scholarly journals First Report of Fusarium falciforme (FSSC 3+4) Causing Rot of Industrial Hemp (Cannabis sativa) in California

Plant Disease ◽  
2021 ◽  
Author(s):  
Kelley Rose Paugh ◽  
Johanna Del Castillo Múnera ◽  
Cassandra L Swett
Keyword(s):  
Root Rot ◽  
Cannabis Sativa ◽  
Negative Control ◽  
Stem Rot ◽  
Tween 20 ◽  
Post Inoculation ◽  
First Report ◽  
Fusarium Falciforme ◽  
Stem Lesions ◽  
Industrial Hemp

Industrial hemp (Cannabis sativa) is a newly legal crop in California that is grown for cannabidiol oil, fiber and seed. In August 2019, whole plant decline and root rot were observed affecting <5% of plants in two industrial fields in Fresno County, CA. Symptoms included chlorotic, collapsed foliage, stem vascular discoloration, and root rot with abundant mycelial growth. Stem and root segments (1-2 cm) from three to five diseased plants were agitated in 0.1% tween-20 and soaked in 70% ethanol for 30 s and 1% NaOCl for 2 min. After incubating for 5 to 7 days on 1:10 potato dextrose agar (PDA) amended with tetracycline, Fusarium selective medium (FSM), and PARP (pimaricin + ampicillin + rifampicin + pentachloronitrobenzene [PCNB] agar) medium, white to pale cream aerial mycelium emerged from tissue of all plants on PDA and FSM but not PARP. Isolates cultured on 0.1% potassium chloride agar formed heads of microconidia on long monophialides consistent with the Fusarium solani species complex (FSSC) (Leslie and Summerell 2008). To obtain pure cultures of two isolates (CS529 and CS530), a single-hyphal tip was excised and grown on PDA. DNA was extracted from actively growing mycelium (PrepMan Ultra kit). The translation elongation factor gene (EF-1α) was amplified via PCR using EF1/EF2 primers (O’Donnell et al. 1998). Sequences of the two isolates were identical and deposited under accession number MW892973 in GenBank. The 599 bp sequence was 99.33% identical to FSSC 3 + 4 (Fusarium falciforme) accessions FD_01443_EF-1a based on FUSARIUM-ID BLAST analysis. To evaluate pathogenicity, stems of hemp plants (cv. ‘Berry Blossom’; n=8 plants per isolate) were wounded by penetrating the epidermis in an area about 0.5-cm square by 1-mm deep and 8-inches above the soil line. A 0.5 cm-diameter plug of 7-day old F. falciforme-colonized PDA was placed against the wound. Inoculation sites were loosely wrapped with parafilm for 2 days. A negative control consisted of a sterile PDA plug (n=3). Treatments were arranged in a completely randomized design in a greenhouse. The experiment was conducted once, due to regulatory restrictions at campus facilities. At 61 days post-inoculation, external stem lesions were significantly larger in diameter (P < 0.05; Tukey’s HSD) in plants inoculated with CS529 (8 ± 1 mm) compared to the control (2 ± 0 mm), and larger but not significant for CS530 (6 ± 1 mm). Internal stem lesions (i.e., rot in stele) were observed in plants inoculated with CS529 (9 ± 3 mm); stem rot was very minor in plants treated with CS530 (1 ± 1 mm) and nonexistent for control plants. No other disease symptoms were observed. F. falciforme was isolated from stems of CS529- and C530-inoculated plants. Sequences of re-isolates matched 100% with accession MW892973. These results suggest that F. falciforme causes rot in hemp in California. These studies specifically confirm stem rot abilities; field observations of root rot indicate root rotting abilities, but further tests are needed for confirmation. This is the first report of F. falciforme causing disease in industrial hemp. FSSC was described as causing foot rot in hemp in Italy (Sorrentino et al. 2019), but these isolates belonged to phylogenetic species 5 (F. solani) not F. falciforme. In addition, F. falciforme was reported as causing root rot in hydroponically grown cannabis (Punja and Rodriguez 2018). These studies provide the foundation for development of management tools for hemp disease.

