Temperature and water potential effects on growth and pathogenicity of Rhizoctonia solani AG-11 to lupin

1999 ◽  
Vol 45 (5) ◽  
pp. 389-395 ◽  
Author(s):  
S Kumar ◽  
K Sivasithamparam ◽  
J S Gill ◽  
M W Sweetingham
Keyword(s):  
Rhizoctonia Solani ◽  
Western Australia ◽  
Small Area ◽  
Linear Growth ◽  
Anastomosis Group ◽  
Potato Dextrose Agar ◽  
Wide Spread ◽  
Damping Off ◽  
Bare Patch ◽  
Ph Range

Rhizoctonia solani anastomosis group (AG) 11 causes serious damping-off and hypocotyl rot of lupins (Lupinus angustifolius L.) and is wide-spread in the northern grain-belt of Western Australia. We compared growth of AG-11 to AG-8, which causes bare-patch of grain crops including lupin. AG-11 grew significantly faster than AG-8 on potato dextrose agar (PDA) at several temperatures (10, 15, 20, 25, or 30°C) and also grew best within the pH range of 4-7. Growth of AG-8 was best at pH 7. There was no difference in the linear growth in soil of both AGs at 10°C, but AG-11 grew at a significantly faster rate at 20°C. Reduction in growth of AG-11 on osmotically adjusted PDA at temperatures between 10 and 30°C was more pronounced than that of AG-8. AG-11 caused very little lupin pre-emergence damping-off and hypocotyl rot at 10°C, and most severe hypocotyl rot was recorded at 20 and 25°C. Severity of hypocotyl rot caused by AG-11 at soil water potentials of -0.1, -0.07, and -0.05 MPa was higher than at -0.03 MPa. It appears that AG-11 is well suited to the environmental conditions of the relatively small area in Western Australia from which it is readily isolated.Key words: Rhizoctonia solani, anastomosis groups, osmotic potential, lupin.

Mycelial Interactions and the Potential Use of Tuft Formation in Characterizing Rhizoctonia solani Isolates Infecting Cereals

1993 ◽  
Vol 41 (2) ◽  
pp. 253 ◽  
Author(s):  
HA Yang ◽  
K Sivasithamparam ◽  
PA Obrien
Keyword(s):  
Rhizoctonia Solani ◽  
Anastomosis Group ◽  
Potato Dextrose Agar ◽  
Bare Patch ◽  
Field Isolates ◽  
Mycelial Interactions ◽  
Causal Pathogen ◽  
Patch Disease ◽  
Potential Use ◽  
Compatible Interactions

Field isolates of Rhizoctonia solani anastomosis group (AG) 8, the most important causal pathogen of cereal bare-patch disease, were paired with each other and with tester strains of other AGs on potato-dextrose agar amended with charcoal (PDCA) to investigate mycelial interactions. Pairings among AG 8 field isolates produced compatible interactions of either tuft or merging reactions. Tufts formed between all paired field isolates from different pectic zymogram groups (ZGs) within AG 8, but pairings between genetically identical isolates showed merging reactions. Pairings of AG 8 field isolates with the tester strains of the other AGs led to incompatible interactions varying from merging line to barrage reactions. As formation of a tuft indicates that the paired isolates are able to anastomose and to form viable heterokaryons, the testing of mycelial interaction types, highlighted by tuft formation, may be used as a rapid procedure to characterise field isolates of R. solani obtained from cereals.

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.

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.

