Specie identification and biology of leafhoppers on table and raisin grapes
PROJECT TITLE: Specie identification and biology of leafhoppers on table and raisin grapes
Project leader: Dr Elleunorah Allsopp (ARC)
Duration: 1 April 2022 – 31 March 2025
Project Summary:
Growers in the Northern Cape, and also in Mpumalanga, Limpopo and some areas in the Western Cape, have reported increasing outbreaks of leafhoppers in table and raisin grape vineyards from November onwards. Leafhoppers feed on phloem or xylem sap and their feeding results in wilting and drying of leaves and growth tips of young shoots. Leafhoppers mostly appear in large numbers at the time when grapes, especially the later ripening cultivars, start to ripen. At this stage chemical control is mostly not possible due to residue concerns. A green leafhopper occurring on grapevines in the Northern Cape has been identified Empoasca distenguenda Paoli. It also occurs on grapevines in Mpumalanga and on citrus, but very little is known about this insect. The identity of other leafhoppers occurring in significant numbers on grapevines in the Northern Cape, their biology and economic damage potential are unknown. Currently, there are no control measures registered for these leafhoppers. The fact that they are indigenous species also raises potential phytosanitary concerns.
Previous research concerning leafhoppers on grapevines in South Africa was restricted to the Western Cape and identified Acia lineatifrons as a sporadic pest causing leaf discolouration on wine grapes (Marais, 1989). More recently, Mgenia fuscovaria was identified as the vector of Aster Yellows phytoplasma on grapevines in the Olifans River and Wabooms River Valleys in the Western Cape (Krüger et al., 2011). No research has been done on any leafhoppers occurring on grapevines in the Northern Cape.
The aim of this research is to obtain knowledge about species identity, leafhopper biology and economic damage potential, all of which is crucial for the development of control measures (chemical and biological) and to address potential phytosanitary concerns.