Environmental factors determine severity of Rhizoctonia damping-off and root rot in subterranean clover

2017 ◽  
Vol 46 (4) ◽  
pp. 357-368 ◽  
Author(s):  
Ming Pei You ◽  
Martin J. Barbetti
Keyword(s):  
Environmental Factors ◽  
Root Rot ◽  
Subterranean Clover ◽  
Damping Off

scholarly journals Characterization and Pathogenicity of Rhizoctonia Species on Canola

Plant Disease ◽  
1999 ◽  
Vol 83 (8) ◽  
pp. 714-721 ◽  
Author(s):  
Ravjit K. Khangura ◽  
Martin J. Barbetti ◽  
Mark W. Sweetingham
Keyword(s):  
Root Rot ◽  
Seedling Emergence ◽  
Subterranean Clover ◽  
Enzyme Electrophoresis ◽  
Nuclear Staining ◽  
Damping Off ◽  
Weed Species ◽  
Bare Patch ◽  
Hyphal Morphology ◽  
Leguminous Crops

A total of 112 Rhizoctonia isolates were collected from various canola (Brassica napus) growing areas of Western Australia. Pectic enzyme electrophoresis differentiated these isolates into six distinct zymogram groups: R. solani, 54% ZG5 (AG2-1), 8% ZG6 (AG2-1), and 1% ZG9 (AG10); binucleate Rhizoctonia, 12% CZG1 (CAG1), 4% CZG4, and 6% CZG5 (AGK); and the remainder unidentified binucleate groups (15%). Binucleate groups were also confirmed by fluorescent nuclear staining and hyphal morphology. One or more isolates from each of the above zymogram groups (including four unidentified binucleate groups) and an isolate of ZG1-1 (AG8) that causes bare patch in cereals and legumes were tested for their pathogenicity on canola. Isolates of ZG5 and ZG1-1 were highly pathogenic on canola, delayed seedling emergence, and caused severe hypocotyl and root rot, respectively. ZG5 also induced postemergence damping-off. Increasing the depth of sowing from 1 to 3 cm significantly delayed seedling emergence and increased disease severity. Four unidentified binucleate isolates (WAC9316, WAC9297, WAC9307, and WAC9290) were moderately pathogenic to canola, while two isolates (WAC9307 and WAC9316) caused significant preemergence damping-off. Two CZG5 isolates were weakly pathogenic. Isolates of ZG5 and ZG1-1 were also tested for their pathogenicity on other rotational crops (narrow-leafed lupin, subterranean clover, wheat, oats, barley, and mustard) and two weed species (wild radish and annual ryegrass). ZG5 caused a severe hypocotyl rot on mustard and mild symptoms of hypocotyl rot on narrow-leafed lupin and clover, but failed to infect any of the cereal hosts, such as wheat, oats, barley, and ryegrass. In contrast, all crops tested were highly susceptible to ZG1-1 except mustard, which was only moderately susceptible. Results indicate that ZG5 is most pathogenic to crucifers and is a mildly virulent pathogen of the leguminous crops but not of cereal crops tested. ZG1-1, known to cause bare patch in legumes and cereals, also can cause severe root rot in canola. This is the first report of hypocotyl rot and pathogenicity of ZG5 on canola in Australia.

scholarly journals Bacillus megaterium-Mediated Synthesis of Selenium Nanoparticles and Their Antifungal Activity against Rhizoctonia solani in Faba Bean Plants

2021 ◽  
Vol 7 (3) ◽  
pp. 195
Author(s):  
Amr H. Hashem ◽  
Amer M. Abdelaziz ◽  
Ahmed A. Askar ◽  
Hossam M. Fouda ◽  
Ahmed M. A. Khalil ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Vicia Faba ◽  
Root Rot ◽  
Antifungal Agents ◽  
Damping Off ◽  
Growth Promoters ◽  
Root Rot Disease ◽  
Rot Disease

