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 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 Crown and Root Rot Caused by Pythium myriotylum on Hemp (Cannabis sativa) in Arizona

Plant Disease ◽  
2021 ◽  
Author(s):  
Jiahuai Hu
Keyword(s):  
Root Rot ◽  
Cannabis Sativa ◽  
Morphological Characteristics ◽  
Crown Rot ◽  
Pathogenicity Test ◽  
Light Cycle ◽  
Pythium Myriotylum ◽  
First Report ◽  
Leaf Chlorosis ◽  
Query Coverage

During August and September 2020, symptoms of leaf chlorosis, stunting, and wilting were observed on indoor hemp plants (Cannabis sativa L. cv. ‘Wedding Cake’) in a commercial indoor facility located in Coolidge, Arizona. Plants were grown in soilless coconut coir growing medium (Worm Factory COIR250G10), watered with 1.5 to 2.1 liters every 24 h through drip irrigation, and supplemented with 18 h of lighting. About 35% of plants displayed symptoms as described above and many symptomatic plants collapsed. To identify the causal agent, crown and root tissues from four symptomatic plants were harvested and rinsed with tap water. Tissue fragments (approx. 2 to 4 mm in size) were excised from the margins of the stem and root lesions, surface sterilized in 0.6% sodium hypochlorite for 1 min, rinsed well in sterile distilled water, blotted dry, and plated on potato dextrose agar (PDA) and on oomycete-selective clarified V8 media containing pimaricin, ampicillin, rifampicin, and pentachloronitrobenzene (PARP). Plates were incubated at room temperature (21-24 oC). Five isolates resembling Pythium were transferred after 3 days and maintained on clarified V8 media. Morphological characteristics were observed on grass blade cultures (Waterhouse 1967). Grass blades were placed on CV8 inoculated with the isolate. After a 1-day incubation at 25°C, the colonized blades were transferred to 8 ml of soil water extract in a Petri dish. Ten sporangia and oogonia were selected randomly and their diameters were measured under the microscope. Sporangia were mostly filamentous, undifferentiated or inflated lobulate, ranging from 7 to 17 µm in diameter. Knob-like appressoria were observed on branching clusters. Bulbous-like antheridia were formed on branched stalk with 1-8 antheridia per oogonium. Globose oogonia were terminal or intercalary and ranged from 21 to 33 µm in diameter. Globose oospores were mostly aplerotic and ranged from 15 to 21 μm in diameter. Based on these morphological characteristics, isolates were tentatively identified as Pythium myriotylum (Watanabe, 2002). Genomic DNA was extracted from mycelial mats of two isolates using DNeasy Plant Pro Kit (Qiagen Inc., Valencia, CA) according to the manufacturer’s instructions. The internal transcribed spacer (ITS) region of rDNA was amplified with primers ITS1/ITS4 and two identical nucleotide sequences were obtained and deposited under accession number MW380925. A BLASTn search revealed ≥ 98% query coverage and 100% match with sequences HQ237488.1, KY019264.1, and KM434129, which were isolates of P. myriotylum from palm, tobacco, and ginger, respectively. To fulfill Koch’s postulates, pathogenicity tests were conducted with 2 isolates using plants of ‘Wedding Cake’ grown in 12 1.9-liter pots filled with a steam-disinfested potting mix (Sungro Professional Growing Mix). Pots were placed in a plastic container and watered to flooding three times a week. Plants were maintained in a greenhouse with 18 h/10 h day/night supplemental light cycle (15-28 oC). Plants were fertilized weekly with Peters Professional fertilizer at 1mg/ml. Four plants were inoculated with each isolate at three weeks after seed sowing by placing two 5-mm mycelial plugs from active growing 4 days-old cultures on PDA media adjacent to the main root mass at an approximately 3 cm depth. Four plants were inoculated with blank PDA plugs as controls. Symptoms of leaf chlorosis, crown rot and wilting were observed after four weeks while control plants remained symptomless. P. myriotylum was re-isolated from necrotic roots of inoculated plants after surface-sterilization, but not from control plants. The pathogenicity test was repeated once. While P. myriotylum often occurs in warmer regions and has a wide host range of >100 host plant species including numerous economically important crops (Wang et al., 2003), there are only two reports of this pathogen on indoor hemp plants in a greenhouse in Connecticut (McGehee et al., 2019) and in Canada (Punja et al., 2019). This is the first report of P. myriotylum causing root and crown rot of indoor hemp in Arizona. A more careful water management in soilless growth medium to reduce periods of saturation would minimize the risk of Pythium root rot in indoor hemp production.

