scholarly journals Brown Root Rot Disease of Phyllanthus myrtifolius: The Causal Agent and Two Potential Biological Control Agents

Plant Disease ◽  
2020 ◽  
Vol 104 (11) ◽  
pp. 3043-3053
Author(s):  
Ka-Tung Leung ◽  
Chi-Yu Chen ◽  
Bang-Jau You ◽  
Miin-Huey Lee ◽  
Jenn-Wen Huang
Keyword(s):  
Disease Severity ◽  
Root Rot ◽  
Leaf Size ◽  
Severity Index ◽  
Disease Diagnosis ◽  
Good Growth ◽  
Bacillus Sp ◽  
New Host ◽  
Practical Applications ◽  
Brown Root Rot

Brown root rot (BRR), caused by Phellinus noxius (Corner) G. Cunningham, occurs on over 200 species of plants, especially woody trees and shrubs. Ceylon myrtle (Phyllanthus myrtifolius [Wight] Müll.Arg.), a common hedge plant, was recently observed to be infected with BRR. Disease diagnosis was performed by completing Koch’s postulates, and Ceylon myrtle was confirmed to be a new host of P. noxius. Typical symptoms of BRR were observed, including reduction in leaf size, dieback of branches, and suspended growth of young leaves. A disease severity index was used to quantify BRR in this study. Compared with Malabar chestnut, Ceylon myrtle was relatively resistant to BRR. Surprisingly, phylogenetic analysis of the ITS and 28S sequences revealed that isolates identified as P. noxius from Taiwan and many other countries were clustered in the same clade but separate from the clade comprising isolates from China, which were designated Pyrrhoderma noxium based on P. noxius. Therefore, to temporarily distinguish these pathogens, the former clade was designated GPN (global P. noxius), whereas the latter clade was designated CPN (China Py. noxium). In biocontrol assays, Streptomyces padanus and Bacillus sp. were selected for BRR control of Ceylon myrtle. Disease severity was reduced from 0.51 to 0.37 by S. padanus and to 0.14 by Bacillus sp. in greenhouse trials. In addition, the two biocontrol agents, especially S. padanus, exhibited good growth-promoting effects on cuttings of Ceylon myrtle. With these double advantages, S. padanus and Bacillus sp. have great potential to control BRR in practical applications.

scholarly journals Digital Video Technology as an Aid for Quantifying Root Rot

HortScience ◽  
1999 ◽  
Vol 34 (2) ◽  
pp. 294-295
Author(s):  
C.C. Pasian ◽  
F. Varela Ramirez ◽  
S. Nameth
Keyword(s):  
Disease Severity ◽  
Root Length ◽  
Root Rot ◽  
Traditional Method ◽  
Root Systems ◽  
Severity Index ◽  
Pythium Ultimum ◽  
Transparent Film ◽  
Video Technology ◽  
Simple Method

Evaluation of disease severity in root systems is usually subjective, based on observation and categorization into an arbitrary scale of several categories. Results obtained using this approach can vary according to the observer's experience. A new, simple method for evaluating and quantifying the root severity index (RSI) was developed. This method consists of surrounding the root pan with a transparent film and tracing all roots with a marker. On a second transparency, only healthy roots are traced. Lengths of both healthy and diseased roots are measured with a root length/area meter (Dias II). The method of peripheral root-ball root tracings was evaluated with poinsettias infected with Pythium ultimum (Trow.). Results indicated that it was as effective as the traditional method of determining RSI for total and peripheral roots.

A ROOT ROT OF SWEET CLOVER AND RELATED CROPS CAUSED BY PLENODOMUS MELILOTI DEARNESS AND SANFORD

1933 ◽  
Vol 8 (4) ◽  
pp. 337-348 ◽  
Author(s):  
G. B. Sanford
Keyword(s):  
Root Rot ◽  
Ph Value ◽  
Practical Importance ◽  
Early Spring ◽  
Good Growth ◽  
Sweet Clover ◽  
Alkaline Reaction ◽  
Rot Disease ◽  
The One ◽  
Brown Root Rot

The occurrence, hosts and symptoms of a hitherto undescribed root rot of Melilotus, Medicago and Trifolium, and the relation of temperature and the reaction of substrate to growth of the pathogen Plenodomus meliloti are discussed, and its pathogenicity demonstrated. It is suggested that the disease be called "brown root rot".Evidence is that the hosts mentioned are susceptible only during the winter and early spring dormancy stage. Normal roots of sweet clover, when frozen at −4 °C. for four days and subsequently kept at 2–3°, 9° and 16 °C., did not become susceptible. The brown root-rot disease is distinct from true winter injury resulting from insufficient hardiness to cold.The temperature range for vegetative growth and pycnidia of P. meliloti is from 0° to 27 °C., with optimum between 15° and 17 °C. Increasingly good growth occurs from 2 °C. to optimum temperature. Severe lesions are produced at 2–3°, 9° and 16 °C. The optimum pH value for growth in potato dextrose decoction is about 6.2, the other limits being approximately pH 3.2 and 8.2. Soils with an alkaline reaction apparently are unfavorable.The disease is characterized by brown lesions, on or within which are an abundance of black to dark brown pycnidia. These bodies, 0.5 to 2 mm. in longest diameter, may have one or more spore bearing chambers. Each chamber may have one to several ostioles, through which the one-celled spores, averaging 5.2 × 2.84 μ, exude. The hyphae do not bear spores.Dissemination of the pathogen by seed would not seem to be of practical importance. Control by crop sanitation is recommended, at least until varieties more resistant are available.