Effect of nitrogen and residual copper on the occurrence of Rhizoctonia bare patch in wheat grown near Esperance, Western Australia

1991 ◽  
Vol 31 (2) ◽  
pp. 259 ◽  
Author(s):  
RF Brennan
Keyword(s):  
Grain Yield ◽  
Rhizoctonia Solani ◽  
Ammonium Nitrate ◽  
Western Australia ◽  
Root Rot ◽  
Plant Nutrition ◽  
Bare Patch ◽  
Grain Yields ◽  
Cu Deficiency ◽  
Rhizoctonia Root Rot

The area of rhizoctonia bare patch and the incidence and severity of rhizoctonia root rot (caused by Rhizoctonia solani Khnn) were reduced by the application of ammonium nitrate fertiliser. Residual copper (Cu) from a Cu fertiliser treatment in 1967 had no effect on the area of rhizoctonia bare patch or the incidence and severity of root rot. With no applied nitrogen (N), 17.6% (mean of residual Cu levels) of the plot was affected by patches while the area of plot affected by patches declined to 4.2% where 92 kg N/ha had been applied. The incidence and severity of rhizoctonia root rot declined from 45.9 and 27.0% to 32.7 and 9.1%, respectively, with the application of N fertiliser. The grain yield of wheat supplied with adequate Cu increased although the level of N fertiliser exceeded that considered adequate for plant nutrition. The response is explained by the control of rhizoctonia bare patch. The area of rhizoctonia patches and the incidence and severity of rhizoctonia root rot decreased with the application of N, and with adequate Cu fertiliser (2.2 kg Cu/ha), the grain yields increased. However, with marginal and deficient levels of applied Cu fertiliser, the application of N fertiliser induced Cu deficiency in wheat plants, and the grain yields declined although rhizoctonia patches were reduced.

scholarly journals Enhanced Antifungal Bioactivity of Coptis Rhizome Prepared by Ultrafining Technology

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Ping-Chung Kuo ◽  
Yao-Tung Lin ◽  
Mei-Lin Yang ◽  
Ming-Yuan Liao ◽  
Guo-Feng Chen ◽  
...  
Keyword(s):  
Rhizoctonia Solani ◽  
Environmental Degradation ◽  
Spectroscopic Method ◽  
Potato Dextrose Agar ◽  
Potential Candidate ◽  
Damping Off ◽  
Bioactive Constituents ◽  
Methanol Extracts ◽  
Crude Extracts ◽  
Vegetable Seedlings

The aim of this study was to identify and quantify the bioactive constituents in the methanol extracts of Coptis Rhizome prepared by ultrafining technology. The indicator compound was identified by spectroscopic method and its purity was determined by HPLC. Moreover, the crude extracts and indicator compound were examined for their ability to inhibit the growth ofRhizoctonia solaniKühn AG-4 on potato dextrose agar plates. The indicator compound is a potential candidate as a new plant derived pesticide to controlRhizoctoniadamping-off in vegetable seedlings. In addition, the extracts of Coptis Rhizome prepared by ultrafining technology displayed higher contents of indicator compound; they not only improve their bioactivity but also reduce the amount of the pharmaceuticals required and, thereby, decrease the environmental degradation associated with the harvesting of the raw products.

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.

Root growth altered by compaction of a sandy loam soil affects severity of rhizoctonia root rot of wheat seedlings

2004 ◽  
Vol 44 (6) ◽  
pp. 595 ◽  
Author(s):  
J. S. Gill ◽  
S. Hunt ◽  
K. Sivasithamparam ◽  
K. R. J. Smettem
Keyword(s):  
Root Growth ◽  
Rhizoctonia Solani ◽  
Soil Profile ◽  
Soil Compaction ◽  
Anastomosis Group ◽  
Soil Conditions ◽  
Wheat Seedlings ◽  
Bare Patch ◽  
Compacted Soil ◽  
The Impact

