First Report of Sclerotium rolfsii Causing Stem Rot of Luffa cylindrica in Brazil

Mexican petunia (Ruellia brittoniana) is an herbaceous flowering perennial with strikingly colored flowers, widely cultivated commercially as a potted plant and a popular garden plant. In July of 2010, root and stem rot that caused death was observed on Mexican petunia at the flower nursery of the Council of Agriculture & Chiayi County in Taiwan. Plants had rotted and girdled stem bases. Necrotic areas were covered with fans of white mycelium as well as abundant spherical sclerotia. A fungus was isolated from infected tissue and sclerotia, and maintained on potato dextrose agar (PDA) plates incubated at 25°C without light. Colonies were white, cottony, often forming fans; pure cultures were prepared by transferring hyphal tips to PDA. Sclerotia formed after 10 days, initially white becoming dark brown with age, and 0.5 to 0.6 mm in diameter. To confirm identity of the causal fungus, the complete internal transcribed spacer (ITS) rDNA region of the causal fungus was amplified using the primers ITS4 and ITS5 (2) and sequenced. The resulting sequence of 687 bp was uploaded in NCBI. The sequence was 98% similar to sequences of Athelia rolfsii (Sclerotium rolfsii) in NCBI (Accession No. JN543691.1). Koch's postulates were performed using two inoculation techniques. The soil near the base of healthy Mexican petunia plants (four plants per pot) were exposed to recently matured sclerotia (10 sclerotia per plant) developed from pure fungal cultures or 10-mm-diameter agar plugs of mycelium (one plug per plant). Noninoculated plants, in a separate pot, were used as a control. All plants were incubated in a growth chamber at 28 to 33°C. Disease symptoms occurred on all inoculated plants by 5 to 7 days and included yellowing of leaves, basal stem rot, and wilt. Ten days after inoculation, inoculated plants were dead whereas control plants remained healthy. The pathogenicity test was repeated twice with similar results and S. rolfsii was reisolated from infected plants in each test. The pathogen has been reported to cause substantial loss of Mexican petunia in Louisiana (1). The disease is becoming more common in Taiwan and could cause losses in Mexican petunia production. To our knowledge, this is the first report of disease on Mexican petunia caused by S. rolfsii in Taiwan. References: (1) G. E. Holcomb. Plant Dis. 88:770, 2004. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, 1990.

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First Report of Stem Rot of Huangjing (Polygonatum sibiricum) Caused by Sclerotium rolfsii

Plant Disease ◽

10.1094/pdis-09-20-1891-pdn ◽

2020 ◽

Author(s):

Qingqun Tan ◽

Dailin Zhao ◽

Xuehui Yang ◽

Na Wang ◽

Haiyong. He

Keyword(s):

