The response of potato (Solanum tuberosum L) to the fungus Rhizoctonia solani

Rhizoctonia solani is a soilborne fungal pathogen of many economically important crops Thirteen closely related anastomosis groups (AGs) of this pathogen have been identified each of which affects different plant species Previous studies have suggested that R solani AG3 is the main cause of disease in potato Rhizoctonia solani infection of potato plants can result in stem canker and tubers with black scurf Affected plants give a reduced yield while affected tubers are considered to have reduced quality resulting in economic loss The current study investigated the response of different potato cultivars and lines to R solani AG3 Thirtytwo potato cultivars/lines many actively used in the Plant Food Research potato breeding programme were screened in a shadehouse pot trial The trial was laid out in an adapted resolvable block design to ensure uniform exposure to environmental factors Each cultivar had six replicates four with and two without AG3 inoculum Plants were grown to maturity and the resulting tubers were assessed for disease (black scurf) Preliminary results show that none of the lines/cultivars tested were resistant but degrees of susceptibility varied In this experiment stem canker was not observed in any of the lines/cultivars

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Anastomosis Groups and Pathogenicity of Rhizoctonia solani and Binucleate Rhizoctonia from Potato in South Africa

Plant Disease ◽

10.1094/pdis-02-15-0236-re ◽

2015 ◽

Vol 99 (12) ◽

pp. 1790-1802 ◽

Cited By ~ 17

Author(s):

N. Muzhinji ◽

M. Truter ◽

J. W. Woodhall ◽

J. E. van der Waals

Keyword(s):

South Africa ◽

Rhizoctonia Solani ◽

Stem Canker ◽

Black Scurf ◽

Bootstrap Support ◽

Internal Transcribed Spacer Region ◽

Binucleate Rhizoctonia ◽

Anastomosis Groups ◽

Potato Plants ◽

Comprehensive Survey

A survey of anastomosis groups (AG) of Rhizoctonia spp. associated with potato diseases was conducted in South Africa. In total, 112 Rhizoctonia solani and 19 binucleate Rhizoctonia (BNR) isolates were recovered from diseased potato plants, characterized for AG and pathogenicity. The AG identity of the isolates was confirmed using phylogenetic analysis of the internal transcribed spacer region of ribosomal DNA. R. solani isolates recovered belonged to AG 3-PT, AG 2-2IIIB, AG 4HG-I, AG 4HG-III, and AG 5, while BNR isolates belonged to AG A and AG R, with frequencies of 74, 6.1, 2.3, 2.3, 0.8, 12.2, and 2.3%, respectively. R. solani AG 3-PT was the most predominant AG and occurred in all the potato-growing regions sampled, whereas the other AG occurred in distinct locations. Different AG grouped into distinct clades, with high maximum parsimony and maximum-likelihood bootstrap support for both R. solani and BNR. An experiment under greenhouse conditions with representative isolates from different AG showed differences in aggressiveness between and within AG. Isolates of AG 2-2IIIB, AG 4HG-III, and AG R were the most aggressive in causing stem canker while AG 3-PT, AG 5, and AG R caused black scurf. This is the first comprehensive survey of R. solani and BNR on potato in South Africa using a molecular-based approach. This is the first report of R. solani AG 2-2IIIB and AG 4 HG-I causing stem and stolon canker and BNR AG A and AG R causing stem canker and black scurf on potato in South Africa.

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In vitro evaluation of fungicidal responses on the growth of pathogenic Rhizoctonia solani Kuhn, antagonistic binucleate Rhizoctonia and Trichoderma harzianum Rifai

Bangladesh Journal of Botany ◽

10.3329/bjb.v39i1.5534 ◽

1970 ◽

Vol 39 (1) ◽

pp. 107-110

Author(s):

Md Maniruzzaman Khandaker ◽

Md Khurshed Alam Bhuiyan ◽

Abul Khair

Keyword(s):

Boric Acid ◽

Rhizoctonia Solani ◽

Key Words ◽

Trichoderma Harzianum ◽

Stem Canker ◽

Black Scurf ◽

Binucleate Rhizoctonia ◽

Crop Fields ◽

Potato Plants

Two pathogenic isolates of Rhizoctonia solani Kuhn causing stem canker/black scurf disease of potato plants and four antagonist isolates, two of binucleate Rhizoctonia and two of Trichoderma harzianum Rifai were isolated from crop fields and evaluated in vitro for their fungicidal responses against eight fungicides. Vitavax was effective in inhibiting the growth of R. solani and binucleate Rhizoctonia but it did not inhibit the growth of T. harzianum at 100 ppm concentration. Terraclor Super X, Dithane M 45 and Boric acid are the fungicides which at 100 ppm concentration did not inhibit the growth of antagonist isolates of T. harzianum and binucleate Rhizoctonia but inhibited the growth of isolates of R. solani to some extent. The in vitro findings suggest that any one of these three fungicides along with antagonist isolates of binucleate Rhizoctonia and T. harzianum can be used as biocontrol agents to reduce soil borne inocula of R. solani. Key words: Rhizoctonia solani; Binucleate; Trichoderma harzianum; Fungicide DOI: 10.3329/bjb.v39i1.5534Bangladesh J. Bot. 39(1): 107-110, 2010 (June)

