First Report of Postharvest Fruit Rot Disease of Hardy Kiwifruit Caused by Diaporthe eres in China

Hardy kiwifruit (Actinidia arguta), as an economically important fruit crop growing in Northeast China with thin, hairless and smooth skin, is susceptible to postharvest decay. In September 2018, infected cultivar Kwilv fruits were obtained from a commercial farm in Liaoning province, northeastern China. The occurring incidence of the rot disease varied from 20% to 90% according to the fruit number in each box during a 7-day-long storage at room temperature, and the initial symptom included a small, soft, chlorosis to light brown lesion and later watery brown lesions. Pure cultures of the same characteristics were obtained from the isolated strains in four rotten fruits on PDA medium. The isolates grew into transparent radial mycelium on PDA in the first two days followed by abundant white, fluffy aerial mycelium. After 14 days, colonies formed white to light brown aerial mycelial mats with gray concentric rings, and they produced gray and embedded pycnidia. Alpha conidia of 4.4 to 8.8 µm × 1.4 to 3.3 µm (n = 50) were abundant in culture, hyaline, aseptate, ellipsoidal to fusiform, while Beta conidia at 20.5 to 28.6 µm × 1.0 to 1.4 µm (n = 50) were hyaline, long, slender, curved to hamate. These morphological characteristics were similar to Diaporthe species (anamorph: Phomopsis spp.) (Udayanga et al. 2014). For identification, DNA was extracted from three single isolates respectively , and the internal transcribed spacer (ITS) region, β-tubulin (BT), and histone (HIS) H3 gene were amplified by using primers ITS1/ITS4 (White et al. 1990), T1/T22 (O'Donnell et al. 1997) and HIS1F/HISR (Gao et al. 2017), respectively. The three isolates produced identical sequences across all three gene regions, which were submitted to NCBI (Genbank accession numbers MT561361, MT561360 and MT855966). Nucleotide BLAST analysis revealed that the ITS sequence shared 99% homology with those of ex-type Diaporthe eres in NCBI GenBank (MG281047.1 and KJ210529.1), so did the BT sequence that had 98% identity to D. eres (MG281256.1 and KJ420799.1) and the HIS 99% identity to D. eres (MG28431.1 and MG281395.1) (Hosseini et al. 2020, Udayanga et al. 2014). Pathogenicity was tested by wound inoculation on the cv. Kwilv fruits. Five mature and healthy fruits were surface-sterilized with 1% NaClO solution, rinsed in sterile distilled water and dried. Every fruit was wounded by penetrate the peel 1-2 mm with a sterile needle, and inoculated with mycelium plugs (5 mm in diameter) of the isolate on PDA, with five inoculated with sterile PDA plugs as controls. Treated fruits were kept in sterilized transparent plastic cans separately under high humidity (RH 90 to 100%) at 28°C. After five days, the same rot symptoms were observed on all fruits inoculated with mycelium while the control remained symptomless. The fungi was re-isolated from the lesions of inoculated fruits and identified as D. eres by sequencing, thus fulfilling Koch's postulates. The pathogenicity experiment was re-performed using D. eres conidial suspension (107 conidia/ml) in sterile distilled water in October 2019 and the same results were obtained. D. eres was recently reported to cause European pear rot in Italy (Bertetti et al. 2018). To our knowledge, this is the first report of D. eres causing a postharvest rot in hardy kiwifruit in China, leading to severe disease and thus huge economic losses in Northeast China. Accordingly, effective measures should be taken to prevent its spreading to other production regions in China.

Download Full-text

First Report of Diaporthe hongkongensis Causing Fruit rot on Peach (Prunus persica) in China

Plant Disease ◽

10.1094/pdis-07-20-1505-pdn ◽

2021 ◽

Author(s):

Zhou Zhang ◽

Zheng Bing Zhang ◽

Yuan Tai Huang ◽

FeiXiang Wang ◽

Wei Hua Hu ◽

...

Keyword(s):

Prunus Persica ◽

Fruit Rot ◽

Hunan Province ◽

Post Inoculation ◽

Distilled Water ◽

Conidial Suspension ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Representative Isolate ◽

