Morphological and molecular identification of Macrophomina phaseolina in the pool of pathogens of sugar beet (Beta vulgaris) root rot : Screening of fungicides for its control

During the summer of 2000 in the Amyndeon area of northern Greece, sugar beet (Beta vulgaris L.) roots with rot symptoms were observed in many fields. Initially, the plants wilted, and leaves soon turned brown and died. Diseased plants appeared in patches in the field. Brown-black lesions were observed in the external part of the root crown while yellow-mustard colored lesions occurred internally. In advanced stages of decay, masses of sclerotia formed in rotted cavities and roots became mummified. Macrophomina phaseolina (Tassi) Goid. (1) was isolated on potato dextrose agar (PDA) from 30 rotted roots collected in five fields. Cultures produced dark multi-septate mycelium and sclerotia, which were black, smooth, spherical to irregular in shape, and varied in size from 100 μm to 1mm in diameter. Five isolates were evaluated for pathogenicity on surface-sterilized 16-week-old sugar beet roots (cv. Rizor) by placing a 5-mm-diameter PDA plug of actively growing mycelium in wounds made with a sterile knife. Sterile PDA plugs were placed in wounds made in control beet roots. Ten roots were inoculated per isolate. Roots were kept at 25°C in the dark for 10 days. Extensive decay of inoculated roots developed, similar to decay observed in the field, and M. phaseolina was reisolated from rotted tissue. Control roots showed no decay. This pathogen has been previously reported as a root rot pathogen of sugar beet in California, India, and countries of the former USSR. Charcoal rot is of minor economic importance since M. phaseolina attacks mainly weakened plants under conditions of high temperature (2). To our knowledge, this is the first report of charcoal root rot of sugar beet in Greece. References: (1) Anonymous. Macrophomina phaseolina. No. 275 in: Descriptions of Plant Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1970. (2) J. E. Duffus and E. G. Ruppel. Diseases. Page 347 in: The Sugar Beet Crop. Science into Practice. D. A. Cooke and R. K. Scott eds. Chapman and Hall, NY, 1993.

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First Report of Aphanomyces Root Rot of Sugar Beet in Nebraska and Wyoming

Plant Disease ◽

10.1094/pdis.2000.84.5.596b ◽

2000 ◽

Vol 84 (5) ◽

pp. 596-596 ◽

Cited By ~ 3

Author(s):

R. M. Harveson

Keyword(s):

Sugar Beet ◽

Beta Vulgaris ◽

Root Rot ◽

Causal Agent ◽

High Plains ◽

Sugar Beets ◽

Koch’S Postulates ◽

First Report ◽

Aphanomyces Cochlioides ◽

Central High

Sugar beet (Beta vulgaris L.) plants exhibiting dull green and chlorotic foliage were first observed in a field near Dalton, NE, in late July 1999. Root symptoms included distal tip rot with internal, yellow-brown, water-soaked tissues. Isolations on MBV medium (1) consistently yielded Aphanomyces cochlioides Drechs. Water cultures produced primary zoospores that encysted at the tips of sporangiophores, followed by release of secondary zoospores within 12 h. Seedlings inoculated with zoospores began to die 2 weeks after emergence in a greenhouse. Symptoms on hypocotyls began as water-soaked lesions that turned black and thread-like. The causal agent was reisolated from infected seedlings, completing Koch's postulates. The disease was subsequently found in more than 15 separate fields, representing 5 of 11 sugar beet-growing counties in Nebraska and 1 county in Wyoming. In October, plants from the same fields were observed with stunted, distorted roots and superficial, scabby lesions associated with latent A. cochlioides infection. The pathogen could not be isolated from this stage but was confirmed by observing mature oospores within thin, stained sections under a microscope. The sections were additionally mixed with sterile potting soil and planted in the greenhouse with sugar beets. Several weeks after emergence, seedlings began to die, and the pathogen was reisolated. This represents the first report of Aphanomyces root rot and its spread in the Central High Plains. It also confirms that the described latent symptoms on sugar beet are caused by A. cochlioides. Reference: (1). W. F. Pfender et al. Plant Dis. 68:845, 1984.

