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 First Report of Damping-Off Caused by Rhizoctonia solani AG-4 on Mediterranean Fan Palm in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 125-125 ◽  
Author(s):  
G. Polizzi ◽  
D. Aiello ◽  
I. Castello ◽  
V. Guarnaccia ◽  
A. Vitale
Keyword(s):  
Rhizoctonia Solani ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Mediterranean Area ◽  
Western Mediterranean ◽  
Fluorescent Light ◽  
Damping Off ◽  
Centraalbureau Voor ◽  
First Report ◽  
Stem Lesions

Mediterranean fan palm (Chamaerops humilis L.), one of just two autochthonous European palms, is native to the western Mediterranean Region in southwestern Europe and northwestern Africa. It can be found growing wild in the Mediterranean area. In Europe, this species is very popular as an ornamental plant. In March 2009, a widespread damping-off was observed in a stock of approximately 30,000 potted 1-month-old plants of C. humilis cv. Vulcano in a nursery in eastern Sicily. Disease incidence was approximately 20%. Disease symptoms consisted of lesions at the seedling shoot (plumule). Stem lesions were initially orange, turned brown, and followed by death of the entire plumule or eophyll. A fungus with mycelial and morphological characteristics of Rhizoctonia solani Kühn was consistently isolated from lesions when plated on potato dextrose agar (PDA) amended with streptomycin sulfate at 100 μg/ml. Fungal colonies were initially white, turned brown with age, and produced irregularly shaped, brown sclerotia. Mycelium was branched at right angles with a septum near the branch and a slight constriction at the branch base. Hyphal cells removed from cultures grown at 25°C on 2% water agar were determined to be multinucleate when stained with 1% safranin O and 3% KOH solution (1) and examined at ×400. Anastomosis groups were determined by pairing isolates with tester strains AG-1 IA, AG-2-2-1, AG-2-2IIIB, AG-2-2IV, AG-3, AG-4, AG-5, AG-6, and AG-11 on 2% water agar in petri plates (3). Anastomosis was observed only with tester isolates of AG-4, giving both C2 and C3 reactions (2). One representative isolate obtained from symptomatic tissues was deposited at the Fungal Biodiversity Centre, Centraalbureau voor Schimmelcultures (CBS No. 125095). Pathogenicity tests were performed on container-grown, healthy, 1-month-old seedlings. Twenty plants of C. humilis cv. Vulcano were inoculated near the base of the stem with two 1-cm2 PDA plugs from 5-day-old mycelial cultures. The same number of plants served as uninoculated controls. Plants were incubated in a growth chamber and maintained at 25°C and 95% relative humidity on a 12-h fluorescent light/dark regimen. Symptoms identical to those observed in the nursery appeared 5 days after inoculation and all plants died within 20 days. No disease was observed on control plants. A fungus identical in culture morphology to R. solani AG-4 was consistently reisolated from symptomatic tissues, confirming its pathogenicity. To our knowledge, this is the first report in the world of R. solani causing damping-off on Mediterranean fan palm. References: (1) R. J. Bandoni. Mycologia 71:873, 1979. (2) D. E. Carling. Page 37 in: Grouping in Rhizoctonia solani by Hyphal Anastomosis Reactions. Kluwer Academic Publishers, the Netherlands, 1996. (3) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.

Relationship of Rhizoctonia solani inoculum density to incidence of hypocotyl rot and damping-off in dry beans

1989 ◽  
Vol 35 (12) ◽  
pp. 1132-1140 ◽  
Author(s):  
A. J. L. Phillips
Keyword(s):  
Phaseolus Vulgaris ◽  
Linear Regression ◽  
Rhizoctonia Solani ◽  
Disease Incidence ◽  
Inoculum Density ◽  
Damping Off ◽  
Dry Beans ◽  
Site Model ◽  
Relationship Of

The effect of inoculum density on preemergence disease incidence was described by linear regression. Variations in virulence among 10 isolates formed a continuum. The effect of inoculum density on hypocotyl disease incidence was described by a limiting site model and variations in virulence among the isolates also formed a continuum. The ability of an isolate to cause preemergence disease was not necessarily related to its ability to cause hypocotyl disease. Both saprophytic colonization and preemergence infection arose from propagules in the spermosphere, while depending on the isolate, infection of hypocotyls was from propagules in either the rhizosphere or the rhizoplane. The observed number of hypocotyl lesions was greater than that estimated from the percentage of plants infected. This effect was more pronounced when seeds were sown at 4 than at 1 cm depth.Key words: beans, epidemiology, Phaseolus vulgaris, Rhizoctonia solani.