Rot Disease

Peach [Prunus persica (L.) Batsch] is an important deciduous fruit tree in the family Rosaceae and is a widely grown fruit in China (Verde et al., 2013). In July and August 2018, a fruit rot disease was observed in a few peach orchards in Zhuzhou city, the Hunan Province of China. Approximately 30% of the fruit in more than 400 trees was affected. Symptoms displayed were brown necrotic spots that expanded, coalesced, and lead to fruit being rotten. Symptomatic tissues excised from the margins of lesions were surface sterilized in 70% ethanol for 10 s, 0.1% HgCl2 for 2 min, rinsed with sterile distilled water three times, and incubated on potato dextrose agar (PDA) at 26°C in the dark. Fungal colonies with similar morphology developed, and eight fungal colonies were isolated for further identification. Colonies grown on PDA were grayish-white with white aerial mycelium. After an incubation period of approximately 3 weeks, pycnidia developed and produced α-conidia and β-conidia. The α-conidia were one-celled, hyaline, fusiform, and ranged in size from 6.0 to 8.4 × 2.1 to 3.1 μm, whereas the β-conidia were filiform, hamate, and 15.0 to 27.0 × 0.8 to 1.6 μm. For molecular identification, total genomic DNA was extracted from the mycelium of a representative isolate HT-1 and the internal transcribed spacer region (ITS), β-tubulin gene (TUB), translation elongation factor 1-α gene (TEF1), calmodulin (CAL), and histone H3 gene (HIS) were amplified and sequenced (Meng et al. 2018). The ITS, TUB, TEF1, CAL and HIS sequences (GenBank accession nos. MT740484, MT749776, MT749778, MT749777, and MT749779, respectively) were obtained and in analysis by BLAST against sequences in NCBI GenBank, showed 99.37 to 100% identity with D. hongkongensis or D. lithocarpus (the synonym of D. hongkongensis) (Gao et al., 2016) (GenBank accession nos. MG832540.1 for ITS, LT601561.1 for TUB, KJ490551.1 for HIS, KY433566.1 for TEF1, and MK442962.1 for CAL). Pathogenicity tests were performed on peach fruits by inoculation of mycelial plugs and conidial suspensions. In one set, 0.5 mm diameter mycelial discs, which were obtained from an actively growing representative isolate of the fungus on PDA, were placed individually on the surface of each fruit. Sterile agar plugs were used as controls. In another set, each of the fruits was inoculated by application of 1 ml conidial suspension (105 conidia/ml) by a spray bottle. Control assays were carried out with sterile distilled water. All treatments were maintained in humid chambers at 26°C with a 12-h photoperiod. The inoculation tests were conducted twice, with each one having three fruits as replications. Six days post-inoculation, symptoms of fruit rot were observed on inoculated fruits, whereas no symptoms developed on fruits treated with agar plugs and sterile water. The fungus was re-isolated and identified to be D. hongkongensis by morphological and molecular methods, thus fulfilling Koch’s Postulates. This fungus has been reported to cause fruit rot on kiwifruit (Li et al. 2016) and is also known to cause peach tree dieback in China (Dissanayake et al. 2017). However, to our knowledge, this is the first report of D. hongkongensis causing peach fruit rot disease in China. The identification of the pathogen will provide important information for growers to manage this disease.

Download Full-text

First Report of Tuber Rot Disease of Kala Zeera Caused by a Member of the Fusarium solani Species Complex in India

Plant Disease ◽

10.1094/pdis-02-12-0148-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1067-1067 ◽

Cited By ~ 1

Author(s):

V. Gupta ◽

D. John ◽

V. K. Razdan ◽

S. K. Gupta

Keyword(s):

Fusarium Solani ◽

Species Complex ◽

Morphological Characteristics ◽

Distilled Water ◽

Conidial Suspension ◽

Potato Dextrose Broth ◽

First Report ◽

Fusarium Solani Species Complex ◽

Rot Disease ◽

Tuber Rot

Bunium persicum (Kala zeera, also black cumin) is an economically important culinary crop that is cultivated for its seed pods and its tuberlike roots. In India, high-altitude regions of Himachal Pradesh, including the Padder valley and the Gurez area of Jammu and Kashmir, are areas of kalazeera production (3). In 2008 to 2009, tuber rot disease of kala zeera was observed during the late spring season in the Padder valley. Symptomatic plants were distributed in localized areas in the field and the symptoms included drying of foliage and rotting of tubers. White mycelia were found on the tubers at the late stages of disease development. Incidence of infection in the surveyed area was 80 to 90%. Yield losses were 50 to 60%. To isolate the causal pathogen, we cultured tissues from symptomatic tubers. Small bits of the infected tissue were surface disinfested in 0.1% mercuric chloride, followed by rinsing three times in sterile distilled water. The surface disinfested tissues were plated on potato dextrose agar (PDA) and incubated at 27°C for 4 days. Pure cultures of the mycelium from the diseased tissues were transferred to a second set of PDA for species identification. The fungus produced three types of spores: small, one-celled, oval microconidia; large, slightly curved, septate macroconidia; and rounded, thick-walled chlamydospores. Microconidia were mostly non-septate and 8.91 to 15.73 × 2.3 to 3.5 μm, whereas macroconidia were three- to five-septate and were 35.55 to 54.74 × 3.91 to 6.5 μm. On the basis of morphological characteristics (1), the fungus was identified and deposited as a member of the Fusarium solani species complex in the Indian Type Culture Collection, New Delhi (ID No. 8422.11). To confirm pathogenicity, healthy tubers were submerged for 20 min in a conidial suspension of the isolated fungus (1 × 105 cfu/ml), which was prepared in potato dextrose broth, incubated for 10 days at 27°C, and centrifuged at 140 rpm. Noninoculated controls were submerged in distilled water. Inoculated and control tubers were then planted in separate pots filled with sterilized soil and kept in a shade house. Symptoms appeared on inoculated tubers 9 to 10 days after planting. Signs of the pathogen in the form of mycelia were present. The tubers rotted and died 12 to 15 days after inoculation. Control tubers did not display any symptoms. F. solani species complex was reisolated from inoculated tubers, fulfilling Koch's postulates. F. solani has been reported to cause corm rot on gladiolus and saffron (2). To our knowledge, this is the first report of the F. solani species complex as pathogenic to tubers of kalazeera in India. References: (1) C. Booth. The Genus Fusarium. 47, 1971. (2) L. Z. Chen et al. J. Shanghai Agric. College 12:240, 1994. (3) K. S. Panwar et al. Agriculture Situation in India. 48:151, 1993.

