Abstract
Strong consumer demand for white grape juice has encouraged growers to plant significant new acreages of the variety ‘Niagara’. However, the 4-year time period required to grow a newly-planted vineyard to its full productive capacity is a major factor influencing the profitability of new vineyards. Therefore, the influence of weed control under the trellis, nitrogen fertilization, irrigation and pruning severity on the development of newly-planted ‘Niagara’ grapevines was evaluated. Weed control had the greatest impact on the development of vine size. Without weed control under the trellis, no combination of nitrogen fertilization, irrigation and pruning severity was capable of producing acceptable vine size. Weed control under the trellis, followed by nitrogen fertilization, irrigation and pruning severity, exhibited a descending order of influence on vine size development. Therefore, growers should apply these practices in that order of priority when establishing new ‘Niagara’ vineyards.