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.

EFFECTIVE FUNGICIDE DOSAGE IN RELATION TO INOCULUM CONCENTRATION IN SOIL

1964 ◽  
Vol 42 (3) ◽  
pp. 301-306 ◽  
Author(s):  
Lloyd T. Richardson ◽  
Donald E. Munnecke
Keyword(s):  
Rhizoctonia Solani ◽  
Linear Relationship ◽  
Control Level ◽  
Quantitative Relationship ◽  
Pathogenic Fungi ◽  
Damping Off ◽  
Sterile Soil ◽  
Pythium Irregulare ◽  
Inoculum Concentration ◽  
Pea Seedlings

A quantitative relationship was established between the fungicide dosage required to control a soil-borne disease and the concentration of mycelial inoculum in soil. The incidence of pre-emergence damping-off was observed in pea seedlings grown in non-sterile soil artifically infested with a series of concentrations of inoculum of Pythium irregulare or Rhizoctonia solani and treated with a dosage series of thiram or methylmercuric dicyandiamide. Parallel linear dosage–control curves were obtained which indicated that the logarithm of the fungicide dosage at the 50% control level increases proportionately with the logarithm of the inoculum density. This linear relationship provides a basis for evaluation of the activity of fungicides against various pathogenic fungi in soil.

scholarly journals Susceptibility of different parsley cultivars to infestation by pathogenic fungi

2012 ◽  
Vol 58 (2) ◽  
pp. 163-170 ◽  
Author(s):  
Jacek Nawrocki
Keyword(s):  
Rhizoctonia Solani ◽  
Fusarium Oxysporum ◽  
Field Experiments ◽  
Pathogenic Fungi ◽  
Fusarium Avenaceum ◽  
Damping Off ◽  
Stemphylium Botryosum ◽  
Cylindrocarpon Destructans ◽  
Second Year

The experiments were carried out in the years 2002 and 2003 on parsley seeds of 6 cultivars: Alba, Berlińska, Cukrowa, Kinga, Lenka, and Vistula. Mycological analysis of parsley seeds showed that the most common inhabitans were fungi from genus <i>Alternaria</i> (mainly <i>A. alternata</i> and <i>A. radicina</i>) and <i>Fusarium</i>, especially <i>F. avenaceum</i> and <i>F. oxysporum</i>. During the glasshouse investigations fungi <i>Alternaria radicina</i>, <i>A. alternata</i> and <i>Fusarium avenaceum</i> were the main reason for parsley damping-off. The highest number of infected seedlings was observed for Berlińska and Kinga, because in both years of experiments these cultivars had the lowest number of healthy seedlings. The highest number of healthy seedlings had cultivars Alba and Lenka, especially in the second year of experiments. In the field experiments not only fungi from genus <i>Alternaria</i> and <i>Fusarium</i> were the most often isolated from diseased parsley seedlings. <i>Fusarium oxysporum</i> was more often isolated from diseased field seedlings than from glasshouse parsley seedlings. Other fungies isolated often from parsley seedlings cultivated in the field were: <i>Pythium</i> spp., <i>Rhizoctonia solani</i>, <i>Cylindrocarpon destructans</i> and <i>Stemphylium botryosum</i>.

scholarly journals Root Diseases and Nematodes in Bahiagrass-Vegetable Rotations

Plant Disease ◽  
1999 ◽  
Vol 83 (1) ◽  
pp. 55-59 ◽  
Author(s):  
D. R. Sumner ◽  
N. A. Minton ◽  
T. B. Brenneman ◽  
G. W. Burton ◽  
A. W. Johnson
Keyword(s):  
Beneficial Effect ◽  
Rhizoctonia Solani ◽  
Disease Severity ◽  
Meloidogyne Incognita ◽  
Pathogenic Fungi ◽  
Plant Populations ◽  
Root Knot Nematodes ◽  
Snap Bean ◽  
Root Diseases ◽  
Root Injury

A double-crop of cucumber-snap bean was grown continuously for 4 years and compared with rotations of 1, 2, or 3 years of bahiagrass followed by vegetables. No nematicides or soil fungicides were applied. Root and hypocotyl disease severity in snap bean from Rhizoctonia solani AG-4 and Pythium spp. was decreased after 2 years of bahiagrass compared with 1 year of bahiagrass and 1 year of vegetables or continuous vegetables. Root galling caused by Meloidogyne incognita was less following 2 or 3 years, but not 1 year, of bahiagrass than following continuous vegetables. The beneficial effect of the rotation with bahiagrass lasted only 1 year. Then root injury from soilborne pathogenic fungi and root-knot nematodes was similar to that in continuous vegetables. Plant populations and yield of vegetables were greater following 3 years of bahiagrass than following 1 year of bahiagrass and 3 years of vegetables or continuous vegetables. Two years of bahiagrass followed by 1 or 2 years of vegetables did not increase yield of vegetables consistently.

