scholarly journals Response of Ancestral Soybean Lines and Commercial Cultivars to Rhizoctonia Root and Hypocotyl Rot

Plant Disease ◽  
2001 ◽  
Vol 85 (10) ◽  
pp. 1091-1095 ◽  
Author(s):  
C. A. Bradley ◽  
G. L. Hartman ◽  
R. L. Nelson ◽  
D. S. Mueller ◽  
W. L. Pederson
Keyword(s):  
Rhizoctonia Solani ◽  
Disease Severity ◽  
Partial Resistance ◽  
Common Disease ◽  
Root Weight ◽  
Soybean Cultivars ◽  
Commercial Cultivars ◽  
Maturity Groups

Rhizoctonia root and hypocotyl rot is a common disease of soybean caused by Rhizoctonia solani. There are no commercial cultivars marketed as resistant to Rhizoctonia root and hypocotyl rot, and only a few sources of partial resistance to this disease have been reported. Ninety ancestral soybean lines, maturity groups (MGs) 000 to X, and 700 commercial cultivars, MGs II to IV, were evaluated for resistance to R. solani under greenhouse conditions. Most of the ancestral lines and cultivars evaluated were susceptible; however, 21 of the ancestral lines and 20 of the commercial cultivars were partially resistant. Of the 21 ancestral lines, CNS, Mandarin (Ottawa), and Jackson are in the pedigree of cultivars previously reported as being partially resistant to R. solani. In an additional study, dry root weights of 21 soybean cultivars were evaluated after inoculation with R. solani. Variation in dry root weight occurred among cultivars, but there was not a significant (P = 0.05) correlation between dry root weight and disease severity.

Evaluation of soybean cultivars for resistance to Phomopsis longicolla and Sclerotinia sclerotiorum using excised leaves

2014 ◽  
Vol 94 (5) ◽  
pp. 955-961 ◽  
Author(s):  
J. X. Zhang ◽  
A. G. Xue
Keyword(s):  
Disease Severity ◽  
Sclerotinia Sclerotiorum ◽  
Partial Resistance ◽  
Sources Of Resistance ◽  
Phomopsis Longicolla ◽  
Breeding Programs ◽  
Resistant Cultivars ◽  
Soybean Cultivars ◽  
Short Season

Zhang, J. X. and Xue, A. G. 2014. Evaluation of soybean cultivars for resistance to Phomopsis longicolla and Sclerotinia sclerotiorum using excised leaves. Can. J. Plant Sci. 94: 955–961. The resistance of short-season soybean cultivars in Canada to Phomopsis longicolla and Sclerotinia sclerotiorum was measured on excised leaves based on the disease severity. Lesions caused by both fungi were first observed at inoculation sites within 24 to 36 h after excised leaflets were inoculated, varying among cultivars, and whole leaflets rot within 5–6 d for susceptible cultivars. Of the 74 cultivars evaluated, 20 were significantly more resistant to P. longicolla (LSD=1.1, P<0.05) and 19 to S. sclerotiorum (LSD=1.0, P<0.05), with mean severity ratings ranging from 1.3 to 2.3 caused by both fungi. Seven cultivars including Medallion, M. Arrow Brown, Alta, Portage, AC Albatros, Comet, and Pagoda, showed partial resistance to both of pathogens. These resistant cultivars identified in this study may be used as sources of resistance in future field breeding programs in Canada.

Effects of straw incorporation on Rhizoctonia solani inoculum in paddy soil and rice sheath blight severity

2013 ◽  
Vol 152 (5) ◽  
pp. 741-748 ◽  
Author(s):  
H. ZHU ◽  
Z. X. WANG ◽  
X. M. LUO ◽  
J. X. SONG ◽  
B. HUANG
Keyword(s):  
Rhizoctonia Solani ◽  
Disease Severity ◽  
Rice Straw ◽  
Paddy Soil ◽  
Sheath Blight ◽  
Soil Productivity ◽  
Rice Sheath Blight ◽  
Important Method ◽  
Pathogen Dynamics ◽  
Straw Incorporation

SUMMARYIncorporation of rice straw into soil has traditionally been an important method of recycling nutrients and improving soil productivity. Currently, although the effects of straw incorporation on disease severity have been documented, the dynamics of the pathogen in soil after straw incorporation are poorly understood. In the present study, rice straw with various proportions of diseased straw was incorporated at three separate locations (SuPu town, SuSong County and FengYang County) in Anhui province, China. The pathogen dynamics in paddy soil and disease severity of sheath blight during two continuous years from April 2010 to April 2012 were investigated. For all three locations, the amount of pathogen inoculum that persisted in the soil increased with increases in the proportion of diseased straw incorporated. Incorporation of 0·3 and 0·5 diseased straw into soil increased the amount of pathogen inoculum in the soil significantly, whereas incorporation of 0·1 diseased straw into soil had no significant effect on the pathogen inoculum compared with the control (no straw incorporated) or disease severity. Incorporation of healthy rice straw (no disease) resulted in a significant decrease in disease severity, whereas proportions of 0·3 and 0·5 diseased straw resulted in a significant increase of disease severity compared with the control. These results suggested that incorporation of diseased straw enhanced pathogen numbers in soil during the whole decomposition period and increased disease severity. To avoid soil-borne disease accumulation, severely diseased straw should be removed from the field or pre-treated before incorporation.

