In vitro effect of crude extracts from eight Algerian steppe plants on mycelial growth and sporulation of Ascochyta pisi Lib.

Se ha estudiado el efecto de extractos crudos de ocho plantas, que crecen en la estepa argelina, contra Ascochyta pisi Lib., uno de los miembros del complejo Ascochyta que causa la antracnosis del guisante, con el objetivo de sustituirlos por fungicidas químicos con reconocida nocividad para el medio ambiente y la salud pública. Con este propósito, se realizó una prueba de control biológico in vitro del crecimiento y la esporulación de A. pisi, agregando extractos de plantas crudas o sus sub-fracciones a su medio de cultivo. Al final de este ensayo, encontramos que los extractos de Artemisia alba Turra, Lycium arabicum Schweinf. Ex Boiss. y Peganum harmala Linn. registraron las mejores tasas de inhibición del crecimiento de patógenos, mientras que Artemisia campestris L. es más efectiva contra su esporulación. This work consists of studying the effect of crude extracts of eight plants growing in the Algerian steppe against Ascochyta pisi Lib., one of the members of the Ascochyta complex causing the Ascochyta blight of pea, with the aim of substituting them for chemical fungicides recognized for their harmfulness to the environment and public health. For this purpose, an in-vitro biocontrol test of the growth and sporulation of A. pisi was achieved by adding to its cultural medium a crude plant extracts or their sub-fractions. At the end of this trial, we found that the extracts of Artemisia alba Turra, Lycium arabicum Schweinf. Ex Boiss. and Peganum harmala Linn. recorded the best growth inhibition rates of pathogenic whereas, Artemisia campestris L. is more effective against its sporulation.

Morphological and Genotypic Characterization of Fungi Associated with the Ascochyta Blight Complex in Western Regions of Algeria

The study is conducted in two growing areas of garden pea (Pisum sativum L.) in northwestern Algeria. Damages caused by Ascochyta sp complex are important in particular for the variety of Kelvedon Wonder. Observations carried out on the infected plants for several years, indicate the presence of superimposed necrosis of different sizes on all aerial organs. However, these observations do not differentiate symptoms by species. The results of morphological and molecular characterization with sequencing in internal transcribed spacer (ITS) regions and inoculation tests on 32 isolates in the laboratory of symbiosis and plant pathology from Toulouse (France), show a reconciliation of the sequencing by polymerase chain reaction (PCR) products and size necrosis for all Ascochyta pinodes and pinodella. Alone, Ascochyta pisi is distinguished by a smaller size necrosis. On the molecular level, all isolates whose ITS regions were amplified by PCR, expresses similar size products (550 bp). This molecular weight is found on a large set of pathogenic fungi. The three species of Ascochyta sp complex do not exhibit polymorphism for Pisum sativum species and have an identical molecular weight. The pathogenicity tests performed showed differences in aggressiveness on the host plant. Ascochyta pinodes is the most aggressive than the other two species. As a result, it causes more damage to the crop.

Preservation methods for isolates of ascochyta blight fungi

Isolates of ascochyta blight fungi, two of <i>Ascochyta pisi</i>, four of <i>Mycosphaerella pinodes</i> and four of <i>Phoma pinodella</i> were stored: A - on slants under mineral oil, B - on CN's medium agar disks, and as conidial suspension: C - in glycerine, D · in water. Viability and pathogenicity of recovered cultures after each consecutive year were assesed from 1991 to 1999. The compared parameters were first of all strongly influenced by the preservation method, but fungus species and number of years had a minor importance. The best for longer storage was method "A" because after 9 years the isolates were viable, highly pathogenic, and cultures recovered from them were clean. Thc method "C'' is good for short keeping (2-3 years), as conidia in vials need only small space and gave clean cultures.

Yariability of dry seed mycobiota of Pisum sativum

Mycobiota of dry pea seeds of cv. Ramir and line R 429/87 harvested at Radzików, Oleśnica Mała and Łagiewniki in 1991—93 was investigated. Among twenty species <i>Alternaria aliernata</i> and <i>Stemphylium botryosum</i> occurred commonly each year. <i>Mycosphaerella pinodes, Ascochyta pisi, Fusarium poae</i> and <i>Cladosporium herbarum</i> were noted on most of the tested seed samples. Percentage of sccee transmitting the fungi varied depending on locations, time and genotypes, being the lowest for Łagiewniki and in 1992. The year 1991 was the most favourable for seed mycobiota development, especially for pathogenic fungi.

