scholarly journals On some cultural characters of tobacco black root rot fungus, Thielaviopsis basicola (Berk. et Br.) Ferraris.

1957 ◽  
Vol 22 (4-5) ◽  
pp. 204-210
Author(s):  
Yoichi YAMAGUCHI
Keyword(s):  
Root Rot ◽  
Thielaviopsis Basicola ◽  
Black Root Rot

scholarly journals Black Root Rot Caused by Thielaviopsis basicola on Lettuce in California

Plant Disease ◽  
2008 ◽  
Vol 92 (9) ◽  
pp. 1368-1368 ◽  
Author(s):  
S. T. Koike
Keyword(s):  
Root Rot ◽  
Disease Incidence ◽  
Control Plant ◽  
Pathogenic Fungi ◽  
Plant Roots ◽  
Peat Moss ◽  
Thielaviopsis Basicola ◽  
Black Root Rot ◽  
Iceberg Lettuce ◽  
Salinas Valley

In 2005 and 2006, field-grown iceberg lettuce (Lactuca sativa) in California's coastal Salinas Valley (Monterey County) was affected by a previously unreported disease. Symptoms were observed on iceberg lettuce at the post-thin rosette stage (8 to 12 leaves). Plants were stunted and slightly chlorotic. Fine feeder roots had numerous, small (4 to 8 mm long), elongated, dark brown-to-black lesions. Larger secondary roots and taproots lacked lesions. No vascular discoloration was present. Isolations from root lesions consistently resulted in gray fungal colonies that formed catenulate, cylindrical, thin-walled, hyaline endoconidia and catenulate, subrectangular, thick-walled, dark aleuriospores. The fungus was identified as Thielaviopsis basicola (2). Conidial suspensions (5.0 × 105) of eight isolates from iceberg lettuce were used for pathogenicity tests. Iceberg cv. Ponderosa and romaine cv. Winchester were grown for 3 weeks in soilless peat moss rooting mix. Roots of 20 plants per cultivar were washed free of the rooting mix and soaked in conidial suspensions for 5 min. Plants were repotted and grown in a greenhouse. Control plant roots were soaked in sterile distilled water (SDW). After 3 weeks, inoculated iceberg exhibited slight chlorosis in comparison with control plants. Feeder roots of all iceberg plants inoculated with the eight isolates exhibited numerous black lesions and T. basicola was reisolated from these roots. Romaine lettuce, however, did not show any foliar symptoms. Small segments of roots had tan-to-light brown discoloration and T. basicola was occasionally reisolated (approximately 40% recovery). Roots of control iceberg and romaine showed no symptoms. Results were similar when this experiment was repeated. To explore the host range of T. basicola recovered from lettuce, two isolates were prepared and inoculated as described above onto 12 plants each of the following: iceberg lettuce (cv. Ponderosa), bean (cv. Blue Lake), broccoli (cv. Patriot), carrot (cv. Long Imperator #58), celery (cv. Conquistador), cotton (cv. Phy-72 Acala), cucumber (cv. Marketmore 76), green bunching onion (cv. Evergreen Bunching), parsley (cv. Moss Curled), pepper (cv. California Wonder 300 TMR), radish (cv. Champion), spinach (cvs. Bolero and Bossanova), and tomato (cv. Beefsteak). Control plant roots of all cultivars were soaked in SDW. After 4 weeks, only lettuce and bean roots had extensive brown-to-black lesions, from which the pathogen was consistently resiolated. Roots of cotton, pepper, spinach, and tomato had sections of light brown-to-orange discoloration; the pathogen was not consistently recovered from these sections. All other species and the control plants were symptomless. This experiment was repeated with similar results except that inoculated peppers were distinctly stunted compared with control plants. To my knowledge, this is the first report of black root rot caused by T. basicola on lettuce in California. Disease was limited to patches along edges of iceberg lettuce fields; disease incidence in these discrete patches reached as high as 35%. Affected plants continued to grow but remained stunted in relation to unaffected plants and were not harvested. Black root rot of lettuce has been reported in Australia (1); that report also showed that lettuce cultivars vary in susceptibility to T. basicola and isolates from lettuce were highly aggressive on bean but not on many other reported hosts of this pathogen. References: (1) R. G. O'Brien and R. D. Davis. Australas. Plant Pathol. 23:106, 1994. (2) C. V. Subramanian. No. 170 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1968.

