cylindrocladium black rot of peanut and red crown rot of soybean in southern China

2017 ◽  
Vol 83 (5) ◽  
pp. 273-282 ◽  
Author(s):  
Yunpeng Gai ◽  
Qiaowen Deng ◽  
Xinglong Chen ◽  
Mingfang Guan ◽  
Xiang Xiao ◽  
...  
Keyword(s):  
Phylogenetic Diversity ◽  
Southern China ◽  
Crown Rot ◽  
Black Rot ◽  
Calonectria Ilicicola ◽  
Red Crown Rot

scholarly journals First Report of Cylindrocladium Black Rot Caused by Cylindrocladium parasiticum on Peanut in Texas

Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1245-1245 ◽  
Author(s):  
T. A. Wheeler ◽  
M. C. Black
Keyword(s):  
Sweet Corn ◽  
Tap Water ◽  
Peat Moss ◽  
Infested Soil ◽  
Calonectria Ilicicola ◽  
Cylindrocladium Parasiticum ◽  
Blue Lake ◽  
Potting Medium ◽  
Bradyrhizobium Sp ◽  
Stem Lesions

During August 2004, Cylindrocladium parasiticum Crous, M.J. Wingf., & Alfenas (teleomorph Calonectria ilicicola Boedijin & Reitsma) was isolated from peanut (Arachis hypogaea L.) cv. NC 7 taken from an irrigated field in Terry County, TX. On 24 September, the mean length of patches with symptoms of dead plants and confirmed for the presence of C. parasiticum was 40 cm (averaged over 52 patches). Pods, pegs, roots, and lower stems of affected plants had decayed black lesions. No perithecia were observed. Roots were plated on water agar, and mycelia growth was transferred to potato dextrose agar (PDA). Conidia and microsclerotia typical of C. parasiticum had formed at 14 days. After 21 days on PDA, the following mean measurements were recorded: macroconidia 57 × 7 μm (usually two septations); stipe 115 × 4 μm; and sphaeropedunculate vesicle 15 × 10 μm. These are within reported ranges for C. parasiticum (1). Four-week-old cultures were comminuted in tap water and added (mycelium and microsclerotia) to potting medium (noninfested nonsterile peanut field soil/peat moss potting mix, 1:1). Peanut-specific Bradyrhizobium sp. was applied before planting. Three 3-day-old peanut cv. Tamrun 88 seedlings were transplanted in infested soil (four replicate pots, five isolates). Root, hypocotyl, pod, peg, and lower stem lesions were evident after 8 (Trial 1, one isolate) and 16 weeks (Trial 2, four isolates). Virulence varied among isolates (3). C. parasiticum was reisolated on acidified PDA after both trials. In Trial 3, six plant species (three replicate pots, five plants per pot) were challenged with one isolate by drenching a tap water suspension of comminuted microsclerotia and mycelium from 4-week-old PDA cultures into potting medium and transplanting peanut seedlings or planting seeds for other hosts. Root rot severity (0 to 5 index) (3) and reisolation percentages were cv. Tamrun 88 peanut 2.0, 100%; cv. Tamrun 96 peanut 2.0, 92%; cv. Hutcheson soybean (Glycine max (L.) Merr.) 3.3, 64%; cv. Blue Lake 274 green bean (Phaseolus vulgaris L.) 2.7, 40%; cv. California Blackeye 8046 southern pea (Vigna unguiculata (L.) Walp. 2.0, 70%; and cv. Jubilee Hybrid sweet corn (Zea mays L.) 0.0, 100%. Noninoculated peanut controls in all trials had no black decayed root lesions and attempts to isolate the fungus were unsuccessful. Peanut seeds planted in the production field were obtained from the southeastern United States. This field had been scheduled for seed production until C. parasiticum was identified. Temperatures and rainfall amounts during the 2004 growing season were less and greater than long-term averages, respectively. No other infested peanut fields have been confirmed or suspected in the region or state. There is continued risk of contamination from shipments of infected seeds from infested areas (2). This pathogen may pose a serious threat to >100,000 ha of peanut production in western Texas and eastern New Mexico. References: (1) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. The American Phytopathological Society, St. Paul, MN, 2002. (2) B. L. Randall-Schadel et al. Plant Dis. 85:362, 2001. (3) R. C. Rowe and M. K. Beute. Phytopathology 65:422, 1975.

scholarly journals First Report of Neocosmospora striata Causing Peanut Pod Rot in China

