scholarly journals Controlling Rhizoctonia Damping-off of Chinese Mustard by Using Endomycorrhizal Rhizoctonia spp. Isolated from Orchid Mycorrhizae

Plant Disease ◽  
2016 ◽  
Vol 100 (1) ◽  
pp. 85-91 ◽  
Author(s):  
Jr-Hau Jiang ◽  
Si-Loi Tam ◽  
Takeshi Toda ◽  
Lung-Chung Chen
Keyword(s):  
Phylogenetic Analysis ◽  
Rhizoctonia Solani ◽  
Disease Severity ◽  
Anastomosis Group ◽  
Effective Strategy ◽  
Damping Off ◽  
Binucleate Rhizoctonia ◽  
Orchid Mycorrhizae ◽  
Almost All ◽  
Test Plants

Inoculation of hypovirulent Rhizoctonia spp. has been recognized as an effective strategy for protecting plants against damping-off caused by pathogenic Rhizoctonia spp. In this study, endomycorrhizal Rhizoctonia spp. isolated from fungal pelotons in orchid plants were used for controlling Rhizoctonia damping-off of Chinese mustard. According to phylogenetic analysis and anastomosis group (AG) determination, the virulence of three isolates of multinucleate Rhizoctonia solani in AG-6; eight isolates of binucleate Rhizoctonia in AG-A, AG-B, AG-G, AG-P, and AG-R; and two isolates of binucleate R. repens were evaluated using test plants. All isolates, except that in AG-R, caused low disease severity in 10-day-old radish (0.10 to 0.61), cucumber (0.28 to 0.54), and Chinese mustard (0.18 to 0.65). By contrast, pathogenic isolates in AG-4 killed almost all test plants with symptoms of collapsed hypocotyl and wilted leaves (0.88 to 0.96). Of the 13 endomycorrhizal Rhizoctonia isolates assessed, AG-P isolates Cno10-3 and CalS1-2 provided 91 and 100% protection, respectively, against R. solani AG-4 in 26-day-old Chinese mustard. This study revealed that endomycorrhizal Rhizoctonia spp. in orchid have the potential to biologically control damping-off of Chinese mustard.

Severity, Distribution, and Losses from Taproot Cankers Caused by Rhizoctonia solani in Peanuts1

1988 ◽  
Vol 15 (2) ◽  
pp. 73-75 ◽  
Author(s):  
John T. Turner ◽  
Paul A. Backman
Keyword(s):  
Rhizoctonia Solani ◽  
Surface Area ◽  
Disease Severity ◽  
Negative Correlation ◽  
Root Rot ◽  
High Frequency ◽  
Significant Negative Correlation ◽  
Anastomosis Group ◽  
Group 4

Abstract Research on the ecology of peanut roots from fields in Georgia, Florida, and Alabama revealed a high frequency of sunken, dark cankers on the taproot which persisted to harvest. Isolations from these cankers resulted in recovery of Rhizoctonia solani anastomosis group 4 (AG-4) from more than 50% of the cankers. A survey of peanut fields being harvested during early September revealed that 28% of the fields had an average of more than 50% of the taproot surface area cankered. In contrast, for fields in the same area harvested one month later, 77% had disease severities of less than 25% and none were greater than 50%. In an experiment conducted in 1984, roots from 64 plots were examined and rated for root rot severity and yield. When taproot disease severity was regressed against yield, a highly significant negative correlation (r2 − 0.60, P<0.01) was found.

scholarly journals First Report of Damping-Off on Basella rubra Caused by Rhizoctonia solani Anastomosis Group 4 in Florida

Plant Disease ◽  
2012 ◽  
Vol 96 (2) ◽  
pp. 288-288 ◽  
Author(s):  
X. Liao ◽  
Y. Fu ◽  
S. Zhang ◽  
Y. P. Duan
Keyword(s):  
Rhizoctonia Solani ◽  
The United States ◽  
Anastomosis Group ◽  
Pathogenicity Test ◽  
Damping Off ◽  
Ambient Conditions ◽  
Microscopic Appearance ◽  
Stem Base ◽  
First Report ◽  
Intergenic Spacer Region

