Yield losses and damage to potato plants caused by Rhizoctonia solani Kuhn

1989 ◽  
Vol 66 (12) ◽  
pp. 821-834 ◽  
Author(s):  
G. J. Banville
Plant Disease ◽  
2015 ◽  
Vol 99 (12) ◽  
pp. 1790-1802 ◽  
Author(s):  
N. Muzhinji ◽  
M. Truter ◽  
J. W. Woodhall ◽  
J. E. van der Waals

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.


Nematology ◽  
2019 ◽  
Vol 21 (6) ◽  
pp. 613-623 ◽  
Author(s):  
James M. Mwangi ◽  
Björn Niere ◽  
Matthias Daub ◽  
Maria R. Finckh ◽  
Sebastian Kiewnick

Summary Globodera pallida infestation on potato is responsible for huge yield losses globally. Screening of potato germplasm for resistance to the nematode at the early stages of a breeding programme can significantly enhance resistance-based management. This study assessed the suitability of tissue culture (TC)-derived potato plants as screening material for resistance to G. pallida. Reproduction of the nematode on TC plants was similar to the reproduction on tuber- and eye-plug-derived plants. The pot volume, inoculum density and inoculation time had a significant effect on the reproduction. A positive correlation was found between the mean number of white females on the root surface and the final number of nematode cysts after extraction. Resistance ranking using TC plants and the tubers yielded comparable results, thus justifying the use of TC in the screening process. Tissue culture plants have the potential of speeding up the screening process and reducing resource requirements, thus lowering breeding cost.


Nematology ◽  
2010 ◽  
Vol 12 (5) ◽  
pp. 783-790 ◽  
Author(s):  
Shuvash Bhattarai ◽  
Patrick P.J. Haydock ◽  
Matthew A. Back ◽  
Martin C. Hare ◽  
William T. Lankford

Abstract This research elucidates interactions between Globodera pallida and Rhizoctonia solani (AG3) by comparing disease development in potato plants inoculated with G. pallida and R. solani. The effects of juvenile population density and time of infestation on R. solani disease were investigated in controlled environments. Plants were inoculated with a range of densities of second-stage juveniles (J2) of G. pallida (800, 4000, 10 000, 20 000 and 40 000 J2/plant) and R. solani at 2, 4 and 6 weeks after planting and a single treatment of G. pallida density and R. solani alone. The experiment demonstrated that greatest disease incidence and severity occurred when high population densities of G. pallida were applied at an early stage of plant development. To determine if this effect could explain differences in R. solani disease incidence and severity following interactions with individual field populations of G. pallida, a glasshouse experiment was conducted using two populations of G. pallida with known hatching characteristics (fast and slow hatching). The experiment revealed that a combination of a fast-hatching population with R. solani caused significantly more R. solani disease incidence and severity than a population of G. pallida with slower hatching characteristics.


Author(s):  
Xiaoyu Wang ◽  
Aimin Wang ◽  
Zhiyi Chen ◽  
Lihui Wei

Rice aggregate sheath spot disease occurs in many countries, causing serious yield losses. In China, the disease-causing fungus Rhizoctonia oryzae-sativae was reported in 1985, and since then, it has rarely been reported in major rice-growing areas after almost 30 years. Compared with Rhizoctonia solani, R. oryzae-sativae has a significantly different physiological morphology and growth status, although both fungi affect rice leaves in very similar ways. The optimum temperature for the suitable growth of R. oryzae-sativae is 31 °C, which is consistent with previous reports. We extracted phytotoxins from R. oryzae-sativae and analyzed its biological activity via the detached leaf and radicle inhibition methods. Rhizoctonia solani and R. oryzae-sativae exhibit differences in terms of pathogenicity and toxins activity, which indicates that these fungi may produce different toxins components. Based on gas chromatography–mass spectrometry data, esters, phenols, and other components were present in the crude toxins extract of R. oryzae-sativae. Our research provides a new method for studying the phytotoxins of R. oryzae-sativae. However, further studies are needed to elucidate the pathogenic mechanisms responsible for the aggregate sheath spot disease on rice.