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.

scholarly journals First report of Fusarium falciforme (FSSC 3+4) causing root rot on chickpea in Mexico

Plant Disease ◽  
2021 ◽  
Author(s):  
Sixto Velarde Felix ◽  
Victor Valenzuela ◽  
Pedro Ortega ◽  
Gustavo Fierros ◽  
Pedro Rojas ◽  
...  
Keyword(s):  
Fusarium Solani ◽  
Root Rot ◽  
Species Complex ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Aerial Mycelium ◽  
Pathogenicity Test ◽  
Conidial Suspension ◽  
Single Spore ◽  
First Report

Chickpea (Cicer aretinium L.) is a legume crop of great importance worldwide. In January 2019, wilting symptoms on chickpea (stunted grow, withered leaves, root rot and wilted plants) were observed in three fields of Culiacan Sinaloa Mexico, with an incidence of 3 to 5%. To identify the cause, eighty symptomatic chickpea plants were sampled. Tissue from roots was plated on potato dextrose agar (PDA) medium. Typical Fusarium spp. colonies were obtained from all root samples. Ten pure cultures were obtained by single-spore culturing (Ff01 to Ff10). On PDA the colonies were abundant with white aerial mycelium, hyphae were branched and septae and light purple pigmentation was observed in the center of old cultures (Leslie and Summerell 2006). From 10-day-old cultures grown on carnation leaf agar medium, macroconidias were falciform, hyaline, with slightly curved apexes, three to five septate, with well-developed foot cells and blunt apical cells, and measured 26.6 to 45.8 × 2.2 to 7.0 μm (n = 40). The microconidia (n = 40) were hyaline, one to two celled, produced in false heads that measured 7.4 to 20.1 (average 13.7) μm × 2.4 to 8.9 (average 5.3) μm (n = 40) at the tips of long monophialides, and were oval or reniform, with apexes rounded, 8.3 to 12.1 × 1.6 to 4.7 μm; chlamydospores were not evident. These characteristics fit those of the Fusarium solani (Mart.) Sacc. species complex, FSSC (Summerell et al. 2003). The internal transcribed spacer and the translation elongation factor 1 alpha (EF1-α) genes (O’Donnell et al. 1998) were amplified by polymerase chain reaction and sequenced from the isolate Ff02 and Ff08 (GenBank accession nos. KJ501093 and MN082369). Maximum likelihood analysis was carried out using the EF1-α sequences (KJ501093 and MN082369) from the Ff02 and Ff08 isolates and other species from the Fusarium solani species complex (FSSC). Phylogenetic analysis revealed the isolate most closely related with F. falciforme (100% bootstrap). For pathogenicity testing, a conidial suspension (1x106 conidia/ml) was prepared by harvesting spores from 10-days-old cultures on PDA. Twenty 2-week-old chickpea seedlings from two cultivars (P-2245 and WR-315) were inoculated by dipping roots into the conidial suspension for 20 min. The inoculated plants were transplanted into a 50-hole plastic tray containing sterilized soil and maintained in a growth chamber at 25°C, with a relative humidity of >80% and a 12-h/12-h light/dark cycle. After 8 days, the first root rot symptoms were observed on inoculating seedlings and the infected plants eventually died within 3 to 4 weeks after inoculation. No symptoms were observed plants inoculated with sterilized distilled water. The fungus was reisolated from symptomatic tissues of inoculated plants and was identified by sequencing the partial EF1-α gene again and was identified as F. falciforme (FSSC 3 + 4) (O’Donnell et al. 2008) based on its morphological characteristics, genetic analysis, and pathogenicity test, fulfilling Koch’s postulates. The molecular identification was confirmed via BLAST on the FusariumID and Fusarium MLST databases. Although FSSC has been previously reported causing root rot in chickpea in USA, Chile, Spain, Cuba, Iran, Poland, Israel, Pakistan and Brazil, to our knowledge this is the first report of root rot in chickpea caused by F. falciforme in Mexico. This is important for chickpea producers and chickpea breeding programs.