Indian spinach (Basella rubra L.) is a red stem species of Basella that is cultivated worldwide as an ornamental and the aerial parts are also consumed as a vegetable. In May of 2011, symptoms of damping-off were observed on approximately 10% of the plants at the stem base around the soil line of seedlings in a greenhouse in Homestead, FL. Lesions were initially water soaked, grayish to dark brown, irregular in shape, and sunken in appearance on large plants, causing the infected seedlings to collapse and eventually die. Symptomatic stem tissue was surface sterilized with 0.6% sodium hypochlorite, rinsed in sterile distilled water, air dried, and plated on potato dextrose agar (PDA). Plates were incubated at 25°C in darkness for 3 to 5 days. A fungus was isolated in all six isolations from symptomatic tissues on PDA. Fungal colonies on PDA were light gray to brown with abundant growth of mycelia, and the hyphae tended to branch at right angles when examined under a microscope. A septum was always present in the branch of hyphae near the originating point and a slight constriction at the branch was observed. Neither conidia nor conidiophores were found from the cultures on PDA. The characteristics of hyphae, especially the right angle branching of mycelia, indicate close similarity to those of Rhizoctonia solani (2,3). The internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced (GenBank Accession No. JN545836). Subsequent database searches by the BLASTN program indicated that the resulting sequence had a 100% identity over 472 bp with the corresponding gene sequence of R. solani anastomosis group (AG) 4 (GenBank Accession No. JF701752.1), a fungal pathogen reported to cause damping-off on many crops. Pathogenicity was confirmed through inoculation of healthy India spinach plants with the hyphae of isolates. Four 4-week-old plants were inoculated with the isolates by placing a 5-mm PDA plug of mycelia at the stem base and covering with a thin layer of the soil. Another four plants treated with sterile PDA served as a control. After inoculation, the plants were covered with plastic bags for 24 h and maintained in a greenhouse with ambient conditions. Four days after inoculation, water-soaked, brown lesions, identical to the symptoms described above, were observed on the stem base of all inoculated plants, whereas no symptoms developed on the control plants. The fungus was isolated from affected stem samples, and the identity was confirmed by microscopic appearance of the hyphae and sequencing the ITS1/ITS4 intergenic spacer region, fulfilling Koch's postulates. This pathogenicity test was conducted twice. R. solani has been reported to cause damping-off of B. rubra in Ghana (1) and Malaysia (4). To our knowledge, this is the first report of damping-off caused by R. solani AG-4 on Indian spinach in Florida and the United States. With the increased interest in producing Asian vegetables for food and ornamental purposes, the occurrence of damping-off on Indian spinach needs to be taken into account when designing programs for disease management in Florida. References: (1) H. A. Dade. XXIX. Bull. Misc. Inform. 6:205, 1940. (2) J. R. Parmeter et al. Phytopathology 57:218, 1967. (3) B. Sneh et al. Identification of Rhizoctonia species. The American Phytopathological Society, St Paul, MN, 1991. (4) T. H. Williams and P. S. W. Liu. Phytopathol. Pap. 19:1, 1976.

scholarly journals Influence of selected Rhizoctonia solani isolates on sugar beet seedlings

2016 ◽  
Vol 56 (2) ◽  
pp. 116-121
Author(s):  
Paweł Skonieczek ◽  
Mirosław Nowakowski ◽  
Jacek Piszczek ◽  
Marcin Żurek ◽  
Łukasz Matyka
Keyword(s):  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Root Rot ◽  
Laboratory Tests ◽  
Anastomosis Group ◽  
Damping Off ◽  
Highly Pathogenic ◽  
Breeding Lines ◽  
Brown Root Rot

Abstract From 2008 to 2010 the levels of sugar beet seedlings infection caused by Rhizoctonia solani were compared in laboratory tests. Seven sugar beet lines were tested: H56, H66, S2, S3, S4, S5 and S6 as well as three control cultivars: Carlos, Esperanza and Janosik. Sugar beet lines with tolerance to rhizoctoniosis and cultivars without tolerance were infected artificially by R. solani isolates: R1, R28a and R28b. These isolates belong to the second anastomosis group (AG), which is usually highly pathogenic to beet roots. The aim of the experiment was to test whether the tolerance of sugar beet genotypes to R. solani AG 2 prevents both root rot, and damping-off of seedlings, induced by the pathogen. Sugar beet lines tolerant to brown root rot in laboratory tests were significantly less sensitive to infection of the seedlings by R. solani AG 2 isolates in comparison to control cultivars. Rhizoctonia solani AG 2 isolates demonstrated considerable differences in pathogenicity against seedlings of sugar beet lines and cultivars. The strongest infection of sugar beet seedlings occurred with the isolate R28b. The greatest tolerance to infection by AG 2 isolates was found for the S5 and S3 breeding lines.

