Surveys between 1989 and 1993 in the major garlic production areas of Spain identified a new leaf spot disease, characterized by white and purple lesions followed by extensive necrosis. Isolation and pathogenicity tests with fungal isolates taken from these spots indicated that Stemphylium vesicarium was the causal agent. Pseudothecia of the teleomorph stage, Pleospora sp., were found on leaf debris from affected plants. Inoculation of garlic and onion plants with residues carrying mature pseudothecia, or with ascospore suspensions obtained from the pseudothecia, resulted in the development of white and purple leaf spots. Wetness periods longer than 24 h were required for symptom development under controlled conditions. Isolates of S. vesicarium from garlic, onion and asparagus caused disease in all three hosts. In garlic, cv. Blanco de Vallelado was most susceptible, while lines B4P17 and B6P1, and cvs Iberose and Golourose were less susceptible to the disease.

Eighteen commercial cultivars of carnation were inoculated with eight isolates of F. oxysporum fsp. dianthi (Fod) from a collection of isolates obtained from diseased plants surveyed in the main growing area of Spain. Susceptible reactions were shown in most cultivars inoculated with six isolates characterized as race 2 when tested on differentials. However, cultivars Elsy and Westcristal were fully resistant to the six isolates, whereas ‘Scarlet King’ showed a variable response, suggesting genetic diversity within race 2 of Fod. In contrast, eight cultivars inoculated with three isolates of races 1 or 8 were usually resistant except for cultivars Nelson and Solar, which were fully susceptible, and ‘Elsy’, which showed resistance to only one of the isolates. Partial polygenic inheritance of resistance to race 2 determines the complexity in the host reactions. Nine cultivars used in the previous experiment were inoculated with 13 Italian isolates of a collection of races of Fod. Cultivar reactions to isolates of different races agreed with some reports but not with others, suggesting an effect of environmental conditions or inoculation method. Reactions under field conditions sometimes differed from reactions with artificial inoculation in the greenhouse and growth chamber, usually more prone to express susceptibility.

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