scholarly journals Evaluation of Caladium Cultivars for Resistance to Pythium Root Rot

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 772E-773 ◽  
Author(s):  
Zhanao Deng* ◽  
Brent K. Harbaugh ◽  
Rick Kelly ◽  
Teresa Seijo ◽  
Robert J. McGovern
Keyword(s):  
Root Rot ◽  
Plant Production ◽  
Higher Plant ◽  
Pythium Root Rot ◽  
Tuber Production ◽  
Commercial Cultivars ◽  
Greenhouse Plant ◽  
Growing Conditions ◽  
Spore Densities ◽  
Highly Virulent

Caladiums (Caladium × hortulanum) are widely grown for their bright colorful leaves. Pythium root rot, caused primarily by P. myriotylum, is one of the most important diseases in caladiums. This disease can dramatically reduce plant growth, impact plant aesthetical value, and lower tuber yield. Pythium infection in the roots may also lead to subsequent entry of Fusarium into tubers resulting in tuber rot. There has been a strong interest in the tuber production and greenhouse plant production industries to identify cultivars that are resistant or tolerant to Pythium. However, few studies have been conducted since the pathogen was identified, and little information is available regarding the existence of any possible resistance in commercial cultivars. Pythium isolates were made from diseased plants collected from different sites; their pathogenicity was confirmed using tissue culture-derived plants. Procedures were developed for oogonia spore production, inoculation, and disease severity assessment. Nineteen major commercial cultivars were inoculated at two spore densities and then maintained in greenhouses under growing conditions favorable for root rotting. Plant appearance, leaf characteristics and severity of root rotting were evaluated 2-3 times after inoculation. Observations indicated that the isolates were highly virulent. They induced visible root rot within 3-5 days, and caused a complete loss of the root system and plant death for some cultivars within 2-3 weeks after inoculation. Several cultivars, including `Candidum' and `Frieda Hemple' which are widely grown cultivars, had much less root rot, higher plant survival, and seemed to have moderate levels of resistance.

scholarly journals Screening for Resistance to Pythium Root Rot among Twenty-three Caladium Cultivars

2005 ◽  
Vol 15 (3) ◽  
pp. 631-634 ◽  
Author(s):  
Zhanao Deng ◽  
Brent K. Harbaugh ◽  
Rick O. Kelly ◽  
Teresa Seijo ◽  
Robert J. McGovern
Keyword(s):  
Root Rot ◽  
Tuber Yield ◽  
Sources Of Resistance ◽  
Aesthetic Value ◽  
Pythium Root Rot ◽  
Landscape Plants ◽  
Tuber Production ◽  
Commercial Cultivars ◽  
Loss Severity ◽  
Pot Plant

Caladiums (Caladium ×hortulanum) are widely grown as pot or landscape plants for their attractive leaves. Pythium root rot (Pythium myriotylum) is one of the most damaging diseases in caladium, severely reducing plant growth, aesthetic value, and tuber yield. Twenty-three commercial cultivars were inoculated with three aggressive isolates of P. myriotylum and evaluated for their resistance to root rot. Three cultivars, `Apple Blossom', `Blizzard', and `Etta Moore', were found to have a moderate level of resistance (partial resistance) to pythium root rot. The rest of these cultivars were susceptible or highly susceptible to Pythium infection, losing up to 94% of their root tissue to rotting within 10 days after inoculation. Data indicated a linear relationship between root rot severity and leaf loss severity on Pythium-inoculated plants and highlight the importance of controlling pythium root rot in caladium pot plant and tuber production. Comparison of some recent releases with their parents for pythium root rot resistance suggests the potential of developing new resistant caladium cultivars using the identified sources of resistance.

scholarly journals Resistance of Nineteen Major Caladium Commercial Cultivars to Pythium Root Rot

EDIS ◽  
1969 ◽  
Vol 2005 (3) ◽  
Author(s):  
Zhanao Deng ◽  
Brent K. Harbaugh ◽  
Richard O. Kelly ◽  
Teresa Seijo ◽  
Robert J. McGovern
Keyword(s):  
Root Rot ◽  
Integrated Management ◽  
Ornamental Plants ◽  
Control Measures ◽  
Publication Date ◽  
Aesthetic Value ◽  
Resistance Level ◽  
University Of Florida ◽  
Pythium Root Rot ◽  
Commercial Cultivars

Caladiums (Caladium xhortulanum) are popular ornamental plants widely grown for their bright colorful leaves. Pythium root rot, caused by P. myriotylum, is one of the few soil-borne diseases in caladium that can dramatically reduce plant growth, aesthetic value, and tuber yield. Identification and use of disease-resistant cultivars has proven to be an important and economically viable strategy for integrated management of major diseases in crops and for reducing the use of pesticides. This strategy will be particularly useful for caladiums in the landscape and home gardens, because in such cases choices of root rot control measures are limited. However, information on the resistance level of commercial caladium cultivars has been lacking. This document is ENH996, one of a series of the Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date December 2, 2004.  ENH996/EP251: Resistance of Nineteen Major Caladium Commercial Cultivars to Pythium Root Rot (ufl.edu)

