Abstract The objective of this study was to evaluate the performance of Geneva(r) apple rootstocks for 'Gala'. The experiment was set in a complete randomized block design with four replications of tree plants per plot. It was used ten Geneva(r) rootstocks and M.9EMLA and M.7EMLA as controls. It was evaluated plant vigor, annual yield, cumulative yield, cumulative yield efficiency and fruit weight. For 'Gala' vigor control, G.10 and G.757 were more efficient than M.9EMLA; CG.2022 was equivalent and the other rootstocks were less efficient. 'G.24', 'G.969', 'G.30' and 'G.210' presented vigor equivalent to 'M.7EMLA'. 'G.896' was the most vigorous. Among dwarfing rootstocks, G.213 and G.757 were the most efficient on cumulative yield, the last showing the highest cumulative yield efficiency. Among semi-dwarfing, G.210 showed the highest cumulative yield and the highest cumulative yield efficiency. 'G.896' induced higher cumulative yield than 'M.7EMLA'. The greatest 'Gala' fruit weight was on 'G.213' and 'CG.2022'.

RESUMOEste estudo teve como objetivo verificar o desempenho agronômico de porta-enxertos de macieira da série Geneva® sobre o controle do vigor, a produção anual e acumulada, a eficiência produtiva e a massa fresca média de frutos das cultivares Gala e Fuji, em relação aos porta-enxertos tradicionalmente usados no meio-oeste de Santa Catarina, M.9 e MM.111. Os porta-enxertos da série Geneva® foram mais eficientes no controle do vigor e na eficiência produtiva da ‘Gala’ e da ‘Fuji’ que o MM.111. Todos induziram maior produção acumulada que o M.9, com maior destaque ao ‘G.213’ e ao ‘G.210’ para as duas cultivares; e ao ‘G.202’ para a ‘Fuji’. Em eficiência produtiva, todos foram superiores ao ‘MM.111’. O ‘G.213’ e o ‘CG.22’ foram mais eficientes que o ‘M.9’ para a ‘Gala’. Para a ‘Fuji’, todos foram mais eficientes que o ‘M.9’, com exceção do ‘CG.22’. Considerando todas as características avaliadas, os porta-enxertos G.213 (ananizante) e G.210 (semiananizante) são as opções mais promissoras de novos porta-enxertos para ambas as cultivares de macieira avaliadas. O G.202 também se mostrou promissor para a ‘Fuji’.

ABSTRACTThe purpose of this study was to evaluate the agronomic performance of some Geneva® apple rootstocks on plant vigor control, annual yield and cumulative yield, cumulative yield efficiency and fruit weight of ‘Gala’ and ‘Fuji’ scions compared to the traditional apple rootstocks ‘M.9’ e ‘MM.111’, used in Brazil. All the Geneva® apple rootstocks were more efficient than MM.111 on vigor control and cumulative yield efficiency of ‘Gala’ and ‘Fuji’ in the Middle West of the state of Santa Catarina. All of them induced higher cumulative yield than the ‘M.9’, mainly for the ‘G.213’ and the ‘G.210’ for both varieties, and the ‘G.202’ for ‘Fuji’. All the Geneva® rootstocks had more cumulative yield efficiency than ‘MM.111’. The ‘G.213’ and ‘CG.22’ were more efficient than ‘M.9’ for ‘Gala’. For ‘Fuji’, all Geneva® rootstocks were more efficient than ‘M.9’, except for ‘CG.22’. Considering all characteristics evaluated, G.213 (dwarfing) and G.210 (semidwarfing) were the most promising rootstocks for both scion varieties. The rootstock G.202 was very promising to ‘Fuji’ as well.

Colletotrichum gloeosporioides e C. acutatum são os agentes etiológicos da Mancha da Gala (MG), na cultura da macieira, no Brasil. Programas de melhoramento visando o desenvolvimento de resistência genética à doença necessitam do conhecimento pleno das características das espécies do patógeno envolvidas. Uma maneira de separar estas espécies é através do estudo da sensibilidade de isolados ao fungicida benomyl. Através do teste de sensibilidade de 39 isolados de C. acutatum e C. gloeosporioides relacionados à MG, em que foram avaliados a taxa de crescimento micelial e o índice de redução deste crescimento, observou-se que dentre os isolados de C. gloeosporioides há um grupo resistente ao fungicida e que difere de todos os isolados desta espécie relatados neste patossistema. Este grupo mostrou-se resistente às concentrações de 5 e 100 µg.mL-1 com índice de redução (IR) variando entre 0% e 8%, e entre 15 e 30%, respectivamente, enquanto o isolado padrão (CG197) apresentou IR de 100% em ambas as concentrações testadas. Os isolados de C. acutatum foram todos resistentes ao fungicida. Devido à resistência de alguns isolados de C. gloeosporioides, a separação de espécies de Colletotrichum associadas à macieira, baseada apenas na resistência ou suscetibilidade ao fungicida benomyl, não deve ser utilizada isoladamente.

In Brazil, Colletotrichum gloeosporioides and C. acutatum are responsible for the occurrence of Gala leaf spot or Glomerella Leaf Spot (GLS) on apple. Breeding programs aiming to develop genetic resistance to disease need a complete understanding of the characteristics of involved species. A study of the sensibility of the isolates to benomyl is a way to separate those species. A sensitivity test of 39 isolates of C. acutatum and C. gloeosporioides involved with GLS, evaluated by growth rate and reduction rate of mycelium, revealed a group of C. gloeosporioides isolates that are resistant to the fungicide. This group showed resistance to concentrations of 5 and 100 µg.mL-1 with reduction rate varying between 0% and 8%, and between 15 and 30%, respectively. While the standard C. gloeosporioides isolate (CG197) showed a reduction rate of 100% at both tested concentrations, all isolates of C. acutatum were resistant to the fungicide. Due to the resistance of some isolates of C. gloeosporioides, the separation of Colletotrichum species on apple should not be based only on resistance or susceptibility to benomyl.