Resistance of rootstocks to grapevine decline and dieback in southern Brazil
Grapevine decline and dieback is a serious problem for grape production in southern Brazil. It is characterized by a set of symptoms that lead to the weakening and death of affected plants. The causes seem to be multiple, including the Brazilian ground pearl (Eurhizococcus brasiliensis), soil fungi and other causes of stress for plants. In this study, we evaluated the performance of 12 rootstocks, with and without chemical control of ground pearl, in two experiments carried out on a site where severe symptoms of grapevine decline were previously observed. In the third vegetative cycle, the number of symptomatic or dead plants was evaluated and the number of cysts of ground pearl and dry weight of roots plant‑1 were estimated. With chemical control of ground pearl, dead plants or plants with decline symptoms were practically absent. However, in the absence of chemical control, the differences between rootstocks were significant. Hybrid rootstocks of Vitis caribaea were more resistant, especially IAC 572 ('Jales') and IAC 571-6, which showed no symptoms of decline. On the other hand, traditional rootstocks, such as 420A, 101-14 and Paulsen 1103, were highly susceptible, with more than 60% of plants with symptoms of decline or dead. There was no association between the number of cysts of ground pearl in roots and incidence of decline, indicating that resistance is manifested more by tolerance to secondary effects of pest attack than by limitations to the establishment of the insect in the roots. Symptoms of fungal attack in roots were very frequent, mainly the black foot disease (Cylindrocarpon sp.), which is probably favored by damage from ground pearl attack.
Dalbó, M.A., Arioli, C.J. and Lopes da Silva, M. (2016). Resistance of rootstocks to grapevine decline and dieback in southern Brazil. Acta Hortic. 1127, 65-70
viticulture, grape, margarodes, Eurhizococcus brasiliensis, Cylindrocarpon