First Report of Root Rot on Pulsatilla koreana Caused by Fusarium oxysporum in China

Windflowers (Pulsatilla spp.) are perennial medicinal plants in the family Ranunculaceae with high economic as well as medicinal value in China. It is commonly used as traditional Chinese medicine (1). In May 2012, a root rot disease was observed on windflower (Pulsatilla koreana Nakai) at flowering stages in fields of Liaoning Province, China. The diseased area was estimated to be over 500 ha in the province and the yield was reduced by 30% on average with up to 45% yield losses in some fields. As the disease progressed, brown lesion production extended onto lateral and main roots, and aboveground tissues shriveled and decayed; in severe cases, white mycelium was clearly visible on diseased root tissue. Isolations from symptomatic roots were made on potato dextrose agar (PDA) and single-spore cultures were obtained. Colonies were initially white, but became pale violet with age, and purple pigments were produced in the agar. Microconidia were abundant, unicellular, oval to reniform, and ranged from 5.6 to 13.1 (9.3) × 2.8 to 4.2 (3.2) μm. Macroconidia were sparse, three-septate, slightly curved, and ranged from 21.9 to 39.4 (31.2) × 3.4 to 4.5 (3.9) μm. The isolated fungus was morphologically similar to Fusarium oxysporum (2). Two isolates were selected for molecular identification, and the internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 (3) and sequenced. The obtained sequences (GenBank Accession Nos. JX669525 and JX669526) showed 99% homology with the sequences of F. oxysporum in GenBank (GQ121303). For pathogenicity tests, the isolate was cultured on PDA for 10 days at 25°C. Inoculations were performed on 10 healthy P. koreana plants by spraying a conidial suspension (2.0 × 105 microconidia ml–1) on roots previously wounded with a metal needle. Ten non-treated plants used as controls were sprayed with distilled water. The inoculated plants were incubated at 25°C under conditions of 12/12 h (light and dark). After 2 weeks, root rot symptoms were similar to the original symptoms observed under field conditions. No disease was observed on water-inoculated control plants. The same fungus was reisolated from the roots of infected plants, satisfying Koch's postulates. To our knowledge, this is the first report of F. oxysporum on P. koreana in China. The disease was hitherto scarcely reported in any other countries, and may deserve more attention in the future. References: (1) S. C. Bang et al. J. Nat. Prod. 68:268, 2005. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Professional, Ames, IA, 2006. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

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First Report of Anthracnose on Hymenocallis littoralis Caused by Colletotrichum siamense in China

Plant Disease ◽

10.1094/pdis-02-21-0405-pdn ◽

2021 ◽

Author(s):

Yong Huang ◽

Yue Qin zhang ◽

Han Hu ◽

Nai Feng

Keyword(s):

Its Region ◽

Leaf Spot Disease ◽

Data Sets ◽

Conidial Suspension ◽

Single Spore ◽

Koch’S Postulates ◽

First Report ◽

Medicinal Value ◽

Sterile Needle ◽

Koch's Postulates

Spider lily (Hymenocallis littoralis (Jacq.) Salisb.) is a widely cultivated horticultural plant worldwide and has ornamental and medicinal value. Spider lily plants were seriously affected by a leaf spot disease in the campus of Guangdong Ocean University and gardens in Zhanjiang city in February 2018 with an incidence of 30 to 100%. Affected leaves usually developed small circular purple spots, which enlarged to oval spots and large irregular spots. The spots were brown at the center, deep purple at the border and surrounded by a yellow halo. Diseased cultivars were collected in Zhanjiang city, Gangzhou city in Guangdong province and and Zhangping city in Fujian province. Symptomatic leaf samples were disinfested with 1% NaOCl, and cultured on sucrose agar (PSA) at 28 °C for one week. Ten single-spore isolates were recovered from PSA medium. Colonies developing on PSA were grayish white with a regular border. Conidia were straight, hyaline with rounded ends, 4.3 to 6.1×12.8 to 32.1μm (n = 50 conidia of each isolate). Fungal mycelia were hyaline, septate, and branched. Conidia were born on a long conidiogenous cell, appressoria were oval, 6.7 to 10.7 × 5.2 to 6.2 μm (n=50). The isolates were morphologically identified as Colletotrichum sp. (Weir et al. 2012). Tests of pathogenicity were performed according to Koch's postulates using three isolates. Fresh wounds were made with a sterile needle on the healthy surface of leaves of H. littoralis at the 4- to 6-leaf stage and each leaf was covered with a piece of cotton drenched with 200 μL of conidial suspension (106 conidia/ml) from each isolate. Control seedlings were inoculated identically except sterile water was used to drench the cotton. Inoculated plants were placed in a moisturizing light incubator at 25℃ and 80% humidity under a 12-h light/dark cycle for 20 days and examined daily to monitor disease symptom development. Small round brown spots were observed at the inoculation sites 3 days after the inoculation. The brown spots developed into large brown lesions 5 days after inoculation. There were no symptoms observed in the water-inoculated plants. A Colletotrichum spp. strain based on morphology was consistently reisolated from leaves lesions fulfilling Koch’s postulates. For molecular identification, the internal transcribed spacer (ITS) region of ribosomal DNA, calmodulin (CAL), Tublin (Tub) and Apmat loci of three isolates were amplified using primer pairs of ITS4/ITS5, CL1C/CL2C, T1/T2 and AM-F/AM-R (Sharma et al. 2015). A phylogenetic tree derived from a neighbor-joining analysis of a concatenated alignment of ITS, CAL, Tub and ApMAT sequences was created. The accession numbers of three isolates GZHLCG, ZJHLCG and FJHLCG used in this study were MW553083, MN540457, MN540458 for ITS, MW553087- MW553089 for CL, MW553090-MW553092 for Tub and MW553084-MW553086 for ApMAT. The sequences of the three isolates were aligned with related species of Colletotrichum (Sharma et al. 2015). Analyses based on concatenated data sets of four genes showed that the sequences had high levels of identity to those of the C. siamense strains. According to both morphological and sequence analyses, the H. littoralis pathogen was identified as C. siamense. There is a report of foliar diseases on H. littoralis caused by Colletotrichum sp. (Tan et al., 2009). To our knowledge, this is the first report of anthracnose on H. littoralis caused by C. siamense in China. Identification of the pathogen provide valuable information for diagnosis and controlling this disease in H. littoralis.