Download Full-text

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.

Download Full-text

First report of root rot of Schisandra chinensis caused by Fusarium acuminatum in Northeast China

Plant Disease ◽

10.1094/pdis-05-21-1052-pdn ◽

2021 ◽

Author(s):

Baoyu Shen ◽

Wensong Sun ◽

Kun Liu ◽

Jing Tian Zhang

Keyword(s):

Root Rot ◽

Apical Cell ◽

Morphological Characteristics ◽

Liaoning Province ◽

Effective Control ◽

Distilled Water ◽

Conidial Suspension ◽

Schisandra Chinensis ◽

First Report ◽

Fusarium Acuminatum

Wuweizi [Schisandra chinensis（Turcz.）Baill.] is used for traditional medicine in northeastern China. In August of 2019, root rot of S. chinensis with an incidence of 30%-50% was observed in a commercial field located in Liaozhong city (41º29’57” N, 122º52’33” E) in the Liaoning province of China. The diseased plants were less vigorous, stunted, and had leaves that turned yellow to brown. Eventually, the whole plant wilted and died. The diseased roots were poorly developed with brown lesion and eventually they would rot. To determine the causal agent, symptomatic roots were collected, small pieces of root with typical lesions were surface sterilized in 2% NaOCl for 3 min, rinsed three times in distilled water, and then plated onto PDA medium. After incubation at 26°C for 5 days, whitish-pink or carmine to rose red colonies on PDA were transferred to carnation leaf agar (CLA). Single spores were isolated with an inoculation needle using a stereomicroscope. Five single conidia isolates obtained from the colonies were incubated at 26°C for 7 days, abundant macroconidia were formed in sporodochia. Macroconidia were falcate, slender, with a distinct curve to the latter half of the apical cell, mostly 3 to 5 septate, measuring 31.3 to 47.8 × 4.8 to 7.5µm (n=50). Microconidia were oval and irregular ovals, 0-1 septate, measuring 5.0 to 17.5 × 2.5 to 17.5µm (n=50). Chlamydospores formed in chains on within or on top of the mycelium. Morphological characteristics of the isolates were in agreement with Fusarium acuminatum (Leslie and Summerell, 2006). To confirm the identity, the partial sequence of the translation elongation factor 1 alpha (TEF1-á) gene of five isolates was amplified using the primers EF-1(ATGGGTAAGGARGACAAG) and EF-2 (GGARGTACCAGTSATCATGTT) (O’Donnell et al. 2015 ) and sequenced. The rDNA internal transcribed spacer (ITS) region for the five isolates was also amplified using the primers ITS1 (TCCGTAGGTGAACCTGCGG) and ITS4 (TCCTCCGCTATTGATATGC) (White et al.1990) and sequenced. The identical sequences were obtained, and one representative sequence of isolate WW31-5 was submitted to GenBank. BLASTn analysis of the TEF-á sequence (MW423624) and ITS sequence (MZ145386), revealed 100%（708/685bp, 563/563bp）sequence identity to F. acuminatum MH595498 and MW560481, respectively. Pathogenicity tests were conducted in greenhouse. Inoculums of F. acuminatum was prepared from the culture of WW31-5 incubated in 2% mung beans juice on a shaker (140 rpm) at 26°C for 5 days. Ten roots of 2-years old plants of S. chinensis were immersed in the conidial suspension (2 × 105 conidia/ml) for 6 hours, and another ten roots immersed in sterilized distilled water in plastic bucket for 6 hours. All these plants were planted into pots with sterilized field soil (two plants per pot). Five pots planted with inoculated plants and another five pots planted with uninoculated plants served as controls. All ten pots were maintained in a greenhouse at 22-26°C for 21 days and irrigated with sterilized water. The leaves of the inoculated plants became yellow，gradually dried up, eventually finally all the aboveground parts died. The roots of the inoculated plants were rotted. Non-inoculated control plants had no symptoms. F. acuminatum was reisolated from the roots of inoculated plants and had morphology identical to the original isolate. The experiment was repeated twice with similar results. F. acuminatum has been reported as a pathogen caused root rot of ginseng (Wang et al. 2016) and not reported on Wuweizi in China. To our knowledge, this is the first report of root rot of S. chinensis caused by F. acuminatum. We have also observed the disease at Benxi city of Liaoning Province in 2020 and it has become an important disease in production of S. chinensis and the effective control method should be adopted to reduce losses.

