ECONOMIC IMPACT OF GRAPEVINE LEAFROLL DISEASE ON VITIS VINIFERA CV. CABERNET FRANC IN FINGER LAKES VINEYARDS OF NEW YORK

Leafroll disease is one of the most important virus diseases of grapevines worldwide. It reduces yields, delays fruit ripening, reduces soluble solids and increases titratable acidity in fruit juice. This study uses a Net Present Value (NPV) approach over a 25-year lifespan of a vineyard to examine the economic impact of grapevine leafroll disease (GLD) on Vitis vinifera cv. Cabernet franc in Finger Lakes vineyards of New York. It identifies optimal disease control options under several scenarios of disease prevalence, yield reduction, and fruit quality effects. The estimated economic impact of GLD ranges from about $25,000 (for a 30% yield reduction and no grape quality penalty) to $40,000 (for a 50% yield reduction and a 10% penalty for poor fruit quality) per hectare in the absence of any control measure. The per-hectare impact of GLD can be substantially reduced to $3,000-$23,000 through roguing if levels of disease prevalence are moderate (1% to 25%). With disease prevalence levels higher than 25%, replacing the entire vineyard is the optimal response, yielding economic losses of about $25,000 per hectare. Furthermore, the use of vines derived from certified, virus-tested stocks in replant sites is predicted to keep the costs associated with GLD infection to about $1,800 per hectare. Also, ‘no intervention’ appears to be the best management strategy when (1) infection levels are high (>25%), yield reduction is moderate (