Biological Activities ◽

Sclerotium Rolfsii ◽

Pcr Amplification ◽

Fungal Species ◽

Its Sequences ◽

Stem Rot ◽

First Report ◽

Athelia Rolfsii ◽

Microscopic Field ◽

Alignment Analysis

Huangjing (Polygonatum sibiricum) is a medicinal plant widely distributed in China, Japan, and Korea. The dried rhizome of Huangjing has been reported to have many pharmacological applications and biological activities, such as antioxidants, immunity enhancement, anti-fatigue, anti-osteoporosis, and anti-aging activity (Cui et al., 2018). In June 2018, we observed some wilted Huangjing plants in commercial plantings in Shuicheng, Guizhou, China (26.22 N, 104.76 E). Symptoms began as moderate to severe wilting of stems and necrosis of leaves, followed by the death of plants. The collar rot appeared on the stem near to the soil. When incubated at 28°C and 100% relative humidity (RH) for 8 to 10 days, the infected stem produced brown sclerotia. We picked the sclerotia and cultured them on potato dextrose agar (PDA) supplemented with 50 μg/ml of streptomycin. The hyphal tips generated by the sclerotia was isolated under microscopic field and transferred to the fresh PDA. Three isolates (HJ-1, HJ-6 and HJ-10) came from the hyphal tips formed the typical clamp connection structure at 6-7 days post-incubation and the sclerotia of them were white and the late ones turned dark brown. The matured sclerotia were globular, 1.5 to 3.3 mm (avg. 2.2) in diameter. The morphologic observation revealed that three isolates were consistent with Athelia rolfsii (Paul et al., 2017). To further confirm the fungal species, the ribosomal internal transcribed spacer (ITS) sequences were amplified and sequenced. Primers and PCR amplification were referenced as previously described (Paul et al., 2017). The sequences were compared to type sequences in GenBank. The ITS sequences (GenBank accession MT478452, MT949696 and MT949697) of the isolates (HJ-10, HJ-1 and HJ-6) were 99% identical with strain 13M-0091 (GenBank accession KT222898) of A. rolfsii, respectively (Paul et al., 2017). A maximum likelihood tree was constructed using MEGA-X version 10.1.6 (Kumar et al., 2018) based on the ITS sequences of the three strains (HJ-10, HJ-1 and HJ-6) and that of Athelia spp. previously deposited in GenBank (Paul et al., 2017). Phylogenetic analysis showed that the isolates (HJ-10, HJ-1 and HJ-6) belong to the A. rolfsii clade. Based on morphology and DNA sequencing, the isolates (HJ-10, HJ-1 and HJ-6) were identified as A. rolfsii. To verify pathogenicity, Huangjing seedlings were inoculated with colonized agar discs of the isolates. Additional Huangjing plants inoculated with uncolonized agar discs were used as the control. After inoculation, Huangjing seedlings were moved to the inoculation chamber under high humidity and 28°C for 3 days and then transferred to a greenhouse. The typical wilting symptoms appeared 8 days after inoculation and were similar to those observed in the field, while control plants remained symptomless. The causing agents were isolated from the lesions and the ITS sequences of them were sequenced again. The alignment analysis of the ITS sequences showed the causing agents are consistent with the original isolates. These studies fulfilled Koch’s postulates. To our knowledge, this is the first report of A. rolfsii causing stem rot on Huangjing.

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First Report of Stem Rot Disease of Rose Mallow (Hibiscus rosa-sinensis) Caused by Sclerotium rolfsii in India

Plant Disease ◽

10.1094/pdis-09-18-1480-pdn ◽

2019 ◽

Vol 103 (9) ◽

pp. 2475

Author(s):

Amar Bahadur ◽

Deeba Kamil ◽

Prasenjit Debnath ◽

Anjali Kumari ◽

Akanksha Tyagi ◽

...

Keyword(s):

Sclerotium Rolfsii ◽

Stem Rot ◽

First Report ◽

Hibiscus Rosa Sinensis ◽

Rot Disease

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First Report of Southern Blight of Ruellia brittoniana Caused by Sclerotium rolfsii in Louisiana

Plant Disease ◽

10.1094/pdis.2004.88.7.770a ◽

2004 ◽

Vol 88 (7) ◽

pp. 770-770

Author(s):

G. E. Holcomb

Keyword(s):

