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.

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)

scholarly journals Mefenoxam Sensitivity, Aggressiveness, and Identification of Pythium Species Causing Root Rot on Floriculture Crops in North Carolina

Plant Disease ◽  
2015 ◽  
Vol 99 (11) ◽  
pp. 1550-1558 ◽  
Author(s):  
E. C. Lookabaugh ◽  
K. L. Ivors ◽  
B. B. Shew
Keyword(s):  
North Carolina ◽  
Host Species ◽  
Root Rot ◽  
Internal Transcribed Spacer ◽  
Ornamental Plants ◽  
Pythium Species ◽  
Selective Media ◽  
Microtiter Plates ◽  
Pythium Root Rot

Herbaceous ornamental plants exhibiting symptoms of Pythium root rot were collected from 26 greenhouses in 21 counties in North Carolina (NC) from 2010 to 2012. Plant symptoms ranged from mild stunting to severe wilting, root rot, and death. Roots were plated on selective media, and 356 isolates of Pythium were recovered from 34 host species. Selected isolates were identified by sequencing of the internal transcribed spacer (ITS) rDNA gene region. Seventeen Pythium species were identified, with P. aphanidermatum, P. irregulare, and P. myriotylum comprising 75% of the 320 isolates sequenced. Twelve of the 26 greenhouses had more than one species present. Mefenoxam sensitivity was tested in vitro by growing isolates in wells of microtiter plates containing clarified V8 agar amended with 100 µg a.i./ml mefenoxam. Colonization was scored after 24 to 48 h using a scale of 0 (no growth) to 5 (entire well colonized). Fifty-two percent of the isolates were resistant to mefenoxam (mean score ≥4). All 32 isolates of P. myriotylum were sensitive, whereas sensitivity varied among isolates of P. aphanidermatum and P. irregulare. Resistant and sensitive isolates of the same species were found within the same greenhouses. The aggressiveness of P. aphanidermatum and P. irregulare isolates was evaluated on poinsettia, Gerbera daisy, and petunia. P. aphanidermatum was more aggressive than P. irregulare on poinsettia and petunia; symptoms were mild and no differences in aggressiveness were observed on Gerbera daisy. Sensitivity to mefenoxam was not related to aggressiveness.

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.

Pruning and training.

2021 ◽  
Author(s):  
Lynette Morgan
Keyword(s):  
Plant Growth ◽  
Ornamental Plants ◽  
Training Methods ◽  
Aesthetic Value ◽  
Diverse Range ◽  
Horticultural Crops ◽  
Plant Form ◽  
Ease Of Access ◽  
The Aesthetic ◽  
And Training

Abstract Manipulation of plant growth via pruning and training methods has been carried out for as long as crops have been cultivated by man. These methods serve to not only improve the aesthetic value of ornamental plants, but also to increase yields, optimise fruit quality and prolong the productive life of horticultural crops. Pruning involves the selective removal of a diverse range of plant tissue. Branches, stems, roots, buds, flowers, leaves and young fruitlets may all be pruned depending on the purpose, species and growth form of the crop this is applied to. Training methods for horticultural applications are primarily used to support the plant and the weight of produce as it develops. Training structurally alters plant form, to alter the shape, size and direction of plant growth, it also allows optimal light interception and air flow and for ease of access for harvesting and other operations.

scholarly journals Integrated Control of Rhizoctonia Crown and Root Rot of Sugar Beet with Fungicides and Antagonistic Bacteria

Plant Disease ◽  
2001 ◽  
Vol 85 (7) ◽  
pp. 718-722 ◽  
Author(s):  
Sebastian Kiewnick ◽  
Barry J. Jacobsen ◽  
Andrea Braun-Kiewnick ◽  
Joyce L. A. Eckhoff ◽  
Jerry W. Bergman
Keyword(s):  
Sugar Beet ◽  
Root Rot ◽  
Integrated Control ◽  
The United States ◽  
Field Trials ◽  
Sugar Yield ◽  
Economic Losses ◽  
Yield Increase ◽  
Leaf Stage ◽  
Crown And Root Rot

Rhizoctonia crown and root rot, caused by the fungus Rhizoctonia solani AG 2-2, is one of the most damaging sugar beet diseases worldwide and causes significant economic losses in more than 25% of the sugar beet production area in the United States. We report on field trials in the years 1996 to 1999 testing both experimental fungicides and antagonistic Bacillus sp. for their potential to reduce disease severity and increase sugar yield in trials inoculated with R. solani AG 2-2. Fungicides were applied as in-furrow sprays at planting or as band sprays directed at the crown at the four-leaf stage, or four- plus eight-leaf stage, while bacteria were applied at the four-leaf stage only. The fungicides azoxystrobin and tebuconazole reduced crown and root rot disease by 50 to 90% over 3 years when used at rates of 76 to 304 g a.i./ha and 250 g a.i./ha, respectively. The disease index at harvest was reduced and the root and sugar yield increased with azoxystrobin compared with tebuconazole. The combination of azoxystrobin applied at 76 g a.i./ha and the Bacillus isolate MSU-127 resulted in best disease reduction and greatest root and sucrose yield increase.

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.

STUDIES ON BROWNING ROOT ROT OF CEREALS: VI. FURTHER CONTRIBUTIONS ON THE EFFECTS OF VARIOUS SOIL AMENDMENTS ON THE INCIDENCE OF THE DISEASE IN WHEAT

1940 ◽  
Vol 18c (6) ◽  
pp. 240-257 ◽  
Author(s):  
T. C. Vanterpool
Keyword(s):  
Root Rot ◽  
Nutrient Deficiencies ◽  
Sweet Clover ◽  
Poor Growth ◽  
Prairie Soils ◽  
Pythium Root Rot ◽  
The Poor ◽  
Copper Manganese ◽  
Supplemental Nutrients ◽  
Severe Leaf

Further work has substantiated earlier findings that phosphatic fertilizers and farm manure will give adequate control of Pythium root rot of wheat in infested prairie soils. The improvement in growth resulting from these amendments is considered to be due to the production of a larger number of quicker growing roots which lessens the chances for infection and leaves more roots healthy, though the same percentage may be affected as in diseased plants showing severe leaf discolorations. Experiments have failed to indicate that the phosphatic materials increase resistance appreciably. Nitrogenous materials when applied singly had virtually no effect on growth, but once ample phosphorus was added, further nitrogen applications gave substantially greater increases than phosphate alone. Phosphorus is apparently the chief limiting element. No difference was found in preliminary tests in the phosphate-fixing power of browning and normal soils. Typical browning soils responded irregularly to small applications of boron, copper, manganese, or zinc, but were not found to be seriously lacking in these elements. Moderate benefits resulted from heavy applications of gypsum and of sulphur. Browning soil was found also to be deficient in phosphate for non-cereals such as alfalfa, buckwheat, carrots, flax, lettuce, and sweet clover. These crops were not attacked by the Pythium spp. pathogenic to cereals. Consequently the poor growth of the non-cereals in browning soil appears to be due to nutrient deficiencies, while the poor growth of cereals is due to both root-destroying fungi and nutrient deficiencies. In both instances phosphorus is probably the chief limiting element. Ground cereal straw, sweet clover hay, and weed hay amendments gave moderate increases m the growth of wheat. No consistent differences were found in the carbon-nitrogen ratios of browning and normal soils. The results as a whole suggest that two of the most practicable means of meeting the browning root-rot situation are, firstly, to supply supplemental nutrients in the form of artificial fertilizers, and secondly, to add organic residues or farm manure regularly to fields subject to the disease.

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