Volume 8 - 2018 - Issue 2


1. Fungi associated with foliar diseases of Tecoma stans in Tlaxcala, Mexico

Authors: Santiago-Santiago V, Ayala-Escobar V, Nava-Díaz C, Solano-Báez AR, Tovar-Pedraza JM

Recieved: 10 February 2018, Accepted: 02 July 2018, Published: 11 July 2018

During 2015, leaves, stems, and pods of Tecoma stans showing symptoms of galls, rust, and powdery mildew were collected from public gardens located in Panotla, Tlaxcala, Mexico. The fungi present in the tissues were characterized morphologically using light microscopy. Galls on leaves, stems, and pods and erumpent pustules on leaves were associated with two rust fungi, Prospodium transformans and P. appendiculatum. The fungus associated with powdery mildew symptoms was identified as Phyllactinia obclavata. To the best of our knowledge, this is the first report of P. obclavata causing powdery mildew in T. stans in Mexico.

Keywords: Prospodium transformans – Prospodium appendiculatum – Phyllactinia obclavata – morphology

 

2. First record of Rhizopus oryzae from stored apple fruits in Saudi Arabia

Authors: Al-Dhabaan FA

Recieved: 09 January 2018, Accepted: 21 April 2018, Published: 12 July 2018

During spring 2017, red delicious and Granny Smith apples with soft rot symptoms were collected from commercial markets in Saudi Arabia. The causal agent was isolated from infected fruits and its pathogenicity was confirmed by inoculation assays. To confirm the identity, total genomic DNA was extracted and multi-locus sequence data targeting two gene markers (ITS, ACT) was sequenced. Phylogenetic analysis confirmed the presence of two distinct clades; Saudi isolate was placed within a clade comprising Rhizopus oryzae and R. delemar reference isolates. Based on morphological characteristics, molecular identification and pathogenicity test, the fungus was identified as Rhizopus oryzae. This is the first report of Rhizopus soft rot caused by R. oryzae from stored apple fruits in Saudi Arabia.

Keywords: Rhizopus soft rot – phylogeny – pathogenicity – morphological characters – sequence data

 

3. Controlling phytophthora blight of cucumber (Cucumis sativus) in a derived savannah, using different spray intervals of a registered fungicide

Authors: Aba SC, Eze SC, Ishieze PU, Omeje TE, Ugwuoke KI

Recieved: 03 April 2018, Accepted: 20 June 2018, Published: 19 July 2018

Phytophthora blight of cucumber, caused by the oomycete pathogen, Phytophthora capsici causes root and crown rot as well as aerial blight of leaves, fruits and stems. This study was conducted in University of Nigeria Nsukka, south eastern Nigeria, to investigate the effectiveness of four different spray regimes against phytophthora blight. D-D Force insecticide and mancozeb fungicide was used on six cucumber lines (Marketer, Poinsett 76 Netherlands, Poinsett 76 Holland, Poinsett France, Poinsett Holland and Super Marketer) in 2013 farming season. Different spray regimes significantly reduced disease incidence weeks after planting. Disease incidence and severity was highest in the control and lowest when plants were sprayed five times at fortnightly intervals. Best results were obtained with variety Super Marketer and it is therefore recommended for Nsukka farmers.

Keywords: cucumber – disease incidence – disease severity – spray intervals

 

4. A new morphotype of Golovinomyces neosalviae infecting Salvia officinalis

Authors: Götz M, Idczak E, Richert-Pöggeler K, Braun U

Recieved: 02 May 2018, Accepted: 13 July 2018, Published: 20 July 2018

In 2017, severe powdery mildew infections of Salvia officinalis were observed at two locations in Germany. Two powdery mildew strains were isolated and molecularly and morphologically characterized. Based on ITS-28S rRNA sequences both isolates were assigned to the recently described Golovinomyces neosalviae. While mycelium and conidial features did not differ from each other and were in accordance with those described before for G. neosalviae, conidiophores were considerably different from any earlier descriptions suggesting the occurrence of a new morphotype. Conidiophores were very variable and up to 800 µm long, often with shoulder-like swellings. Moreover, they showed single or multiple branching which has not yet been described for Golovinomyces species. 