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First Report of Zucchini Collapse by Fusarium solani f. sp. cucurbitae Race 1 and Plectosporium tabacinum in Italy

Plant Disease ◽

10.1094/pdis-91-3-0325a ◽

2007 ◽

Vol 91 (3) ◽

pp. 325-325 ◽

Cited By ~ 7

Author(s):

S. Vitale ◽

M. Maccaroni ◽

A. Belisario

Keyword(s):

Fusarium Solani ◽

Fusarium Species ◽

Morphological Characteristics ◽

Its Region ◽

Conidial Suspension ◽

Single Spore ◽

Running Water ◽

First Report ◽

Race 1 ◽

Rot Disease

Zucchini plant collapse has been often associated with Fusarium solani f. sp. cucurbitae race 1, which is the causal agent of Fusarium crown and foot rot disease of cucurbits. In Italy, F. solani f. sp. cucurbitae race 1 has been reported on zucchini (Cucurbita pepo) in a greenhouse in the Tuscany Region (4). In spring 2005, a severe outbreak was observed on zucchini in a vast area of cultivation in the province of Venice. Isolations from necrotic vessels gave more than 20 single-spore cultures. On the basis of morphological characteristics, they were identified as F. solani (2) and Plectosporium tabacinum (3). The internal transcribed spacer (ITS) region of rDNA was amplified and sequenced. A fragment of 454 and 531 bp was 99% homologous with sequence PSU66732 and AF150472 of F. solani f. sp. cucurbitae race 1 and P. tabacinum, respectively, in the NCBI database. The nucleotide sequences have been assigned Accession No. AM408782 for F. solani f. sp. cucurbitae race 1 and AM408781 for P. tabacinum. Pathogenicity tests were conducted with four isolates of each species on 15-day-old zucchini plants and on fruit. Plants were inoculated by dipping the roots in a conidial suspension of 106 spores ml-1 for 10 min. Control plants were dipped in sterile water. Five replicates for the inoculated and control plants were used. All plants were maintained in a greenhouse at approximately 24°C. After 14 days, inoculations with F. solani f. sp. cucurbitae race 1 gave symptoms of a cortical rot at the base of the stem with a progressive yellows and wilting of leaves, while plants inoculated with P. tabacinum displayed a moderate wilting. Fruit were washed under running water, disinfected with a solution of 3% sodium hypochlorite and 5% ethanol for 1 min, and inoculated with 6-mm-diameter mycelial plugs cut from the margin of 10-day-old cultures grown on PDA. Plugs were inserted into holes (approximately 2 mm deep) made with a sterile 7-mm-diameter cork borer. Five replicates per isolate were used. Fruit were kept at room temperature (22 to 24°C) in a moist chamber. All isolates induced symptoms of fruit rotting 10 days after inoculation. All controls remained healthy. The colonies reisolated from the inoculated plants and fruit were morphologically identical to the original isolates. The results obtained proved that F. solani f. sp. cucurbitae race 1 can be considered the major pathogen in zucchini collapse, at the same time P. tabacinum may play a role in this syndrome as reported for other cucurbits (1). To our knowledge, this is the first report of zucchini plant collapse caused by F. solani f. sp. cucurbitae race 1 and P. tabacinum, and the first report of P. tabacinum on zucchini in Italy. References: (1) V. J. Garcia-Jimenez et al. EPPO Bull. 30:169, 2000. (2) P. E. Nelson et al. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University, University Park, 1983. (3) M. E. Palm et al. Mycologia 87:397, 1995. (4) G. Vannacci and P. Gambogi. Phytopathol. Mediterr. 19:103, 1980.

