Sporogenesis in Spilocaea oleagina was investigated in the field in relation to climatic conditions, in a 2‐year trial. At the beginning of each trial, a standard number of infected leaves still attached to the plant were gently scraped in order to remove completely all the fungal structures present on the lesion. At 1‐week intervals, four such leaves were detached from the plant, examined in the laboratory for new conidiophores and conidia production, and rated for number of conidia produced by 100 conidiophores. In the first year of the trial, the fungus showed intense activity from the first week of April (beginning of the trial) to the end of April. This activity continued at reduced intensity with small variations until the end of September. In the second year (starting at the beginning of December), the fungus showed an initial lag, starting producing conidia in the last week of December. Activity increased progressively until the beginning of April. After a relatively static period during summer, the fungus resumed intense activity during September and October (end of the trial). Sporogenesis in S. oleugina appears to be linked to climatic conditions, especially to RH, maximum activity of the fungus being recorded during rainy or highly humid periods.

No abstract

Of the 44 currently accepted species of Phytophthora, 18 have been reported in the Mediterranean area. The status of each is briefly reviewed. On citrus, P. citrophthora and P. nicotianae var. parasitica are mainly responsible for foot rot and gummosis, and in addition P. hibernalis, P. syringae, P. cifricola and P. cactorum for brown rot of fruits. The incidence of these species is closely linked to their temperature requirements. The use of sour orange as a resistant rootstock has long provided satisfactory control of foot rot and gummosis, while chemical treatments are effective against brown rot. However, there are indications that, with changingcultural practices, the resistance of sour orange is less well expressed, and the species is incidentally also susceptible to citrus tristeza closterovirus. Alternative rootstocks are therefore being sought.

Three wild isolates and three mutants of Phoma tracheiphila (Petri) Kanc. et Ghilk. were tested for virulence on young Lemon trees. Their respective culture filtrates were tested for toxicity to Tomato cuttings and Sour orange and Lemon leaves. No relationship between phytotoxicity of metabolites produced in vitro and virulence resulted.