1970 ◽  
Vol 39 (1) ◽  
pp. 107-110
Author(s):  
Md Maniruzzaman Khandaker ◽  
Md Khurshed Alam Bhuiyan ◽  
Abul Khair

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)


Author(s):  
Sorina DINU ◽  
Oana Alina BOIU-SICUIA ◽  
Florica CONSTANTINESCU

Some Bacillus based bioproducts were analyzed for their plant growth promotion and Rhizoctonia solani biocontrol potential in potato plants. The bioproducts were formulated as concentrated aqueous suspension, each containing one of the following plant beneficial bacteria: Bacillus safensis Rd.b2, Bacillus spp. 75.1s and Cp.b4 strains. These were applied on potato seeding material in order to evaluate plant growth promotion effects. The biocontrol efficacy was also evaluated, using Rhizoctonia solani DSM 63002 as plant pathogen, and Prestige 290FS as reference chemical treatment.In the plant growth-promotion experiments, several biologic parameters were biometrically evaluated. Best results regarding plant growth and vigor were obtained using CropMax, a commercial phytostimulatory product. However, the bacterial treatment with Bacillus spp. Cp.b4 and 75.1s showed an improved plant growth compared to the untreated control. An efficacy of 93.75% against Rhizoctonia dumping-off was registered when using the Prestige 290FS chemical control. Mix treatments based on this pesticide, in low dose, combined with Cp.b4 or 75.1s biocontrol strains significantly reduced the pathogenic attack, showing 85 to 87.5% efficacy.The present research demonstrated that the bacterial bioproducts based on Bacillus spp. 75.1s and Cp.b4 strains increase plant growth and are highly effective in controlling Rhizoctonia attack in potato plants.


Author(s):  
Shweta Singh ◽  
Jaiganesh Rengarajan ◽  
Iyappan Sellamuthu

The adverse effect of pesticides used for controlling pests and the diseases caused by them is extensively rising. To overcome this harmful environmental impact, alternative methods are being studied and developed. Out of many possible methods, one effective method is to use plant extracts which embodies natural substances having antifungal properties. In an attempt towards enhancement of sustainable antifungal approach, four different concentrations of four plant extracts Citrus limon, Azadirachta indica, Ocimum gratissimum and Acalypha indica, were tested for their antifungal activity against Rhizoctonia solani, which is a serious threat for plants, and is responsible for considerable crop and yield losses. The aim of this study is to minimize yield losses and to regain the attention of formers towards exploiting natural resources for diseases control. From the results, it can be concluded that different concentrations of plant extracts have caused substantial inhibition in the mycelial growth of R. solani. The leaf extract of Ocimum gratissimum was highly effective in inhibiting mycelial growth, at the concentration of 500mg/ml of extract followed by Citrus limon, Azadirachta indica, and Acalypha indica. These plants might have potential for the development of natural fungicide for the management of diseases caused by fungal pathogens. Also, fungicides developed from these botanical extracts can prove to be highly effective for the management of plant diseases and would be simply obtainable, nonpolluting, biodegradable and economical.


1990 ◽  
Vol 68 (1) ◽  
pp. 43-49
Author(s):  
B. E. Otrysko ◽  
G. J. Banville ◽  
A. Asselin

We tested the hypothesis that phenolic compounds initiate the formation of sclerotia in Rhizoctonia solani AG 3. Water soluble substances were recovered in situ from the underground parts of undisturbed potato plants by adsorption onto columns fitted with a water circulating device. These extracts inhibited mycelial growth of five isolates of R. solani belonging to anastomosis groups AG 1, AG 2, AG 3 and AG 4. However, there was no effect on the initiation of sclerotia. Fourteen phenolic compounds were bioassayed in vitro at concentrations ranging from 10−3 to 10−6 M against these same isolates. Phenolic acids had no significant effect on mycelial growth, whereas the substituted aldehydes were inhibitory at 10−3 and 10−4 M. There was no visible effect on sclerotial initiation.


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