scholarly journals A Pictorial Disease Severity Key and the Relationship Between Severity and Incidence for Black Root Rot of Pansy Caused by Thielaviopsis basicola

Plant Disease ◽  
2008 ◽  
Vol 92 (10) ◽  
pp. 1394-1399 ◽  
Author(s):  
Warren E. Copes ◽  
Katherine L. Stevenson
Keyword(s):  
Disease Severity ◽  
Root Rot ◽  
Disease Incidence ◽  
Predictive Ability ◽  
Reliable Estimate ◽  
Regression Equations ◽  
Thielaviopsis Basicola ◽  
Black Root Rot ◽  
Fertility Treatments ◽  
The Relationship

A pictorial key was developed and the relationship between disease severity (S) and incidence (I) was examined to aid in the assessment of black root rot of pansy caused by Thielaviopsis basicola. The key consisted of photographs of root segments that represented nine disease severity levels ranging from 1 to 91%. Pansies that had received different fertility treatments, as part of seven separate experiments, were inoculated with T. basicola. Four weeks after inoculation, roots were washed, and incidence and severity of black root rot were visually assessed using a grid-line-intersect method. Disease incidence ranged from 1.3 to 100%, and severity ranged from 0.1 to 21.4% per plant. Four different mathematical models were compared to quantitatively describe the I-S relationship for the combined data from all seven experiments. Although all models provided an adequate fit, the model that is analogous to the Kono-Sugino equation provided the most reliable estimate of severity over the entire range of disease incidence values. The predictive ability and accuracy of this model across data sets was verified by jackknife and cross-validation techniques. We concluded that incidence of black root rot in pansy can be assessed more objectively and with greater precision than disease severity and can be used to provide reliable estimates of disease severity based on derived regression equations that quantify the I-S relationship for black root rot.

The occurrence in Denmark of black root rot of pea caused by Thielaviopsis basicola

1993 ◽  
Vol 42 (5) ◽  
pp. 820-823 ◽  
Author(s):  
L. BØDKER ◽  
N. LEROUL ◽  
V. SMEDEGAARD-PETERSEN
Keyword(s):  
Root Rot ◽  
Thielaviopsis Basicola ◽  
Black Root Rot

scholarly journals Outbreak of Black Root Rot in Catharanthus roseus Caused by Thielaviopsis basicola

Plant Disease ◽  
1999 ◽  
Vol 83 (4) ◽  
pp. 396-396
Author(s):  
R. J. McGovern ◽  
T. E. Seijo
Keyword(s):  
Catharanthus Roseus ◽  
Root Rot ◽  
Selective Medium ◽  
Thielaviopsis Basicola ◽  
Madagascar Periwinkle ◽  
Black Root Rot ◽  
Potting Medium ◽  
Rainy Weather ◽  
Bedding Plant ◽  
Blue Shade