scholarly journals First report of Pythium aphanidermatum causing crown and root rot on industrial hemp in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Jia Chen ◽  
Zhimin Li ◽  
Cheng Yi ◽  
Chunsheng Gao ◽  
Litao Guo ◽  
...  
Keyword(s):  
Root Rot ◽  
Cannabis Sativa ◽  
Eastern China ◽  
Pythium Aphanidermatum ◽  
Its Sequencing ◽  
Disease Symptoms ◽  
First Report ◽  
Query Coverage ◽  
Crown And Root Rot ◽  
Industrial Hemp

In July 2020, symptoms of crown and root rot were observed on about 10% of 4-month-old plants of industrial hemp Cannabis sativa cultivar Yunma-1 in Weifang City, Shandong Province in eastern China (Fig 1). During this month, the local temperature ranged from 19-32°C, and the total precipitation was 148mm. The disease symptoms included leaf chlorosis, crown and root rot, stunted growth, and wilting (Figs. 1 and 2). The diseased stem and root tissues were collected and cut into fragments of 0.5cm each. The fragments were surface-sterilized by dipping into 1% NaClO for 1 min, rinsed in sterile water and plated on potato dextrose agar (PDA) and on oomycetes-selective medium PARP (Jeffers and Martin 1986). The plates were incubated at 25°C in the dark for 3 days and 18 total single-hyphal purified isolates were obtained for further analyses with 8 from PDA and 10 from PARP. The colonies of all 18 isolates were white, had abundant aerial hyphae, and were cottony in appearance, resembling Pythium spp (Watanabe 2002). The grass-leaf method (Van Der Plaats-Niterink 1981) induced their sexual reproduction. The size and shape of hyphae, oogonia, antheridia, and oospores were all consistent with those of Pythium aphanidermatum (Fig 3). DNA was extracted from three isolates and their internal transcribed spacer (ITS) regions of rDNA were amplified and sequenced using the primers ITS1/ITS4 (White et al. 1990). The ITS sequences of all three isolates were identical to each other (GenBank accession OK091124.1) and showed a 100% query coverage and 99.88% nucleotide sequence identity with that of type strain of P. aphanidermatum (GenBank accession AY598622.2). Pathogenicity tests were performed with three isolates on hemp cultivar B1. Sterile substrates were prepared in 2L-pots containing peat soil and vermiculite in a 2:1 ratio, with test hemp plants grown from rooted stem cuttings. Plants were kept in a greenhouse at 22 to 27°C under 16 h photoperiod, watered every two days (about 200ml each time) and supplied commercial nutrient solution once a week. A month after transplanting to pots, a wound of 1 mm deep and 10 mm long (made by a sterilized needle) on the surface of the root crown area of the main stem was inoculated with an 8-mm-diameter agar disk of mycelia grown on PDA for 4 days. Six plants were tested for each isolate and three plants were inoculated with sterile agar medium without mycelia as negative controls. The experiment was repeated twice. After one month, plants inoculated with P. aphanidermatum isolates showed the same disease symptoms as observed on field plants while all negative control plants remained disease-free. P. aphanidermatum was reisolated from the diseased tissue and confirmed to be identical to those inoculated based on ITS sequencing and colony morphology. To our knowledge, this is the first report of P. aphanidermatum causing crown and root rot on hemp in China. With an estimated 66,700 hectares hemp cultivation in China producing over US$1 billion worth of hemp fiber (McGrath 2020), this pathogen represents a serious threat to the hemp industry. This pathogen has been reported on hemp in the US and Canada (Beckerman et al. 2017; Punja et al. 2018). The origin of P. aphanidermatum on hemp in China and its relationship to those in North America remain to be examined.

scholarly journals First Report of white root rot of hemp (Cannabis sativa L.) caused by Dematophora necatrix in Campania region (Southern Italy)

Plant Disease ◽  
2021 ◽  
Author(s):  
Roberto Sorrentino ◽  
Gian Maria Baldi ◽  
Valerio Battaglia ◽  
Francesco Raimo ◽  
Giulio Piccirillo ◽  
...  
Keyword(s):  
Root Rot ◽  
Cannabis Sativa ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
New Host ◽  
Campania Region ◽  
First Report ◽  
History Of ◽  
Industrial Hemp ◽  
Dematophora Necatrix

