First Report of Root Rot of White Mulberry Caused by Simultaneous Infections of Phytophthora megasperma and P. multivora in Italy

In August 2002, Phytophthora megasperma Drechs. was isolated from wilted plants of Asparagus officinalis L. cv. Guelph Millenium displaying spear and crown rot. Six affected plants were sampled in a commercial asparagus field located in the Saguenay-Lac-Saint-Jean Region (300 km northeast of Montreal, Quebec, Canada). The fungus was isolated from asparagus fern stalks, crown tissue, and spears after a rainy period and identified using morphological and cultural characteristics (2). In pinkish 4-week-old cultures, unbranched stalks bore abundant sporangia, which were ovoid to obpyriform in shape, 15 to 45 m long, and 10 to 30 m in diameter. Characteristic circular oospores >30 m in diameter were produced on V8 juice agar at 25°C in darkness after 1 month. Pathogenicity was tested on asparagus cvs. Guelph Millenium and Jersey Knight. A mycelium suspension (3 ml at 106 CFU/ml) prepared from 1-week-old shaken potato dextrose (PD) broth was sprayed on 30 1-week-old seedlings grown in petri plates filled with sterilized, moist, sandy soil and held at 20°C (day/night). Controls received sterile PD broth. Within 3 weeks of incubation in the dark, inoculated seedlings exhibited necrotic symptoms similar to those observed initially, while controls remained healthy. The pathogen was isolated from 75% of the ‘Guelph Millenium’ and 98% of the ‘Jersey Knight’ symptomatic seedlings, but not isolated from the control seedlings. In North America, disease caused by P. megasperma resulting in yield loss has been reported in California and New York (1,3). In Canada, the etiology of asparagus diseases is not well characterized. To our knowledge, this is the first report of P. megasperma on asparagus plants in Canada. References: (1) P. A. Ark and J. T. Barrett. Phytopathology 28:754, 1938. (2) D. C. Erwin et al. Phytophthora: Its Biology, Taxonomy, Ecology, and Pathology. The American Phytopathological Society, St Paul, MN, 1983. (3) T-L. Kuan and D. C. Erwin. Phytopathology 70:333, 1980.

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First Report of Fusarium oxysporum Causing Root Rot in Ophiopogon bodinieri in China

Plant Disease ◽

10.1094/pdis-07-19-1542-pdn ◽

2020 ◽

Vol 104 (4) ◽

pp. 1254

Author(s):

B. H. Lu ◽

Z. Wang ◽

G. J. Yi ◽

G. W. Tan ◽

F. Zeng ◽

...

Keyword(s):

Fusarium Oxysporum ◽

Root Rot ◽

First Report

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First report of Athelia rolfsii (Curzi) causing stem and root rot on stevia (Stevia rebaudiana Bertoni) in Ecuador

Journal of Plant Pathology ◽

10.1007/s42161-021-00819-z ◽

2021 ◽

Author(s):

Jefferson Bertin Vélez-Olmedo ◽

Sergio Vélez-Zambrano ◽

Bianca Samay Angelino Bonfim ◽

Edisson Cuenca Cuenca ◽

Susana García ◽

...

Keyword(s):

Root Rot ◽

Stevia Rebaudiana ◽

First Report ◽

Stevia Rebaudiana Bertoni ◽

Athelia Rolfsii

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First Report of Root Rot Caused by Fusarium avenaceum on Coptis chinensis in Chongqing, China

Plant Disease ◽

10.1094/pdis-05-20-1110-pdn ◽

2020 ◽

pp. PDIS-05-20-1110

Author(s):

P. Y. Mei ◽

X. H. Song ◽

Z. Y. Zhu ◽

L. Y. Li

Keyword(s):

Root Rot ◽

Fusarium Avenaceum ◽

Coptis Chinensis ◽

First Report

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

Plant Disease ◽

10.1094/pdis.1997.81.10.1216b ◽

1997 ◽

Vol 81 (10) ◽

pp. 1216-1216 ◽

Cited By ~ 4

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.

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