scholarly journals Diversity and Pathogenicity of Rhizoctonia Species from the Brazilian Cerrado

Plant Disease ◽  
2018 ◽  
Vol 102 (4) ◽  
pp. 773-781 ◽  
Author(s):  
Angel José Vieira Blanco ◽  
Marília Oliveira Costa ◽  
Roberto do Nascimento Silva ◽  
Fábio Suzart de Albuquerque ◽  
Arthur Tavares de Oliveira Melo ◽  
...  
Keyword(s):  
Root Rot ◽  
Agricultural Soils ◽  
Common Beans ◽  
Tropical Zone ◽  
Maize Production ◽  
Root Rots ◽  
North Brazil ◽  
Staining Methods ◽  
Waitea Circinata ◽  
Rhizoctonia Zeae

Eighty-one Rhizoctonia-like isolates were identified based on morphology and nuclei-staining methods from natural and agricultural soils of the Cerrado (Brazilian savanna). The nucleotide similarity analysis of ITS1-5.8S-ITS2 regions identified 14 different taxa, with 39.5% of isolates assigned to Waitea circinata (zeae, oryzae, and circinata varieties), while 37.0% belonged to Thanatephorus cucumeris anastomosis groups (AGs) AG1-IB, AG1-ID, AG1-IE, AG4-HGI, and AG4-HGIII. Ceratobasidium spp. AG-A, AG-F, AG-Fa, AG-P, and AG-R comprised 23.5%. Rhizoctonia zeae (19.8%), R. solani AG1-IE (18.6%), and binucleate Rhizoctonia AG-A (8.6%) were the most frequent anamorphic states found. Root rot severity caused by the different taxa varied from low to high on common beans, and tended to be low to average in maize. Twenty-two isolates were pathogenic to both hosts, suggesting difficulties in managing Rhizoctonia root rots with crop rotation. These results suggest that cropping history affects the geographical arrangement of AGs, with a prevalence of AG1 in the tropical zone from central to north Brazil while the AG4 group was most prevalent from central to subtropical south. W. circinata var. zeae was predominant in soils under maize production. To our knowledge, this is the first report on the occurrence of W. circinata var. circinata in Brazil.

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.

Waitea circinata. [Distribution map].

2013 ◽  
Author(s):  
Keyword(s):  
New York ◽  
South Carolina ◽  
Rhode Island ◽  
Tamil Nadu ◽  
Creeping Bentgrass ◽  
Distribution Map ◽  
South Wales ◽  
Waitea Circinata ◽  
Rhizoctonia Zeae ◽  
Distribution In Europe

Abstract A new distribution map is provided for Waitea circinata [Rhizoctonia zeae] (Warcup) & Talbot. Fungi: Basidiomycota: Corticiales. Hosts: creeping bentgrass (Agrostis stolonifera), bluegrass (Poa spp.), rice (Oryza sativa), maize (Zea mays), wheat (Triticum spp.). Information is given on the geographical distribution in Europe (Hungary), Asia (Bangladesh, Cambodia, China, Hubei, Sichuan, India, Andhra Pradesh, Tamil Nadu, Iran, Japan, Honshu, Kyushu, Shikoku, Korea Republic, Malaysia, Sarawak, Myanmar, Nepal, Taiwan, Thailand, Turkey, Vietnam), Africa (Malawi, South Africa), North America (Canada, British Columbia, Ontario, USA, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Idaho, Illinois, Indiana, Kentucky, Louisiana, Massachusetts, Minnesota, Mississippi, Nevada, New Jersey, New York, North Carolina, North Dakota, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Texas, Virginia, Washington, West Virginia, Wisconsin), Central America & Caribbean (Cuba, El Salvador, Panama), South America (Brazil, Para, Tocantins, Colombia, Venezuela), Oceania (Australia, New South Wales, Queensland, Western Australia, Fiji, New Zealand).

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.