Industrial hemp (Cannabis sativa L.) was cultivated in Italy until the end of the Second World War. Since then, it has been abandoned and substituted with other crops mainly due to legal restrictions and public concerns. Public legislation passed in 2016, has allowed for the production of hemp seeds, flowers and fibers (law n. 242/2016). During a 2019 survey on hemp sanitary status in the province of Naples (40°57'6"12 N, 14°22'37"56 E), hemp ‘Kompolty’ with symptoms of root rot were observed at a private farm and collected for further analysis at the phytosanitary laboratory of CREA in Caserta. Death generally occurred within 2-3 weeks after the appearance of the first symptoms, occurring on ca. 10% of plants, consisting of yellowing, canopy wilt and signs of roots covered with white mycelium and fan-like mycelium under the bark. The causal agent, was isolated from small root segments, excised from symptomatic plants, the surface was disinfected with 2% sodium hypochlorite, placed on potato dextrose agar (PDA) amended with streptomycin sulphate (100mg/L) and incubated in the dark at 25°C for 5 days. Small pieces (2-3 mm) at the edge of the resulting colonies were sub-cultured onto PDA and incubated at 25°C in the dark for one week. The mycelia from 15 isolates showed pear-shaped swellings adjacent to the septa. The conidia were aseptate, hyaline, ellipsoid to ovoid, and 3-5 × 2.5-3 µm (n=50). Based on the morphological characteristics, the fungus was identified as Rosellinia necatrix Berl. ex Prill. (Singleton et al., 1992) a fungus taxonomically revised to Dematophora necatrix R. Hartig (Wittstein et al., 2020). To confirm the identification, total DNA was extracted from five isolates using a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and the ITS spacer was PCR-amplified with primers ITS1-ITS4 (White et al., 1990). The size-expected amplicons of 536 bp were purified and sequenced, the resulting sequence was trimmed and deposited in GenBank under the accession number MK937913. BLAST-n analysis revealed 98.83% nucleotide identity with some representative isolates of D. necatrix (MK888684.1; KT343972.1). To fulfill Koch’s postulates, the pathogenicity tests were carried out on fifteen 4-weeks-old potted hemp plants ‘Kompolty’. The inoculation was performed by adding 3 g of millet seeds inoculated with ten mycelial plugs, taken from the margins of a D. necatrix actively growing colony, per liter of sterile peat and perlite substrate in single pots. Moreover, ten hemp plants were inoculated with sterilized millet seed and served as negative controls. All plants were incubated at 25°C. After three weeks, inoculated plants exhibited foliar chlorosis, apical wilting, and death in two weeks, similar to what was observed in the field. Control plants did not show any symptoms. The fungus was isolated from the roots in all fifteen inoculated plants and confirmed to be D. necatrix based on morphological and molecular analysis, carried out with a second primer pair EF1-983F/ EF1-2218R targeting the transcription elongation factor 1- (Rehner and Buckley., 2005) (MW541068) that showed 99.67% nt in BLAST-n analysis. To our knowledge, this is the first report of D. necatrix infecting hemp in Europe. The farm where the problem arose has a history of cultivation for the production of apples for over 30 years. Therefore, an adaptation of D. necatrix to the new host is hypothesized. An in-depth knowledge on the diseases of hemp will be needed to relaunch hemp cultivation in this area.

scholarly journals First Report of Pythium aphanidermatum Crown and Root Rot of Industrial Hemp in the United States

Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 1038 ◽  
Author(s):  
J. Beckerman ◽  
H. Nisonson ◽  
N. Albright ◽  
T. Creswell
Keyword(s):  
United States ◽  
Root Rot ◽  
The United States ◽  
Pythium Aphanidermatum ◽  
First Report ◽  
Crown And Root Rot ◽  
Industrial Hemp

scholarly journals First Report of Root and Stem Rot Disease on Papaya Caused by Fusarium falciforme in India

Plant Disease ◽  
2019 ◽  
Vol 103 (10) ◽  
pp. 2676 ◽  
Author(s):  
A. K. Gupta ◽  
R. Choudhary ◽  
B. M. Bashyal ◽  
K. Rawat ◽  
D. Singh ◽  
...  
Keyword(s):  
Stem Rot ◽  
First Report ◽  
Rot Disease ◽  
Fusarium Falciforme