Download Full-text

First Report of Alternaria alternata Causing Fruit Rot on Fig (Ficus carica) in Montenegro

Plant Disease ◽

10.1094/pdis-07-13-0770-pdn ◽

2014 ◽

Vol 98 (3) ◽

pp. 424-424 ◽

Cited By ~ 2

Author(s):

N. Latinović ◽

S. Radišek ◽

J. Latinović

Keyword(s):

Alternaria Alternata ◽

Direct Sequencing ◽

Disease Incidence ◽

Morphological Characteristics ◽

Fruit Rot ◽

Conidial Suspension ◽

Culture Collections ◽

First Report ◽

Control Fruit ◽

Rot Disease

In July 2012, a fruit rot disease was observed in several commercial fig tree orchards located in the Podgorica region in Montenegro. Symptoms on fruits initially appeared as small circular to oval, light brown, necrotic, sunken spots located mostly on the areas surrounding the ostiolar canal with an average diameter of 5 to 10 mm, which gradually enlarged in size leading to total fruit rot. Disease incidence on fruit across the fields ranged from 15 to 20% but the disease did not increase further due to hot and dry conditions thereafter. No foliar symptoms were observed. Small pieces (5 mm2) of symptomatic fruits were excised from the junction of diseased and healthy tissue, surface sterilized in 70% ethanol solution for 1 min, washed in three changes of sterile distilled water, air dried, and transferred to potato dextrose agar (PDA). After 2 to 3 days of incubation at 25°C, a fungus was consistently isolated. The isolates had radial growth and produced sooty black colonies. Microscopic observations of the colonies revealed brown septate hyphae and simple or branched conidiophores 30 to 65 μm long and 3 to 4.5 μm wide. Dark brown conidia were in chains (3 to 7), sized 10 to 35 × 5 to 9 μm, ellipsoid to ovoid, with 2 to 5 transverse and a few (1 to 3) to no longitudinal septa. Based on morphological characteristics, the fungus was identified as Alternaria alternata (3). For molecular identification, DNA was extracted from mycelia and conidia of two representative single spore isolates designated as ALT1-fCG and ALT2-fCG. PCR was carried out using internal transcribed spacer (ITS) region primers ITS4/ITS5 and A. alternata species-specific primers AAF2/AAR3 (1). Both primer pairs gave PCR products that were subjected to direct sequencing. BLAST analysis of the 546-bp ITS4/ITS5 (KF438091) and 294-bp AAF2/AAR3 (KF438092) sequences revealed 100% identity with several A. alternata isolates. Pathogenicity tests were conducted on 30 detached almost ripe and healthy fig fruit (cv. Primorka) by spraying them with a conidial suspension of the isolated fungus (106 conidia/ml) with a handheld sprayer. Thirty fruit inoculated with sterile water served as the non-inoculated control. Inoculated and control fruit were kept in a moist chamber at 25°C. Symptoms appeared on inoculated fruit 2 to 3 days after inoculation and all fruit were completely rotted 5 to 6 days after inoculation. Control fruit did not display any symptoms. A. alternata was consistently re-isolated from inoculated fruit, fulfilling Koch's postulates. The fig fruit rot caused by A. alternata has been reported before in California (2) and elsewhere mainly as postharvest pathogen. To our knowledge, this is the first report of fruit rot caused by A. alternata on fig in Montenegro. Considering Podgorica as the largest fig-producing area and the importance of fig as a traditionally grown crop, it could pose a threat to fig production in Montenegro. Voucher specimens are available at the culture collections of the University of Montenegro, Biotechnical Faculty. References: (1) P. Konstantinova et al. Mycol. Res. 106:23, 2002. (2) T. J. Michailides et al. Plant Dis. 78:44-50, 1994. (3) E. G. Simmons. Page 775 in: Alternaria and Identification Manual. CBS Fungal Biodiversity Centre, 2007.