Incidence of root and hypocotyl diseases in lupin crops in Western Australia between 1986 and 2005

2010 ◽  
Vol 61 (3) ◽  
pp. 241 ◽  
Author(s):  
G. J. Thomas ◽  
W. J. MacLeod ◽  
M. W. Sweetingham
Keyword(s):  
Crop Rotation ◽  
Western Australia ◽  
Root Rot ◽  
Plant Density ◽  
Management Systems ◽  
Sowing Depth ◽  
Root Rots ◽  
The Past ◽  
Predominant Pathogen ◽  
Growing Region

Three separate surveys were carried out in commercial lupin crops in the major lupin growing region of Western Australia in 1986, 1990, and 2004–05. In total, 333 sites were sampled and plants assessed for the incidence and cause of root and hypocotyl rots. Measurements were made of plant density and sowing depth at all sites. In all surveys, root rot was more common than hypocotyl rot. Root rot occurred in more than 95% of sites in each survey; however, a greater proportion of sites had high levels of root rot in early surveys. The incidence of root rot within sites decreased from an average of 34.9% in 1986 to 10.2% in 2004–05. Hypocotyl rot incidence varied among surveys, incidence of infected paddocks, and within-paddock incidence was greatest in the 1990 survey. Hypocotyl rot incidence was lowest in the 2004–05 survey. Rhizoctonia solani and Pleiochaeta setosa were commonly isolated from root lesions and R. solani was the predominant pathogen isolated from hypocotyl lesions. Analysis of the R. solani isolates by pectic zymogram showed that the ZG3 strain was most regularly isolated from roots and hypocotyls. This series of surveys indicates that the incidence of root rots in commercial lupin paddocks in Western Australia has decreased dramatically over the past 20 years; however, root rot still occurs in most paddocks regardless of soil type, location, crop rotation, and management systems.

Simulated soil and plant management effects on root rots of subterranean clover

1986 ◽  
Vol 37 (6) ◽  
pp. 633 ◽  
Author(s):  
RW Smiley ◽  
PA Taylor ◽  
RG Clarke ◽  
FC Greenhalgh ◽  
P Trutmann
Keyword(s):  
Root Rot ◽  
Subterranean Clover ◽  
Plant Management ◽  
Root Rots ◽  
Root Diseases ◽  
Organic Debris ◽  
Pasture Soil ◽  
Management Procedures ◽  
Controlled Environments ◽  
Management Effects

Pasture productivity in southern Australia is often limited by root diseases of complex etiology. The influences of simulated plant and soil management procedures on subterranean clover (Trifolium subterranean cv. Woogenellup) root rots were evaluated in controlled environments, using a soil from an irrigated and from a dryland pasture. Root rot incidence and severity were high in soils collected and used as intact cores, and low to moderate in soils disturbed while being collected. Simulated cultivation of soil in cores also reduced root rots in the dryland pasture soil that had little surface litter, but not in the irrigated pasture soil which had high levels of organic debris (and pathogen inocula) distributed through the surface 0-11 cm. Root rot was mild on plants in continually moist cores at 10�C, and severe in cyclically wetted and dried cores at 10, 15 and 20�C, and in continually moist cores at 15 and 20�C. Root rots were reduced by treatment of seeds with Rhizobium, fungicides, or both, by drenching soils with fungicides, and by planting the resistant T. yanninicum cvv. Larisa, Meteora and Trikkala. Removal of seedling leaves, to simulate grazing, accentuated root rot severity. The identified pathogens included species of Pythium, Fusarium, Rhizoctonia, and nematodes. Integrated strategies for controlling root rots of subterranean clover are considered promising in view of these studies with cores of pasture soils.

scholarly journals First Report of Root Rot of Bean and Soybean Caused by Rhizoctonia zeae in Turkey

Plant Disease ◽  
2005 ◽  
Vol 89 (2) ◽  
pp. 203-203 ◽  
Author(s):  
I. Erper ◽  
G. Karaca ◽  
I. Özkoç
Keyword(s):  
Tap Water ◽  
Pathogenicity Test ◽  
First Report ◽  
Rhizosphere Soils ◽  
Soybean Seedlings ◽  
Oat Seeds ◽  
Soybean Plants ◽  
Waitea Circinata ◽  
Rhizoctonia Zeae ◽  
Corn Kernels