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First report of root rot of Polygonatum odoratum caused by Fusarium acuminatum in China

Plant Disease ◽

10.1094/pdis-03-21-0501-pdn ◽

2021 ◽

Author(s):

Li Xiao Li ◽

Song Wen Sun ◽

Yu Bao Shen ◽

Kun Liu ◽

Jing Tian Zhang

Keyword(s):

Root Rot ◽

Apical Cell ◽

Its Region ◽

Liaoning Province ◽

Conidial Suspension ◽

Field Soil ◽

Species Identity ◽

Potato Dextrose Broth ◽

First Report ◽

Fusarium Acuminatum

Polygonatum odoratum (Mill.) Druce is used in traditional Chinese medicine and also consumed as a vegetable. In July of 2020, a root rot was observed on P. odoratum in a commercial field located in Benxi city (41º23’32” N, 124º04’27” E), Liaoning province of China. About 35% diseased plants in the field exhibited poor vigor, were stunted, and had yellow or brown leaves. Affected plants wilted and died. Roots of the plants were poorly developed, had brown lesions, and later rotted. To determine the causal agent, symptomatic roots with typical lesions were cut into small pieces, surface sterilized in 2% sodium hypochlorite (NaOCl) for 3 min, rinsed three times in sterile water, and plated onto PDA medium. After 5 days of incubation at 26°C, whitish-pink to red colonies growing from the root samples were observed and transferred to carnation leaf agar (CLA). Ten single conidia isolates obtained from the colonies on CLA were incubated at 26°C for 10 days. Abundant macroconidia were formed in sporodochia on CLA. Macroconidia were falcate, slender, distinctively curved in the bottom half of the apical cell, had 3 to 5 septa, and 33.1 - 46.3 × 5.0 - 7.2 μm (n=50). Chlamydospores formed in chains or single, measuring 13.8 to 14.5 μm in diameter. Microconidia were not observed on CLA. Morphologically, the isolates were identified as Fusarium acuminatum (Leslie and Summerell, 2006). To confirm the species identity, the partial translation elongation factor 1 alpha (TEF1-α) gene and rDNA internal transcribed spacer (ITS) region of isolate YZ5-2 were amplified and sequenced (O’Donnell et al. 2015; White et al.1990). BLASTn analysis of both TEF sequence (MW423623) and ITS sequence (MW423626), revealed 100% (696/692 bp) and 99.64% (563/602 bp) sequence identity with F. acuminatum LC546967 and MF509746, respectively. Pathogenicity tests were carried out in the greenhouse. A conidial suspension (2 × 106 conidia per ml) of the isolate YZ5-2 was prepared from 7-day-old cultures grown in potato dextrose broth (PDB) o n a shaker (140 rpm) at 26±1°C. Five 12-liter pots were filled with sterilized field soil and each pot was drenched with 300ml of conidial suspension. Five control pots with sterilized field soil and 300 ml PDB were also included. Roots of 20 healthy P. odoratum plants were surface disinfected in 2% NaOCl for 3 min, and rinsed with sterilized water. Prior to planting, 2-3 pinholes (1.5× 1.0 mm) were made using a toothpick on the root surface of each plant, and they were then planted in each pot (2 plants per pot). All ten pots were maintained in a greenhouse at 22-26°C for 40 days. Plants grown in the pots inoculated with the conidial suspension were stunted, had yellowed leaves and were wilted. The roots of the affected plants were rotted. Disease symptoms were similar to those observed in field. Non-inoculated control plants had no symptoms. F. acuminatum was reisolated from inoculated plants and was identical to the original isolate. The experiment was repeated twice with similar results. To our knowledge, this is the first report of root rot of P. odoratum caused by F. acuminatum in China. The disease has since been observed on P. odoratum in fields in Liaoyang and Qingyuan city in Liaoning Province of China, and it has become an important threat to P. odoratum production in China.

