Table grape rootstocks in South Africa

Several scion cultivars grafted onto different rootstocks were evaluated in more than one region. This was done in soils that were physically, chemically and biologically different. Tables 5 to 9 show the variation recorded for different scion-rootstock combinations regarding production and vigour. Root-knot nematode populations in most trial plots were low, probably due to the nematode control measures applied, except in the Prime trial at Fulham in the Northern Cape. No root-knot larvae were found in any of the root samples, although old galls were present. Also, no living females or egg sacs were found, indicating that nematode control measures applied were effective. Root-knot larvae found in soils were likely from eggs hatched in the soil or originated from cover crops or weeds in the row. Judicious and optimal fertiliser use (applied only when needed and in the required quantities) could lead to cost-saving while simultaneously reducing the negative impact its use may have on the environment. Fertiliser requirements are affected by the rootstock (which may affect the uptake of macro and micro plant nutrients) and the trial block’s physical and chemical characteristics (which affect the availability of plant nutrients to the vines).

The tables mentioned above show the variation in the rootstock effect on the petiole nutrient status and the important role of scion-rootstock interaction concerning the petiole nutrient status. Rootstocks in the various groups differed considerably regarding cane mass and yield as measured in the different trial sites. However, rootstock performance was not constant between sites, neither was the effect of rootstock and scion-rootstock combination constant regarding petiole nutrient status. These differences emphasise the influence that soil texture, plant nutrient availability, rootstock and especially scion cultivar has on grapevine performance. Site-specific sustainable fertilisation guidelines can be established by researchers and/or advisors for specific scion-rootstock combinations based on available research results and information obtained from commercial vineyards.

Photo: Jan Avenant

56 Table Grape Rootstocks in South Africa