scholarly journals First Report of Soybean Seedling Disease caused by Rhizoctonia solani AG-7 in Taiwan

Plant Disease ◽  
2021 ◽  
Author(s):  
Yu-Cheng Lin ◽  
Min-Nan Tseng ◽  
Hao-Xun Chang
Keyword(s):  
Rhizoctonia Solani ◽  
Tap Water ◽  
Disease Incidence ◽  
Soil Surface ◽  
Anastomosis Group ◽  
Damping Off ◽  
Soybean Seedlings ◽  
Fungal Inoculum ◽  
Potential Pathogen ◽  
Causal Pathogen

From August to November 2020, reduced emergence and damping-off of soybean seedlings were observed in two fields (Benzhou and Wandan) in Taiwan. Disease incidence was approximately 40% in Benzhou by field scouting. The roots of damping-off seedlings were brown. Affected seedlings could be easily pulled out from the soil and the lesions on the roots/stem were generally dry and sunken. These symptoms suggested the possibility of Rhizoctonia infection. Soil surrounding symptomatic seedlings were collected to bait the potential pathogen and symptomatic plants were used for pathogen isolation. The diseased tissues were washed with tap water and surface-disinfected with 1% bleach before placing on the Dexon selection medium at 26°C for 2 days (Ko and Hora 1971). Hyphae were transferred to potato dextrose agar (PDA), and a brown colony with brown and irregular-shaped sclerotia grew from 90 out of 99 isolates. The hyphae exhibited typical characteristics of Rhizoctonia solani, including a constriction and a septum near the end of branching hyphae (Ajayi-Oyetunde and Bradely, 2018). Two isolates from Benzhou and two isolates from Wandan were tested for their pathogenicity, and eight surface-disinfected seeds were distributed evenly on the water agar plates covered by 2-day-old mycelia at 25°C in dark for 7 days. All isolates caused cotyledon rot and reduced germination. To verify their pathogenicity in pots, double-sterilized sorghum seeds were inoculated with two strains and incubated at 25°C for 2 weeks to be used as fungal inoculum (Ajayi-Oyetunde and Bradely, 2017). A layer of 15 ml of fungal inoculum was placed 5 cm beneath the soil surface in pots. Four soybean seeds were planted approximately 3 cm above the inoculum in each pot. After two weeks, reddish lesions on the hypocotyls or taproots of all seedlings in the inoculated pots were observed, while seedlings in the control pots inoculated with sterile sorghum seeds remained healthy. The pathogen was re-isolated from lesions and had identical morphology to the original isolates. To characterize the fungal identity, the internal transcribed spacer (ITS) was sequenced using the primers ITS1/ITS4 (Sharon et al., 2006). Using BLASTN in the NCBI database, the sequence (GenBank no. MW410857 and MW410858) showed 100% (639/639 bp) similarity to KF907734 and 99.83% (635/636 bp) similarity to AF354099, both belong to R. solani anastomosis group 7 (AG-7) (Hua et al. 2014; Gonzalez et al. 2001). Phylogenetic analysis comparing sequences with different AGs (Ajayi-Oyetunde and Bradely, 2017) grouped our isolates within the AG-7 clade with a 100% bootstrap confidence. In the anastomosis test, an incompatible zonation and unequal mycelial growth rates were observed when AG-7 isolates were paired with an AG-1 IA isolate. On the other hand, the compatible tuft reaction was observed when two AG-7 isolates were paired, and the compatible merge reaction was observed in the self-pairing tests (Macnish et al. 1997). Accordingly, the molecular and morphological characterizations confirmed the causal pathogen as R. solani AG-7. R. solani AG-7 was first reported on radishes in Japan (Homma et al., 1983), first found on carnation in Taiwan (Lo et al., 1990), and in field soils of various crops but not soybean (Chuang, 1997). It was suggested that Rhizoctonia diseases of soybean may be present in Taiwan, but molecular confirmation was lacking (Anonymus, 1979). As R. solani AG-7 causes diseases of soybean in the US and Japan (Baird et al., 1996), the importance of AG-7 as an endemic pathogen of soybean in Taiwan should be recognized and its prevalence determined as a first step to managing this disease.