To determine the species of Rhizoctonia on bean and soybean plants grown in Samsun (Turkey), field surveys were performed at 104 locations during 2001 and 2002. Rhizoctonia spp. were obtained from isolations from the necrotic lesions on the hypocotyl and rhizosphere soils. Species were identified according to Ogoshi (3) on the basis of hyphal and colony morphology and anastomosis reaction with known tester isolates (provided by M. Hyakumachi, Gifu University, Japan). Fifty Rhizoctonia spp. isolates obtained from these locations were identified as Rhizoctonia zeae (teleomorph Waitea circinata var. zeae). Nine of the 27 bean isolates and 8 of the 23 soybean isolates were recovered from plant tissues. These isolates had optimum temperature (32°C) for growth. Colonies were orange when young, becoming salmon colored with age. Sclerotia formed both on the agar surface or submerged in the medium. Superficial sclerotia were more uniform and nearly spherical, mostly 0.2 to 0.5 mm in diameter, and they were first orange and then turned brown. Pathogenicity was tested with three R. zeae isolates grown on sterile oat seeds at 25°C for 10 days. Bean and soybean seedlings grown in 1-liter plastic pots containing sterile potting mix (field soil/composted manure/sand 2:2:1 [v/v]) at true-leaf stage were inoculated by placing five infested oat seeds adjacent to the roots. Sterile oat seeds were used for controls. After 3 to 4 weeks of incubation at 17 to 25°C in a glasshouse, roots of the plants were cleaned with tap water and evaluated for disease severity. Four replicate pots were used for each isolate/plant combination. All isolates produced superficial brown lesions on roots and hypocotyls similar to those observed on plants used for isolations and root growth declined. R. zeae was reisolated from the lesions on all bean and soybean plants used for the pathogenicity test. While R. zeae was previously reported from Johnsongrass roots (1) and corn kernels (2), to our knowledge, this is the first report of R. zeae isolated from bean and soybean plants and rhizosphere soils in Turkey. References: (1) E. Demirci, and C. Eken. Plant Dis. 83:200, 1999. (2) E. Demirci and S. Kordali. Plant Dis. 83:879, 1999. (3) A. Ogoshi. Rev. Plant. Prot. Res. 8:93, 1975.

scholarly journals INFLUENCE OF SEED TREATMENT AND VARIETY ON PLANTS DAMAGE OF SPRING BY ROOT ROTS

2020 ◽  
Vol 14 (4) ◽  
pp. 16-19
Author(s):  
Aleksey Balykin ◽  
Leonid Shashkarov
Keyword(s):  
Powdery Mildew ◽  
Spring Wheat ◽  
Root Rot ◽  
Seed Treatment ◽  
Treatment Control ◽  
Root Rots ◽  
Seed Dressing ◽  
Chuvash Republic ◽  
Wheat Seeds

The article discusses the issues of root rot, leaf and stem diseases (septoria, powdery mildew, rust) during tillering-exiting the tube, fusarium and smut during heading, depending on varietal characteristics and seed dressing in the conditions of the Chuvash Republic. Margarita, Simbirtsit and Prokhorovka varieties were studied. The second factor is seed treatment in three grades: 1. Without treatment (control one). 2. Seed treatment with Benlat. 3. Seed treatment with Nano-Gro. The results of the analysis of lesions by root rot, leaf and stem diseases (septoria, powdery mildew, rust) during tillering-exiting the tube, fusarium and smut during heading are presented. The effect of Nano-Gro in combination with the seed dresser Benlat was also studied. It has been shown that pre-sowing treatment of wheat seeds with Nano-Gro solution helps to reduce damage by root rot, leaf and stem diseases (septoria, powdery mildew, rust) during tillering-exiting the tube, fusarium and smut during ear formation in spring wheat.

scholarly journals Diseases of Sugarcane and their Control in Puerto Rico

1969 ◽  
Vol 55 (2) ◽  
pp. 139-146
Author(s):  
Lii-Jang Liu ◽  
José Adsuar ◽  
Enrique Pérez
Keyword(s):  
Puerto Rico ◽  
Root Rot ◽  
Economic Importance ◽  
Hot Water ◽  
Root Rots ◽  
High Incidence ◽  
Disease Survey ◽  
Sugar Mills ◽  
Low Incidence ◽  
Methods Of Control