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 Fusarium redolens Causing Root Rot of Soybean in Minnesota

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1069-1069 ◽  
Author(s):  
J. C. Bienapfl ◽  
D. K. Malvick ◽  
J. A. Percich
Keyword(s):  
Root Rot ◽  
Fusarium Species ◽  
Apical Cell ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Aerial Mycelium ◽  
Pathogenic Fungi ◽  
The United States ◽  
First Report ◽  
Root Necrosis

Multiple Fusarium species have been found in association with soybean (Glycine max) plants exhibiting root rot in the United States (3). Soybean plants that lacked apparent foliar symptoms, but exhibited 2- to 5-mm brown, necrotic taproot lesions and lateral root necrosis were observed in Minnesota in one field each in Marshall and Otter Tail counties in July of 2007, as well as in one field in Marshall County in July of 2008. Sampling was conducted as part of a study investigating root rot in major soybean-production areas of Minnesota. Plants were arbitrarily dug up at the R3 growth stage. Root systems were washed, surface disinfested in 0.5% NaOCl for 3 min, rinsed in deionized water, and dried. Fusarium isolates were recovered from root sections with necrotic lesions embedded in modified Nash-Snyder medium (1). One resulting Fusarium colony from one plant per county was transferred to half-strength acidified potato dextrose agar (PDA) and carnation leaf agar (CLA) to examine morphological characteristics (4). Culture morphology on PDA consisted of flat mycelium with sparse white aerial mycelium. On CLA, thick-walled macroconidia with a hooked apical cell and a foot-shaped basal cell were produced in cream-colored sporodochia. Macroconidia ranged from 32.5 to 45.0 μm long. Microconidia were oval to cylindrical with 0 to 1 septa, ranged from 7.5 to 11.25 μm long, and were produced on monophialides. Chlamydospores were produced abundantly in chains that were terminal and intercalary in the hyphae of 4-week-old cultures. Morphological characteristics of the three isolates were consistent with descriptions of F. redolens (2,4). The identity of each isolate was confirmed by sequencing the translation elongation factor 1-α (TEF) locus (4). BLAST analysis of the TEF sequences from each isolate against the FUSARIUM-ID database resulted in a 100% match for 17 accessions of F. redolens (e.g., FD 01103, FD 01369). Each F. redolens isolate was tested for pathogenicity on soybean. Sterile sorghum grain was infested with each isolate and incubated for 2 weeks. Sterile sorghum was used for control plants. Soybean seeds of cv. AG2107 were planted in 11.4-cm pots ~1 cm above a 25-cm3 layer of infested sorghum or sterile sorghum. Two replicate pots containing four plants each were used per treatment and the experiment was repeated once. Root rot was assessed 28 days after planting. Each F. redolens isolate consistently caused taproot necrosis on inoculated plants, whereas control plants did not exhibit root necrosis. Isolations were made from roots of inoculated and control plants and the isolates recovered from inoculated plants were identified as F. redolens based on morphological characteristics and TEF sequences. Fusarium species were not isolated from control plants. To our knowledge, this is the first report of F. redolens causing root rot of soybean; however, it is possible F. redolens has been found previously and misidentified as F. oxysporum (2,4). Results from inoculations suggest that F. redolens may be an important root rot pathogen in Minnesota soybean fields. References: (1) J. C. Bienapfl et al. Acta Hortic. 668:123, 2004. (2) C. Booth and J. M. Waterston. No. 27 in: CMI Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, England, 1964. (3) G. L. Hartman et al. Compendium of Soybean Diseases. 4th ed. The American Phytopathological Society, St. Paul, MN, 1999. (4) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006.