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First Report of Fusarium oxysporum f. sp. lycopersici Race 3 and F. oxysporum f. sp. radicis-lycopersici in Tomatoes in the Azapa Valley of Chile

Plant Disease ◽

10.1094/pdis-03-14-0303-pdn ◽

2014 ◽

Vol 98 (10) ◽

pp. 1432-1432 ◽

Cited By ~ 4

Author(s):

G. Sepúlveda-Chavera ◽

W. Huanca ◽

R. Salvatierra-Martínez ◽

B. A. Latorre

Keyword(s):

Fusarium Oxysporum ◽

Tap Water ◽

Universal Primers ◽

Conidial Suspension ◽

Laboratory Manual ◽

First Report ◽

Solanum Lycopersicum L ◽

Vascular Discoloration ◽

Seedling Roots ◽

Pcr Assays

Tomato (Solanum lycopersicum L.) is an important crop in the Azapa Valley (18°35′ S, 69°30′ W) in northern Chile, with approximately 600 ha of fresh tomatoes under greenhouses. Cultivars resistant to Fusarium oxysporum f. sp. lycopersici (FOL) races 1 and 2 are mainly used. However, in 2012 and 2013, Fusarium wilt incidence was 2 to 3%. Symptoms appeared unilaterally and consisted of yellowing, leaf wilting of lower leaves, dark brown vascular discoloration, and plant death. The aim of this study was to determine the causal agent of tomato wilt in seven tomato greenhouses in the Azapa Valley. Stem samples (5 × 5 mm) were obtained 10 cm of the stem base from wilted tomatoes ‘Naomi’ (BIOAMERICA S.A., Chile) or from Maxifort tomato rootstock (De Ruiter Seed, USA), both FOL resistant to races 1 and 2. Samples were washed with tap water, surface sterilized with 1% NaClO for 3 min, and incubated on sterile moist paper towels in petri plates for 5 days at 22°C. Mycelial fragments from white colonies, emerging from diseased tissues, were transferred to PDA. Six Fusarium isolates were characterized by the presence of hyaline macroconidia, mostly 3 to 5 septate, slightly curved (19.2 to 32.1 × 2.9 to 4.5 μm) and single-celled, oval to elongated microconidia (3.1 to 8.9 × 2.0 to 4.0 μm). Chlamydospores were single or in pairs. These isolates were identified as F. oxysporum (3). The identity of F. oxysporum was confirmed by PCR assays using genomic DNA of each isolated and the universal primers Uni F and Uni R that generate a 672-bp PCR product. The pathogenic form and races were determined by PCR assays using the specific primers uni, sp13, sp23, and sprl that were able to discriminate all the three FOL races as well as F. oxysporum f. sp. radicis-lycopersici (FORL) isolates (2). The sp13 and sp23 primers amplified DNA bands of 445 and 518 bp, confirming the identity of FOL race 3. However, sprl amplified a fragment of 947 bp corresponding to FORL (2). Pathogenicity tests were conducted on 25-day-old seedlings (10 seedlings per isolate) of tomato ‘Poncho Negro,’ which is susceptible to FOL and FORL. Seedling roots were cut, submerged for 5 min in conidial suspension of 2 × 106 conidia/ml, and transplanted to 250-ml plastic containers with sterile substrate (sand/peat, 1:1). Equally treated non-inoculated seedlings were left as controls. The first symptoms induced by each of the five FOL isolates appeared 8 days after incubation under greenhouse and were characterized by yellowing of older leaves, sometimes affecting one side of the plant, vascular discoloration of the stem, and eventually plant death. In contrast, all seedlings inoculated with a FORL isolate developed a necrotic lesion and vascular discoloration at the base of the stems near the soil line, followed by wilting and plant death. Control plants remained asymptomatic. F. oxysporum was re-isolated only from inoculated plants, completing Koch's postulates. FOL and FORL were reported earlier in other tomato growing areas of Chile (1), located over 1,000 km south of the Azapa Valley. However, this is the first report of FOL race 3 and FORL in the Azapa Valley and FOL race 3 is reported for the first time in Chile. References: (1) S. Acuña. Compendio de Fitopatógenos de Cultivos Agrícolas. Servicio Agrícola y Ganadero. Gobierno de Chile, 2008. (2) Y. Hirano and T. Arie. J. Gen. Plant Pathol. 72:273, 2006. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006.