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Formation of canker lesions on stems and black scurf on tubers in experimentally inoculated potato plants by isolates of AG2-1, AG3 and AG5 of Rhizoctonia solani: a pilot study and literature review

Agricultural and Food Science ◽

10.2137/145960609790059415 ◽

2008 ◽

Vol 18 (3-4) ◽

pp. 223 ◽

Cited By ~ 4

Author(s):

M.J. LEHTONEN ◽

P.S. WILSON ◽

P. AHVENNIEMI

Keyword(s):

Pilot Study ◽

Rhizoctonia Solani ◽

Stem Canker ◽

Potato Production ◽

Anastomosis Group ◽

Black Scurf ◽

Potato Tubers ◽

Potato Plants ◽

Production Areas ◽

Potato Crops

Development of black scurf on potato tubers (cv. Nicola) was compared in plants inoculated with isolates of Rhizoctonia solani of three anastomosis groups (AG2-1, AG3 and AG5) which occur in potato crops in Finland. All isolates induced stem canker lesions but only isolates of AG3 formed efficiently black scurf on progeny tubers. Among the AG2-1 and AG5 isolates tested, only one AG2-1 isolate formed a few sclerotia on 13.5 % of the progeny tubers in one experiment. The data indicate that isolates of AG3 differ from those of AG2-1 and AG5 in having a higher ability to form sclerotia on tubers. Therefore, while AG2-1 and AG5 isolates have a broader host range, AG3 is more efficient in producing black scurf, which provides this anastomosis group with more efficient means of dissemination on seed potatoes. These differences probably explain the predominance of AG3 (98.9 % of isolates) in potato crops in Finland and other northern potato production areas.;

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Anastomosis Grouping of Rhizoctonia solani Associated with Black Scurf and Stem Canker of Potato in South Africa

Plant Disease ◽

10.1094/pdis.2004.88.1.83b ◽

2004 ◽

Vol 88 (1) ◽

pp. 83-83 ◽

Cited By ~ 8

Author(s):

M. Truter ◽

F. C. Wehner

Keyword(s):

South Africa ◽

Rhizoctonia Solani ◽

Rating Scale ◽

Solanum Tuberosum L ◽

Potato Cultivar ◽

Stem Canker ◽

Potato Production ◽

Black Scurf ◽

Chi Square ◽

Chi Square Analysis

Rhizoctonia disease (black scurf of tubers and stem canker) of potato (Solanum tuberosum L.) caused by Rhizoctonia solani Kühn was first recorded in South Africa in 1918 (3). Although the sclerotial form on tubers is one of the most common potato diseases in the country, it is not known which anastomosis groups (AGs) of R. solani are involved. Between 1999 and 2001, R. solani was isolated from 28 plant and 56 soil samples collected in 7 (Eastern Free State, Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga, Northern Cape, and Sandveld) of the 14 potato-production regions of South Africa and screened for hyphal anastomosis with tester strains of R. solani AG-1 to AG-10 according to Carling et al. (1). Of the 411 isolates from tubers with black scurf symptoms, 408 were AG-3 and three were AG-5. Symptomless tubers yielded two AG-3 isolates and three AG-5 isolates. Of 39 isolates from symptomatic stems and roots, 32 were AG-3, five were AG-4, and two were AG-5. Of the 127 isolates obtained from soil, 86, 28, 7, 3, and 3 were AG-3, AG-4, AG-5, AG-7, and AG-8, respectively. More than one AG was isolated from five of the seven regions. Virulence of 40 isolates representative of the above AGs was determined in triplicate on sprouts growing from seed tubers of potato cultivar Up-to-Date in a sand/soil mixture as described by Carling and Leiner (2) but using cultures grown in cornmeal/sand instead of colonized agar disks as inoculum. Damage to sprouts (lesions, girdling, and death) was assessed after 28 days at 16 to 28°C according to the 0 to 4 rating scale (2). Chi-square analysis of the data indicated that AG-3 was the most virulent, with isolates from sclerotia on tubers and lesions on stems more aggressive than those from symptomless tubers or soil. AG-4 and AG-5 caused significantly less disease than AG-3, but none of the AG-7 and AG-8 isolates showed any virulence to potato sprouts. References: (1) D. E. Carling et al. Phytopathology 77:1609, 1987. (2) D. E. Carling and R. H. Leiner. Phytopathology 80:930, 1990. (3) E. M. Doidge. S. Afr. Fruit Growers 5:6, 1918.

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