Fusarium crown and root rot of tomato (Lycopersicon esculentum) caused by Fusarium oxysporum f. sp. radicis‐lycopersici is a new devastative disease of tomato greenhouse crops in Tunisia. Nothing is known neither about the population of this pathogen in this region, nor about the population of F. oxysporum f. sp. lycopersici the causal agent of Fusarium wilt of tomato. In order to examine the genetic relatedness among the F. oxysporum isolates by intergenic spacer restriction fragment length polymorphism (IGS‐RFLP) analysis and to elucidate the origin of the formae specialesradicis‐lycopersici in Tunisia by looking for genetic similarity of Tunisians isolates with isolates from a foreign source, the genetic diversity among F. oxysporum f. sp. radicis‐lycopersici and F. oxysporum f. sp. lycopersici populations was investigated. A total of 62 isolates of F. oxysporum, obtained from symptomless tomato plants, were characterized using IGS typing and pathogenicity tests on tomato plants. All Fusarium isolates were highly pathogenic on tomato. Fusarium oxysporum f. sp. radicis‐lycopersici isolates were separated into five IGS types. From the 53 F. oxysporum f. sp. radicis‐lycopersici isolates, 34 isolates have the same IGS types (IGS type 25), and the remaining 19 isolates were distributed into four IGS types. However, the only nine isolates of F. oxysporum f. sp. lycopersici have six different IGS types. This difference of diversity between the two formae speciales suggests that F. oxysporum f. sp. radicis‐lycopersici isolates have a foreign origin and may have been accidentally introduced into Tunisia.

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A crown, foot and fruit rot of watermelon has been observed in most of the watermelon production areas in Tunisia. A survey conducted from 2000 to 2001 allowed the isolation of 291 isolates which were identified as Fusarium solani. These isolates were identified as F. solani f. sp. cucurbitae (Fsc) and races 1 and 2 characterized on the basis of pathogenicity tests on watermelon seedlings and muskmelon fruits. These results were confirmed by counts of the number of septa in the macroconidia. About 271 isolates were identified as Fsc race 1, 12 isolates were identified as Fsc race 2 and eight isolates were not pathogenic. Race 1 is widely distributed in watermelon production areas in Tunisia and race 2 has a lower incidence but it is present in the north, the middle and southern Tunisian watermelon cropping areas. Additionally, a study to compare the virulence of 122 isolates of Fsc race 1 showed different degrees of virulence among them. This is the first report of Fsc races 1 and 2 in Tunisia.

Au cours des prospections effectuées dans les oliveraies de la délégation de Mahres (région de Sfax) située au centre-est de la Tunisie, 12 cas de dépérissement d'oliviers âgés, du cv. 'Chemlali' ont été observés dans deux parcelles voisines. Dans ces deux vergers, les oliviers malades sont répartis en foyers. Les investigations au champ et au laboratoire ont permis de mettre en évidence la présence du champignon Verticillium dahliae , qui est ainsi signalé pour la première fois en Tunisie sur olivier.