Pythium myriotylum is recovered most frequently from Pythium soft-rot infected ginger rhizomes in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Paul Daly ◽  
Yifan Chen ◽  
Qimeng Zhang ◽  
Hongli Zhu ◽  
Jingjing Li ◽  
...  
Keyword(s):  
Severe Disease ◽  
Zingiber Officinale ◽  
Soft Rot ◽  
Temperature Dependent ◽  
Pythium Myriotylum ◽  
Disease Symptoms ◽  
Ginger Rhizome ◽  
Oomycete Pathogen ◽  
Dependent Growth ◽  
Pythium Soft Rot

Pythium soft rot is a major soil-borne disease of crops such as ginger (Zingiber officinale). Our objective was to identify which Pythium species were associated with Pythium soft-rot of ginger in China, where approximately 20% of global ginger production is from. Oomycetes infecting ginger rhizomes from seven provinces were investigated using two molecular markers, the internal transcribed spacer (ITS) and cytochrome c oxidase subunit II (CoxII). In total, 81 isolates were recovered and approximately 95% of the isolates were identified as Pythium myriotylum and the other isolates were identified as either P. aphanidermatum or P. graminicola. Notably, the P. myriotylum isolates from China did not contain the SNP in the CoxII sequence found previously in the P. myriotylum isolates infecting ginger in Australia. A subset of 36 of the isolates was analyzed repeatedly by temperature-dependent growth, severity of disease on ginger plants and aggressiveness of colonization of ginger rhizome sticks. In the pathogenicity assays, 32/36 of the isolates were able to significantly infect and cause severe disease symptoms on the ginger plants. A range of temperature-dependent growth, disease severity and aggressiveness in colonization was found with a significant moderate positive correlation between growth and aggressiveness of colonization of the ginger sticks. This study identified P. myriotylum as the major oomycete pathogen in China from infected ginger rhizomes and suggests that P. myriotylum should be a key target to control soft rot of ginger disease.

scholarly journals Performance and Resistance to Phytophthora Crown and Root Rot in Squash Lines

2020 ◽  
Vol 30 (5) ◽  
pp. 608-618 ◽  
Author(s):  
Kyle E. LaPlant ◽  
Gregory Vogel ◽  
Ella Reeves ◽  
Christine D. Smart ◽  
Michael Mazourek
Keyword(s):  
Root Rot ◽  
Cucurbita Pepo ◽  
Field Experiments ◽  
Phytophthora Capsici ◽  
Severe Disease ◽  
Field Trials ◽  
Disease Symptoms ◽  
Resistant Lines ◽  
Oomycete Pathogen ◽  
Crown And Root Rot

Phytophthora crown and root rot, caused by the oomycete pathogen Phytophthora capsici, is a devastating disease of squash and pumpkin (Cucurbita pepo). No currently available cultivars provide complete resistance to this disease. Three newly developed squash lines and four hybrids were evaluated in greenhouse and field experiments for their resistance to phytophthora crown and root rot as well as for their horticultural performance. The three newly developed lines ranked among the most resistant entries included in 2 years of field trials. In addition, in a separate greenhouse experiment, one of the lines was shown to display the least severe disease symptoms among a group of accessions previously reported to possess partial resistance to phytophthora crown and root. Furthermore, the resistance was observed to be robust to several isolates of P. capsici. However, the phytophthora-resistant lines had reduced yield relative to standard squash cultivars. These lines are useful for continued breeding efforts toward a phytophthora crown and root rot-resistant cultivar.

scholarly journals First Report in China of Soft Rot of Ginger Caused by Pythium aphanidermatum

Plant Disease ◽  
2014 ◽  
Vol 98 (7) ◽  
pp. 1011-1011 ◽  
Author(s):  
Y. Li ◽  
L. G. Mao ◽  
D. D. Yan ◽  
X. M. Liu ◽  
T. T. Ma ◽  
...  
Keyword(s):  
Aerial Mycelium ◽  
Zingiber Officinale ◽  
Average Diameter ◽  
Soft Rot ◽  
Pythium Aphanidermatum ◽  
Selective Medium ◽  
Rrna Gene ◽  
Distilled Water ◽  
First Report ◽  
Pythium Soft Rot