A bedding plant grower in southwest Florida reported severe losses in potted Catharanthus roseus (Madagascar periwinkle) transplanted on various dates in December 1997. Symptoms included yellowing of lower leaves, defoliation, black root rot, and plant death. Thielaviopsis basicola was consistently isolated from blackened roots on a selective medium (1). A disease survey was conducted during mid March 1998 of 7,500 periwinkle plants in the two cultivar series Pacific (cvs. Punch, Red, and White) and Cooler (cvs. Grape, Icy, Peppermint, Pink, and Raspberry). Black root rot symptoms were observed in 21 to 53% of periwinkles transplanted between 3 and 11 December, and in 0 to 19% of plants transplanted between 21 and 29 December. The two cultivar series did not appear to differ in their susceptibility to T. basicola. The fungus was consistently isolated from symptomatic periwinkle roots, from roots of chlorotic violas (Viola cornuta), and from a potting medium used for early December transplanting. Pathogenicity of isolates of T. basicola from periwinkle, viola, and the contaminated medium was investigated. Inocula were produced by growing the fungus on acidified potato dextrose agar for 18 days. Conidia, chlamydospores, and hyphae of T. basicola were suspended in deionized water (100 ml/95 mm culture plate). One milliliter of inoculum suspensions of each of the three isolates was used to inoculate 12 plants of pansy (Viola × Wittrockiana) cv. Majestic Giant Blue Shade. An equal number of plants served as noninoculated controls. In addition, 5 ml of each isolate suspension was used to inoculate three six-plant replications of periwinkle cv. Pink Cooler. Plants were incubated in a controlled environment chamber at day/night temperatures of 24/22°C with a 12-h photoperiod. After 22 days, moderate to severe root discoloration was produced in pansy by the viola isolate of the fungus, while periwinkle and potting medium isolates produced only minimal discoloration. Chlamydospores typical of T. basicola were observed in the roots of all inoculated pansies, and in the roots of one of 12 non-inoculated controls. After 38 days, periwinkle plants were rated for foliar yellowing (0 = no yellowing, to 3 = severe yellowing) and percent defoliation, and fresh weights of shoots and roots were obtained. T. basicola was recovered on the selective medium from roots of all inoculated plants and from 68% of the noninoculated controls, indicating that secondary spread had occurred. All three isolates of the fungus caused yellowing and defoliation, but only the periwinkle and potting medium isolates significantly reduced both shoot and root weights in periwinkle, compared with control plants. T. basicola has not been previously reported to cause black root rot in C. roseus, and a contaminated potting medium used during early December may have provided initial inocula for the outbreak. The unseasonably cool and rainy weather prevalent during winter 1997 and spring 1998 (“El Niño”) may have also promoted the unusual appearance of the disease. Reference: (1) L. P. Specht and G. J. Griffin. Can. J. Plant Pathol. 7:438, 1985.

Evaluation of application methods and biocontrol efficacy of Paenibacillus alvei strain K-165, against the cotton black root rot pathogen Thielaviopsis basicola

2011 ◽  
Vol 58 (1) ◽  
pp. 68-73 ◽  
Author(s):  
Chariklia Schoina ◽  
Ioannis A. Stringlis ◽  
Iakovos S. Pantelides ◽  
Sotirios E. Tjamos ◽  
Epaminondas J. Paplomatas
Keyword(s):  
Root Rot ◽  
Thielaviopsis Basicola ◽  
Black Root Rot ◽  
Biocontrol Efficacy ◽  
Paenibacillus Alvei ◽  
Application Methods

scholarly journals Efficacy of Seed Treatment Chemicals for Black Root Rot, Caused by Thielaviopsis basicola, on Cotton

Plant Disease ◽  
2009 ◽  
Vol 93 (4) ◽  
pp. 354-362 ◽  
Author(s):  
Harun Toksoz ◽  
Craig S. Rothrock ◽  
Terrence L. Kirkpatrick
Keyword(s):  
Root Rot ◽  
Seed Treatment ◽  
Root Colonization ◽  
Selective Medium ◽  
High Rate ◽  
Infested Soil ◽  
Thielaviopsis Basicola ◽  
Black Root Rot ◽  
Seedling Disease ◽  
Wide Range

The efficacy of triazole and host resistance–inducing seed treatment chemicals was examined for black root rot on cotton caused by Thielaviopsis basicola in both artificially and naturally infested soils with and without nematodes. In naturally infested soil, myclobutanil was effective in reducing root and hypocotyl discoloration over a wide range of soil population densities. Treatments containing high rates (42 g a.i./100 kg seed) of myclobutanil provided greater reductions in disease than low rates (21 g a.i./100 kg seed) in some experiments. Acibenzolar-S-methyl applied to the seed reduced black root rot or colonization by T. basicola on seedlings in artificially infested soils. Rates of acibenzolar-S-methyl did not differ in efficacy. In controlled studies, root colonization by T. basicola was significantly lower when seeds were treated with both myclobutanil and acibenzolar-S-methyl than with either chemical alone. In naturally infested soil under low (24 CFU/g soil) and high (154 CFU/g soil) populations of T. basicola, a combination of myclobutanil and acibenzolar-S-methyl at the high rate resulted in the lowest root discoloration and colonization. The nematicide seed treatment abamectin improved the control of black root rot in the presence of Meloidogyne incognita. The semi-selective medium TB-CEN allowed the importance of T. basicola to be evaluated in the presence of other pathogens that contribute to the seedling disease complex on cotton by quantifying the isolation frequency and percent colonization of T. basicola.

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