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Occurrence and importance of root rots caused by fungal pathogens on sugar beet grown in Konya province of Turkey

Sugar Industry ◽

10.36961/si25276 ◽

2020 ◽

pp. 674-681

Author(s):

Rıza Kaya ◽

Meltem Avan ◽

Cemre Aksoy ◽

Fikret Demirci ◽

Yakup Zekai Katircioğlu ◽

...

Keyword(s):

Sugar Beet ◽

Rhizoctonia Solani ◽

Root Rot ◽

Fungal Pathogens ◽

Fusarium Culmorum ◽

Macrophomina Phaseolina ◽

Growth Stages ◽

Aphanomyces Cochlioides ◽

Root Rots ◽

Phytophthora Spp

Sugar beet is extensively grown in Konya province of Turkey and about one third of production of Turkey is obtained from this region. Recently root rots have been observed at all the growth stages of sugar beet especially at later stages near the harvest. During 2015–2017 growing years, 866 fields were visited and diseased samples having root rot symptoms were collected. Various root rot pathogens were isolated from 691 fields; Rhizoctonia solani being the most common (15% of the fields) followed by Fusarium oxysporum, F. solani, Phoma betae, Aphanomyces cochlioides and Pythium spp. Apart from these pathogens, Fusarium culmorum, F. equiseti, F. sambucinum, F. verticillatum, unidentified Fusarium spp., Macrophomina phaseolina and Phytophthora spp. were also determined. All the fungal pathogens were isolated from both of the sugar beet growing stages of 0–12 BBCH and 31–49 BBCH, some of them being high ratios at the late stages. Some isolates of A. cochlioides, P. betae, Pythium spp., Phytophthora spp., and R. solani were highly aggressive when tested by a soil inoculum layer technique. Effects of twelve fungicides, in sixteen different combination and rate, on the most virulant and common four pathogens, A. cochlioides P. betae, Py. ultimum var. ultimum, Rhizoctonia solani, were investigated by the same technique. None of the fungicide mixes inhibited all four pathogens. Thiram + metalaxyl + hymexazol + pyraclastrobin mix sufficiently prevented disease development of the first three pathogens but not R. solani.

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Sugarbeet root rot in drought conditions

Zbornik Matice srpske za prirodne nauke ◽

10.2298/zmspn0519103j ◽

2005 ◽

pp. 103-111 ◽

Cited By ~ 1

Author(s):

Stevan Jasnic ◽

Vera Stojsin ◽

Ferenc Bagi

Keyword(s):

Sugar Beet ◽

Root Rot ◽

Weather Conditions ◽

Macrophomina Phaseolina ◽

Economic Damage ◽

Beet Root ◽

Genus Fusarium ◽

Leaf Chlorosis ◽

Sugar Beet Root ◽

Plant Vitality

In recent years several types of sugarbeet root rot have occurred in our country causing significant economic damage. The most frequent symptoms are leaf chlorosis and brown-black wet necrosis of the root. The necrosis spread through the entire root and vascular strands. In the course of this study F. oxysporum was the most frequently isolated from infected sugar beet roots. The incidence of other fungi (Fusarium solani, Rhizoctonia solani and Macrophomina phaseolina) was much lower and it depended on weather conditions. High temperatures occurring during dry years encourage the development of F. oxysporum, the causer of sugar beet root rot. In 2000, an extremely dry year, plant vitality was satisfactory in the experiment with irrigation and the average root rot incidence was low (2,91%). In the nonirrigated variant the average incidence was high (71,02%). It may be concluded on the basis of the results from five years (2000-2004) that the major causal agents of sugarbeet root rot in our country are species from genus Fusarium, especially F. oxysporum. Fusarium wilt and root rot are due to the increased frequency of dry and warm years.

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Plant regeneration from protoplasts of sugar beet (Beta vulgaris)

Physiologia Plantarum ◽

10.1034/j.1399-3054.1995.940223.x ◽

1995 ◽

Vol 94 (2) ◽

pp. 342-350 ◽

Cited By ~ 1

Author(s):

Steffen Lenzner ◽

Kurt Zoglauer ◽

Otto Schieder

Keyword(s):

Plant Regeneration ◽

Sugar Beet ◽

Beta Vulgaris

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