Fungi occurrence on seeds of field pea

Seeds of four edible cultivars of <em>Pisum sativum</em> and three fodder harvested in 2004-2006 from eight localities, scattered in all region suitable for pea production in Poland, were evaluated for fungi occurrence on CN agar medium in Petri plates. The highest number (27) of species was isolated in 2004, while the lowest (16) in 2006. Number of fungi inhabiting seeds was influenced mainly by environmental conditions of locality and years. <em>Alternaria alternata</em> dominated in each sample of 450 seeds. Species of <em>Penicillium</em> contaminated seeds as the next and infection by <em>Stemphylium botryosum</em> was at similar level. <em>Fusarium poae</em> was the most often occurring species of this genera. Pea specific pathogens: <em>Mycosphaerella pinodes, Phoma pinodella</em> and <em>Ascochyta pisi</em> infected more seeds in 2004 and 2005 than 2006, and at the last season only <em>A. pisi</em> was noted. In general, level of infection by those pathogens was low, reaching on an average only 2.56%, with the highest for A. pisi, and the lowest for <em>M. pinodes</em>.

Occurrence of pathotypes of Ascochyta pisi (Lib.) in the Olsztyn district

The causal agents of leaf and pods spot-pot of peas and field peas in the Olsztyn district was the fungus <i>Ascochyta pisi</i> (Lib.). Investigated isolates of <i>A. pisi</i> differed by macroscopic and microscopic features. From diseases leaves and pods of peas and field peas obtained also saprophitic fungi among which <i>Alternaria alternata, Botrytis cinerea, Cladosporium c1adosporioides, Epicoccum purpurascens, Stemphylium botryosum, Sordaria fimicola</i> and <i>mycelia starilia</i> were dominated. In the study of the identification and distribution of pathotypes of <i>A. pisi</i> five pathotypes were identified among which pathotype 2 were dominated. The identified the pathotypes differed by macroscopic and microscopic features.

Crop rotation as a factor differentiating the intensity of the diseases of field pea (Pisum sativum L.)

The research was conducted in the years 1998-2001. The aim of the research was to determine the health of the field pea cv. Kormoran grown in four various crop rotations and to determine the patogens causing the root-rot. On the pea plants the following diseases were found: root rot (complex of fungi), ascochyta blight (<em>Ascochyta pisi, Phoma pinodella, Mycospaerella pinodes</em>) and fusarium foot rot (<em>Fusarium</em> spp.). All the diseases occurred in the highest intensity on the pea cultivated in three-field crop rotation without manure. The weather conditions affected the intensity of the diseases. From the roots of seedlings with the symptoms of root rot 44,7% of fungi with pathogenic potential in relation to pea were obtained. The most commonly isolated were <em>Fusarium oxysporum</em> (26,7% of all isolates), <em>Rhizoctonia solani</em> (10,7%), <em>F.solani</em> (3,3%), <em>F.avenaceum</em> (2,7%) and <em>F.equiseti</em> (1,3%). From the infected root necks, 55,3% of potential pathogens of field pea were obtained. Among the isolates the most commonly found was <em>F.oxysporum</em> (31,1% of all isolates). Other fungi of the <em>Fusarium</em> genus constituted 15,4% of isolates, <em>R.solani</em> 7,0%, and <em>Sclerotinia sclerotiorum</em> 1,8%.

Studies on the susceptibility of peas and field peas cultivars to Ascochyta pisi (Lib.)

The aim of the work was to find the plants resistant to <i>Ascochyta pisi</i> causing leaf and spot-pot of peas and field peas. Fourty five cultivars of peas and field peas and 6 breeding materials were tested in field in the period 1975-1978. Cultivars: Bartel, Birte, Borek, Cebeco, Finale and Paloma were to be less susceptible. In laboratory and greenhouse conditions peas and field peas cultivares were examined for susceptible to pathotypes 2 and 4 of <i>Ascochyta pisi</i>. The results obtained proved that cultivars: Borel, cebeco, Finale and Paloma were to be less susceptible to two pathotypes of <i>Ascochyta pisi</i>.