Keywords: branched conidiophores – conidia – morphology – powdery mildew – sage

 

5. First report of squash leaf curl virus detected in Proboscidea louisianica in Mexico

Authors: Díaz-Nájera JF, Ayvar-Serna S, Vargas-Hernández M, Sahagún-Castellanos J, Alvarado-Gómez OG, Tejeda-Reyes MA

Recieved: 06 June 2018, Accepted: 10 July 2018, Published: 20 July 2018

Squash leaf curl virus (SLCV) was detected in Proboscidea louisianica and identified based on the nucleotide sequence of the viral capsid protein genome. Phylogenetic analysis confirmed that the begomovirus was associated with viral symptoms of the host weed. This is the first report of SLCV detected in P. louisianica.

Keywords: begomovirus diagnosis – PCR – weed

 

6. Efficacy of Allium sativum extract as post-harvest treatment of fruit rot of mango

Authors: Nur Fatimma A, Munirah MS, Sharifah Siti Maryam SAR, Najihah A, Nur Ain Izzati MZ

Recieved: 16 March 2018, Accepted: 20 July 2018, Published: 02 August 2018

Fruit rot caused by Lasiodiplodia species is among the most significant post-harvest fungal disease of mango fruit. The use of chemical synthetic fungicides to control plant diseases can contaminate the environment and affect human health. An alternative method to circumvent these problems is to use extracts from plants that can produce antifungal compounds. Aqueous extract of garlic (Allium sativum) was screened for its inhibitory effect against L. theobromae in vitro and it was shown to have antifungal activity by forming an inhibition zone. In addition, L. theobromae growing on garlic extract amended agar did not produce any conidia. Healthy unripe mango fruits were soaked in different concentration of garlic extract for different times. Soaking fruit for 4 hours in 100% concentration extract prevented lesion development.  It is concluded that garlic extract can suppress growth of L. theobromae and improve the marketability of mango fruit without using chemical synthetic fungicides to control post-harvest diseases.

Keywords: antifungal – mango – Lasiodiplodia theobromae – garlic extract – inhibition

 

7. Are pathogenic isolates of Stemphylium host specific and cosmopolitan?

Authors: Brahamanage RS, Hyde KD, Li XH, Jayawardena RS, McKenzie EHC, Yan JY

Recieved: 16 July 2018, Accepted: 12 August 2018, Published: 17 August 2018

Stemphylium is a genus of filamentous ascomycetes comprising plant pathogens and saprobes in the family Pleosporaceae (Pleosporales, Dothideomycetes). Species of Stemphylium are known from a broad range of plant hosts including a variety of agricultural crops. This paper briefly discusses the occurrence of pathogenic isolates of Stemphylium on different host species, pathogenicity, disease severity, distribution and molecular phylogenetic affinities of pathogenic isolates of Stemphylium.

Keywords: N/A

 

8. Colletotrichum tropicale causal agent of anthracnose on noni plants (Morinda citrifolia) in Guerrero, Mexico

Authors: Ayvar-Serna S, Díaz-Nájera JF, Plancarte-Galán PJ, Vargas-Hernández M, Alvarado-Gómez OG, Tejeda-Reyes MA, Mena-Bahena A

Recieved: 03 August 2018, Accepted: 15 August 2018, Published: 23 August 2018

During sampling in March 2014 severe anthracnose symptoms were observed, mainly in foliage, on noni plants (Morinda citrifolia) in Cocula, State of Guerrero, Mexico. Fungal monosporic colonies were isolated from leaves with anthracnose symptoms. The morphological characteristics matched those of conidia of Colletotrichum tropicale. DNA analysis was performed on mycelium of the fungus by PCR amplification of ITS sequences. The identification and pathogenicity of isolates was confirmed by inoculation of the pathogen onto healthy plants free from disease. Control plants remained healthy, while those inoculated with the pathogen developed lesions and symptoms of rot anthracnose eight days after inoculation. The morphological, molecular characteristics and pathogenicity tests of the isolates confirmed that C. tropicale is the causal agent of anthracnose in M. citrifolia.

Keywords: anthracnose – diagnosis – Morinda citrifolia – PCR

 

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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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