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First report of fruit blight caused by Alternaria alternata on sesame in Northeast China

Plant Disease ◽

10.1094/pdis-01-21-0047-pdn ◽

2021 ◽

Author(s):

Hongsen Cheng ◽

De Xue Gao ◽

Huijie Sun ◽

Yanbin Na ◽

Jing Xu

Keyword(s):

Alternaria Alternata ◽

Morphological Characteristics ◽

Its Region ◽

Liaoning Province ◽

Oilseed Crop ◽

Distilled Water ◽

Conidial Suspension ◽

First Report ◽

Health Products ◽

Blight Disease

Sesame (Sesamum indicum L.) is an important oilseed crop in China and it is also used in food and health products. In August of 2019, a blight sesame fruit was observed in a field of Liaoyang city, Liaoning province of China. Initial disease symptoms consisted of brown or dark brown spots on fruit. With time, lesions coalesced and the whole fruit turned dark brown or black. Most of the diseased fruit had thin and small, deformed, necrotic, hardened cracked epidermal lesions. Lesions were also produced on stem and petioles leading to leaf abscission. The disease results in premature fruit death, and in turn, considerable yield losses. To determine the causal agent, symptomatic fruit with developing lesions were collected, and surface sterilized in 2% NaClO for 3 min, rinsed three times in distilled water, and plated onto PDA medium. After incubation at 25°C for 5 days, a dark olivaceous fungus with abundant, branched, brown to black, and septate hyphae was consistently isolated. Twenty single spores were separated with an inoculation needle under stereomicroscope. The conidia were in chains, brown, obclavate, ovoid or ellipsoid, with 1-6 transverse septa and 0-4 longitudinal or oblique septa 12.5 to 45 × 6.5 to 14.5 μm in size. Conidiophores were septate, light brown to olive brown, measuring 22-60 μm × 2-4 μm. The morphological characteristics of the 20 isolates all matched the description of Alternaria alternata (Simmons, 2007). The internal transcribed spacer (ITS) region of rDNA of 15 isolates was amplified using primers ITS1/ITS4 (White et al. 1990) and EF1-728F/EF1-986R (Carbone et al. 1999) and sequenced. Identical sequences were obtained and the sequence of the isolate ZMHG12 was submitted to GenBank (Accession no. MW418181 and MW700316). BLAST analysis of the sequences of the isolates of ZMHG12 showed 100% to A. alternata (KP739875 and LC132712). In pathogenicity tests, a conidial suspension (2.5 × 105 conidia per ml) was prepared from 7 days-old cultures of isolate ZMHG12 grown on PDA at 25°C. Fruit of 10 two-month-old potted sesame plants (Variety “Liaozhi 8”) were sprayed with the conidia suspension until runoff. Another 10 plants sprayed with distilled water to served as non-inoculated controls. All plants were maintained for 48 h in a humid chamber with a temperature of 25°C to 26°C, and then moved to a greenhouse. Ten days after inoculation, all fruit of inoculated plants exhibited symptoms similar to those observed in the field and non-inoculated control plants remained symptomless. The experiment was repeated twice with similar results. A. alternata has been reported as a pathogen caused leaf blight disease of sesame in Pakistan (Nayyar et al. 2017). To our knowledge, this is the first report of A.alternata causing fruit blight of sesame in China. To date, we have observed the disease on sesames in fields of Fuxin, Chaoyang and Tieling city in Liaoning Province, and Tongliao city in Inner Mongolia of China, and it has become an important disease in sesame production of China. References : Simmons E. G. 2007. Alternaria: An identification manual. CBS Fungal Biodiversity Center, Utrecht, Netherlands. White T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego. Carbone I., et al. 1999. Mycologia, 91: 553-556. Nayyar, B. G., et al. 2017. Plant Pathology Journal, 33 (6): 543-553.

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First Report of Fusarium Wilt of Lettuce Caused by Fusarium oxysporum f. sp. lactucae in Arizona

Plant Disease ◽

10.1094/pdis.2003.87.10.1265c ◽

2003 ◽

Vol 87 (10) ◽

pp. 1265-1265 ◽

Cited By ~ 23

Author(s):

M. E. Matheron ◽

S. T. Koike

Keyword(s):

