Browsing by Author "Walton, V. M."
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- ItemEffects of Pesticides and Fungicides Used on Grapevines on the Mealybug Predatory Beetle Nephus 'boschianus' (Coccinellidae, Scymnini)(South African Society for Enology and Viticulture, 2001) Walton, V. M.; Pringle, K. L.The effects of frequently used grapevine insecticides and fungicides on adults of the predatory beetle Nephus 'boschianus' of vine mealybug, Planococcus ficus (Signoret), were determined under laboratory conditions. When applied as cover sprays the pesticides chlorpyrifos, endosulfan, cypermethrin, chlorfenapyr and mercaptothion were very toxic to the predator, whilst the fungicides penconazole, fosetyl-Al, mancozeb and an insecticidal soap plus oil mixture were harmless. These results suggest that the insecticides may be harmful to a biological control system where N. 'boschianus' populations were dominant during the season. The three fungicides and the soap plus oil mixture, however, should be compatible with biological control by N. 'boschianus'.
- ItemEffects of pesticides used on table grapes on the mealybug parasitoid coccidoxenoides peregrinus (timberlake) (hymenoptera : encyrtidae)(South African Society for Enology and Viticulture, 1999) Walton, V. M.; Pringle, K. L.The effects of regularly used table grape insecticides and fungicides on 1-day-old adults of the parasitoid Coccidoxenoides peregrinus (Timberlake) of vine mealybug, Planococcus ficus (Signoret), were determined in the laboratory. The insecticides chlorpyrifos, endosulfan and cypermethrin were highly toxic to the parasitoid, while the fungicides penconazole and mancozeb were not. These results suggest that the insecticides may be detrimental to a biological control system using C. peregrinus while the two fungicides tested should be compatible with augmentative releases of C. peregrinus.
- ItemA survey of mealybugs and associated natural enemies in vineyards in the Western Cape Province, South Africa(South African Journal of Enology & Viticulture, 2004) Walton, V. M.; Pringle, K. L.A survey of mealybugs and their associated natural enemies occurring in vineyards was conducted in the Western Cape Province during the 1999/2000 and 2000/2001 seasons. Planococcus ficus (Signoret) was the dominant mealybug and was found for the first time on roots of grapevines. This has far-reaching implications for the control of this important vine leafroll virus vector as control measures have been focused on above-ground control. Other mealybugs recorded on vines were Pseudococcus longispinus (Targioni-Tozzetti) and Ferrisia malvastra (McDaniel). Pseudococcus viburni (Maskell) and Ps. solani Ferris were found on weeds in vineyards. The more frequently recorded natural enemies of P. ficus were species of Nephus predatory beetles and the parasitoids, Coccidoxenoides perminutus Girault, Anagyrus sp. and Leptomastix dactylopii (Howard).
- ItemVine mealybug, planococcus ficus (signoret) (hemiptera: pseudococcidae), a key pest in South African vineyards. a review(South African Society for Enology and Viticulture, 2004) Walton, V. M.; Pringle, K. L.Vine mealybug, Planococcus ficus (Signoret), is a key pest in vineyards in the Western Cape and North-West Provinces of South Africa and more recently in the USA. This pest was first reported in the Western Cape Province in 1943. The taxonomy and identification of this species are made difficult by complex slide-mounting techniques and the lack of qualitative characteristics. Vine mealybug is polyphagous with a wide range of host plants. P. ficus causes direct crop loss due to desiccation of bunches in the case of wine grapes and unsightly honeydew excretion on bunches in the case of table grapes. High infestations of P. ficus can cause early leaf loss and resultant weakening of vines. Vine mealybug also vectors the vine leafroll virus. This pest is currently controlled using chemical, biological and cultural control techniques in an integrated pest-management system. This system relies on the use of pheromone and physical monitoring techniques, which provide information on infestation levels.