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

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1187-1187
Author(s):  
J. J. Sadowsky ◽  
T. D. Miles ◽  
A. M. C. Schilder
Keyword(s):  
United States ◽  
North Carolina ◽  
Root Rot ◽  
The United States ◽  
Vaccinium Corymbosum ◽  
Conidial Suspension ◽  
Centraalbureau Voor ◽  
First Report ◽  
Stem Lesions ◽  
Β Tubulin

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

scholarly journals Novel Preparation Technique of Hyperimmune Globulins against Bovine Coronavirus as Surrogate of Beta Coronavirus

2021 ◽  
Vol 10 (4) ◽  
pp. 340-343
Keyword(s):  
Neutralization Test ◽  
Histopathological Examination ◽  
Negative Control Group ◽  
Negative Control ◽  
Tween 20 ◽  
Control Group ◽  
Post Inoculation ◽  
Preparation Technique ◽  
Bovine Coronavirus ◽  
High Level

Consuming time and effort to prepare hyperimmune globulins using Freund’s adjuvant is a sophisticated and harsh technique. In this work, a novel, safe, and rabid method was proposed using monolaurin as an immune-stimulating agent in hyperimmune globulins production against Bovine coronavirus (BCoV). The mentioned virus was used as a surrogate to family Betacoronavirus. Bovine coronavirus (Mabus strain) with titer log10 5.8 tissue culture infective dose infectivity (TCID50)/ml was used in this experiment. The inactivation of the virus was done using 1% ascorbic acid for 24h. Monolaurin emulsion (10% w/v) of was prepared by sonication using tween 20 and water. The inactivated bovine coronavirus was added to the emulsion by 20% of the final volume. The immunoglobulins were prepared by inoculating the inactivated virus with the adjuvant in rabbits and evaluated on the Madin-Darby bovine kidney (MDBK) cell line by virus neutralization test (VNT). The effect of the adjuvant was assessed by histopathological examination of vital organs such as the kidney and liver. The antibody titer against the BCoV was reached its peak, log2 1024 TCID50/ml, at the 3rd-week post-inoculation in the rabbits. The level of the globulin reached a high level and its peak (14.3g/dL) at the end of the experiment. No abnormalities were seen in the livers and kidneys of the negative control group of rabbits. Monolaurin showed a new level of safety and efficacy when used as an adjuvant during the preparation of the immunoglobulins against BCoV.

scholarly journals First Report of Sweet potato leaf curl Georgia virus on Sweet Potato in China

Plant Disease ◽  
2013 ◽  
Vol 97 (10) ◽  
pp. 1388-1388 ◽  
Author(s):  
Y. Qin ◽  
Z. Zhang ◽  
Z. Qiao ◽  
Q. Qiao ◽  
D. Zhang ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Nucleotide Sequence ◽  
Sweet Potato ◽  
Leaf Growth ◽  
Negative Control ◽  
Post Inoculation ◽  
Natural Occurrence ◽  
Potato Leaf ◽  
First Report ◽  
Leaf Curl