Rhizoctonia root-rot disease causes severe economic losses in a wide range of crops, including Vicia faba worldwide. Currently, biosynthesized nanoparticles have become super-growth promoters as well as antifungal agents. In this study, biosynthesized selenium nanoparticles (Se-NPs) have been examined as growth promoters as well as antifungal agents against Rhizoctonia solani RCMB 031001 in vitro and in vivo. Se-NPs were synthesized biologically by Bacillus megaterium ATCC 55000 and characterized by using UV-Vis spectroscopy, XRD, dynamic light scattering (DLS), and transmission electron microscopy (TEM) imaging. TEM and DLS images showed that Se-NPs are mono-dispersed spheres with a mean diameter of 41.2 nm. Se-NPs improved healthy Vicia faba cv. Giza 716 seed germination, morphological, metabolic indicators, and yield. Furthermore, Se-NPs exhibited influential antifungal activity against R. solani in vitro as well as in vivo. Results revealed that minimum inhibition and minimum fungicidal concentrations of Se-NPs were 0.0625 and 1 mM, respectively. Moreover, Se-NPs were able to decrease the pre-and post-emergence of R. solani damping-off and minimize the severity of root rot disease. The most effective treatment method is found when soaking and spraying were used with each other followed by spraying and then soaking individually. Likewise, Se-NPs improve morphological and metabolic indicators and yield significantly compared with infected control. In conclusion, biosynthesized Se-NPs by B. megaterium ATCC 55000 are a promising and effective agent against R. solani damping-off and root rot diseases in Vicia faba as well as plant growth inducer.

scholarly journals First Report of Phytophthora megasperma and Pythium irregulare As Olive Tree Root Pathogens

Plant Disease ◽  
1997 ◽  
Vol 81 (10) ◽  
pp. 1216-1216 ◽  
Author(s):  
M. E. Sánchez-Hernández ◽  
A. Ruiz-Dávila ◽  
A. Trapero-Casas
Keyword(s):  
Root Rot ◽  
Olive Tree ◽  
The United States ◽  
Damping Off ◽  
Phytophthora Megasperma ◽  
Root Rots ◽  
Foliar Symptoms ◽  
Root Pathogens ◽  
Root Necrosis ◽  
Olive Trees

Several species of the genus Phytophthora are associated with root rot and trunk cankers in olive trees (Olea europaea L.). Among them, Phytophthora megasperma has been cited as being associated with olive root rots in Greece (1). Unidentified species of Pythium and Phytophthora have also been associated with olive tree root rots in the United States. However, the status of P. megasperma and Pythium spp. as olive tree root pathogens has remained unclear. Following a 5-year period of severe drought in southern Spain, autumn-winter rainfall rates in 1996 to 1997 steadily increased in both quantity and frequency. Under these unusually wet conditions, olive trees remained waterlogged for several months. During this period, we observed foliar wilting, dieback, and death of young trees, and later found extensive root necrosis. In 46 of 49 affected plantations surveyed, P. megasperma was consistently isolated from the rotted rootlets, particularly in young (<1- to 10-year-old trees) plantations. This fungus was not detected on plant material affected by damping-off from several Spanish olive tree nurseries. The opposite situation occurred with P. irregulare. This species was not associated with rotted rootlets in the field. In contrast, it was consistently isolated from necrotic rootlets from young olive plants affected by damping-off. These plants were grown in a sand-lime-peat soil mixture under greenhouse conditions and showed foliar wilting and extensive necrosis of the root systems. Pathogenicity tests were conducted with several isolates of P. megasperma and P. irregulare on 6-month-old rooted cuttings of olive, under both weekly watering and waterlogged conditions. Under waterlogged conditions, both fungal species produced extensive root necrosis 2 weeks after inoculation that resulted in wilting of the aerial parts and rapid plant death. Waterlogged control plants remained without foliar symptoms but a low degree of root necrosis was recorded. In addition, under weekly watering conditions, plants inoculated with either species showed some degree of root rot but foliar symptoms were not evident. No differences in pathogenicity were observed within the Phytophthora or Pythium isolates. Reference: (1) H. Kouyeas and A. Chitzanidis. Ann. Inst. Phytopathol. Benaki 8:175, 1968.

Pythium intermedium. [Descriptions of Fungi and Bacteria].

1964 ◽  
Author(s):  
G. M. Waterhouse
Keyword(s):  
North America ◽  
South America ◽  
Geographical Distribution ◽  
Root Rot ◽  
Crop Plants ◽  
Foot Rot ◽  
Damping Off ◽  
Wide Range

Abstract A description is provided for Pythium intermedium. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On a wide range of hosts represented by the following families: Begoniaceae, Bromeliaceae, Chenopodiaceae, Compositae, Coniferae, Cruciferae, Euphorbiaceae, Geraniaceae, Gramineae, Leguminosae, Liliaceae, Linaceae, Moraceae, Onagraceae, Ranunculaceae, Rosaceae, Solanaceae, Ulmaceae, Violaceae; also in the Equisetales and Filicales. DISEASES: Damping-off of seedlings, foot rot and root rot of ornamentals, occasionally of crop plants and trees. GEOGRAPHICAL DISTRIBUTION: Asia (China); Australia & Oceania (Hawaii); Europe (England, Belgium, France, Germany, Holland, Sweden, U.S.S.R.); North America (U.S.A.); South America (Argentina). TRANSMISSION: A common soil inhabitant.