A sugarcane disease survey was conducted over different mill zones of Puerto Rico during the fall of 1969 and the spring of 1970. It covered the plantations of 10 sugar mills. The results obtained to date indicate that the diseases of major importance are ratoon stunting, chlorotic streak, pineapple disease, and root rot caused by a complex of Pythium, Fusarium and nematodes. The specific disease problems are identified in each area. Special attention was given to disease distribution, economic importance, and possible methods of control. Although in general low incidence of ratoon stunting was observed in commercial plantings, data obtained from previous variety tests indicate this malady to be potentially dangerous. Hot water treatment of seedpieces should be conducted to prevent its further spread. The significance of chlorotic streak disease as a factor in yield decline in Puerto Rico has not yet been completely evaluated. The high incidence of this disease, under present conditions, has given rise to concern. Pineapple disease caused by Thielaviopsis paradoxa greatly affects the germination of P.R. 980, especially in areas with poor drainage. Root rots caused by Pythium, Fusarium and nematodes reduced germination of P.O.J. 2878 and H. 328560 by as much as 40 percent in poorly-drained areas.

ROOT WOUNDS AND ASSOCIATED ROOT ROTS OF WHITE SPRUCE

1961 ◽  
Vol 37 (4) ◽  
pp. 401-411 ◽  
Author(s):  
R. D. Whitney
Keyword(s):  
Root Rot ◽  
Root Systems ◽  
White Spruce ◽  
Root Rots ◽  
Crown Root ◽  
Root Fungi ◽  
Dead Root ◽  
Highly Correlated ◽  
Individual Trees

The root systems of 656 trees from 7 to 180 years old at three locations in Manitoba and Saskatchewan were examined for wounding and root rot. Twenty-seven per cent of 1170 diseased roots bore wounds caused by Hylobius spp. larvae which were associated with the entry of root-rotting or staining fungi. The fungi appeared to have entered mainly through insect-girdled roots, one-half inch in diameter or smaller, and to a less extent directly through the decorticated wood of larger roots. In individual trees, root rot and stain was highly correlated (r = 0.5357) with Hylobius wounding. Wounds caused by excessive moisture, root compression, and animal trampling were associated with the entrance of fungi in 7.1, 4.7, and 1.5 per cent, respectively, of the diseased roots. Eight per cent of the diseased roots were infected from established decay in the root crown. Root cankers and dead root ends, both of unknown cause, were associated with the entry of root fungi in 7.3 and 5.7 per cent of the roots respectively.

scholarly journals Sites Availability for Minimalizing and Soil-Conservation Tillage of Soils in Slovakia

2011 ◽  
Vol 57 (2) ◽  
pp. 68-75 ◽  
Author(s):  
Jozef Vilček ◽  
Karol Kováč
Keyword(s):  
Soil Conservation ◽  
Agricultural Soils ◽  
Conservation Tillage ◽  
Climatic Conditions ◽  
Soil Science ◽  
Soil Conditions ◽  
Land Area ◽  
Arable Soils ◽  
Maize Production ◽  
Production Area

Sites Availability for Minimalizing and Soil-Conservation Tillage of Soils in SlovakiaThere is an alternative technology of traditional agricultural soil processing, so called minimalizing cultivation, which is based on reduction of some operating processes used in common. It is possible to perform this technology only in particular soil conditions. Total land area of sites, which are avail-able for the application of minimalizing cultivation is about 693 thousand hectares, which presents approximately 28% of agricultural and 48% of arable soils. 60% of this land area occurs in the maize production area and 39% in the sugar beet production area, thus in the most favourable agricultural local-ities regarding climate and soil. According to the administrative structuring of Slovakia 43% of agricultural soils suitable for minimalizing technologies occurs in Nitra district and about 27% in Trnava district. Identification of areas, suitable for such technologies application, is possible by the information databases of Soil Science and Conservation Research Institute, which have been elaborated for this purpose in geographic and informative systems. Regarding input parameters, they were chosen as follows: climatic conditions of given locality, steepness, depth, stoniness and soil texture.

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