scholarly journals First Report of Damping-Off on Seedlings of Coffee Caused by Rhizoctonia solani AG-4 HG I, AG-1 IB and Binucleate Rhizoctonia AG-A in China

Plant Disease ◽  
2018 ◽  
Vol 102 (8) ◽  
pp. 1658
Author(s):  
S. F. Ren ◽  
W. J. Bao ◽  
F. Li ◽  
C. Y. Li ◽  
W. H. Dong ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Damping Off ◽  
First Report ◽  
Binucleate Rhizoctonia

A Binucleate Rhizoctonia anastomosis group (AG-W) is the causal agent of sugar beet seedling damping-off disease in China

2019 ◽  
Vol 155 (1) ◽  
pp. 53-69
Author(s):  
Can Zhao ◽  
Yuting Li ◽  
Huajun Liu ◽  
Siwei Li ◽  
Chenggui Han ◽  
...  
Keyword(s):  
Sugar Beet ◽  
Anastomosis Group ◽  
Causal Agent ◽  
Damping Off ◽  
Binucleate Rhizoctonia

scholarly journals Formulation of Binucleate Rhizoctonia spp. and Biocontrol of Rhizoctonia solani on Impatiens

Plant Disease ◽  
2001 ◽  
Vol 85 (12) ◽  
pp. 1241-1248 ◽  
Author(s):  
E. W. Honeycutt ◽  
D. M. Benson
Keyword(s):  
Rhizoctonia Solani ◽  
Shelf Life ◽  
Rice Flour ◽  
Trichoderma Virens ◽  
Damping Off ◽  
Salt Solutions ◽  
Binucleate Rhizoctonia ◽  
Controlled Atmospheres ◽  
Plastic Bags ◽  
Over Time

Isolates BNR621 and P9023 of binucleate Rhizoctonia spp. (BNR) in Pesta and rice flour formulations were evaluated for control of preemergence damping-off of impatiens caused by R. solani. Amendment of a soilless potting mix with the formulations at 0.47% (vol:vol) 3 days prior to seeding and infesting did not improve control compared to amendment 1 day prior to seeding and infesting regardless of whether the moistened amended potting mix was stored in closed plastic bags or in plug trays under a mist system. BNR fungi were no more effective in biocontrol of R. solani in formulations amended at 0.9%. Control of damping-off was comparable but not consistent between formulations of BNR fungi and the fungicide thiophanatemethyl. Damping-off was controlled better with formulations of BNR fungi than with SoilGard based on Trichoderma virens. Shelf life of Pesta and rice flour formulations at 4°C was determined by assessing viability of BNR isolates over time. Viability of the BNR isolates, measured as CFU/g of formulation, declined to approximately 68 to 79% of the original propagule concentration after 6 months in Pesta and rice flour formulations, with the greatest decline in the first 2 months. Shelf life of BNR isolates in formulation significantly affected control of preemergence damping-off but was isolate dependent. Preemergence damping-off was only 5 to 7% with fresh formulations but increased to 30 to 50% with 4-month-old formulations. Controlled atmospheres, maintained with saturated salt solutions, were established to measure the effect of water activity on shelf life of formulations. Water activities (aw) of 0.12 and 0.33 aw enhanced BNR survival in formulations by approximately 2 to 3 months compared with aw of 0.53 and 0.75 aw. Storage of Pesta and rice flour formulations at 4°C significantly improved BNR survival by 4 to 5 months compared with storage at 25°C. These results suggest that improved shelf life of BNR isolates is needed before formulated products can be developed for biocontrol of preemergence damping-off.

scholarly journals Impact of Cellulose-Rich Organic Soil Amendments on Growth Dynamics and Pathogenicity of Rhizoctonia solani