Fusarium Oxysporum ◽

Root Rot ◽

The United States ◽

San Joaquin Valley ◽

Fluorescent Light ◽

Lettuce Seedling ◽

Disease Symptoms ◽

First Report ◽

Root Rot Disease ◽

Rot Disease

A new wilt and root rot disease was observed in 6 and 11 commercial fields of lettuce (Lactuca sativa) in western Arizona during the fall of 2001 and 2002, respectively. Distance between infested sites ranged from approximately 0.5 to 39 km. Five head lettuce cultivars as well as a red leaf lettuce cultivar were affected. Disease symptoms included yellowing and wilting of leaves, as well as stunting and plant death. The cortex of the crown and upper root of infected plants usually was decayed and reddish brown. Disease symptoms first appeared at the time of plant thinning and continued to develop up to plant maturity. Fusarium oxysporum was consistently isolated from symptomatic plant roots. Seeds of cv. Lighthouse were planted in nonsterile vermiculite within 3.0-cm-square × 7.0-cm-deep cells in a transplant tray and thinned to a single plant per cell. When the first true leaves were emerging, 10 individual seedlings were inoculated with a single-spore isolate of F. oxysporum recovered from diseased lettuce root cortex tissue. Inoculum was prepared by growing the fungus on potato dextrose agar in 100-mm-diameter × 15-mm-deep plastic petri dishes at 28°C with a 12-h photoperiod under fluorescent light. Once the fungus completely covered the agar surface, 50 ml of sterile distilled water was added to the dish, and the mycelia and conidia on the surface were scraped off the agar and suspended in the water. This fungal suspension was decanted, and a 2-ml aliquot containing 1.8 × 105 CFU was pipetted into the vermiculite near the stem of each lettuce seedling. Ten plants grown in noninfested vermiculite served as uninoculated controls. After inoculation, plants were maintained in a growth chamber at 28°C with a 12-h photoperiod under fluorescent light for 3 weeks. Symptoms of yellowing, wilt, vascular decay, and often plant death developed during the incubation period on all inoculated plants but not on control plants. Fusarium oxysporum was consistently reisolated from inoculated plants but not from uninoculated plants. The experiment was repeated and yielded the same results. A wilt and root rot disease of lettuce attributed to F. oxysporum f. sp. lactucae was first reported in Japan in 1967 (3) and subsequently in the United States (San Joaquin Valley of California) in 1993 (2), and Italy in 2002 (1). The researchers of the U.S. report did not cite the earlier work from Japan and described the pathogen as F. oxysporum f. sp. lactucum. The Arizona isolate used to demonstrate pathogenicity was of the same vegetative compatibility group as an isolate of the pathogen from lettuce in California reported in 1993. Several companies grow and harvest lettuce in Arizona and California. At the end of production and harvest in the fall, tractors, implements, and harvesting equipment are transported from the San Joaquin Valley in California to western Arizona. The similarity between the isolate of F. oxysporum f. sp. lactucae from western Arizona and the San Joaquin Valley of California suggest a possible introduction of the pathogen into Arizona from California, perhaps on soil adhering to farm equipment. To our knowledge, this is the first report of F. oxysporum f. sp. lactucae infecting lettuce in Arizona. References: (1) A. Garibaldi et al. Plant Dis. 86:1052, 2002. (2) J. C. Hubbard and J. S. Gerik. Plant Dis. 77:750, 1993. (3) T. Matuo and S. Motohashi. Trans. Mycol. Soc. Jpn. 8:13, 1967.

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

Plant Disease ◽

10.1094/pdis-05-21-1123-pdn ◽

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.

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First Report of a Leaf Spot on Hazel Leaves Caused by Phyllosticta coryli in Liaoning Province of China

Plant Disease ◽

10.1094/pdis-02-13-0213-pdn ◽

2013 ◽

Vol 97 (9) ◽

pp. 1254-1254 ◽

Cited By ~ 10

Author(s):

J. Sun ◽

D.-M. Wang ◽

X.-Y. Huang ◽

Z.-H. Liu

Keyword(s):

