One of the best-performing rootstocks currently available is Ruggeri.
Ruggeri has many benefits. It is drought tolerant, performs well in saline soils, is one of the best, or close to, yielding stock for all varieties, imparts good vigour, is phylloxera resistant and allows for good colour development in red varieties.
Recently, however, there have been concerns reported about vines grafted on Ruggeri rootstock. The main problem has been the sudden death of vines, typically in mid-summer when water and crop load demands are highest. A survey of all CCW growers with plantings on Ruggeri has been undertaken to determine the extent of the problems being experienced with this stock. The survey found that 7% of patches had losses of greater than 20 vines in a patch, with one patch suffering 25% loss in four-year-old vines. Similar problems have also occurred on 101-14 rootstock.
Investigations show that the decline may be occurring as a result of one or a combination of factors. The main factors appear to be a soil-borne fungal disease of the rootstock called Cylindrocarpon or ‘Black Foot’ and nematodes, particularly the root-knot nematode. Black Foot has been isolated from the rootstock part of the vine in most of the cases investigated so far. Once a significant part of the trunk is affected the ability of the rootstock to move water and nutrients is severely impaired. The presence of high levels of parasitic nematodes further impairs vine performance.
Although there are concerns about this rootstock, there are still 93% of Ruggeri plantings that are performing well with minor, or no, evidence of the problems described. Growers considering Ruggeri as a rootstock should discuss with their nursery the most appropriate treatments to minimise the risks of fungal infection or nematode damage.
For more information about this issue please contact Andrew Weeks 8584 7897 or email.