scholarly journals THE REACTION OF SWEETCLOVER VARIETIES TO BROWN ROOT ROT

1969 ◽  
Vol 49 (2) ◽  
pp. 181-183 ◽  
Author(s):  
B. Berkenkamp ◽  
H. Baenziger
Keyword(s):  
Root Rot ◽  
Geographic Origin ◽  
Lotus Corniculatus ◽  
New Host ◽  
Melilotus Alba ◽  
Brown Root Rot

Several varieties of Melilotus alba and M. officinalis were evaluated in the spring of 4 years for their resistance to Plenodomus meliloti. Survival and yield were a reflection of resistance which was related to lesioning of roots and formation of pycnidia. Survival was correlated with lesioning of roots (r = − 0.73) and pycnidial formation (r = − 0.67). There was evidence that the reaction of a variety could vary depending on the geographic origin of the seed. A new host, Lotus corniculatus, is reported.

Suppression of Root Diseases and Weeds in Peas(Pisum sativum)Treated with Dinitrophenol and Dinitroaniline Herbicides

Weed Science ◽  
1978 ◽  
Vol 26 (6) ◽  
pp. 589-593
Author(s):  
R. F. Sacher ◽  
H. J. Hopen ◽  
B. J. Jacobsen
Keyword(s):  
Pisum Sativum ◽  
Weed Control ◽  
Disease Severity ◽  
Root Rot ◽  
Fungal Pathogens ◽  
Severity Index ◽  
Disease Severity Index ◽  
Aphanomyces Euteiches ◽  
Root Diseases ◽  
Dinitroaniline Herbicides

Dinoseb (2-sec-butyl-4,6-dinitrophenol) and certain dinitroaniline herbicides suppressed root rot caused byAphanomyces euteichesDrechs. and other fungal pathogens in peas(Pisum sativumL.). Dinoseb was the most effective. At 6.72 kg/ha pre-plant incorporated (PPI) it reduced the disease severity index (DSI) in glasshouse bioassays to the level considered safe for general use by commercial growers. In fields tests disease severity was reduced and yield of peas was increased with dinoseb. Dinitroaniline herbicides reduced DSI values to the level considered safe for early crop peas. A simplified DSI method of measuring root rot based on mid-season root symptoms was found to be effective. Weed control was superior with the dinitroanilines and propachlor (2-chloro-N-isoproylacetanilide). Dinoseb significantly reduced weed populations relative to untreated plots. Several dinitroaniline treatments caused stunting and stand reduction.

EVALUATION OF NONIONIC SURFACTANTS FOR CONTROL OF CLUBROOT OF CABBAGE USING BAREROOT AND PLUG TRANSPLANTS OF TWO CULTIVARS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 607b-607
Author(s):  
W. Tietjen ◽  
P.J. Nitzsche ◽  
W.P. Cowgill ◽  
M.H. Maletta ◽  
S.A. Johnston
Keyword(s):  
Brassica Oleracea ◽  
Disease Severity ◽  
Nonionic Surfactants ◽  
Plasmodiophora Brassicae ◽  
Severity Index ◽  
Effective Control ◽  
Disease Severity Index

`Market Prize' and `Bravo' cabbage (Brassica oleracea Var. capitata L.), transplanted as peat plug and bareroot plants into a field naturally infested with Plasmodiophora brassicae, Woronin, were treated immediately after planting with a liquid or a granular surfactant. APSA 80™, applied in transplant water, significantly reduced percent clubbing and disease severity index (DSI) compared to control treatments. Miller Soil Surfactant Granular™ did not significantly reduce percent clubbing or DSI. There was a significant effect of cultivar on percent clubbing and DSI. There was no significant effect of transplant type on percent clubbing or DSI. This year's study culminates five years of investigation of surfactants for clubroot control. Specific surfactants have proven to be an effective control of clubroot in cabbage. Chemical names used: nonylphenoxypolyethoxyethanol (APSA 80™); alpha-alkanoic-hydro omega-hydroxy poly (oxyethylene) (Miller Soil Surfactant Granular™).