Evaluation of the effectiveness of biocontrol bacteria against avocado white root rot occurring under commercial greenhouse plant production conditions

2013 ◽  
Vol 67 (2) ◽  
pp. 94-100 ◽  
Author(s):  
María Ángeles González-Sánchez ◽  
Antonio de Vicente ◽  
Alejandro Pérez-García ◽  
Rosa Pérez-Jiménez ◽  
Diego Romero ◽  
...  
Keyword(s):  
Root Rot ◽  
Plant Production ◽  
White Root Rot ◽  
Biocontrol Bacteria ◽  
Greenhouse Plant ◽  
Production Conditions

scholarly journals Screening for Resistance to Pythium Root Rot among Twenty-three Caladium Cultivars

EDIS ◽  
2019 ◽  
Vol 2005 (11) ◽  
Author(s):  
Zhanao Deng ◽  
Brent K. Harbaugh ◽  
Rick O. Kelly ◽  
Teresa Seijo ◽  
Robert J. McGovern
Keyword(s):  
Root Rot ◽  
Integrated Management ◽  
Cooperative Extension Service ◽  
Publication Date ◽  
University Of Florida ◽  
Resistant Cultivars ◽  
Evaluation Procedures ◽  
Pythium Root Rot ◽  
Commercial Cultivars ◽  
Screening For Resistance

Pythium root rot, caused by Pythium myriotylum (Ridings and Hartman, 1976), is a very damaging disease to caladium plants (Caladium x hortulanum). Use of disease-resistant cultivars has been an effective and economically viable strategy for integrated management of major diseases in numerous crops. This strategy could be used to control pythium root rot in caladium if resistant cultivars could be identified or developed. In an evaluation of 19 major commercial cultivars, 'Candidum', 'Candidum Jr.', 'Frieda Hemple', and 'White Christmas' were found to have a moderate level of resistance to Pythium. To find more resistant cultivars, twenty-three additional commercial cultivars were screened using the same Pythium isolates, inoculation and evaluation procedures as described earlier (Deng et al. 2004). This document is ENH1008, one of a series of the Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date September 27, 2005. ENH1008/EP259: Screening for Resistance to Pythium Root Rot among Twenty-three Caladium Cultivars (ufl.edu)

scholarly journals Pythium Root Rot and Growth Responses of Organically Grown Geranium Plants to Beneficial Microorganisms

HortScience ◽  
2009 ◽  
Vol 44 (6) ◽  
pp. 1622-1627 ◽  
Author(s):  
Valérie Gravel ◽  
Claudine Ménard ◽  
Martine Dorais
Keyword(s):  
Pseudomonas Putida ◽  
Root Rot ◽  
Dry Weight ◽  
Pythium Ultimum ◽  
Organic Production ◽  
Plant Production ◽  
Trichoderma Atroviride ◽  
Growth Responses ◽  
Pythium Root Rot ◽  
Organically Grown

Pythium root rot, caused by Pythium ultimum, is responsible for important losses in geranium plant production, mainly as a result of the decrease in the plant overall quality. An organic production system for geranium plants based on fertilization using a filtered suspension of dehydrated hen manure was compared with a conventional fertilization system to evaluate their tolerance to root disease. Under typical greenhouse conditions, geranium plants were inoculated with a suspension of Pseudomonas putida, Trichoderma atroviride, a mixture of both or with Trichoderma harzianum, and a commercially available product, Rootshield®, 1 and 4 weeks after planting. Four weeks after the first inoculation, Pseudomonas putida and Trichoderma atroviride stimulated plant growth (shoot and root dry weight) compared with the control regardless of the fertilization. The results also showed that the colonization of geranium roots by Pythium spp. was significantly lower for organically grown plants for all treatments compared with the inoculated control under conventional fertilization. Inoculation with T. atroviride under conventional fertilization was the only treatment that did not significantly reduce root colonization by Pythium spp. compared with the conventional control. For both organically and conventionally grown plants, the coinoculation with both P. putida and T. atroviride resulted in the weakest colonization of roots by the pathogen. The inoculation of P. putida, T. atroviride, and the mixture of the bacterium and the fungus also significantly increased the fresh and dry weight of roots regardless of the fertilization used. All microorganism treatments in conventionally grown plants significantly increased the fresh and dry weight of the shoot compared with the control.

scholarly journals Pythium Root Rot Resistance in Commercial Caladium Cultivars

HortScience ◽  
2005 ◽  
Vol 40 (3) ◽  
pp. 549-552 ◽  
Author(s):  
Zhanao Deng ◽  
Brent K. Harbaugh ◽  
Rick O. Kelly ◽  
Teresa Seijo ◽  
Robert J. McGovern
Keyword(s):  
Root Rot ◽  
Tuber Yield ◽  
Integrated Control ◽  
Ornamental Plants ◽  
Aesthetic Value ◽  
Pythium Root Rot ◽  
Yield Information ◽  
Loss Severity ◽  
Highly Virulent ◽  
Potential Use