Begomoviruses infecting sweet potato (Ipomoea batatas) are phylogenetically distinct from other members of the genus Begomovirus, and have been named “sweepoviruses” (1). Sweepoviruses cause sweet potato yield losses and cultivar decline, and have been found in China (1,3). In 2011, a survey was conducted to determine the incidence, genetic diversity, and distribution of sweepoviruses in China. Thirty sweet potato cuttings showing upward leaf curl, leaf roll, chlorosis, and stunting were collected from fields in Jiangsu, Guangxi, Guizhou, Shanxi, Henan, and Hebei Provinces. Five-leaf growth stage I. setosa plants were inoculated by side-grafting with scions from these samples, and grown in an insect-proof greenhouse in 20-cm-diameter clay pots. Each sample was grafted onto three replicate plants. Healthy, non-grafted I. setosa plants were used as the negative control treatment. Total nucleic acids were extracted from 100 mg fresh leaves harvested 30 days post-inoculation (dpi) from symptomatic and negative control plants using the Universal Genomic DNA Extraction Kit (TaKaRa, Dalian, China). Universal primers for amplification of Geminiviruses (BM-V [5′-KSGGGTCGACGTCATCAATGACGTTRTAC-3′] and BM-C [5′-AARGAATTCATKGGGGCCCARARRGACTGGC-3′]) (2) were used to amplify the begomovirus A component by PCR assay. A DNA fragment of the expected size (2.8 kb) was obtained from grafted leaf samples of the Hebei Province plant, and was cloned into the pMD-19T vector (TaKaRa). The recombinant plasmid was transformed into competent cells of Escherichia coli strain JM109, and the inserted fragment sequenced. The nucleotide sequence obtained (GenBank Accession No. JX448368) was 2,785 nt long, and contained two open reading frames (ORFs) in the virion sense, and four ORFs in the complementary sense, similar to other monopartite begomoviruses (1). The sequence was compared with sequences in GenBank using BLAST. The results revealed the greatest nucleotide sequence identity, 90.8%, with that of the Sweet potato leaf curl Georgia virus (SPLCGV) from Georgia, United States (AF326775). The sequence also shared identities of <89% with other sweepoviruses, and was therefore designated SPLCGV-China: Hebei: 2011. Comparison of the complete genome sequence of SPLCGV-China: Hebei: 2011 with SPLCGV revealed an 18 nucleotide insertion between AV-1 and AC-3. The results confirmed that the sweet potato sample from which SPLCGV-China: Hebei: 2011 was obtained was infected with SPLCGV. To our knowledge, this is the first report of the natural occurrence of SPLCGV in China. This study will assist with understanding the presence of this virus and genetic diversity of sweepoviruses in China. References: (1) H. P. Bi and P. Zhang. Arch. Virol. 157:441, 2012. (2) R. W. Briddon and P. G. Markham. Mol. Biotechnol. 1:202, 1994. (3) Y. S. Luan et al. Virus Genes 35:379, 2007.

scholarly journals First Report of Pythium ultimum Crown and Root Rot of Industrial Hemp in the United States

Plant Disease ◽  
2018 ◽  
Vol 102 (10) ◽  
pp. 2045-2045 ◽  
Author(s):  
J. Beckerman ◽  
J. Stone ◽  
G. Ruhl ◽  
T. Creswell
Keyword(s):  
United States ◽  
Root Rot ◽  
Pythium Ultimum ◽  
The United States ◽  
First Report ◽  
Crown And Root Rot ◽  
Industrial Hemp

scholarly journals First Report of Fusarium asiaticum Causing Stem Rot of Ligusticum chuanxiong in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Tingting Zhu ◽  
Linxuan Li ◽  
Antonios Petridis ◽  
George Xydis ◽  
Maozhi Ren
Keyword(s):  
Disease Incidence ◽  
Elongation Factor ◽  
Stem Rot ◽  
Post Inoculation ◽  
Pathogenicity Test ◽  
First Report ◽  
Ligusticum Chuanxiong ◽  
Fusarium Asiaticum ◽  
Sterile Needle ◽  
Yellow Pigments