Ginger (Zingiber officinale Roscoe) is an important commercial crop planted on more than 13,000 ha annually in Anqiu city, Shandong Province, China. From 2010 to 2011, the incidence of Pythium soft rot disease on cv. Laiwu Big Ginger reached 40 to 75% in Anqiu and yield losses of up to 60% were observed. The disease symptoms included brown spots on ginger rhizomes followed by soft rot, stems and leaves above ground becoming withered and yellow, and water soaking on the collar region. The soft rot did not produce offensive odors, which is different from bacterial rots (2). Forty symptomatic rhizomes were sampled from eight farms. Martin's method (1) was used to isolate the pathogen. Ten pieces from each rhizome were washed with sterile distilled water for 30 s and plated on Martin's selective medium at 26°C in a chamber without light. Colonies grew with cottony aerial mycelium. Main hyphae were 5.7 to 9.6 μm wide. Globose sporangia consisting of terminal complexes of swollen hyphal branches were 11.4 to 18.3 μm wide. The average diameter of zoospores was 9.2 μm. The oogonia were globose and smooth, with a diameter of 21 to 33 μm. The sequences of the rRNA gene internal transcribed spacer (ITS) regions 1 and 2 and the 5.8S gene of five isolates were amplified using primers ITS1 and ITS4 (4), and the nucleotide sequence was the same as isolate No. 2, which was deposited in GenBank (Accession No. KC594034). A BLAST search showed 99% identity with Pythium aphanidermatum strain 11-R-8 (Accession No. JQ898455.1). Pathogenicity tests of five isolates were carried out in a greenhouse. Sixty plants (cv. Laiwu Big Ginger) were grown for 30 days in plastic pots (diameter 20 cm) in sandy soil (pH 5.48) and inoculated. Ten plants were used as untreated controls. Five isolates were grown on Martin's liquid medium for 72 h and the spores were harvested in sterile distilled water. Aqueous spore suspensions of the five isolates were adjusted with deionized water to 1 × 108 CFU/ml and injected with a syringe into the soil around the rhizome of the plants. Plants were then placed in the greenhouse at 24 to 26°C and assessed for rhizome rot on the 14th day after inoculation. The inoculated isolates were recovered from the diseased rhizomes, confirming their pathogenicity. To our knowledge, this is the first report of ginger Pythium soft rot caused by P. aphanidermatum in China. Ginger Pythium soft rot caused by P. myriotylum is reported in Taiwan (3). References: (1) F. N. Martin. Page 39 in: The Genus Pythium. American Phytopathological Society, St. Paul, MN, 1992. (2) E. E. Trujillo. Diseases of Ginger (Zingiber officinale) in Hawaii, Circular 62, Hawaii Agricultural Experiment Station, University of Hawaii, December 1964. (3) P. H. Wang. Lett. Appl. Microbiol. 36:116, 2003. (4) T. J. White. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

Pythium myriotylum. [Descriptions of Fungi and Bacteria].

1966 ◽  
Author(s):  
G. M. Waterhouse
Keyword(s):  
Geographical Distribution ◽  
Robinia Pseudoacacia ◽  
Solanum Melongena ◽  
Aerial Mycelium ◽  
Zingiber Officinale ◽  
Soft Rot ◽  
Fruit Rot ◽  
Ananas Comosus ◽  
Damping Off ◽  
Pythium Myriotylum

Abstract A description is provided for Pythium myriotylum. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Ananas comosus, Arachis hypogaea, Carica papaya, Citrullus vulgaris, Cucumis sativus, Lycopersicon esculentum, Medicago sativa, Nicotiana tabacum, Oryza sativa, Phaseolus vulgaris, Robinia pseudoacacia, Solanum melongena, Zingiber officinale. DISEASES: Damping-off of seedlings including tobacco, black locust and watermelon; seedling root rot of lucerne, papaw and tomato; soft rot of ginger rhizomes and fruit rot of watermelon, cucumber and eggplant. GEOGRAPHICAL DISTRIBUTION: Common only in warm climates: Africa (Madagascar, Nigeria, Sierra Leone, South Africa); Asia (Ceylon, India, Sumatra); Australasia (Australia); North America (U.S.A.). TRANSMISSION: Soil-borne. Incidence reported highest in virgin soil containing abundant decomposing organic matter (37: 244). Spread by aerial mycelium under conditions of high humidity (10: 210). Transport over long distances on ginger rhizomes has been reported (22: 197).

scholarly journals Pythium Soft Rot Management in Ginger (Zingiber officinale Roscoe) – A Review

2020 ◽  
pp. 106-115
Author(s):  
Sunita Behera ◽  
Parshuram Sial ◽  
Himangshu Das ◽  
Kedareswar Pradhan
Keyword(s):  
Seed Treatment ◽  
Management Strategies ◽  
Zingiber Officinale ◽  
Soft Rot ◽  
Copper Oxychloride ◽  
Trichoderma Spp ◽  
Sowing Time ◽  
Main Production ◽  
Rot Disease ◽  
Pythium Soft Rot