Download Full-text

First report of chili pepper fruit rot caused by Fusarium incarnatum in China

Plant Disease ◽

10.1094/pdis-09-19-1996-pdn ◽

2021 ◽

Author(s):

Xiao Qin Zhu ◽

Dongmei Liu ◽

Quanchun Hong ◽

Yifang Lu ◽

Dongli Pei

Keyword(s):

Chili Pepper ◽

Fruit Rot ◽

Effective Control ◽

Economic Losses ◽

Hainan Province ◽

Pathogenicity Test ◽

Distilled Water ◽

Conidial Suspension ◽

First Report ◽

Pepper Fruit

Pepper (Capsicum annuum L.), with annual production over 1 million tons, is ranked the first vegetable crop in Hainan Province, China. In December 2018, fruit rot of chili pepper , with yield loss of up to 15%, was found in 10 fields (12 hm2) in Yacheng (18°N, 109°E), Hainan Province, China. Water-soaked and soft lesions developed on fruit, with white to light gray fungal mycelium present inside. The diseased fruit turned soft and decayed at the later stages. Diseased tissue was cut into 12 pieces of 0.5×0.5 cm, surface-disinfected with 2% sodium hypochlorite for 2 min, followed by 70% ethanol for 30 s, rinsed with sterile distilled water five times, and plated onto potato dextrose agar (PDA). After growing on PDA for 2 to 3 days at 28°C in an incubator without light, 10 pure culture isolates were obtained. All isolates had abundant dense white aerial mycelia that became beige with age. The macroconidia were slightly curved with four to seven septa, 29.51 to 42.15 × 4.29 to 6.22 μm. Spindle-shaped mesoconidia with three to four septa were abundantly produced, 20.34 to 24.54 × 4.58 to to 11.70 × 2.35 to 3.20 μm. Chlamydospores were absent. Based on the morphological characteristics, the fungus was tentatively identified as Fusarium incarnatum (Leslie and Summerell 2006). An isolate SQHP-01 was chosen for molecular identification and pathogenicity test. Two DNA fragments of the isolate, the internal transcribed spacer (ITS) and translation elongation factor genes (EF-1α) were amplified for sequencing. BLAST analysis showed that sequences of ITS (GenBank acc. no. MN317371) and EF-1α (acc. No. MN928788) had 99.61 to 100% identity with those of known F. incarnatum (MN480497 and KF993969). Phylogenetic analysis was conducted using neighbor-joining algorithm based on ITS and EF-1a genes separately, and the isolate was well clustered with F. incarnatum both with 100% bootstrap support. Pathogenicity test of the isolate were carried out twice on five healthy chili pepper fruit. After surface-disinfection, fruit were wounded at three different points and 20 μl of conidial suspension (106 conidia/ml) were deposited on each wound. Unwounded inoculation was conducted by spreading 100 μl of the suspension on each fruit surface including the pedicel and calyx. The fruit spread with sterile distilled water represented the negative control. All fruit treatments were placed on the moist sterile cotton in moist chambers at 25°C with 16 h light and 8 h darkness. After 4 to 6 days, water-soaked necrotic lesions appeared on the wounded fruit, the symptoms identical to those observed in the field. Water-soaked necrotic lesions developed on the pedicel and calyx of unwounded fruit. No symptoms were observed on the control fruit. The morphology and sequences of re-isolated fungal isolates from the tested peppers were the same as the original isolate. To our knowledge, this is the first report of F. incarnatum (synonym of F. semitectum) causing fruit rot on chili pepper in China. F. incarnatum has been reported to cause root rot of greenhouse pepper in China (Li et al. 2018), fruit rot of bell pepper in Trinidad (Ramdial et al. 2016) and Pakistan (Tariq et al. 2018). Effective control strategies need to be developed to prevent the economic losses caused by the disease in chili pepper.

Download Full-text

First Report of Crown Rot of Grafted Cucumber Caused by Fusarium solani in China

Plant Disease ◽

10.1094/pdis-03-10-0217 ◽

2010 ◽

Vol 94 (11) ◽

pp. 1377-1377 ◽

Cited By ~ 2

Author(s):

B.-J. Li ◽

Y. Liu ◽

Y.-X. Shi ◽

X.-W. Xie ◽

Y.-L. Guo

Keyword(s):