Root Rot ◽

High Speed ◽

Sclerotium Rolfsii ◽

Stem Rot ◽

Basal Stem Rot ◽

First Report ◽

Southern Blight ◽

Agar Plug ◽

Leaf Yellowing ◽

Pathogenicity Tests

Ruellia brittoniana, Mexican petunia, is an herbaceous flowering perennial grown in hardiness zones 8 to 10 in the southern and western United States. Popular dwarf forms with flower colors of white, pink, and blue are used as ground covers and borders. In April of 2003, root and stem rot that caused plant death was observed on cv. Katie (dwarf form, pink flowers) at a wholesale nursery in southern Louisiana. Plants were growing in a vermiculite and sand mix. The grower had purchased the plants from an out-of-state source, and approximately one-half of 1,440 plants were dead or dying. Symptoms included wilt, basal stem rot, and root rot. Peripheral roots were covered with a white mycelial layer that contained white sclerotial initials and small, brown sclerotia. Fungal isolates from infected roots grown on potato dextrose agar (PDA) produced white mycelia and 1- to 2-mm-diameter dark brown sclerotia. Sclerotia were nearly round with smooth surfaces and distributed over the entire colony. Isolates were identified as Sclerotium rolfsii on the basis of mycelial characteristics and color, size, and distribution of sclerotia. Two-month-old seedlings (6 to 10 cm high) of R. brittoniana, from seed of cv. Katie, were used in pathogenicity tests. Inoculum was grown in 10-cm-diameter plastic, culture dishes on PDA medium. Blended inoculum was prepared from a single 1-week-old culture that was composed of mycelia and sclerotia and blended 4 to 6 s at high speed in 100 ml of distilled water. In test one, 5 ml of inoculum was placed at the base of each inoculated plant. In test two, a single 5-mm-diameter agar plug with mycelium plus four sclerotia was placed beside plant stems near soil line. In test three, 5 ml of blended inoculum was dripped on exposed roots after plants were removed from pots. In test four, exposed plant roots were dipped in the blended inoculum. Each test contained 10 inoculated plants, and 10 noninoculated plants served as controls. All plants were placed in a dew chamber maintained at 28°C for 2 days and then returned to a greenhouse to observe development of symptoms and signs of disease. In tests one and two, basal stem rot and wilt developed on inoculated plants after 2 days and after 5 to 8 days all were dead. Inoculated plants from tests three and four were alive 4 months after inoculation, but were showing symptoms including leaf yellowing and drop, moderate to severe root rot, and some plants had begun to show white mycelia and white sclerotial initials on peripheral roots by January 2004. All noninoculated plants remained healthy and S. rolfsii was reisolated from infected plants in each test. To my knowledge, this is the first report of S. rolfsii causing disease on R. brittoniana.

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First Report of Stem Rot on Hosta plantaginea caused by Sclerotium rolfsii in Korea

The Plant Pathology Journal ◽

10.5423/ppj.2010.26.3.297 ◽

2010 ◽

Vol 26 (3) ◽

pp. 297-297 ◽

Cited By ~ 6

Author(s):

Jin-Hyeuk Kwon ◽

Tran Thi Phuong Chi ◽

Jin-Woo Kim

Keyword(s):

Sclerotium Rolfsii ◽

Stem Rot ◽

First Report

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Screening of biological control agent fungi against peanut stem rot (Sclerotium rolfsii Sacc.) in the peatlands of Kuala Pesisir Nagan Raya, Aceh, Indonesia

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/667/1/012007 ◽

2021 ◽

Vol 667 (1) ◽

pp. 012007

Author(s):

I Subandar ◽

L Hakim ◽

I Suliansyah ◽

S Syakur

Keyword(s):

Biological Control ◽

Biological Control Agent ◽

Sclerotium Rolfsii ◽

Control Agent ◽

Stem Rot

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A Comparison of Disease Assessment Methods for Southern Stem Rot of Peanut

Peanut Science ◽

10.3146/pnut.29.1.0012 ◽

2002 ◽

Vol 29 (1) ◽

pp. 66-71 ◽

Cited By ~ 4

Author(s):

S. L. Rideout ◽

T. B. Brenneman ◽

K. L. Stevenson

Keyword(s):

Alternative Assessment ◽

Disease Incidence ◽

Sclerotium Rolfsii ◽

Correlation Coefficients ◽

Assessment Method ◽

Assessment Methods ◽

Alternative Methods ◽

Stem Rot ◽

Disease Assessment ◽

Time Required

Abstract Southern stem rot (caused by the soilborne fungus Sclerotium rolfsii Sacc.) of peanut (Arachis hypogaea L.) traditionally has been assessed based on the percentage of infected 30.5-cm row segments, commonly referred to as disease incidence. Several alternative disease assessment methods were evaluated in four fungicide trials during the growing season (aboveground ratings) and immediately after peanut inversion (belowground ratings). Pearson's correlation coefficients compared disease assessments and yields for all trials. Across all disease assessment methods, belowground assessments at inversion showed a stronger correlation with yield than in-season aboveground assessments. Several of the alternative assessment methods showed a stronger negative correlation with yield than did the traditional disease incidence rating. However, none of the alternative methods were consistently more precise across all assessment dates and trials. There was a significant positive correlation between many of the alternative methods and the traditional disease incidence method. Furthermore, none of the alternative methods was better than the traditional method for detecting differences among fungicide treatments when subjected to ANOVA and subsequent Waller-Duncan mean separation tests (k-ratio = 100). Based on comparisons of the time required to assess disease intensity, the traditional disease assessment method was found to be the most time efficient method of those tested in this study.

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