Ginger crop is affected by various diseases. Among them rhizome/soft rot is the most damaging one and main production constraint in ginger growing areas. This disease is mainly caused by the Pythium spp. along with association of some others micro-organisms. The severity of Pythium soft rot disease is influenced by different factors related to seed, environment and soil. This study was focused on Pythium soft rot of ginger with special reference to different management strategies. Different cultural measures viz. seed rhizome treatment before storage and sowing, selection of disease free seed rhizome, sowing time, application of soil amendments, good drainage of soil, soil solarization etc. are the important measures for management of ginger soft rot. Seed treatment and soil drenching are the two options of chemical control of soft rot. Seed rhizomes treated with fungicides azoxystrobin 25%, tebuconazole 25.9%, copper oxychloride 50%, carbendazim 50%, propiconazole 25%, metalaxyl-M 4% + mancozeb 64%, metiram 55% + pyraclostrobin 5%, carbendazim 12% + mancozeb 63%, tebuconazole 25% + trifloxystrobin 25% and metalaxyl 8% + mancozeb 64% resulted in effective management. Different fungicide formulations viz. carbendazim 50%, copper oxychloride 50%, metalaxyl-M 4% + mancozeb 64%, metiram 55% + pyraclostrobin 5%, carbendazim 12% + mancozeb 63%, tebuconazole 25% + trifloxystrobin 25% etc. found effective for spraying. Seed treatment and application of Trichoderma spp. found suitable for effective biological management.

scholarly journals First Report of Sclerotinia Stem Rot and Watery Soft Rot Caused by Sclerotinia sclerotiorum on Sand Rocket (Diplotaxis tenuifolia) in Italy

Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1241-1241 ◽  
Author(s):  
A. Garibaldi ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
Relative Humidity ◽  
Sclerotinia Sclerotiorum ◽  
Severe Disease ◽  
Soil Surface ◽  
Soft Rot ◽  
Sclerotinia Stem Rot ◽  
First Report ◽  
Initial Symptoms ◽  
Stem Necrosis ◽  
White Mycelium

Several species of Diplotaxis (D. tenuifolia, D. erucoides, and D. muralis), known as wild or sand rocket, are widely cultivated in Italy. Rocket is used in Mediterranean cuisine as salad, a component of packaged salad products, and as a garnish for food. In winter 2003, a severe disease was observed on D. tenuifolia grown in unheated glasshouses on commercial farms near Albenga in northern Italy. Initial symptoms included stem necrosis at the soil level and darkening of leaves. As stem necrosis progressed, infected plants wilted and died. Wilt, characterized by the presence of soft and watery tissues, occurred within a few days on young plants. The disease was extremely severe in the presence of high relative humidity and mild temperature (15°C). Necrotic tissues became covered with white mycelium that produced dark sclerotia. Diseased stem tissue was disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 ppm streptomycin sulfate. Sclerotinia sclerotiorum (1) was consistently recovered from infected stem pieces. Sclerotia observed on infected plants measured 1.23 to 3.00 × 1.40 to 5.38 mm (average 2.10 × 2.85 mm). Sclerotia produced on PDA measured 1.00 to 4.28 × 1.00 to 6.01 mm (average 2.38 × 3.23 mm). Pathogenicity of three isolates obtained from infected plants was confirmed by inoculating 30-day-old plants of D. tenuifolia grown in 18-cm-diameter pots in a glasshouse. Inoculum, 2 g per pot of wheat kernels infested with mycelium and sclerotia of each isolate, was placed on the soil surface around the base of each plant. Three replicates of five pots each were used per isolate. Noninoculated plants served as controls. The inoculation trial was repeated once. All plants were kept at temperatures ranging between 10 and 26°C (average 15°C) with an average relative humidity of 80% and were watered as needed. Inoculated plants developed symptoms of leaf yellowing within 12 days, soon followed by the appearance of white mycelium and sclerotia, and eventually wilted. Control plants remained symptomless. S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of infection of D. tenuifolia by S. sclerotiorum in Italy as well as worldwide. The disease currently has been observed in the Liguria Region but not yet in other areas where sand rocket is cultivated. The economic importance of this disease for the crop can be considered medium at the moment, but is expected to increase in the future. Reference: (1) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift, 75, 1949.

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