2021 ◽  
Vol 9 (6) ◽  
pp. 1285
Author(s):  
Anna Clocchiatti ◽  
Silja Emilia Hannula ◽  
Muhammad Syamsu Rizaludin ◽  
Maria P. J. Hundscheid ◽  
Paulien J. A. klein klein Gunnewiek ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Disease Severity ◽  
Disease Incidence ◽  
Pathogenic Fungus ◽  
Pathogenic Fungi ◽  
Paper Pulp ◽  
Damping Off ◽  
Cellulolytic Bacteria ◽  
Arable Soils ◽  
Saprotrophic Fungi

Cellulose-rich amendments stimulate saprotrophic fungi in arable soils. This may increase competitive and antagonistic interactions with root-infecting pathogenic fungi, resulting in lower disease incidence. However, cellulose-rich amendments may also stimulate pathogenic fungi with saprotrophic abilities, thereby increasing plant disease severity. The current study explores these scenarios, with a focus on the pathogenic fungus Rhizoctonia solani. Saprotrophic growth of R. solani on cellulose-rich materials was tested in vitro. This confirmed paper pulp as a highly suitable substrate for R. solani, whereas its performance on wood sawdusts varied with tree species. In two pot experiments, the effects of amendment of R. solani-infected soil with cellulose-rich materials on performance of beetroot seedlings were tested. All deciduous sawdusts and paper pulp stimulated soil fungal biomass, but only oak, elder and beech sawdusts reduced damping-off of beetroot. Oak sawdust amendment gave a consistent stimulation of saprotrophic Sordariomycetes fungi and of seedling performance, independently of the time between amendment and sowing. In contrast, paper pulp caused a short-term increase in R. solani abundance, coinciding with increased disease severity for beet seedlings sown immediately after amendment. However, damping-off of beetroot was reduced if plants were sown two or four weeks after paper pulp amendment. Cellulolytic bacteria, including Cytophagaceae, responded to paper pulp during the first two weeks and may have counteracted further spread of R. solani. The results showed that fungus-stimulating, cellulose-rich amendments have potential to be used for suppression of R. solani. However, such amendments require a careful consideration of material choice and application strategy.

scholarly journals Rhizoctonia Anastomosis Groups Associated with Diseased Rooibos Seedlings and the Potential of Compost as Soil Amendment for Disease Suppression

Plant Disease ◽  
2015 ◽  
Vol 99 (7) ◽  
pp. 1020-1025 ◽  
Author(s):  
Y. T. Tewoldemedhin ◽  
S. C. Lamprecht ◽  
M. Mazzola
Keyword(s):  
South Africa ◽  
Internal Transcribed Spacer ◽  
Anastomosis Group ◽  
Disease Suppression ◽  
Western Cape ◽  
Damping Off ◽  
Western Cape Province ◽  
Internal Transcribed Spacer Region ◽  
Binucleate Rhizoctonia ◽  
Compost Amendment

Rhizoctonia spp. associated with rooibos in the Western Cape province of South Africa were recovered during the 2008 season by planting seedlings in rhizosphere soils collected from 14 rooibos nurseries. In all, 75 Rhizoctonia isolates were obtained, of which 67 were multinucleate and 8 were binucleate Rhizoctonia spp. The identity of these isolates to anastomosis group (AG) was determined through sequence analysis of the ribosomal DNA internal transcribed spacer region. The collection of multinucleate isolates included representatives of AG-2-2 (67%), AG-4 HGI (14%), AG-11 (5%), and R. zeae (3%). Binucleate AGs included AG-Bo (4%) and AG-K (4%) and an unidentified binucleate Rhizoctonia (3%). Rhizoctonia solani AG-2-2 was the most widely distributed species of Rhizoctonia detected among the 11 nurseries sampled. All AGs recovered from rooibos have been previously reported on crop plants in South Africa, with the exception of R. zeae. However, this is the first study to classify the Rhizoctonia AGs recovered from rooibos. In glasshouse bioassays, the most virulent Rhizoctonia AGs on rooibos and lupin were AG-2-2, AG-4 HGI, and AG-11. Although plant damage was less than that observed for lupin and rooibos, oat was significantly affected by AG-2-2 and AG-4 HGI. Two composts sourced from independent suppliers were evaluated for disease suppression under glasshouse conditions. Compost amendment suppressed damping-off by most R. solani AGs, except for AG-4 HGI. Furthermore, within AG-2-2, suppression by compost was isolate specific.

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