Volume 1 - 2011 - Issue 1


1. Tropical phythopathogens 1: Pseudocercospora punicae

Authors: Phengsintham P, Chukeatirote E, McKenzie EHC, Hyde KD, Braun U

Recieved: 14 June 2011, Accepted: 21 June 2011, Published: 30 June 2011

The present paper is the first in a series, which aims to describe important tropical plant pathogens, with illustrations and description and notes on symptoms. Leaf and fruit spot/blotch disease of Punica granatum is caused by Pseudocercospora punicae and the fungus and symptoms of the disease are illustrated and described in this paper. Punica granatum (pomegranate) has worldwide importance due to consumer demand for this high nutritional, therapeutic and medicinal fruit. The host, however, suffers from a cercosporoid disease that causes spotting on leaves, blotching of fruits and premature fruit drop. Pseudocercospora punicae leaf and fruit spots appear as subcircular to irregular brown to dark brown or black blotches which are 1–12 mm in diameter for fruit spots and 1–4 mm in diameter for leaf spots. Conidophiores are 7–22 × 3–4 µm and some are distinct in having geniculate characters, whereas the conidia are 42–72 × 2–4 µm. The partial sequence (771 bp) of the large subunit (LSU) rRNA gene of this species is also provided.

Keywords: hyphomycetes, leaf spot – resistance – systematic fungicide – taxonomy – Thailand

 

2. The genus Asterostomula from Kerala, India, including one new species

Authors: Hosagoudar VB, Sabeena A, Jacob-Thomas

Recieved: 10 April 2011, Accepted: 29 April 2011, Published: 30 June 2011

Asterostomula is the anamorph of Echidnodes and Prillieuxina and comprises 13 species and one variety. The present paper gives an account of two species; Asterostomula syzygii sp. nov. is described as a new species on Syzygium sp., while A. loranthi is reported for the first time from India. The species are characterized and illustrated with line drawings.

Keywords: Anamorph – Black mildew –New record – New species

 

3. Genus Cercospora in Thailand: Taxonomy and Phylogeny (with a dichotomous key to species)

Authors: To-Anun C, Hidayat I, Meeboon J.

Recieved: 24 November 2010, Accepted: 30 November 2010, Published: 30 June 2011

Cercospora Fresen. is one of the most importance genera of plant pathogenic fungi in agriculture and is commonly associated with leaf spots. The genus is a destructive plant pathogen and a major agent of crop losses worldwide as it is nearly universally pathogenic, occurring on a wide range of hosts in almost all major families of dicotyledonous, most monocotyledonous families, some gymnosperms and ferns. The information regarding Cercospora leaf spots in Thailand is scattered and mainly based on Chupp’s generic concepts. Therefore, this paper provides an update that includes synonyms, morphological descriptions, illustrations, host range, geographical distribution and literature related to the species. This will benefit mycologists, plant pathologists and quarantine officials who need to study this group of fungi. The present study represents a compilation of 52 species of Cercospora s. str. associated with 29 families of host plants collected from several provinces in Thailand between 2004 and 2008. Twenty-four species represent C. apii s. lat. Plant families of Asteraceae, Amaranthaceae, Convolvulaceae, Euphorbiaceae, Fabaceae, Lamiaceae and Solanaceae, are commonly found infected with Cercospora s. str. Three species, Cercospora arecacearum, C. habenariicola and C. neobougainvilleae, have been validity published as new species from Thailand.

Keywords: diversity – hyphomycetes – leaf spot – taxonomy – Thailand.

 

4. Fusaria and other fungi associated with seedling blight and root rot of flax in the Nile Delta

Authors: Aly AA, Omar MR, Mansour MTM, Zayed SME, Abd-Elsalam KA.

Recieved: 14 January 2011, Accepted: 19 January 2011, Published: 21 July 2011

Fifty-five samples of blighted flax (Linum usitatissimum) seedlings or rotted roots of adult plants were randomly obtained from six flax producing governorates in the Nile Delta. The mean percenttages of fungal recovery from samples showed that Fusarium spp. (30.7%) were the most dominant fungi present. Other fungi occurred at frequencies ranging from 0.3–12.1%. Isolation frequencies of Fusarium spp. did not significantly differ from between governorates. The nature of the previous crop had an important bearing on the activity of flax root-colonizing Fusarium spp. Thus, samples preceeded by rice had the lowest isolation frequency (23.7%), while those preceeded by cotton had significantly higher isolation frequency (42.8%). Regression analysis revealed that root colonization incidence (RCI) and root colonization severity (RCS) relationship of root-colonizing fungi of flax conformed to the linear model. According to the generated model, RCI accounted for 81.7% of the total variation in RCS. Fusarium spp. were remotely related to Pythium spp. in their prevalence pattern, while they were unrelated to the other fungi. A total of 112 randomly selected isolates were tested for pathogenicity on seedlings of flax cultivar Giza 7 under greenhouse conditions. Fusarium spp. represented 50.0 and 51.5% of the tested isolates and demonstrated convincingly that Fusarium spp. are the major causal agents of flax seedling blight and root rot in the Nile Delta as they accounted for 57.0% of the pathogenic isolates. Thirty-six Fusarium spp. isolates were identified to species level and tested for pathogenicity on seedlings of flax cultivar Giza 7 under greenhouse conditions. F. oxysporum (50.0%) and F. solani (33.3%) were the predominant species. Other species were F. lateritium (5.5%), F. semitectum (2.7%), and unidentified Fusarium spp. (8.3%). Most pathogenic isolates belonged to F. oxysporum (47.0%) and F. solani (35.2%). The high frequency of F. oxysporum and F. solani, and their ability to cause considerable losses during seedling stage, strongly suggest that they are the most important pathogenic fusaria involved in the etiology of seedling blight and root rot of flax in the Nile Delta.

Keywords: Egypt – Fusarium – Linum usitatissimum – soil-borne fungi

 

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Plant Pathology & Quarantine Online publishes reviews, research articles, methodology papers, and taxonomic works in the field of plant pathology. The official journal language is English.

 

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