scholarly journals Sensitivity of Rhizoctonia solani AG-2-2 from Sugar Beet to Fungicides

Plant Disease ◽  
2016 ◽  
Vol 100 (12) ◽  
pp. 2427-2433 ◽  
Author(s):  
Sahar Arabiat ◽  
Mohamed F. R. Khan
Keyword(s):  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Root Rot ◽  
The United States ◽  
Damping Off ◽  
Growth Assay ◽  
The Mean ◽  
Crown And Root Rot ◽  
Mean Concentration

Rhizoctonia damping-off and crown and root rot caused by Rhizoctonia solani are major diseases of sugar beet (Beta vulgaris L.) worldwide, and growers in the United States rely on fungicides for disease management. Sensitivity of R. solani to fungicides was evaluated in vitro using a mycelial radial growth assay and by evaluating disease severity on R. solani AG 2-2 inoculated plants treated with fungicides in the greenhouse. The mean concentration that caused 50% mycelial growth inhibition (EC50) values for baseline isolates (collected before the fungicides were registered for sugar beet) were 49.7, 97.1, 0.3, 0.2, and 0.9 μg ml−1 and for nonbaseline isolates (collected after registration and use of fungicides) were 296.1, 341.7, 0.9, 0.2, and 0.6 μg ml−1 for azoxystrobin, trifloxystrobin, pyraclostrobin, penthiopyrad, and prothioconazole, respectively. The mean EC50 values of azoxystrobin, trifloxystrobin, and pyraclostrobin significantly increased in the nonbaseline isolates compared with baseline isolates, with a resistant factor of 6.0, 3.5, and 3.0, respectively. Frequency of isolates with EC50 values >10 μg ml−1 for azoxystrobin and trifloxystrobin increased from 25% in baseline isolates to 80% in nonbaseline isolates. Although sensitivity of nonbaseline isolates of R. solani to quinone outside inhibitors decreased, these fungicides at labeled rates were still effective at controlling the pathogen under greenhouse conditions.

scholarly journals Preliminary Findings of New Citrus Rootstocks Potentially Tolerant to Foot Rot Caused by Phytophthora

Horticulturae ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 389
Author(s):  
Lidia Aparicio-Durán ◽  
Juan M. Arjona-López ◽  
Aurea Hervalejo ◽  
Rocío Calero-Velázquez ◽  
Francisco J. Arenas-Arenas
Keyword(s):  
Root Rot ◽  
Brown Rot ◽  
Lesion Length ◽  
Post Inoculation ◽  
Foot Rot ◽  
Damping Off ◽  
Citrus Industry ◽  
Breeding Programs ◽  
Phytophthora Spp ◽  
Branch Canker

Phytophthora spp. are one the most common soil-borne pathogens in citrus crops, in which Phytophthoranicotianae and P. citrophthora are the most relevant species, causing disease problems worldwide, such as foot rot and gummosis of the trunk, branch canker, brown rot of fruit, feeder root rot in orchards, and seedling damping-off in nurseries. Phytophthora-tolerant citrus rootstocks are essential for its control and for the success of the citrus industry. The aim of this study was to determine the susceptibility of new citrus rootstocks with low HLB incidence to Phytophthora diseases. Thus, plants of several commercial and new citrus rootstocks originating in different breeding programs were inoculated with an isolate of P. nicotianae. Thirty days post inoculation (DPI), the damage of lesion length in stem was measured for each plant. These results displayed a different susceptibility response to the damage caused by P. nicotianae among the citrus rootstocks tested. Thus, eleven new citrus rootstocks (B11R3T25, B11R5T25, B11R5T49, B11R5T60, B11R5T64, N40R1T18, N40R1T19, N40R3T25, WGFT + 50-7, UFR-6, and CL-5146), which have not been previously studied against Phytophthora diseases, improved the tolerance effect of Carrizo citrange. Our findings provide useful information for citrus growers on rootstock selection to address incidence problems caused by Phytophthora spp.

Sign in / Sign up

Export Citation Format

Share Document