Leaf Spot ◽

Control Strategies ◽

Morphological Characteristics ◽

Leaf Tissue ◽

Its Region ◽

Liaoning Province ◽

Single Spore ◽

First Report ◽

Leaf Spots ◽

Microscopic Morphology

Hazel (Corylus heterophylla Fischl) is an important nut tree grown in China, especially in Liaoning Province, and is rich in nutritional and medicinal values. In August 2011, leaf spotting was observed on hybrid hazel (Dawei) leaves in Paotai Town, Wafangdian County of Liaoning Province. By August 2012, the disease had spread to Zhangdang Town, Fushun County. Symptoms initially appeared on both sides of leaves as pinpoint brown spots, which enlarged and developed into regular, dark brown lesions, 3 to 9 mm in diameter. The lesions were lighter in color in the center compared to the margin. To identify the pathogen, leaf pieces (3 to 5 mm) taken from the margins, including both symptomatic and healthy portions of leaf tissue, were surface-disinfected first in 75% ethanol for 5 s, next in 0.1% aqueous mercuric chloride for 50 s, and then rinsed with sterilized water three times. Leaf pieces were incubated on potato dextrose agar (PDA) at 25°C for 14 days in darkness. Single spore isolates were obtained from individual conidia. For studies of microscopic morphology, isolates were grown on synthetic nutrient agar (SNA) in slide cultures. Colonies grew up to 45 to 48 mm in diameter on PDA after 14 days. Pycnidia appeared on the colonies after 12 days. Conidiophores were short. Pycnidia were dark brown, subglobose, and 150 to 205 μm in diameter. Conidia were unicellular, colorless, ovoid to oval, and from 2.4 to 4.5 × 1.6 to 2.4 μm. On the basis of these morphological characteristics, the isolates were tentatively identified as Phyllosticta coryli Westend (2). The rDNA internal transcribed spacer (ITS) region was amplified using primers ITS1 and ITS4 and sequenced (GenBank Accession No. KC196068). The 490-bp amplicons had 100% identity to an undescribed Phyllosticta species isolated from Cornus macrophylla in Gansu, Tianshui, China (AB470897). On the basis of morphological characteristics and nucleotide homology, the isolate was tentatively identified as P. coryli. Koch's postulates were fulfilled in the growth chamber on hazelnut leaves inoculated with P. coryli conidial suspensions (107 conidia ml–1). Eight inoculated 1-year-old seedlings (Dawei) were incubated under moist conditions for 8 to 10 days at 25°C. All leaf spots that developed on inoculated leaves were similar in appearance to those observed on diseased hazel leaves in the field. P. coryli was recovered from lesions and its identity was confirmed by morphological characteristics. P. coryli was first reported as a pathogen of hazel leaves in Bull of Belgium (2). In China, P. coryli was first reported on Corylus heterophylla Fisch. in Jilin Province (1). To our knowledge, this is the first report of P. coryli causing leaf spot on hybrid hazel in Liaoning Province of China. The outbreak and spread of this disease may decrease the yield of hazelnut in northern regions of China. More studies are needed on control strategies, including the possible resistance of hazel cultivars to P. coryli. References: (1) Y. Li et al. J. Shenyang Agric. Univ. 25:153, 1994. (2) P. A. Saccardo. Sylloge Fungorum Vol. III, page 31, 1884.

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First report of panicle rot caused by Fusarium asiaticum on foxtail millet in China

Plant Disease ◽

10.1094/pdis-04-21-0856-pdn ◽

2021 ◽

Author(s):

Fanxin Kong ◽

Haijin Zhang ◽

Zhi Liu ◽

Guoqiu Chen ◽

Jing Xu

Keyword(s):

Foxtail Millet ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Its Region ◽

Liaoning Province ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Dark Cycle ◽

First Report ◽

Fusarium Asiaticum

Foxtail millet [ Setaria italica (L.) P. Beauv.] is one of the most important nutritious food crops. It is used for wine and health products in China. In August of 2019, panicle rot symptoms with up to 85% of panicles infected were observed on foxtail millet (cultivar Chaogu 8) in a commercial field located in Chaoyang city of Liaoning Province, China. Typical disease symptoms included brown spots on spikelets at early stages and brown-colored withering and rot of whole panicles at late stages, with the symptoms being more severe at the tip of the panicles. Under high humidity conditions, pink or salmon-colored molds developed on panicles. Symptomatic spikelet pieces were surface-disinfested with 70% ethanol for 1 min followed by 2% NaOCl for 3 min, rinsed with sterilized water for three times, and placed on potato dextrose agar (PDA) medium at 25°C. After 5 days, colonies turned pink to dark red with fluffy aerial mycelium and pigmentation with the age. Ten pure cultures were obtained from single conidia of mycelium grown on carnation leaf agar (CLA) medium at 25°C under a 12-h light-dark cycle using an inoculation needle under stereomicroscope. Macroconidia were hyaline, falcate with foot cells, 3–5 septate and size: 28.5- 44.0 μm × 3.8 - 4.9 μm. Chlamydospores were globose to subglobose (5.4 to 13.8 μm). No microconidia were produced on CLA. Black, ostiolate subglobose perithecia were formed on CLA after one month of incubation at 20°C under a 12-h light-dark cycle. Morphological characteristics of the fungus were in agreement with the description of Fusarium asiaticum (O’Donnell et al. 2004; Leslie and Summerell 2006). To validate this identification, partial translation elongation factor 1 alpha (TEF1-a) gene, and rDNA internal transcribed spacer (ITS) region of five isolates were amplified and sequenced (O’Donnell et al. 2015; White et al.1990). Identical sequences were obtained, and the sequence of one representative isolate (JGF-3) was submitted to GenBank. BLASTn analysis of both TEF sequence (MW685833) and ITS sequence (MW423687), revealed 100% sequence identity with F. asiaticum KT380120 and MT322117, respectively. Pathogenicity test were conducted on cultivar Chaogu 8 of foxtail millet. Inoculum was prepared from the culture of JGF-3 incubated in 2% mung beans juice on a shaker (140 rpm) at 25°C for 48 h. Conidial suspension (5 × 105 conidia per ml) was prepared and sprayed onto the panicles of 20 plants at the initial flowering stage and 20 additional plants that were sprayed with distilled water served as the non-inoculated controls. Treated plants were covered with plastic bags for 48 h and maintained at a greenhouse with day and night temperatures of 26 and 24°C, respectively. Two weeks after inoculation, all inoculated panicles exhibited symptoms similar to the syptoms observed in the field. No symptoms were observed in the non-inoculated control plants. The experiment was repeated twice with similar results. F. asiaticum was reisolated from the inoculated plants and its morphological characteristics matched those of the original isolates; the fungus was not reisolated from the non-inoculated plants. To our knowledge, this is the first report of F. asiaticum causing panicle rot of foxtail millet in China. To date, the disease has been observed to be present in Fuxin and Tieling city of Liaoning Province. Panicle rot can become an important disease in foxtail millet in China. References: O’Donnell, K., et al. 2004. Fungal Genetics and Biology 41: 600. Leslie, J. F., and Summerell, B. A. 2006. The Fusarium laboratory manual. Blackwell Publishing, Ames, pp 176-179. O’ Donnell, K., et al. 2015. Phytoparasitica 43: 583. White, T. J., et al. 1990. Academic Press, San Diego, CA, pp 315-322.