Caladiums (Caladium ×hortulanum) are popular ornamental plants widely grown for their bright colorful leaves. Pythium root rot, caused by Pythium myriotylum, is one of the few soil-borne diseases in caladium that dramatically reduces plant growth, aesthetic value, and tuber yield. Information on the reaction of caladium cultivars to P. myriotylum is not available, but would be valuable for integrated control of this disease and for breeding new resistant cultivars. Three Pythium isolates obtained from decaying roots of plants collected from a field production site and two greenhouses were evaluated for pathogenicity and potential use in experiments to screen commercial caladium cultivars for resistance. All three isolates were found to be highly virulent; they were able to cause obvious root rotting within 3 to 5 days and severe root rotting and leaf losses on susceptible cultivars within 10 days after inoculation. Nineteen major commercial cultivars were evaluated for their resistance to these isolates. Fifteen of the cultivars were susceptible or highly susceptible to Pythium infection. Four widely grown cultivars, `Candidum', `Candidum Jr.', `Frieda Hemple', and `White Christmas', were found to have a moderate level of resistance (partial resistance) to pythium root rot. Pythium infection also caused leaf discoloration, epinasty, wilting, and collapse. Regression analyses revealed a linear relationship between the root rot and leaf loss severity on Pythium-inoculated plants.

Long-term in vitro Storage Technique of Valuable Birch Genotypes and Plant Production on its Basis

2019 ◽  
pp. 57-67
Author(s):  
T.M. Tabatskaya ◽  
N.I. Vnukova
Keyword(s):  
Plant Production ◽  
High Survival ◽  
Ex Vitro ◽  
Regenerative Capacity ◽  
In Vitro Storage ◽  
Interspecific Differences ◽  
Regenerated Plants ◽  
Growing Conditions

A technique for the long-term (up to 27 years) in vitro storage of valuable birch genotypes under normal (25 °C, 2.0 klx, 16-h day and 8-h night) and low temperature (4 °C, 0.5 klx, 6-h day and 18-h night) growing conditions on hormone-free media has been described. The study explored for the first time the influence of different strategies to store the clones of Betula pubescens and B. pendula var. сarelica (6 genotypes) on the regenerative capacity of collection samples, adaptive potential of regenerated plants and plant production by the in vitro and ex vitro techniques. It was established that both storage strategies provided a persistently high survival rate (82-100%) and regenerative capacity of in vitro shoots (the multiplication coefficient of 4.2-6.3 and rhizogenic activity of 90-100%). The clones retained their characteristics of height growth under the in vitro and ex vitro conditions, and demonstrated intraclonal homogeneity and lack of signs of somaclonal variability. The plants showed substantial interspecific differences at the stage of multiplication and transfer to the greenhouse. The highest percentage of acclimated plants (75-98% depending on the clone genotype) was obtained after planting of micro plants straight in the greenhouse, which simplified the technology and made plant production less costly. long-term in vitro storage, birch, species, genotype, micropropagation, ex vitro adaptation, plant material

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.

Identification of metalaxyl and ethaboxam insensitive Pythium sylvaticum pathogenic to pulse crops in Montana, USA.

2021 ◽  
Author(s):  
Lipi Parikh ◽  
Swarnalatha Moparthi ◽  
Frankie Crutcher ◽  
Mary Burrows
Keyword(s):  
Root Rot ◽  
Damping Off ◽  
Management Options ◽  
Fungicide Sensitivity ◽  
Root Rots ◽  
Pulse Crops ◽  
Pythium Root Rot ◽  
Pythium Sylvaticum ◽  
Potential Pathogenicity

Pythium root rot and damping-off caused by Pythium spp. are important diseases of pulse crops. In a 2016 pathogen survey from dry pea growing fields in Montana, along with commonly known causal agents P. ultimum and P. irregulare, an isolate identified as P. sylvaticum (LPPY17) was isolated from the rhizosphere of a diseased pea plant collected from Valley County, MT. Root rots and damping-off caused by P. sylvaticum have not previously been reported for chickpea, pea, and lentil crops. The isolate LPPY17 was tested for fungicide resistance in vitro, and results indicated a reduced sensitivity to metalaxyl and ethaboxam containing fungicides. LPPY17 was also tested for pathogenicity on chickpea, pea, and lentil seedlings in the greenhouse, and the results from the study revealed LPPY17 is capable of causing both root rots and damping off. Due to the potential pathogenicity and reduced fungicide sensitivity of this species, in the future it will be important to monitor for P. sylvaticum in pulse root rot surveys and diagnostics, as management options may be different from other common Pythium spp.

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