WINETECH Technical Yearbook 2019

process not only mealybug predators, but also other beneficial insects are killed: • Acetamiprid (45 days) – table grapes only. • Borax + Orange oil – no withholding period. • Carbaryl (14 days). • Chlorpyrifos (28 days). • Dichlorvos (7 days). • Dimethoate (28 days). • Methidathion (8 days) – only one application. • Mevinphos (7 days). • Spirotetramat – not after pea berry stage. • Sulfoxaflor (28 days). CONCLUSION We have the knowledge and the means to control ants and mealybug. If mealybug is absent, the leafroll virus cannot spread to healthy vines. The only distribution can then take place by the vector(s) from already infected plant material. With thanks to Petrie de Kock and Pieter le Roux for their technical input.

CHEMICAL CONTROL AT ROOT LEVEL IN THE SOIL • Imidacloprid (112 days). • Clothianidin (90 days). • Thiamethoxam (application one month after harvest). Soil application at the time of establishment of new blocks. Some registrations are available for autumn application. WINTER AND SUMMER CHEMI CAL CONTROL ON SECTIONS OF THE PLANT THAT ARE ABOVE THE SOIL WINTER This is a good option considering the fact that the population of natural enemies during winter is low: • Chlorpyrifos – before budburst. • Prothiophos – before budburst. • Profenofos – application during dormancy of grapevine. SUMMER NB: This is the last resort, seeing that in the

– For more information, contact Lucinda Heyns at lucinda@winetech.co.za.