scholarly journals Cotton resistance to ramulose and variability of Colletotrichum gossypii f. sp. cephalosporioides

2006 ◽  
Vol 32 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Jefferson Fernandes do Nascimento ◽  
Laércio Zambolim ◽  
Francisco Xavier Ribeiro do Vale ◽  
Paulo Geraldo Berger ◽  
Paulo Roberto Cecon
Keyword(s):  
Disease Severity ◽  
Disease Incidence ◽  
Disease Index ◽  
Mato Grosso ◽  
Progress Curve ◽  
Commercial Cultivars ◽  
Resistant Group ◽  
The Relationship ◽  
Highly Virulent ◽  
Susceptible Group

Four cultivars and 21 lines of cotton were evaluated for resistance to ramulose (Colletotrichum gossypii f. sp. cephalosporioides) in a field where the disease is endemic. The seeds of each genotype were planted in 5 x 5 m plots with three replications. The lines CNPA 94-101 and 'CNPA Precoce 2'were used as standard susceptible and resistant references, respectively. The disease incidence (DI) was calculated from the proportion of diseased plants in the plot. The disease index (DIn) was calculated from the disease severity using a 1 to 9 scale, and was evaluated at weekly intervals starting 107 days after emergence. The data collected was used to calculate the area under disease progress curve (AUDPC). In general, the DIn increased linearly with time and varied from 20.0 to 57.1 and AUDPC from 567 to 1627 among the genotypes which could be clustered in to two distinct groups. The susceptible group contained two cultivars and nine lines and the resistant group contained one cultivar and 12 lines. The relationship between disease index and evaluation times was linear for the 25 genotypes tested. The line CNPA 94-101, used as susceptible standard, was the most susceptible with an average DI = 83.4, DIn = 57.1 and AUDPC = 1627.7. The line CNPA 96-08 with DI = 37.8, DIn = 20.0 and AUDPC = 567.7 was the most resistant one. Among the commercial cultivars 'IAC 22' was the most susceptible and 'CNPA Precoce 2', used as resistant standard was the most resistant. The variability in virulence of the pathogen was studied by spray inoculating nine genotypes with conidial suspensions (10(5)/mL) of either of the 10 isolates. The disease severity was evaluated 30 days later using a scale of 1 to 5. The virulence of the isolate was expressed by DIn. All the isolates were highly virulent but their virulence avaried for several genotypes and could be clustered in two distinct groups of less and more virulent isolates. The isolate MTRM 14 from Mato Grosso was the least virulent while Minas Gerais was the most virulent, with DIn of 6.36 and 46.47, respectively. In this experiment the line HR 102 and the cultivar 'Antares' were the most resistant ones with DIns of 18.32 and 19.14, respectively.

scholarly journals Temperature, Moisture, and Seed Treatment Effects on Rhizoctonia solani Root Rot of Soybean

Plant Disease ◽  
2003 ◽  
Vol 87 (5) ◽  
pp. 533-538 ◽  
Author(s):  
A. E. Dorrance ◽  
M. D. Kleinhenz ◽  
S. A. McClure ◽  
N. T. Tuttle
Keyword(s):  
Soil Moisture ◽  
Rhizoctonia Solani ◽  
Root Rot ◽  
Seed Treatment ◽  
Anastomosis Group ◽  
Control Measures ◽  
Root Weight ◽  
Wide Range ◽  
Plant Stand ◽  
Growth Chamber Studies

The effects of temperature and soil moisture on infection and disease development by Rhizoctonia solani on soybean were studied individually. In addition, the anastomosis group of R. solani isolates recovered from soybean from 35 fields in 15 counties was determined. All of the 44 isolates recovered in this study were AG-2-2 IIIB. Five isolates of R. solani were able to infect and colonize soybean roots and hypocotyls at 20, 24, 28, and 32°C in growth chamber studies. The temperatures evaluated in this study were not limiting to the isolates tested. In greenhouse studies, nine R. solani isolates and a noninoculated control were evaluated at 25, 50, 75, and 100% soil moisture holding capacity (MHC). Root weights were greater and percent stand averages higher at 50 and 75% than at 25 or 100% MHC; however, as percentage of control, the main effect on percent moisture for percent stand, plant height, or root weight was not significant. There were significant differences among the isolates for the percent stand, root rot rating, and root fresh weight of soybean in each study. In both temperature and moisture studies, the R. solani isolates could be separated as predominantly causing (i) seed rot, as detected by greatly reduced plant stand; (ii) root rot generally having no effect on plant stand but a high root rot rating and low root weight; or (iii) hypocotyl lesions, having no effect on plant stand, a low root rot score, and a high number of red lesions on the hypocotyl. In the greenhouse seed treatment evaluations of five fungicides, there was no fungicide by isolate interaction using these pathogenic types of R. solani. None of the seed treatments evaluated in this study provided 100% control of the four isolates tested. Due to the wide range of environmental factors that permit R. solani infection and disease on soybeans, other control measures that last all season, such as host resistance, should be emphasized.