Disease Incidence ◽

Apical Cell ◽

Morphological Characteristics ◽

Crown Rot ◽

Liaoning Province ◽

Economic Losses ◽

Peat Moss ◽

Conidial Suspension ◽

Internal Transcribed Spacer Region ◽

First Report

Grafting has been widely and effectively used in cucumber (Cucumis sativus) cultivation for approximately 30 years in China to avoid Fusarium wilt caused by Fusarium oxysporum Schl. f. sp. cucumerinum Owen. In greenhouses, 90% of cucumbers are grafted onto pumpkin (Cucurbita moschata) rootstock. However, in March 2009, a severe crown rot causing yellowing and wilting of the leaves was observed on grafted cucumber in a large number of greenhouses in Lingyuan, western Liaoning Province in China. Symptoms consisted of dark brown, water-soaked lesions and a dense, white mycelial mat at the base of the stem. Lingyuan is the largest district for cucumber cultivation using grafting techniques in solar greenhouses in China. In 30 surveyed greenhouses in Sanshijiazi Village in the city of Lingyuan, the incidence of affected plants ranged from 10 to 40%, which caused serious economic losses. Fusarium spp. were isolated from the surface-sterilized basal stems of symptomatic plants on potato dextrose agar and incubated on potato sucrose agar for 4 days at 25°C. Colonies of the isolates produced a brown pigmentation and sparse, aerial mycelia, with a cream color on the underside. Conidiophores were elongated and branched or unbranched. Microconidia were abundant, hyaline, ellipsoid to ovoid, and 6 to 14 × 2.5 to 3.5 μm. Macroconidia were cylindrical, abundant, mostly two to six septate, 22 to 63 × 3.2 to 5.0 μm, with the apical cell rounded and blunt, and the basal cell rounded. On the basis of morphological characteristics, the fungus was identified as F. solani (C. Booth). For confirmation, the internal transcribed spacer region of rDNA was amplified and sequenced. A 449-bp sequence shared 99% homology with that of a F. solani GenBank accession previously reported from Japan (No. AF150473.1). The new sequence was deposited in GenBank (Accession No. HM015882). Pathogenicity of three isolates was determined in two experiments using different methods of inoculation. In one, 30 seedlings of pumpkin (C. moschata) with one true leaf each were inoculated by dipping their roots in a suspension of 106 spores ml–1, while control plants were mock inoculated with sterile water. Plants were then potted in a sterile mix of peat moss and vermiculite (2:1 vol/vol). In the other, pregerminated pumpkin seeds were sown in the same medium with a conidial suspension added at a rate of 106 spores ml–1, while other seeds were sown in sterile soil as controls. Plants for both experiments were maintained in a greenhouse at 25°C. Twelve days after inoculation, inoculated plants in both experiments showed a cortical rot on the crown and stem base with a brown, water-soaked appearance. Twenty-one days later, inoculated plants developed wilting and yellowed leaves. Disease incidence was 100%. No symptoms occurred on the control plants. Both experiments were repeated once with the same results. The pathogen was recovered from symptomatic tissue, confirming Koch's postulates. F. solani has been previously reported to cause root rot on cucurbit in California (2) and crown rot on grafted cucumber in the Netherlands (1). To our knowledge, this is the first report of crown rot of grafted cucumber caused by F. solani in China. References: (1) L. C. P. Kerling and L. Bravenboer. Neth. J. Plant Pathol. 73:15, 1967. (2) T. A. Tousson and W. C. Snyder. Phytopathology 51:17, 1961.

Download Full-text

First Report of Pepper Fruit Rot Caused by Fusarium concentricum in China

Plant Disease ◽

10.1094/pdis-03-13-0325-pdn ◽

2013 ◽

Vol 97 (12) ◽

pp. 1657-1657 ◽

Cited By ~ 6

Author(s):

J. H. Wang ◽

Z. H. Feng ◽

Z. Han ◽

S. Q. Song ◽

S. H. Lin ◽

...

Keyword(s):