First report of white root rot caused by Dematophora necatrix on Panax pseudoginseng in China

2021 ◽  
Author(s):  
Zunwei Ke ◽  
Gaolei Cai ◽  
Fan Zhang ◽  
Jianhua Gong ◽  
Yang Zhou ◽  
...  
Keyword(s):  
Root Rot ◽  
White Root Rot ◽  
First Report ◽  
Dematophora Necatrix

scholarly journals First Report of Fusarium stem and root rot of Gerbera jamesonii caused by Fusarium incarnatum in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Shuning Chen ◽  
Wei Sun ◽  
Huizhu Yuan ◽  
Xiaojing Yan
Keyword(s):  
Root Rot ◽  
Vascular System ◽  
Elongation Factor ◽  
Morphological Observation ◽  
Conidial Suspension ◽  
Gerbera Jamesonii ◽  
Gene Sequences ◽  
Plastic Container ◽  
First Report ◽  
Brown Discoloration

Gerbera (Gerbera jamesonii Bolus) is an important cut flower grown globally. In 2020, gerbera plants (Redaicaoyuan, Baimawangzi, and Hongditan cultivars) with roots, crowns, and stems rot were found in a greenhouse in Nanping, Fujian, China. Approximately 30% of the 60,000 plants showed symptoms. Diseased plants were stunted with chlorotic leaves. The leaves and flower heads were wilted and withered. Brown discoloration with red to black streaks occurred in the vascular system of the crown and stem. The stem pieces (3×3 mm) showing the symptom were surface-disinfected with 1% NaClO for 1 min and washed three times with sterilized water. The stem pieces were then dried and placed on potato dextrose agar (PDA) at 25℃ inside a dark chamber. Ten single-spored isolates were identified as Fusarium incarnatum based on morphological features. White to light brown mycelia were observed among the isolates on PDA medium. Falculate, multicelluar, straight to slightly curved macroconidia produced in monophialide sporodochia without distinctive foot shaped basal cell; and chlamydospores produced in some isolates (Leslie and Summerell). The size of macroconidia was 36.4 ± 5.20 × 4.6 ± 1.3 μm (n = 100) with 3 to 5 septates. Microconidia were mostly 0 to 1 septate measured 14.6 ± 1.9 × 2.6 ± 0.5 μm (n=100). Based on the morphological observation, isolates were further identified by molecular method. The ITS1/4 region combined with partial gene fragments of translation elongation factor (EF-1α, primer EF1/EF2, Geiser et al.) and calmodulin (CAM, primer CL1/CL2A, O’Donnell.) from the isolates were amplified and sequenced. All of the three tested isolates showed identical gene sequences. Sequences amplified from one represented isolate FIN-1 were submitted to Genbank. BLAST searches revealed that ITS1/4 (MW527088), EF-1α (MW556488), and CAM (MW556487) had 99.22%, 99.53%, 99.42% identity compared to F. incarnatum (MN480497, MN233577, and LN901596, respectively) in GenBank. FUSARIUM-ID (Geiser et al. 2004) analysis also showed 99 to 100% similarity with sequences of the F. incarnatum-equiseti species complex (FIESC) (FD_01636 for CAM, FD_01643 for EF-1α). The phylogenetic analysis was conducted using neighbor-joining algorithm based on the ITS, EF-1α, and CAM gene sequences. The isolate was clustered with F. incarnatum clade. Then, the pathogenicity of the fungus was confirmed by performing Koch’s postulates. Pure single-spored cultures were grown on carboxymethyl-cellulose (CMC) medium for sporulation. G. jamesonii plants used for pathogenicity tests were grown on sterilized potting soil in a plastic container to the ten-leaf stage prior to inoculation. Spores harvested from the CMC medium were adjusted to a concentration of 1×105 conidial/ml. Twelve healthy rooted gerbera seedlings were inoculated by drenching 10 ml of the conidial suspension onto roots. Twelve gerbera seedlings treated with 10 ml sterile water served as control treatments. Plants were grown in the glasshouse at temperatures of 23°C, relative humidity >70%, and 16 h light per day. After 10 days, blackening stems and withered leaf edges began to appear on inoculated seedlings, whereas control seedlings remained healthy. F. incarnatum was consistently re-isolated from the symptomatic stems, whereas no isolates were obtained from the control seedlings. The assay was conducted twice. To the best of our knowledge, this is the first report of F. incarnatum causing stem and root rot on G. jamesonii.

