WINETECH Technical Yearbook 2020

PHOTO 7. Growth tip death followed by die back of shoot node-by-node.

PHOTO 5. Chardonnay shoots show a typical grey waxy substance and leaves have a triangular shape.

PHOTO 6. Thin and stunted shoots do not lignify properly.

through the vineyard. This is typical of disease transmission by an insect vector. RECOMMENDATIONS The high incidence and rapid progression of AY disease in some vineyards indicate a need for control of the disease in the form of an integrated management strategy. This includes the use of disease-free planting material, chemical control of the insect vector and sanitation practices, such as the removal of infected young vines in newly planted

transmission by an insect vector. An integrated management strategy to control AY includes the use of disease-free planting material, chemical control of the insect vector, sanitation practices, such as the removal of infected young vines in newly planted vineyards, and weed control. This research was funded by Winetech, the ARC and Technology and Human Re­ sources for Industry Programme (THRIP) – project WW 06/40.

vineyards to reduce disease inoculum. Weed control is important, as the weeds can serve as an overwintering host for the leafhopper vector or as a source of the phytoplasma. SUMMARY Chardonnay is very sensitive to AY infection, showing rapid decline and death of vines. The disease does not spread randomly, but from cluster of infected vines on the side of the vineyard adjacent to an infected vineyard. This is typical of disease

PHOTO 8. Infected bunches shrivel and dry out before ripening.

For more information, contact Roleen Carstens at roleen@saplant.co.za.

WINETECH TECHNICAL YEARBOOK 2020 51