Fusarium Species ◽

Fruit Rot ◽

Post Inoculation ◽

Distilled Water ◽

Conidial Suspension ◽

Average Growth ◽

First Report ◽

Control Fruit ◽

Pepper Fruit ◽

Fruit Samples

Pepper (Capsicum annuum L.) is an important vegetable crop worldwide. Some Fusarium species can cause pepper fruit rot, leading to significant yield losses of pepper production and, for some Fusarium species, potential risk of mycotoxin contamination. A total of 106 diseased pepper fruit samples were collected from various pepper cultivars from seven provinces (Gansu, Hainan, Heilongjiang, Hunan, Shandong, Shanghai, and Zhejiang) in China during the 2012 growing season, where pepper production occurs on approximately 25,000 ha. Pepper fruit rot symptom incidence ranged from 5 to 20% in individual fields. Symptomatic fruit tissue was surface-sterilized in 0.1% HgCl2 for 1 min, dipped in 70% ethanol for 30 s, then rinsed in sterilized distilled water three times, dried, and plated in 90 mm diameter petri dishes containing potato dextrose agar (PDA). After incubation for 5 days at 28°C in the dark, putative Fusarium colonies were purified by single-sporing. Forty-three Fusarium strains were isolated and identified to species as described previously (1,2). Morphological characteristics of one strain were identical to those of F. concentricum. Aerial mycelium was reddish-white with an average growth rate of 4.2 to 4.3 mm/day at 25°C in the dark on PDA. Pigments in the agar were formed in alternating red and orange concentric rings. Microconidia were 0- to 1-septate, mostly 0-septate, and oval, obovoid to allantoid. Macroconidia were relatively slender with no significant curvature, 3- to 5-septate, with a beaked apical cell and a foot-shaped basal cell. To confirm the species identity, the partial TEF gene sequence (646 bp) was amplified and sequenced (GenBank Accession No. KC816735). A BLASTn search with TEF gene sequences in NCBI and the Fusarium ID databases revealed 99.7 and 100% sequence identity, respectively, to known TEF sequences of F. concentricum. Thus, both morphological and molecular criteria supported identification of the strain as F. concentricum. This strain was deposited as Accession MUCL 54697 (http://bccm.belspo.be/about/mucl.php). Pathogenicity of the strain was confirmed by inoculating 10 wounded, mature pepper fruits that had been harvested 70 days after planting the cultivar Zhongjiao-5 with a conidial suspension (1 × 106 spores/ml), as described previously (3). A control treatment consisted of inoculating 10 pepper fruits of the same cultivar with sterilized distilled water. The fruit were incubated at 25°C in a moist chamber, and the experiment was repeated independently in triplicate. Initially, green to dark brown lesions were observed on the outer surface of inoculated fruit. Typical soft-rot symptoms and lesions were observed on the inner wall when the fruit were cut open 10 days post-inoculation. Some infected seeds in the fruits were grayish-black and covered by mycelium, similar to the original fruit symptoms observed at the sampling sites. The control fruit remained healthy after 10 days of incubation. The same fungus was isolated from the inoculated infected fruit using the method described above, but no fungal growth was observed from the control fruit. To our knowledge, this is the first report of F. concentricum causing a pepper fruit rot. References: (1) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (2) K. O'Donnell et al. Proc. Nat. Acad. Sci. USA 95:2044, 1998. (3) Y. Yang et al. 2011. Int. J. Food Microbiol. 151:150, 2011.

Download Full-text

First report of Coniella castaneicola causing leaf blight on blueberry (Vaccinium virgatum) in China

Plant Disease ◽

10.1094/pdis-05-21-1122-pdn ◽

2021 ◽

Author(s):

Jiahao Lai ◽

Guihong Xiong ◽

Bing Liu ◽

Weigang Kuang ◽

Shuilin Song

Keyword(s):

Molecular Identification ◽

Morphological Characteristics ◽

Leaf Blight ◽

Yield Potential ◽

Effective Control ◽

Economic Losses ◽

Distilled Water ◽

First Report ◽

Fungal Isolates ◽

Blight Disease

Blueberry (Vaccinium virgatum), an economically important small fruit crop, is characterized by its highly nutritive compounds and high content and wide diversity of bioactive compounds (Miller et al. 2019). In September 2020, an unknown leaf blight disease was observed on Rabbiteye blueberry at the Agricultural Science and Technology Park of Jiangxi Agricultural University in Nanchang, China (28°45'51"N, 115°50'52"E). Disease surveys were conducted at that time, the results showed that disease incidence was 90% from a sampled population of 100 plants in the field, and this disease had not been found at other cultivation fields in Nanchang. Leaf blight disease on blueberry caused the leaves to shrivel and curl, or even fall off, which hindered floral bud development and subsequent yield potential. Symptoms of the disease initially appeared as irregular brown spots (1 to 7 mm in diameter) on the leaves, subsequently coalescing to form large irregular taupe lesions (4 to 15 mm in diameter) which became curly. As the disease progressed, irregular grey-brown and blighted lesion ran throughout the leaf lamina from leaf tip to entire leaf sheath and finally caused dieback and even shoot blight. To identify the causal agent, 15 small pieces (5 mm2) of symptomatic leaves were excised from the junction of diseased and healthy tissue, surface-sterilized in 75% ethanol solution for 30 sec and 0.1% mercuric chloride solution for 2 min, rinsed three times with sterile distilled water, and then incubated on potato dextrose agar (PDA) at 28°C for 5-7 days in darkness. Five fungal isolates showing similar morphological characteristics were obtained as pure cultures by single-spore isolation. All fungal colonies on PDA were white with sparse creeping hyphae. Pycnidia were spherical, light brown, and produced numerous conidia. Conidia were 10.60 to 20.12 × 1.98 to 3.11 µm (average 15.27 × 2.52 µm, n = 100), fusiform, sickle-shaped, light brown, without septa. Based on morphological characteristics, the fungal isolates were suspected to be Coniella castaneicola (Cui 2015). To further confirm the identity of this putative pathogen, two representative isolates LGZ2 and LGZ3 were selected for molecular identification. The internal transcribed spacer region (ITS) and large subunit (LSU) were amplified and sequenced using primers ITS1/ITS4 (Peever et al. 2004) and LROR/LR7 (Castlebury and Rossman 2002). The sequences of ITS region (GenBank accession nos. MW672530 and MW856809) showed 100% identity with accessions numbers KF564280 (576/576 bp), MW208111 (544/544 bp), MW208112 (544/544 bp) of C. castaneicola. LSU gene sequences (GenBank accession nos. MW856810 to 11) was 99.85% (1324/1326 bp, 1329/1331 bp) identical to the sequences of C. castaneicola (KY473971, KR232683 to 84). Pathogenicity was tested on three blueberry varieties (‘Rabbiteye’, ‘Double Peak’ and ‘Pink Lemonade’), and four healthy young leaves of a potted blueberry of each variety with and without injury were inoculated with 20 μl suspension of prepared spores (106 conidia/mL) derived from 7-day-old cultures of LGZ2, respectively. In addition, four leaves of each variety with and without injury were sprayed with sterile distilled water as a control, respectively. The experiment was repeated three times, and all plants were incubated in a growth chamber (a 12h light and 12h dark period, 25°C, RH greater than 80%). After 4 days, all the inoculated leaves started showing disease symptoms (large irregular grey-brown lesions) as those observed in the field and there was no difference in severity recorded between the blueberry varieties, whereas the control leaves showed no symptoms. The fungus was reisolated from the inoculated leaves and confirmed as C. castaneicola by morphological and molecular identification, fulfilling Koch’s postulates. To our knowledge, this is the first report of C. castaneicola causing leaf blight on blueberries in China. The discovery of this new disease and the identification of the pathogen will provide useful information for developing effective control strategies, reducing economic losses in blueberry production, and promoting the development of the blueberry industry.

