Cultural Practices in Table Grapes

Cover crops 

Cover crops are grown to prevent wind or soil erosion especially on sandy soils. Cover crops also minimize dust on the grape bunch. In some regions, cover crops are not usually grown until the vine roots are well established (4 – 5 years old), that competition of cover crops for nutrient and moisture is minimized and thus vine productivity is not harmed.

Pruning

Pruning is the shaping of the rootstock and the vine stock aims to adjust the balance of foliage and fruit on the vine in order to ensure maximum growth potential and high yields. Pruning in the winter is required to prepare the next year's harvest on entirely new growth. It provides a satisfactory shape for the vine in the first 3 – 4 years.

The bulk of the previous season's growth is pruned, leaving a specified number of canes, which varies according to local practices, the variety, and vigor of the vines. It is short pruned, leaving only two to six canes in the following years. 

Seasonal removal of basal leaves and newly grown lateral shoots, just prior to fruit set, opens up the vine canopy, allowing better light and spray penetration as well as improving maturity. Cutting of leaves and side stems and bunch thinning or removal before veraison at mid-season can help bring forward ripening and increase berry size. Growers can improve overall berry quality by removing poorly developed bunches. Girdling at veraison initiates ripening, however it can ring-bark the vine reducing vigor and it can kill the vine in severe cases.

Growth Regulators 

Growth regulators is application of hydrogen cyanamide just prior to winter pruning will promote early, uniform bud break. Application of growth hormone, Gibberellic acid, at flowering can reduce berry set by around 30% and it resulted in enlargement of berry size in an elongated oval shape.

Rootstock

Choice of the rootstock directly influences vigor, performance, and yield of the table grape. Rootstocks vary in their tolerance and sensitivity to specific conditions (e.g. pH, lime, salt/water stress, diseases). Soil factors including natural fertility, management, and available soil moisture can have significant roles in rootstock selection, vine spacing, and other practices.

Selection of rootstocks with high nutrient uptake and well adapted to the soil and climate will contribute to the sustainability of table grape production by increasing nutrient use efficiency and decreasing cost of production. The ability of different rootstocks to extract nutrients is related to the spatial root distribution and root diameter. The choice of an appropriate rootstock improves tolerance to soil borne diseases and level of salts in the soil.

Double cropping 

The crop production cycle in table grapes is usually two times per year in the dry tropics, where weather is uniform throughout the year, for example San Francisco valley in Brazil. A key practice in double cropping is to reduce post-harvest irrigation in order to induce flowering of the second crop cycle. In Australia, 4 weeks after the first harvest the grapes are normally pruned to secure the second harvest in late season when market prices are good. 

The first and the second fruit sets usually produce about 40 t/ha and 10 – 15 t/ha berries, respectively. Double cropping requires better management of nutrient to increase productivity. Particular attention must be given to early applications of potassium, calcium, and magnesium, and post-harvest applications of nitrogen, phosphorus and potassium. Both cycles require sufficient amount of nutrients to prevent the second harvest drawing nutrients away from the first production season.