Francois Halleen

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Several species of Botr yosphaeria are known to occur on grapevines, causing a wide range of disorders including bud mortality, dieback, brown wood streaking and bunch rot. In this study the 11 Botryosphaeria spp. associated with grapevines growing in various parts of the world, but primarily in South Africa, are distinguished based on morphology, DNA(More)
Little information is presently available on the disease aetiology and epidemiology of the fungi involved in the decline of young vines. To address this question, four rootstock-scion combinations, originating from three commercial nurseries in the Wellington area of the Western Cape Province of South Africa were investigated during the 1999/2000 season.(More)
A Cylindrocarpon species with up to 10 microm wide, straight and predominantly 3-septate macroconidia, subglobose to ovoidal microconidia and chlamydospores, is described as Cyl. pauciseptatum. It is most similar to Cyl. austrodestructans but no chlamydospores and microconidia are formed in the latter. Similar macroconidia also occur in Cyl. theobromicola,(More)
Several hyphomycetes were recently isolated from asymptomatic or symptomatic vascular tissues of grapevines showing Petri disease symptoms in South Africa. In most cases, their status as pathogens was unknown and pathogenicity studies were, therefore, conducted to determine their potential as decline pathogens. The fungi included Acremonium cf. charticola,(More)
Black foot disease is a serious disease of grapevine crops in most areas where vines are grown. Mainly two species of Cylindrocarpon, C. destructans and C. macrodidymum, are associated with this disease. Recent studies have revealed a tremendous molecular variation within the former but only slight molecular variation within the latter, indicating that C.(More)
The presence of Phaeomoniella chlamydospora and Phaeoacremonium spp., the causal organisms of Petri disease of grapevine, in canes of rootstock vines in four mother blocks was determined monthly by means of isolations from the basal and fourth internodes. The canes were generally free from fungal, yeast and bacterial infection with only 2.4% of the total(More)
A diatrypaceous ascomycete with polysporous asci and reniform to allantoid, pigmented ascospores was isolated from grapevine canes in South Africa and Australia. The fungus was identified as Cryptovalsa ampelina based on its characteristic morphology. Subsequent phylogenetic analyses confirmed this species to belong to the Diatrypaceae. Pathogenicity was(More)
Wound protection during all stages of grapevine propagation is of utmost importance to prevent infection of propagation material by decline and dieback pathogens. In semi-commercial nursery trials, grapevine rootstock and scion cuttings were soaked in water (control), chemical or biological sanitation products prior to cold storage, prior to grafting(More)
The incidence of grapevine trunk disease pathogens in grapevine rootstock mother plants from different cultivars, ages and growing areas in South Africa was determined by means of isolations from the basal and pruning wound end s of 2-year-old stubs. Phaeoacremonium spp. and Cylindrocarpon spp. occurred at very low incidences (average 0.12% and 0.17%,(More)
Trunk disease pathogens of grapevines, viz. Phaeomoniella chlamydospora, Eutypa lata and several species in Botryosphaeriaceae, Phaeoacremonium and Phomopsis are known to infect fresh pruning wounds by means of air-borne inoculum released after rainfall or prolonged periods of high relative humidity. Recent surveys have demonstrated that most or all of(More)