Download Full-text

First Report of Strawberry Fruit Rot Caused by Alternaria tenuissima in Korea

Plant Disease ◽

10.1094/pdis.2001.85.5.563b ◽

2001 ◽

Vol 85 (5) ◽

pp. 563-563 ◽

Cited By ~ 5

Author(s):

H. B. Lee ◽

C.-J. Kim ◽

S. H. Yu

Keyword(s):

Fruits And Vegetables ◽

Morphological Characteristics ◽

West Germany ◽

Fruit Rot ◽

Conidial Suspension ◽

Strawberry Fruit ◽

Alternaria Tenuissima ◽

First Report ◽

The Usa ◽

Dark Green

A strawberry (Fragaria × ananassa Duch.) fruit rot disease has been observed in several vinyl-house fields at Nonsan and Taejon, Chungnam district, Korea, especially following moist and cool conditions in the spring and again in September. Over the past 7 years, incidence of the disease has ranged from 0.2 to 2.0%. Early symptoms on fruits were characterized by small, irregular lesions, which were slightly sunken and appeared light green to black in color as sporulation began. Conidia were 25 to 55 μm long by 10 to 17 μm wide; beaks, when present, were 2 to 3 μm wide and up to 40 μm long; and conidiophores were 20 to 110 μm long by 3 to 5 μm wide. Older lesions were circular, largely sunken, firm, and dark-green to almost black because of abundant sporulation. The fungus isolated from infected fruit tissues was identified as Alternaria tenuissima (Fries) Wiltshire, based on the morphological characteristics of the conidia and conidiophores. Pathogenicity tests were conducted by inoculating slightly wounded, ripe (red) and immature (green) fruits with a conidial suspension (1 × 106 conidia/ml). Twenty-four ripe and immature fruits were inoculated with each of six isolates in duplicate and placed in a moist chamber for 48 h at 25°C and then transferred to vinyl-house field. After 7 to 10 days fruit rot symptoms were visible on the inoculated fruits and appeared nearly identical to lesions observed in the field, although there were differences in aggressiveness among isolates. Control fruits sprayed with distilled water did not develop any symptoms. Green fruits were generally more resistant to infection than ripe ones. The causal fungus was easily reisolated from lesions on inoculated strawberries. Alternaria fruit rot of strawberries has been reported from the USA, UK, and West Germany (2). Howard and Albregts (1) first reported a strawberry fruit rot caused by A. tenuissima in Florida, but the disease is generally not considered important. However, occasionally losses from this disease have been extensive in Korea. To the authors' knowledge, this is the first report of strawberry fruit rot caused by Alternaria tenuissima in Korea. References: (1) C. M. Howard and E. E. Albregts. Phytopathology 63:638–639, 1973. (2) A. L. Snowdon. Pages 250–252 in: A Color Atlas of Post-Harvest Diseases and Disorders of Fruits and Vegetables. Vol. 1. 1990. Wolfe Scientific, London.

Download Full-text