Browsing by Author "Hattingh, M. J."
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- ItemSpread of phytophthora cinnamomi in a naturally infested vineyard soil(South African Society for Enology and Viticulture, 1985) Marais, P. G.; Hattingh, M. J.Phytophthora cinnamomi Rands. was isolated from rootstocks of dead or diseased vines in vineyards from 14 districts in the Cape Province of South Africa. It was recovered in vineyard soil to a depth of 320 mm. Downhill spread of the pathogen was more rapid through a soil with a perched water table (Estcourt: Rosmead soil series) than through a freely draining soil (Clovelly: Blinkklip soil series). Lateral movement of the fungus through soil occurred to a limited extent. The disease potential index of newly ingested soil was usually higher than that of areas previously infested. The results indicated the danger of introducing P. cinnamomi to poorly drained soils by planting infected vines.
- ItemSusceptibility to phytophthora cinnamomi of two grapevine rootstock clones after thermotherapy(South African Society for Enology and Viticulture, 1984) Marais, P. G.; Hattingh, M. J.The grapevine rootstocks 99 Richter clone I/30/1H74 infected with grapevine fleck and leafroll and 99 Richter Prosperi Super subclone 5 infected with stem pitting and leafroll were more susceptible to Phytophthora cinnamomi without treatment than after heat treatment to eliminate viruses. Recent field observations by various local workers (unpublished) and claims by local growers suggested that 99 Richer (Vitis berlandieri P. x V rupestris S.) grapevine rootstock material previously subjected to thermotherapy is more susceptible to Phytophthora cinnamomi Rands than untreated material. This contribution provides data on the effect of thermotherapy on the susceptibility of two 99 Richter rootstock clones to P. cinnamomi.