Plant Disease ◽  
2012 ◽  
Vol 96 (1) ◽  
pp. 146-146 ◽  
Author(s):  
W. M. Sun ◽  
L. N. Feng ◽  
W. Guo ◽  
D. Q. Liu ◽  
Z. H. Yang ◽  
...  
Keyword(s):  
Yellow River ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Its Region ◽  
Black Rot ◽  
First Report ◽  
Cylindrocladium Parasiticum ◽  
Arachis Hypogaea L ◽  
Rot Disease ◽  
Template Dna

In 2008, an outbreak of pod rot of peanut (Arachis hypogaea L.) occurred on most of the peanut cultivars in the Old Yellow River drainage area, the largest peanut-growing region in China. Disease incidence reached as high as 90% in some fields, causing severe yield losses. The black rot of pods and blackened, nonrotting taproots is similar to symptoms of peanut black rot caused by Cylindrocladium parasiticum, but the reddish orange perithecia of C. parasiticum were not found on the taproots close to the surface of the soil. The foliage of affected plants was generally asymptomatic, but some plants turned greener. This pod rot disease was further investigated in 2008 and 2010. Twenty-three Fusarium-like isolates were obtained from symptomatic, surface-disinfested pods with a frequency of 82%. These isolates were fast growing, with flat, thin, and grayish white colonies when cultured on potato dextrose agar (PDA) at 28°C for 3 to 4 days. The hyaline, elongated to cylindrical conidia, aggregated in slimy heads on conidiogenous cells developed from undifferentiated hyphae when observed with the light microscope. The size of conidia (single celled or one septum) varied from 3 to 9 μm long and 1.5 to 3.5 μm wide on the basis of the measurement of 50 spores. Some conidia appeared slightly curved. Ascomata formed within 10 to 14 days, with a punctate appearance on the colony. The cerebriform ascomata were dark brown, pyriform, ostiolate, glabrous, 120 to 170 × 90 to 130 μm, and with necks 30 to 50 μm long. Asci measured 60 to 90 × 6 to 10 μm, were cylindrical to cylindric-clavate, thin walled, and had an apical ring. Ascospore arrangement was obliquely uniseriate or partially biseriate, very pale yellow to hyaline, ellipsoidal, and measured 8 to 12 × 4.5 to 6 μm. Some spores had a median transverse straight or curved septum and were slightly constricted at the septum, with 6 to 10 thin, transverse, hyaline flanges. Morphological characteristics of the isolates with ascomata dark brown and ascospores with 6 to 10 transverse hyaline flanges matched the description for Neocosmospora striata (1). The internal transcribed spacer (ITS) region of rDNA was amplified from extracted template DNA with primer pairs ITS4/ITS5 and sequenced. A 591-bp amplicon (GenBank Accession No. HM461900) had 99% sequence identity with Fusarium solani (HQ607968 and HQ608009) and N. vasinfecta (GU213063), which indicated that these fungi belong to the genus Neocosmospora or Fusarium, although there is no direct sequence evidence that they are N. striata. N. striata has only been previously reported in Japan (2). This species is unique because of the dark brown ascomata and there is no comparable species (1). Koch's postulates were completed by surface-disinfesting 80 peanut pods of cv. Jihua 9813 and soaking them in conidial suspensions (105 conidia/ml) for 2 min. Another 80 other pods soaked in sterile water served as controls. All peanuts were incubated in moist petri dishes under darkness at 28°C. Symptoms similar to those originally observed in the field formed within 10 days on all inoculated peanut pods and not the controls. N. striata was reisolated from all affected peanut pods. To our knowledge, this is first report of N. striata causing peanut pod rot in China and the first description of the anamorph of the fungus. References: (1) P. F. Cannon et al. Trans. Br. Mycol. Soc. 82:673, 1984. (2) S. Udagawa et al. Trans. Mycol. Soc. Jpn. 16:340, 1975.

scholarly journals First report of root rot on Manglietia decidua caused by Calonectria ilicicola in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Run Hua Yi ◽  
Jun Jie Su ◽  
Huan Jin Li ◽  
Dong Li ◽  
Gui Gen Long
Keyword(s):  
Root Rot ◽  
Disease Incidence ◽  
Aerial Mycelium ◽  
Jiangxi Province ◽  
Diseased Plant ◽  
Species Identity ◽  
High Sequence Identity ◽  
First Report ◽  
Calonectria Ilicicola ◽  
Glucose Agar

