Browsing by Author "Meyer, A. J."
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- ItemDistribution of longidoridae in the viticultural regions of the Cape Province(South African Society for Enology and Viticulture, 1994) Malan, Antoinette P.; Meyer, A. J.Soil samples from five viticultural regions in the Cape Province were analysed for the presence of longidorid nematodes. Sixteen species of Xiphinema were found, the most common species being X. elongatum, X. americanum and X. brevicolle. X. index was recorded from three of the five regions. A survey in the Theewaterskloof area was conducted and nine Xiphinema species were recorded but X. index was absent.
- ItemDual cultures of meloidogyne javanica and grapevine rootstocks on artificial media(South African Society for Enology and Viticulture, 1990) Loubser, J. T.; Meyer, A. J.Grapevine rootstock cultivars were cultured on more than one artificial medium. Meloidogyne javanica was inoculated on the roots of different cultivars on seven media and penetration and development were recorded. Plate cultures of roots allowed microscopic examination of nematode development. Nematode reproduction occurred on susceptible rootstocks only, suggesting similar results for field and in vitro screening. However, root and nematode development was low and inconsistent, indicating problems which will have to be resolved before general application of the technique.
- ItemInteraction between a South African population of xiphinema index and different grapevine rootstocks(South African Society for Enology and Viticulture, 1993) Malan, Antoinette P.; Meyer, A. J.Thirty-one grapevine rootstocks were used to test for reproduction, root feeding symptoms and transmission of grapevine fanleaf virus by a South African population of Xiphinema index. Grapevine fanleaf virus was transmitted within four months to the roots and systemically spread within six months to the leaves of all the rootstocks tested. No root damage and a low reproduction rate of X. index were found on the rootstocks Harmony, Freedom and 1613 C, all which have V. Longii and Othello in their parentage.
- ItemPopulation dynamics of the root-knot nematodes meloidogyne incognita (kofoid & white) chitwood and m. javanica (treub) chitwood on grapevines in two different regions of South Africa(South African Society for Enology and Viticulture, 1987) Loubser, J. T.; Meyer, A. J.Two root-knot nematode species, Me/oidogyne incognita and M.javanica, were studied with regard to their seasonal population fluctuations on grapevines growing in two vastly different climatic areas. Regular observations on reproduction and numbers of larvae in the soil were compared with patterns of root growth, soil temperature and moisture. Population fluctuations of the two species showed similar trends in spite of the climatic differences in the two areas, but M. incognita in the northern Cape reached higher populations. Larvae populations in the soil declined in summer in both areas and increased during autumn to reach peaks in winter. With the onset of root growth in spring, larvae numbers decreased in the soil, as a result of large scale root penetration.
- ItemThe reproduction and life cycle of a South African population of xiphinema index(South African Society for Enology and Viticulture, 1999) Malan, Antoinette P.; Meyer, A. J.The seasonal fluctuation of a South African Xiphinema index population, the influence of four hosts on the length of the life cycle and the reproductive rate with fig as host at three different temperatures, were studied. Reproduction was highest during early summer (November and December ) when the mean maximum dayly air temperature was between 25 and 30°C. Under controlled conditions at 25±2°C the duration of the life cycle of X. index was between 75 and 85 days with the grapevine rootstock Fairy as host, between 55 and 65 days with Jacquez rootstock and between 45 and 55 days with fig and Paulsen 775 rootstock. Using fig as host, the highest reproductive rate of the nematode was at 28°C, with a 216-fold increase and the lowest at l8°C, with no adults after 85 days.
- ItemResistance of grapevine rootstocks to meloidogyne incognita under field conditions(South African Society for Enology and Viticulture, 1987) Loubser, J. T.; Meyer, A. J.Resistance of grapevine rootstocks to root-knot nematodes (Meloidogyne incognita) was studied in field trials. Resistance was found to be adequately expressed by the degree of galling. A highly significant positive correlation exists between nematode populations in the soil as well as nematode reproduction and galling, while grapevine growth and yield were negatively related to the degree of infestation. However, information regarding rootstock tolerance and intolerance (sensitivity) was not considered reliable. It was further shown that a susceptible scion would not lower the resistance of the rootstock involved. Based on their rate of galling, rootstocks Ramsey, 99 Richter PS, Dogridge, Freedom, Harmony and 101-14 Mgt are resistant while Jacquez, 140 Ruggeri, Grezot-1, Maleque 44-53 and Constantia Metallica are susceptible.
- ItemStrategies for chemical control of root-knot nematodes (meloidogyne spp.) in established vineyards(South African Society for Enology and Viticulture, 1986) Loubsera, J. T.; Meyer, A. J.Grape-vine root growth was measured for vertical and horizontal distribution as well as seasonal growth periods. The persistance of aldicarb and fenamiphos in the soil as well as in leaves and fruit of grape-vines was monitored over a prolonged period to establish behaviour patterns which inflnence chemical control strategies. Most roots occurred within 600 mm from the trunk, both vertically and horizontally. Two periods of root development occurred annually. Accordingly applications of nematicides should be made in a band covering 600 mm on both sides of the vine trunk, either after harvest and/or during budburst. Results on residues of aldicarb and fenamiphos stress the importance of adequate water supply after application. Both nematicides will reach the bulk of the roots if correctly placed and were still detected after 42 days and 70 days respectively. Applications during spring with aldicarb and fenamiphos at the dosages used will have no effect on the fermentation of grape musts nor result in toxic residues exceeding 0,05 mg/kg in the grapes.