Patrón Vid RS9
RS-3 and RS-9 rootstocks originating from interspecific crossings between Ramsey (vitis champinii) and Schwarzmann (vitis riparia x vitis rupestris). The Ramsey parent provides vigour as well as high resistance to endoparasitic nematodes. The Schwarzmann parent has less vigour, is highly resistant to ectoparasitic nematodes and provides a mechanism for resistance to Meloidogyne javanica.
RS-9 is the first low-vigour which, like RS-3, is resistant to these diseases.
RS-9 resistance to nematodes resembles RS-3. However, it is more sensitive to ring nematodes and more resistant to Xiphinema index. Its resistance to the grapevine fan leaf virus has not been assessed. RS-9 does not present transplanting rejection problems after uprooting in V. vinifera vineyards.
RS-3 and RS-9 provide 3 different types of mechanisms acting together to provide resistance to nematodes. For instance, when nematodes approach the root tip, a hypersensitivity response is triggered. A few young individuals may survive this mechanism by avoiding this area and developing into females which produce eggs very easily. However, such females are only partially efficient in infecting large plant cell areas suitable for feeding. Females from parent nematodes die within 30-60 days, and their feeding area is unsuitable beyond the third generation. The infected area is very reduced and only affects very young roots.
RS-3 is relatively tolerant to the grapevine fan leaf virus. In a 3-year study, it showed more tolerance than the Boerner rootstock. Evidence has been found that the roots, leaves and stems of RS-3 and RS-9 are resistant to the invasive vine mealybug (an insect of the Pseudococcidae family especially present in mild and humid climates).
Differences and similarities between RS-3 and RS-9:
Apart from the differences in vigour commented above, RS-9 resistance to nematodes resembles RS-3. However, it is more sensitive to ring nematodes and more resistant to Xiphinema index. Its resistance to the grapevine fan leaf virus has not been assessed. RS-9 does not present transplanting rejection problems after uprooting in V. vinifera vineyards.
