Wilt of guava (Psidium guajava), a serious disease occurring in most guava producing areas of the Northern and Mpumalanga provinces of South Africa, was shown to be induced by a fungus tentatively identified as Penicillium vermoesenii. This fungus is the cause of a blight of ornamental palms in the United States and Belgium and its occurrence on guava is enigmatic. Pathogenicity tests were conducted in the glasshouse and under field conditions. Symptoms on trees include wilting, chlorosis and defoliation.

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The genus Hyalorhinocladiella was characterized by its simple conidiophores with conidiogenous cells that proliferate sympodially. However, recent studies revealed that the Hyalorhinocladiella anamorph of Ophiostoma ips has annellidic conidium development. The aim of this study was to determine whether other species in the genus share this characteristic. Conidium development was examined in the type species, Hyalorhinocladiella minuta-bicolor, and in the Hyalorhinocladiella anamorph of Ophiostoma minus. Light and fluorescence microscopy indicated that conidia developed by sympodial proliferation. In contrast, scanning and transmission electron microscopy revealed distinct annellations on the conidiogenous cells. Conidium development in Hyalorhinocladiella is therefore annellidic, and the appearance of sympodial development results from displacement of the long axis of the conidiogenous cell through percurrent proliferation. The circumscription of the genus Hyalorhinocladiella is therefore revised to include annellidic conidium development.RCsumC : Le genre Hyalorhinocladiella a t t t caracttrist par ses conidiophores simples, munis de cellules conidiogbnes qui prolifbrent de f a~o n sympodiale. Des ttudes rtcentes ont cependant revtlt que l'anamorphe de I'Ophiostoma ips possbde un developpement conidien annelidique. Le but de l'etude ttait de determiner si d'autres espbces du genre partagent cette caracttristique. Les auteurs ont examine le developpement conidien chez le type de cette espbce 1'~Hj~alorhinocladiella minuta-bicolor et l'anamorphe de 1'Ophiostoma minus. La rnicroscopie photonique et en fluorescence indique que les conidies se developpent par proliftration sympodiale. Au contraire, la rnicroscopie tlectronique par balayage et par transmission rtvble des annellations bien visible sur les cellules conidiogbnes. Le dtveloppement conidien chez les Hyalorhinocladiella est constquemment annelidique et I'apparence de developpement sympodial resulte d'un deplacement du long axe de la cellule conidiogbne, via une proliferation percurrente. La dtlimitation du genre Hyalorhinocladiella est constquemment reviste pour inclure le dtveloppement conidien andlidique.

We used both aerobic and anaerobic liquid co-cultures, prepared with Luria Bertani broth, to study the effect of bacteria on the survival of Candida albicans in the external environment, away from an animal host. The bacteria were represented by Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Clostridium, Enterobacter, Klebsiella pneumoniae, Kluyvera ascorbata and Serratia marcescens. Under aerobic conditions, the yeast's growth was inhibited in the presence of bacterial growth; however, under anaerobic conditions, yeast and bacterial growth in co-cultures was similar to that observed for pure cultures. Subsequent assays revealed that the majority of bacterial strains aerobically produced extracellular hydrolytic enzymes capable of yeast cell wall hydrolysis, including chitinases and mannan-degrading enzymes. In contrast, except for the A. hydrophila strain, these enzymes were not detected in anaerobic bacterial cultures, nor was the antimicrobial compound prodigiosin found in anaerobic cultures of S. marcescens. When we suspended C. albicans cells in crude extracellular enzyme preparations from K. pneumoniae and S. marcescens, we detected no negative effect on yeast viability. However, we found that these preparations enhance the toxicity of prodigiosin towards the yeast, especially in combination with mannan-degrading enzymes. Analyses of the chitin and mannan content of yeast cell walls revealed that less chitin was produced under anaerobic than aerobic conditions; however, the levels of mannan, known for its low permeability, remained the same. The latter phenomenon, as well as reduced production of the bacterial enzymes and prodigiosin, may contribute to anaerobic growth and survival of C. albicans in the presence of bacteria.