Rhizoctonia solani Anastomosis Group 8 damages seedling roots of wheat, causing the 'bare-patch' disease. This makes the first 4 weeks after germination the most critical period for disease development. As the field inoculum of the pathogen is mainly concentrated in the surface 10 cm of soil, the rate of root growth becomes critical for the vulnerable tissues of the root to escape the attack from the inoculum zone. To evaluate the effect of alteration of root growth by soil compaction on disease severity, a study was undertaken in 40-cm-deep pots made from PVC pipes (8.7 cm diameter). Four depths of soil compaction (whole soil profile compacted, whole soil loose, upper 10 cm loose and compacted below, upper 20 cm loose and compacted below) were tested using sieved soil. Effective root length of infected seedlings was higher in the pots where the whole soil profile was compacted than others. Reduction in dry root weights, where soil was compacted to heights of 0, 17.5, 27.5 or 37.5 cm following inoculation, were 68, 30, 74 and 56%, respectively. Reduction in shoot weights was 52, 22, 66 and 44%, respectively. Eight days after incubation, microbial activity was greater where the soil was highly compacted than where there was a low level of soil compaction. Saprophytic growth in soil of Rhizoctonia solani Anastomosis Group 8 was higher in loosely packed soil than in compacted soil. This shows that higher impact of disease under compacted soil conditions is due to reduced root growth and that disturbing the soil below seeds can reduce the impact of disease.

Evidence that each Rhizoctonia bare patch is dominated by an individual zymogram group (ZG) of Rhizoctonia solani AG-8

1993 ◽  
Vol 44 (6) ◽  
pp. 1175 ◽  
Author(s):  
GC MacNish ◽  
MW Sweetingham
Keyword(s):  
Rhizoctonia Solani ◽  
Western Australia ◽  
Soil Cores ◽  
Undisturbed Soil ◽  
Wheat Seedlings ◽  
Bare Patch ◽  
Infection Focus ◽  
Undisturbed Soil Cores

Studies of rhizoctonia bare patches in the southern part of the cereal belt of Western Australia indicate that each patch is dominated by an individual pectic zymogram group (ZG) of R. solani AG-8. R. solani was isolated from plants sampled from patches or from wheat seedlings grown in undisturbed soil cores removed from patches. The Rhizoctonia spp. isolated were characterized using electrophoresis in pectin-acrylamide gels. Four patch-forming zymogram groups (ZG1-1, ZG1-2. ZG1-4 and ZG1-5) were isolated. Of 121 patches examined, only five yielded more than one ZG. Two of these were due to the coalescing of two patches dominated by different zymogram groups. For the remaining three, there was only an occasional isolation of a ZG different from the dominant ZG. This may indicate a new infection focus endeavouring to establish in soil that another ZG occupies. Occasionally, patch-forming ZG1-1, ZG1-2, ZG1-4 and ZG1-5 were isolated from non-patch sites.

Effect of Low Temperature on the Aggressiveness of Rhizoctonia solani AG 2-2 Isolates on Sugar Beet (Beta vulgaris) Seedlings

Plant Disease ◽  
2021 ◽  
Author(s):  
Douglas H. Minier ◽  
Linda E. Hanson
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Anastomosis Group ◽  
Damping Off ◽  
Sugar Beets ◽  
Disease Symptoms ◽  
Severity Scores ◽  
Soil Temperatures

Rhizoctonia solani anastomosis group (AG) 2-2 can cause seedling damping-off in sugar beets and substantial losses may occur in all regions where beets are grown. Sugar beets are planted early in the season when soil temperatures are low in order to maximize the length of the growing season and minimize the risk of damping-off. However, predictive models that indicate there is little to no risk of Rhizoctonia damping-off at temperatures <15°C may not be entirely reliable. We tested this possibility by inoculating sugar beet seedlings in a growth chamber at 11°C with 35 R. solani AG 2-2 isolates that were representative of the genetic diversity present in AG 2-2. Although disease progress and growth rate were greatly reduced at 11°C, considerable disease symptoms did develop in inoculated plants. Three weeks after inoculation, 16% of the plants were dead and 77% of the isolates tested had average disease severity scores that were significantly greater than those of the mock inoculated control. This confirms our concern about the possibility for low-temperature infection of sugar beets and indicates that waiting until the soil warms up to above 15°C to apply fungicide could leave the crop at risk. Aggressiveness does not appear to be related to subgroup or growth rate but rather depends on the response of the specific isolate to low temperature.

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