Ligusticum chuanxiong (known as Chuanxiong in China) is a traditional edible-medicinal herb, which has been playing important roles in fighting against COVID-19 (Ma et al. 2020). In March 2021, we investigated stem rot of Chuanxiong in six adjacent fields (~100 ha) in Chengdu, Sichuan Province, China. The disease incidence was above 5% in each field. Symptomatic plants showed stem rot, watersoaked lesions, and blackening with white hyphae present on the stems. Twelve symptomatic Chuanxiong plants (2 plants/field) were sampled. Diseased tissues from the margins of necrotic lesions were surface sterilized in 75% ethanol for 45 s, and 2% NaClO for 5 min. Samples were then rinsed three times in sterile distilled water and cultured on potato dextrose agar (PDA) at 25ºC for 72 h. Fourteen fungal cultures were isolated from 18 diseased tissues, of which eight monosporic isolates showed uniform characteristics. The eight fungal isolates showed fluffy white aerial mycelia and produced yellow pigments with age. Mung bean broth was used to induce sporulation. Macroconidia were sickle-shaped, slender, 3- to 5-septate, and averaged 50 to 70 μm in length. Based on morphological features of colonies and conidia, the isolates were tentatively identified as Fusarium spp. (Leslie and Summerell 2006). To identify the species, the partial translation elongation factor 1 alpha (TEF1-α) gene was amplified and sequenced (O’Donnell et al. 1998). TEF1-α sequences of LCSR01, LCSR02 and LCSR05 isolates (GenBank nos. MZ169386, MZ169388 and MZ169387) were 100%, 99.72% and 99.86% identical to that of F. asiaticum strain NRRL 26156, respectively. The phylogenetic tree based on TEF1-α sequences showed these isolates clustered with F. asiaticum using Neighbor-Joining algorithm. Furthermore, these isolates were identified using the specific primer pair Fg16 F/R (Nicholson et al. 1998). The results showed these isolates (GenBank nos. MZ164938, MZ164939 and MZ164940) were 100% identical to F. asiaticum NRRL 26156. Pathogenicity test of the isolate LCSR01 was conducted on Chuanxiong. After wounding Chuanxiong stalks and rhizomes with a sterile needle, the wounds were inoculated with mycelia PDA plugs. A total of 30 Chuanxiong rhizomes and stalks were inoculated with mycelia PDA plugs, and five mock-inoculated Chuanxiong rhizomes and stalks served as controls. After inoculation, the stalks and rhizomes were kept in a moist chamber at 25°C in the dark. At 8 days post inoculation (dpi), all inoculated stalks and rhizomes exhibited water-soaked and blackened lesions. At 10 dpi, the stalks turned soft and decayed, and abundant hyphae grew on the exterior of infected plants, similar to those observed in the field. No disease symptoms were observed on the control plants. The pathogen was re-isolated from the inoculated tissues and the identity was confirmed as described above. Ten fungal cultures were re-isolated from the 10 inoculated tissues, of which nine fungal cultures were F. asiaticum, fulfilling Koch’s postulates. To our knowledge, this is the first report of F. asiaticum causing stem rot of Chuanxiong in China. Chuanxiong has been cultivated in rotation with rice over multiple years. This rotation may have played a role in the increase in inoculum density in soil and stem rot epidemics in Chuanxiong. Diseased Chuanxiong may be contaminated with the mycotoxins produced by F. asciaticum, 3-acetyldeoxynivalenol or nivalenol, which may deleteriously affect human health. Therefore, crop rotations should be considered carefully to reduce disease impacts.

scholarly journals First Report of Stem Rot and Wilt of Sunflower Caused by Sclerotinia minor in Spain

Plant Disease ◽  
2002 ◽  
Vol 86 (6) ◽  
pp. 697-697
Author(s):  
M. L. Molinero-Ruiz ◽  
J. M. Melero-Vara
Keyword(s):  
Helianthus Annuus ◽  
Root Rot ◽  
Mycelial Growth ◽  
Disease Incidence ◽  
Potato Dextrose Agar ◽  
Stem Rot ◽  
Sclerotinia Minor ◽  
Stem Base ◽  
First Report ◽  
White Mycelium

In 2001, sunflower (Helianthus annuus L.) plants with symptoms of stem and root rot and wilt were observed in Soria, Spain. Light brown, water-soaked lesions developed on the collar of infected plants and extended along the stem, affecting the pith and causing early and sudden wilt. White mycelium and sclerotia (0.5 to 2 mm long) formed in the pith of stems. The sclerotia were disinfested in NaClO (10% vol/vol) for 1 min, transferred to potato dextrose agar (PDA), and incubated at 20°C. The fungus consistently obtained was identified as Sclerotinia minor Jagger (1). Pathogenicity was confirmed in a greenhouse experiment (15 to 25°C, 13 h light). Seven-week-old plants of six genotypes of sunflower (‘Peredovik’, HA89, HA821, HA61, RHA274, and HA337) were inoculated by placing one PDA disk with active mycelial growth adjacent to each basal stem just below the soil line and covering it with peat/sand/silt (2:2:1, vol/vol). Six plants of each genotype were inoculated without wounding, and another six were inoculated immediately after stem base wounding with a scalpel; six wounded and uninoculated plants were used as controls. First symptoms (wilting) appeared 4 days after inoculation in all genotypes. Two weeks after inoculation, the percentage of dead plants ranged from 33 to 92% (depending on cultivar), white mycelium was observed at the base of affected plants, and sclerotia were present in the pith of diseased plants. There was no effect of plant wounding on disease incidence or severity, and the fungus was reisolated from inoculated plants. To our knowledge, this is the first report of S. minor in Spain. Reference: (1) L. M. Kohn. Mycotaxon IX 2:365, 1979.

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