Current control of phytosanitary insect pests in table grape vineyards of the Hex River Valley, South Africa
Phlyctinus callosus (Coleoptera: Curculionidae), a key phytosanitary pest of South African table grapes, is controlled using sticky Plantex® trunk barriers, while Epichoristodes acerbella (Lepidoptera: Tortricidae), another important phytosanitary pest, is controlled using DiPel® (Bacillus thuringiensis var. kurstaki). Other less important pests are Gonocephalum simplex (Coleoptera: Tenebrionidae), Dysdercus fasciatus (Hemiptera: Pyrrhocoridae) and Gryllus bimaculatus (Orthoptera: Gryllidae). Bunches of grapes in vineyards were sampled for all phytosanitary pests during the 2003/2004 season, by both direct inspection and by shaking individual bunches to collect insects that fell. Insects moving up the vine trunk were collected with cardboard collars. The heads and bases of vines were also inspected. Cover crops and surrounding habitats were sampled by sweep netting. Pheromone traps, using E. acerbella pheromone capsules, were placed in vineyards. Abundance of pests was related to presence or absence of sticky trunk barriers, use of DiPel® (Bacillus thuringiensis var. kurstaki), mean rainfall and maximum temperature, height and type of cover crop. The effects of surrounding habitats, time of day pests were active and the time of year they were found was also evaluated. Use of Plantex® trunk barriers gave effective preventive control of P. callosus. DiPel® was effective against E. acerbella larvae. Numbers of P. callosus weevils increased after periods of high ambient temperatures, while E. acerbella numbers decreased following rainfall. Most phytosanitary pests infested vineyards from adjacent vineyards, with few pests recorded in cover crops or in surrounding uncultivated habitats. Thus, successful long-term reduction in phytosanitary rejections of table grapes from the Hex River Valley, South Africa, requires the coordinated control of phytosanitary pests within vineyards.