A major limiting factor in grape production throughout the world is grapevine trunk diseases (e.g. eutypa dieback, esca, black dead arm, phomopsis cane and leaf spot) (Pearson & Goheen, 1988). In 2005, a survey was carried out in north-eastern Spain to determine fungal pathogens associated with such diseases. Symptoms observed during this survey included general decline of vine, internal black wood streaking, central and sectorial necrosis and wood decay. A plant with necrosis around the pith of the trunk, visible in a transverse section was sampled and isolations made. Necrotic material was selected, surface sterilized in 70% ethanol for 1 min, air-dried under sterile conditions and plated onto streptomycinamended malt extract agar (MEA).Several Phaeoacremonium spp. were isolated. Of these, P. aleophilum was the most prevalent species. One isolate, however, was identified as P. viticola based on conidiophore-and conidia-morphology (short and unbranched, often consisting of a single cylindrical phialide of 2-5 μ m in length; hyaline, obovoid or reniform, 4 μ m long), and colony colour on MEA (greyish pink). Identity was confirmed by PCR using the species-specific primer pair T1-Pbr8 (Mostert et al ., 2006). Pathogenicity of P. viticola isolated from this study was tested by inoculation of 2-month-old pot grown seedlings of Vitis vinifera cv. Malvar. The soil of seven plants was inoculated by drenching with 40 mL spore suspension (10 7 spores mL -1 ).A further seven control plants were inoculated with 40 mL of sterile distilled water. The plants were maintained in a growth chamber at 24ºC and 40% relative humidity. Symptoms were checked periodically for two months. By the end of the experiment all seedlings inoculated with P. viticola showed symptoms which ranged from defoliation (four plants with only the apical leaf remaining), crown necrosis (one plant), epinasty (one plant), to death (one plant). Control plants inoculated with sterile water remained symptomless. Phaeoacremonium viticola was re-isolated from the infected plants. Similar symptoms caused by P. viticola have been previously described (Dupont et al ., 2000), but this is the first report of the disease in Spain. ) showing necrotic spots on leaves, occasionally followed by death of affected plants, were observed in commercial, plastic houses heated by geothermic water in Kebili (southern Tunisia). Crude sap from leaves with symptoms was used for mechanical inoculation onto a set of differential host plants. Necrotic local lesions on inoculated leaves or cotyledons and systemic necrotic spots were observed on melon plants. Necrotic local lesions and no systemic symptoms were produced on cucumber ( Cucumis sativus ). In contrast, no symptoms were observed on non-cucurbit plants.
ReferencesThe observed symptoms and host range were similar to those described for Melon necrotic spot virus (MNSV). The presence of MNSV was established by DAS-ELISA using a specific antiserum prepared at INRA. MNSV was detected in seven samples with symptoms.