scholarly journals Pathotype Grouping of Cercospora sojina Isolates on Soybean and Sensitivity to QoI Fungicides

Plant Disease ◽  
2020 ◽  
Vol 104 (2) ◽  
pp. 373-380
Author(s):  
Alemu Mengistu ◽  
Jeffery D. Ray ◽  
Heather M. Kelly ◽  
Binbin Lin ◽  
Hao Yu ◽  
...  
Keyword(s):  
Disease Severity ◽  
Common Disease ◽  
Cercospora Sojina ◽  
Qoi Fungicides ◽  
Sensitivity Tests ◽  
Pathogenicity Group ◽  
Significant Yield ◽  
Northern United States ◽  
High Level ◽  
Selection Of

Frogeye leaf spot (FLS), caused by Cercospora sojina, is a common disease of soybean in the southern and northern United States and causes significant yield loss. The use of the current race scheme for classification for C. sojina does not take into account the range of disease severity reactions within each differential. The objective of this research was to better understand the diversity among C. sojina isolates through the development and use of pathogenicity groups. In this study, 83 isolates acquired from 2006 to 2009 were screened using 12 soybean (Glycine max) differentials. Disease severity on the 12 differentials ranged from 0 to 9, where 0 is immune and 9 is very susceptible. The average severity for each isolate across differentials ranged from 1 to 7. The 83 isolates were grouped into five pathogenicity groups (PG): PG1, PG2, PG3, PG4, and PG5, reflecting the severity grouping. Using the 12 differentials, PG1 isolates were differentiated by the lack of infection on Davis, Peking, Kent, Palmetto, Hood, CNS, Tracy, and Richland. PG2 had a range of infections on a scale of 1 to 2 on all differentials except on Davis; PG3 isolates had severity ranging from 3 to 4 except on Davis. PG4 isolates caused no infection on Davis, a maximum disease severity of 5 on Peking, while the rest of differentials had severities from 5 to 6. PG5 isolates caused no infection on Davis, severity of 7 on CNS, and severity of 8 on Kent, Hood, and Palmetto. The remaining seven differentials had severities of 9. Across the geographical locations, the predominant pathotypes were PG3 and PG4 and represented 84% of the tested isolates. Azoxystrobin fungicide sensitivity tests showed that 88% of the isolates were sensitive and dominated the population, while only 6% had a high level of fungicide resistance, suggesting that FLS resistance to the QoI fungicide group was not yet completely developed and had not spread to other areas at the time when these isolates were acquired. The overall virulence profile of the isolates indicated that there was variation in disease severity, suggesting that selection of resistance for each PG may produce lines with more precisely defined interactions to specific pathotypes of C. sojina. This may improve the screening and selection of useful resistance genes that could be pyramided for resistance to each pathogenicity group.

scholarly journals Effect of substrates to formulate Trichoderma harzianum based bio-fungicide in controlling seedling disease (Rhizoctonia solani) of brinjal

2017 ◽  
Vol 42 (1) ◽  
pp. 159-170 ◽  
Author(s):  
MI Faruk ◽  
ML Rahman
Keyword(s):  
Rhizoctonia Solani ◽  
Rice Bran ◽  
Wheat Bran ◽  
Trichoderma Harzianum ◽  
Agricultural Research ◽  
Root Weight ◽  
Agricultural Research Institute ◽  
Seedling Disease ◽  
House Condition ◽  
Shoot Weight

Efficacy of three different substrates viz., rice bran, wheat bran, grass pea bran and their combinations with mustard oilcake (MOC) were tested to formulate a suitable Trichoderma harzianum based bio-fungicide for controlling seedling disease of brinjal caused by Rhizoctonia solani in tray soil as well as in seedbed soil under net house condition of Bangladesh Agricultural Research Institute (BARI), Gazipur during 2010 to 2014. The results of three years experiments revealed that T. harzianum bio-fungicides formulated in five different combinations of substrates viz., (1) rice bran + wheat bran, (2) rice bran + mustard oilcake (MOC) (3) rice bran + grasspea bran, (4) rice bran + wheat bran + MOC and (5) rice bran + grasspea bran +MOC were equally effective to control the soil borne seedling disease of brinjal caused by Rhizoctonia solani in tray soil and seedbed condition. In addition, vegetative growth of brinjal seedlings viz., shoot length, shoot weight, root length and root weight were enhanced significantly by the T. harzianum bio-fungicides in R. solani inoculated seedbed condition.Bangladesh J. Agril. Res. 42(1): 159-170, March 2017

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&lt;0.01) was found.

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.

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