scholarly journals First Report of Fusarium proliferatum Causing Root Rot on Soybean (Glycine max) in the United States

Plant Disease ◽  
2011 ◽  
Vol 95 (10) ◽  
pp. 1316-1316 ◽  
Author(s):  
M. M. Díaz Arias ◽  
G. P. Munkvold ◽  
L. F. Leandro
Keyword(s):  
United States ◽  
Root Rot ◽  
Morphological Characteristics ◽  
Dry Weight ◽  
The United States ◽  
Growth Stages ◽  
Species Identity ◽  
First Report ◽  
Soybean Roots ◽  
Soybean Diseases

Fusarium spp. are widespread soilborne pathogens that cause important soybean diseases such as damping-off, root rot, Fusarium wilt, and sudden death syndrome. At least 12 species of Fusarium, including F. proliferatum, have been associated with soybean roots, but their relative aggressiveness as root rot pathogens is not known and pathogenicity has not been established for all reported species (2). In collaboration with 12 Iowa State University extension specialists, soybean roots were arbitrarily sampled from three fields in each of 98 Iowa counties from 2007 to 2009. Ten plants were collected from each field at V2-V3 and R3-R4 growth stages (2). Typical symptoms of Fusarium root rot (2) were observed. Symptomatic and asymptomatic root pieces were superficially sterilized in 0.5% NaOCl for 2 min, rinsed three times in sterile distilled water, and placed onto a Fusarium selective medium. Fusarium colonies were transferred to carnation leaf agar (CLA) and potato dextrose agar and later identified to species based on cultural and morphological characteristics. Of 1,230 Fusarium isolates identified, 50 were recognized as F. proliferatum based on morphological characteristics (3). F. proliferatum isolates produced abundant, aerial, white mycelium and a violet-to-dark purple pigmentation characteristic of Fusarium section Liseola. On CLA, microconidia were abundant, single celled, oval, and in chains on monophialides and polyphialides (3). Species identity was confirmed for two isolates by sequencing of the elongation factor (EF1-α) gene using the ef1 and ef2 primers (1). Identities of the resulting sequences (~680 bp) were confirmed by BLAST analysis and the FUSARIUM-ID database. Analysis resulted in a 99% match for five accessions of F. proliferatum (e.g., FD01389 and FD01858). To complete Koch's postulates, four F. proliferatum isolates were tested for pathogenicity on soybean in a greenhouse. Soybean seeds of cv. AG2306 were planted in cones (150 ml) in autoclaved soil infested with each isolate; Fusarium inoculum was applied by mixing an infested cornmeal/sand mix with soil prior to planting (4). Noninoculated control plants were grown in autoclaved soil amended with a sterile cornmeal/sand mix. Soil temperature was maintained at 18 ± 1°C by placing cones in water baths. The experiment was a completely randomized design with five replicates (single plant in a cone) per isolate and was repeated three times. Root rot severity (visually scored on a percentage scale), shoot dry weight, and root dry weight were assessed at the V3 soybean growth stage. All F. proliferatum isolates tested were pathogenic. Plants inoculated with these isolates were significantly different from the control plants in root rot severity (P = 0.001) and shoot (P = 0.023) and root (P = 0.013) dry weight. Infected plants showed dark brown lesions in the root system as well as decay of the entire taproot. F. proliferatum was reisolated from symptomatic root tissue of infected plants but not from similar tissues of control plants. To our knowledge, this is the first report of F. proliferatum causing root rot on soybean in the United States. References: (1) D. M. Geiser et al. Eur. J. Plant Pathol. 110:473, 2004. (2) G. L. Hartman et al. Compendium of Soybean Diseases. 4th ed. The American Phytopathologic Society, St. Paul, MN, 1999. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Oxford, UK, 2006. (4) G. P. Munkvold and J. K. O'Mara. Plant Dis. 86:143, 2002.

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