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.

Trichoderma protoplast fusion: a tool for improving biocontrol agents

1990 ◽  
Vol 36 (1) ◽  
pp. 6-9 ◽  
Author(s):  
S. Pe'er ◽  
I. Chet
Keyword(s):  
Cell Wall ◽  
Key Words ◽  
Protoplast Fusion ◽  
Trichoderma Harzianum ◽  
Pathogenic Fungus ◽  
Sclerotium Rolfsii ◽  
Pathogenic Fungi ◽  
Damping Off ◽  
Dual Cultures ◽  
Young Thalli

Protoplasts from two auxotrophic mutants of Trichoderma harzianum Rifai (ATCC 32173), obtained from young thalli following cell wall digestion by NovoZym 234, were fused in 33% PEG suspended in 10 mM Tris-HCl and 10 mM CaCl2, pH 7.5. The frequency of fusion between lysine- and arginine-requiring auxotrophs resulting in prototrophic strains was about 5%. These prototrophic strains were classified into parental and nonparental types. Colonies developed from single conidia of the nonparental phenotype exhibited prototrophic parental or recombinant phenotypes. The ability of both prototrophic and parental strains to overgrow the soil-borne pathogenic fungi Rhizoctonia solani, Sclerotium rolfsii, and Pythium aphanidermatum in dual cultures was used to evaluate their antagonistic capability. The antagonistic abilities of the prototrophic strains were found to vary with each pathogenic fungus. The prototrophic strain A2 overgrew all the pathogenic fungi more rapidly than the parental strains. Strain A2 effectively controlled Rhizoctonia damping-off of cotton seedlings, in the greenhouse, when compared with the parental strains. Protoplast fusion appears to be a useful tool for combining desirable traits from parental strains to produce improved biocontrol strains. Key words: Trichoderma harzianum, biocontrol, protoplast fusion.

scholarly journals Isolation and Identification of Ssome Lactobacillus Spp. Bacteria and Evaluation Their Efficacy in The Management of Damping off Disease on Peas

2021 ◽  
Vol 910 (1) ◽  
pp. 012106
Author(s):  
Duha Faisal Ajaj ◽  
Abdullah Abdulkarim Hassan
Keyword(s):  
Pathogenic Fungus ◽  
Pathogenic Fungi ◽  
Dry Weight ◽  
Root Systems ◽  
Damping Off ◽  
Biochemical Tests ◽  
Isolation And Identification ◽  
Local Cultivar ◽  
Lactobacillus Spp ◽  
Significant Superiority

Abstract Twenty-eight isolates of Lactobacillus bacteria were isolated from the rhizosphere of pea plants grown in the fields of five districts in Salah al-Din, which included: Tikrit, Al-Alam, Al-Sharqat, Samarra and Baiji, diagnosed according to phenotypic and biochemical tests. Results showed the effect of L. paralimentarius 1081 on vegetative growth characteristics. Treatment of (bacterial filtrate + Ridomil in the presence of pathogenic fungi) was recording the highest values in dry weight of the vegetative and root systems, was 3.91 and 1.23 g respectively in the local cultivar, compared with the lowest values was 2.60 g and 0.76 g respectively in the Syrian cultivar. All treatments inducing plant resistance compared with healthy plants, and the highest activity of the Peroxidase and Polyphenol oxides in the treatment of (Bacterial filtrate + ridomil in the presence of pathogenic fungi), were 1.08 and 1.33 units/ml in the local cultivar, compared to the Syrian cultivar were 0.015 and 0.013, respectively. Results showed a significant decrease in the severity of infection for all treatments compared to the pathogenic fungus treatment, and the lowest infection severity of the vegetative and root systems was recorded in the treatment of (Bacterial filtrate + ridomil in the presence of pathogenic fungi), which was 14.11 and 12.47% in the local cultivar. There was a significant superiority of all treatments in productivity parameters of pea compared to the treatment of pathogenic fungi only, the highest of those parameters including weight of pods and grains weight/plant were recorded in the treatment (Bacterial filtrate + ridomil in the presence of pathogenic fungi) for the local cultivar was 18.07 g and 14.04 g compared to 10.43 g and 8.20 g in the treatment of the Syrian cultivar with pathogenic fungi only.

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