Evidence for the heritability of resistance to brown root rot of alfalfa, caused byPhoma sclerotioides

2005 ◽  
Vol 27 (1) ◽  
pp. 64-70 ◽  
Author(s):  
C.R. Hollingsworth ◽  
F.A. Gray ◽  
R.W. Groose
Keyword(s):  
Root Rot ◽  
Brown Root Rot

scholarly journals Association of Pathogenic Th17 Cells with the Disease Severity and Its Potential Implication for Biological Treatment Selection in Psoriasis Patients

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Cristina Aguilar-Flores ◽  
Octavio Castro-Escamilla ◽  
Elizabeth M. Ortega-Rocha ◽  
César Maldonado-García ◽  
Fermín Jurado-Santa Cruz ◽  
...  
Keyword(s):  
Disease Severity ◽  
Peripheral Blood ◽  
Th17 Cells ◽  
Life Quality ◽  
Severity Index ◽  
Experimental Models ◽  
Cutaneous Lesions ◽  
Potential Implication ◽  
Th17 Lymphocytes ◽  
Pasi Score

Psoriasis is an inflammatory autoimmune disease characterized by cutaneous lesions in plaques. It has been proposed that the immune response has a key role in the disease progression. Particularly, the Th17 cells through IL-17 can contribute to maintain the inflammatory process. The pathogenic Th17 phenotype has been described in human diseases and associated with high severity in inflammatory experimental models. However, it is not clear if the pathogenic phenotype could be present in the skin and peripheral blood as well as its possible association to severity in psoriasis. In the lesional skin, we found high infiltration of Th17 cells and the pathogenic phenotype, finding a correlation between the frequency of Th17 cells and the Psoriasis Area and Severity Index (PASI) score. In peripheral blood, we observed a pool of Th17 lymphocytes with potential to acquire pathogenic features. Interestingly, the percentage of pathogenic Th17 cells (CD4+ RORγt+ IFN-γ+) correlates with disease severity. Moreover, we distinguished three groups of patients based on their IL-17/IFN-γ production by Th17 lymphocytes, which seems to be related with a dynamic or stable potential to express these cytokines. Remarkably, we evaluated the cytokine production by Th17 cells as an immunological marker for the adequate selection of biologic therapy. We found that patients analyzed by this immunological approach and treated with antibodies against IL-17 and TNFα showed great improvement depicted by reduction in PASI and Dermatology Life Quality Index (DLQI) score as well as the percentage of Body Surface Area (BSA). Altogether, our results highlight the importance of the assessment of the pathogenic phenotype in Th17 cells as an immune personalized analysis with the potential to support the therapy choice in the clinical practice.

The epidemiology of common root rot in Manitou wheat: disease progression during the growing season

1974 ◽  
Vol 52 (7) ◽  
pp. 1757-1764 ◽  
Author(s):  
P. R. Verma ◽  
R. A. A. Morrall ◽  
R. D. Tinline
Keyword(s):  
Triticum Aestivum ◽  
Disease Severity ◽  
Plant Development ◽  
Root Rot ◽  
Growing Season ◽  
Cochliobolus Sativus ◽  
Infection Rates ◽  
Common Root ◽  
Common Root Rot ◽  
Disease Rating

Common root rot in Triticum aestivum cultivar Manitou caused primarily by Cochliobolus sativus was followed during plant development in 1969, 1970, and 1971 at Matador, Saskatchewan. Plants were sampled at intervals, and three variables based mainly on the occurrence of lesions on subcrown internodes were studied: number of diseased plants per square meter; percentage of diseased plants; and disease rating which integrated percentage of diseased plants and disease severity on each plant. All variables increased with time, and the progression curves in all 3 years were hyperbolic, indicating that the increases were like those of a simple interest disease as described by Van der Plank. In two of the years, almost 100% of the plants were diseased considerably before the end of the season. The transformation proposed by Van der Plank for simple interest diseases, log10[1/(1 − x)], was applied to the percentages of diseased plants, and regressions were calculated. The slopes of these lines (infection rates) were as follows: 1969, 0.99% plants per day; 1970, 1.32%; and 1971, 1.96%. In 1969 the onset of disease was later than in 1970 and 1971, and there was correspondingly less disease at the end of the growing season.

EVALUATION OF ALFALFA CULTIVARS FOR REACTION TO CROWN AND ROOT ROT

1985 ◽  
Vol 65 (1) ◽  
pp. 95-98 ◽  
Author(s):  
R. MICHAUD ◽  
C. RICHARD
Keyword(s):  
Disease Severity ◽  
Root Rot ◽  
Dry Matter ◽  
Forage Yield ◽  
Dry Matter Yield ◽  
Crown And Root Rot ◽  
Disease Free

Fourteen alfalfa cultivars were grown for 2 yr at three locations and evaluated for forage dry matter yield and crown and root rot. Significant differences were found among cultivars for dry matter yield. All cultivars were affected by crown and root rot, most cultivars showing between 20 and 30% of infected tissues. Differences were observed among as well as within the cultivars for disease severity. The frequency of disease-free plants was less than 1.3% of the plants evaluated. Correlation between root rot index and forage yield was −0.87 [Formula: see text] when data were pooled over years and locations.Key words: Lucerne, root rot, cultivar, yield

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