Manglietia decidua (Magnoliaceae) was a class I endangered plant in China. During 2018-2020, a severe root rot (about 10% - 90% disease incidence ) was observed on 2-year-old seedlings in the nursery in Yichun, Jiangxi province (N27°52’20”; E114°27’46”). Symptoms started on leaves showing dehydration and chlorosis, the root of diseased plant became black and rotted, and in severe cases, the plants withered and died. The symptomatic root tissues were cut and dipped in a 3% hydrogen peroxide solution for 5 mins, rinsed thrice with sterile water, and then placed on potato glucose agar medium containing ampicillin (50mg/L). The plates were kept in an incubator at 25-28°C for 2-3 days in the dark. The Calonectria-like fungus was consistently isolated from 100% of tissues and the colonies were feathery, moderate white aerial mycelium, surface pale brown, reverse with white outer margin, and brown inner region. The perithecia produced on carnation leaf agar were solitary, subglobose to ovoid, dark red-brown, and measured 273.8 - 427.2 × 362.6 - 628.9 µm (av. 360.9 × 429.9 µm) (n = 31). Clavate asci contained eight spores and tapered into a long thin stalk. Ascospores were hyaline, guttulate, straight to slightly curved with rounded ends, 36.8- 66.1×4.4-7.3 μm (av. 49.9 × 5.9 μm) (n = 52), 1-septate, constricted at the septum and aggregated in the upper third of the ascus. On PDA，conidia formed on penicillate conidiophores within 10 days were hyaline, 1(-3)-septate, cylindrical, rounded at both ends, straight, 36.5-61.7 × 5.0-7.2 μm (av. 50.7 × 6.2 µm) (n=48). Isolate HML 20 and 27 were used to further confirm species identity by five loci analysis：ITS (MZ389092 and MZ389093), ACT (MZ398252 and MZ398253), HIS3 (MZ398254 and MZ398255), TEF1-α (MZ398256 and MZ398257), and TUB2 (MZ398258 and MZ398259). NCBI BLASTN showed the high sequence identity with Calonectria ilicicola ex-type culture CBS 190.50 (CMW 30998) (Liu et al 2020): 100 % for ITS (MT359727), TUB2 (AY725631), and HIS3 (MT335506), 99.22% for ACT (MT335036), 99.80% for TEF1-α (MT412797). Maximum likelihood (ML) analysis and Bayesian inference (BI) based on the combined ITS, tub2, his3 and tef1 sequence using RAxML v.1.0.0 and MrBayes v. 3.2.1 software revealed that isolate HML 20 and 27 clustered together with C. ilicicola strains in C. kyotensis species complex. Thus, the fungus was identified as C. ilicicola (anamorph: Cylindrocladium parasiticum) based on morpho-molecular criteria (Lombard et al. 2010). Pathogenicity was determined under greenhouse conditions (25-30 ℃). The 2-year-old plants grown in 25-cm pots for 20 days were inoculated. Five 6-mm mycelial plugs from 7-day culture on PDA were buried 5 cm under the soil adjacent to the unwounded taproot of each plant and the plants were watered regularly to keep the soil moisture content at about 15%. After ten days, inoculated plants began to show chlorosis symptoms on leaves and collapsed within 15 to 20 days, while no symptoms were observed on control plants. The same colonial fungus was successfully reisolated. Calonectria ilicicola is an economically important plant pathogen worldwide, which causes diseases on Arachis hypogaea, Cinnamomum kanahirai, Glycine max, Medicago sativa, Sassafras randaiense, and Vaccinium spp. etc. in China (Gai et al 2017, Fei et al 2018, Zhang et al 2020 ). As far as we know, it is first report of C. ilicicola causing root rot on M. decidua. At present, this disease is an important threat to the conservation of M. decidua.

scholarly journals First Report of Soybean Stem Blight Caused by Phomopsis longicolla in Guangdong Province, Southern China

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 844-844
Author(s):  
X. Chen ◽  
R. Pan ◽  
D. Xu ◽  
C. Ji ◽  
M. Deng
Keyword(s):  
Southern China ◽  
Disease Incidence ◽  
Guangdong Province ◽  
Fluorescent Light ◽  
Width Ratio ◽  
Fruiting Bodies ◽  
Phomopsis Longicolla ◽  
First Report ◽  
Stem Blight ◽  
Seed Decay