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First Report of Basal Stem Rot of Apple Cactus (Cereus peruvianus monstruosus) Caused by Fusarium oxysporum in Italy

Plant Disease ◽

10.1094/pdis-03-11-0216 ◽

2011 ◽

Vol 95 (7) ◽

pp. 877-877

Author(s):

A. Garibaldi ◽

P. Pensa ◽

D. Bertetti ◽

A. Poli ◽

M. L. Gullino

Keyword(s):

United States ◽

Fusarium Oxysporum ◽

The United States ◽

Stem Rot ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Single Spore ◽

Basal Stem Rot ◽

First Report

During the summer of 2010, 20% of 7,000 4-month-old plants of apple cactus (Cereus peruvianus monstruosus) showed symptoms of a basal stem rot in a commercial nursery located in Liguria (northern Italy). Affected plants showed yellow orange-to-pale brown color from the crown level to the stem apex and a water-soaked rot was observed on the stem starting from the base. Brown discoloration was observed in the vascular system. Eventually stems bent, plants collapsed and died, and affected tissues dried out. A Fusarium sp. was consistently and readily isolated from symptomatic tissue on Komada selective medium. Isolates were purified and subcultured on potato dextrose agar (PDA). Single-spore cultures on PDA, Spezieller Nährstoffarmer agar (SNA) (3), and carnation leaf-piece agar (CLA) (2) were incubated at 26 ± 1°C (12-h fluorescent light, 12-h dark). On PDA, cultures produced a thick growth of white-to-pink mycelium and pale pink pigments in the agar. On SNA, cultures produced short monophialides with unicellular, ovoid-elliptical microconidia measuring 4.3 to 8.2 × 2.3 to 3.8 (average 6.0 × 2.8) μm. Chlamydospores were abundant, single or paired, terminal and intercalary, rough walled, and 6 to 8 μm in diameter. On CLA, cultures produced orange sporodochia with macroconidia that were 3 to 4 septate, nearly straight with a foot-shaped basal cell and a short apical cell, and measured 31.1 to 51.5 × 4.4 to 3.5 (average 43.2 × 3.8) μm. Such characteristics are typical of Fusarium oxysporum (3). Amplification of the ITS (internal transcribed spacer) of the rDNA using primers ITS1/ITS4 (4) yielded a 498-bp band. Sequencing and BLASTn analysis of this band showed an E-value of 0.0 with F. oxysporum. The nucleotide sequence has been assigned GenBank Accession No. JF422071. To confirm pathogenicity, five 6-month-old healthy plants of C. peruvianus monstruosus were inoculated by dipping roots in a conidial suspension (2.4 × 106 CFU/ml) of F. oxysporum isolated from affected plants. Inoculum was obtained from pure cultures of three single-spore isolates grown for 10 days on casein hydrolysate liquid medium. Roots were not wounded before the inoculation. Plants were transplanted into pots filled with steam-sterilized substrate (sphagnum peat/perlite/pine bark/clay 50:20:20:10). Five noninoculated plants served as a control. Plants were placed in a climatic chamber at 25 ± 1°C (12-h fluorescent light, 12 h-dark). Basal stem rot and vascular discoloration in the crown and stem developed within 30 days on each inoculated plant. Noninoculated plants remained healthy. F. oxysporum was consistently isolated from symptomatic plants. The pathogenicity test was conducted twice. F. oxysporum has been reported on Cereus spp. in the United States (1). To our knowledge, this is the first report of F. oxysporum on C. peruvianus monstruosus in Italy as well as in Europe. Currently, this disease is present in a few nurseries in Liguria. References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St Paul, MN, 1989. (2) N. L. Fisher et al. Phytopathology 72:151, 1982. (3) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell, Ames, IA, 2006. (4) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

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