Although large-spored Alternaria species of the section Porri are considered to be the major agents responsible for leaf spot and blight of Solanaceae, small-spored Alternaria species are also frequently isolated from symptomatic tissues. A survey of the north-western regions of Algeria during the 2017–2018 growing seasons revealed that amongst the 623 Alternaria isolates from tomato, potato, pepper, eggplant and black nightshade, 8% could not be morphologically assigned to either section Porri or section Alternaria. In order to more precisely determine the taxonomic position of these isolates, detailed morphological characterizations and multi-locus phylogenetic analyses were performed. Based on these analyses, the isolates were grouped into four main clades: section Ulocladioides, section Infectoriae, including two new species, section Embellisioides, and section Eureka, including one new species. These isolates were also characterized for their virulence under green-house conditions. They were able to produce leaf spot symptoms on tomato plants but with variable levels.

In northwestern Algeria, severe early blight symptoms on tomato crops are regularly observed. In 2013, diseased samples were collected in different farms of the Mostaganem region. Large-spore Alternaria isolates were recovered and characterized based on morphological and molecular characters as belonging to A. solani and A. grandis. Isolates of these two species generated typical symptoms when inoculated on tomato plants in greenhouse experiments. To our knowledge, this is the first report of A. grandis on Solanaceae plants in Algeria and in Africa and the first report of A. grandis on tomato.

Alternaria species have often been reported as plant pathogens and are commonly isolated from diseased plant hosts. During an investigation of this genus in Algeria, seven Embellisia-like isolates were collected from Apiaceae. Phylogenetic analysis using sequences at four loci, the internal transcribed spacer of the rDNA region (ITS), glyceraldehyde-3-phosphate dehydrogenase (gpd), translation elongation factor 1-alpha (tef1), and RNA polymerase second largest subunit (rpb2), revealed that these isolates grouped into three sections, namely Embellisia, Embellisioides, and Eureka. Four isolates had significant differences with their closest species and were determined to be new species, namely Alternaria longiformis and A. radicicolaspp. nov. The three other isolates of section Eureka were identified as A. eureka and A. hungarica, the latter species being described as a new record in Algeria. Detailed descriptions of new species are provided based on colony color, aspect, diameter, conidial size, septa, sporulation patterns and compared with other relevant Alternaria species within same sections. All these species were weakly pathogenic on carrot, coriander, and fennel under greenhouse experiments. Apiaceae may constitute a reservoir of Alternaria species that could represent potential pathogens for other plant families.

Leaf blight and spot caused by Stemphylium spp. and Alternaria spp. are the most common destructive tomato diseases in north-western Algeria. During 2018 growing seasons, more than 30% of samples collected from plants grown in greenhouses or open fields were infected with Stemphylium. Initial symptoms were small, multiple, irregular to oval, yellow leaf spots, which enlarged to brown lesions later. In these lesions, Stemphylium mostly co-occurred with Alternaria spp. Twenty nine Stemphylium isolates were characterized based on morphological features, and multi-locus phylogenies using ITS, gpd, and cmdA genomic loci. Five Stemphylium species (S. lycopersici, S. gracilariae, S. eturmiunum, S. vesicarium, S. lycii) were associated with tomato leaf spot, of which S. lycii is a new report for tomato. Pathogenicity tests on healthy 2-months-old tomato seedlings reproduced symptoms similar to those observed in tomato crops. The tested fungus isolates differed in pathogenicity. Two isolates of S. lycopersici were more aggressive than those of the other species, causing major lesions on tomato plants. The five identified Stemphylium species are reported for the first time as new pathogens for tomato in Algeria, and S. lycopersici, S. gracilariae, S. eturmiunum, and S. lycii as new species of Algerian mycoflora.

Coriander (Coriandrum sativum, Family Apiaceae) is an important condiment plant in Algeria. It is grown all year and the entire young plants and fruits are used in preparing soups and the leaves are used for flavouring sauces, salads and tadjins, and as a dehydrated product. In 2017 and 2018, a severe foliar blight (disease incidence 61.8% and severity 34%, n= 136) was observed in commercial coriander cultivated in Saint Remy and Gdyel (wilaya Oran), Algeria. Symptoms were oval or irregular dark brown lesions on leaves. For pathogen isolation, small pieces (5 to 10 mm2) of disease lesions were sterilized by immersion in 2% sodium hypochlorite (NaOCl) for 2 min, rinsed three times with sterile distilled water, and incubated on potato carrot agar (PCA) for 7 days at room temperature (20 to 26°C). A total of 228 Alternaria isolates were obtained from 186 samples and grouped into five sections based on growth pattern and morphological characters (Simmons 2007). Isolation frequency showed that small-spored iso...

Symptoms of foliar blight were observed on turfgrass in Oran (Algeria), including yellow chlorotic patches on leaves during the 2020 summer (temperatures between 35 and 40°C). Symptoms extended downward from leaf tips and entire leaves became blighted, leading to irregular discoloured areas that later turned brown. Isolations from infected plants included 214 isolates identified as Curvularia or Bipolaris, based on morphological traits. Other isolates included Fusarium, Myrothecium and Acremonium spp. Three molecular loci, ITS rDNA, gpd and tef1, were amplified and sequenced. Morphological and multi-locus phylogenetic analyses revealed four fungal species viz. B. sorokiniana, C. spicifera, C. verruculosa, C. geniculata, and two additional Curvularia lineages, some of these fungi are reported are first records for Algeria. Koch’s postulates were confirmed by inoculating potted turfgrass with spore suspensions of 16 isolates and re-isolating of the inoculated pathogens from symptomatic tissues. Bipolaris sorokiniana was the most virulent pathogen causing numerous foliar necrotic lesions similar to those observed in the field. Other isolates infected basal leaves only, and caused less severe symptoms. The results show that Curvularia species may be secondary pathogens infecting stressed plants, and that simultaneous occurrence of high temperatures and poor water quality have influenced disease progression. Correct identification of these pathogens is important for applying appropriate and timely disease management.