In October 2011, a disease resembling stem blight of soybean was found in Zengcheng City, Guangdong Province, southern China. Symptoms began as a brown fusiform lesions on the stems, usually at the nodes. The lesions then darkened, elongated, and often girdled the stems, causing wilt of the above stems. The whole plant eventually died. There were many small, black, raised fruiting bodies in the lesions. The disease incidence was about 20%. Lesions with typical symptoms were sampled from diseased plants. Microscopic examination revealed that the fruiting bodies were pycnidia in which alpha-conidia were common but beta-conidia were rare. Alpha-conidia were hyaline, ellipsoidal to fusiform, guttulate, and measured 7.0 (4.3 to 10.0) × 3.0 (1.8 to 4.3) μm. The length/width ratio of alpha-conidia was 2.3 (1.4 to 4.5). Beta-conidia were hyaline, filiform, hamate, and measured 28.7 (18.2 to 35.7) × 1.8 (1.2 to 2.8) μm. A fungus was consistently isolated from the lesions on acidified potato dextrose agar (APDA, pH 4.5) at 25°C under intermittent fluorescent light (12 h daily). The colonies were floccose, dense, and white, with occasional green-yellow areas; the reverse was colorless with large, black stromata. To induce the production of fruiting bodies, autoclaved soybean stems were placed on the colonies growing on water agar at 25°C in darkness. Pycnidia with long beaks were observed on the stems 7 days later. The fungus was identified as Phomopsis longicolla (2). The rDNA internal transcribed spacer (ITS) region of the fungus was amplified with universal primers ITS4/ITS5 and sequenced (4). The sequences of two isolates were submitted to GenBank (Accession Nos. JX827608 and JX827609). BLASTn analysis showed that there was 99 to 100% similarity with sequences of P. longicolla deposited in GenBank (EF026104, AY857868, HQ130441, JF309198, JF309199, and AF132796). Pathogenicity tests were conducted on 14-day-old seedlings (cv. Huaxia 3) inoculated by placing mycelial plugs (5 mm in diameter and 4 days old) on slight cuts made on the lower stems (six replicates). The plugs were covered with a piece of wet cotton to maintain moisture. The control seedlings were treated the same but without mycelial plugs. All treated plants were incubated in 25°C in humid champers. Typical brown lesions with black raised pycnidia on the stems were observed 14 days after inoculation and P. longicolla was reisolated from these stem lesions. No disease was observed on control plants. To further verify that the fungus can cause seed decay, seeds were disinfected by 0.02% sodium hypochlorite and inoculated by putting them on the surface of the fungal colonies grown on APDA (pH 4.5) at 25°C. The control seeds were treated the same but without fungal colonies. All of the inoculated seeds decayed within 30 days whereas the control seeds maintained healthy. P. longicolla has been described as a pathogen causing serious stem blight and seed decay on soybean (3). The disease has been previously reported in Heilongjiang Province, northern China, but it was not known elsewhere in China (1). To our knowledge, this is the first report of P. longicolla on soybean in Guangdong Province, southern China. The pathogen may pose a serious threat to the production of soybean in this region of China. References: (1) Y. Cui et al. Plant Pathol. 58:779, 2009. (2) T. W. Hobbs et al. Mycologia 77:535, 1985. (3) S. Li et al. Plant Dis. 94:1035, 2010. (4) A. W. Zhang et al. Plant Dis. 81:1143, 1997.

Comparison of North Carolina, Georgia, and Florida Isolates of Cylindrocladium parasiticum

1999 ◽  
Vol 26 (2) ◽  
pp. 80-84
Author(s):  
J. E. Hollowell ◽  
B. B. Shew ◽  
M. K. Beute
Keyword(s):  
North Carolina ◽  
Root Rot ◽  
Regional Differences ◽  
Black Rot ◽  
Temperature Growth ◽  
Seedling Disease ◽  
Cylindrocladium Parasiticum ◽  
Temperature Controlled ◽  
Gradient Plate ◽  
Temperature Optima

Abstract Thirteen isolates of Cylindrocladium parasiticum Crous, Wingfield & Alfenas from North Carolina and 11 from Georgia were grown on plates of PDA at 20,25, and 30 C on a temperature-gradient plate. Culture diameters were measured daily for 6 d. Significant differences were not observed among isolates grown at 20 C and cultures was smaller as compared with those grown at 25 and 30 C. At 25 and 30 C, isolates varied consistently in growth. On average, Georgia isolates grew slightly less than North Carolina isolates, and all isolates grew better at the warmer temperature. Growth of three North Carolina isolates was compared to four Florida isolates in a second experiment. Florida isolates grew significantly faster than North Carolina isolates at all temperatures. Isolates from the three states were compared for their ability to cause root rotting on peanut at 25 and 30 C. Plants were grown in soil infested at a standardized inoculum density in temperature-controlled water bath tanks for 7 wk at which time roots were rated for Cylindrocladium black rot development. Georgia isolates caused more root rot than either North Carolina or Florida isolates at both temperatures and also caused more seedling disease. State effects were significant; Florida isolates caused less root rot than Georgia isolates. Temperature by state interactions were not significant which means that high temperature-tolerant isolates of C. parasiticum have not evolved from regional differences in soil temperature. Further, North Carolina field isolates do not appear to have changed in temperature optima since the 1970s.

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