Época de desfolha e sua influência no desempenho vitícola da uva 'Sauvignon Blanc' em região de elevada altitudeLeaf removal timing and its influence on wine grape performance 'Sauvignon Blanc' in high altitude region

Downy mildew (Plasmopara viticola) and botrytis bunch rot (Botrytis cinerea) are important diseases in the highlands of Santa Catarina State, a relatively new wine-growing region in Brazil. Although it is known that training systems can affect microclimate and subsequent disease development, this has not been examined in the highlands of Brazil. Thus, the purpose of this study was to evaluate the influence of Y-trellis (YT) and vertical shoot positioning (VSP) training system on downy mildew and botrytis bunch rot disease development in "Cabernet Sauvignon" cultivar. Experiments were carried out in commercial vineyards in São Joaquim, SC Municipality, southern Brazil, during the year 2012-2013 and 2013-2014 growing seasons. Downy mildew incidence and severity were quantified weekly from the first symptoms appearance on leaves, and botrytis bunch rot incidence was , S C I E N T I A H O R T I C U L T U RA E 1 8 5 (2 0 1 5 )2 evaluated at harvest. Disease progress curves were constructed compared according to: (a) beginning of symptoms appearance; (b) time to maximum disease incidence and severity; (c) maximum disease incidence and severity; and (d) area under the incidence and severity disease progress curve. Results showed significant differences in downy mildew and botrytis bunch rot intensity among grape training systems, where VSP training system showed significantly lower area under the incidence and severity disease progress curve and intensity of downy mildew and botrytis bunch rot in both 2012-2013 and 2013-2014 growing seasons. Collectively, the results of this study suggest VSP training system should be recommended for grapevine production to reduce both downy mildew and botrytis bunch rot in the highlands regions of southern Brazil.

Buscando alcançar um adequado balanço vegeto-produtivo, este trabalho teve como objetivo avaliar o efeito do aumento da carga de gemas planta-1, no momento da poda, nas características produtivas e equilíbrio vegetativo da videira Cabernet Franc cultivada em região de elevada altitude de Santa Catarina. O presente trabalho foi conduzido durante a safra 2016/2017, em um vinhedo comercial, localizado no munícipio de São Joaquim. Utilizaram-se videiras da cultivar Cabernet Franc enxertadas sobre o porta-enxerto ‘Paulsen 1103’. Os tratamentos consistiram em quatro diferentes níveis de cargas de gemas: 15, 30, 50 e 75 gemas planta-1. Avaliou-se no momento da colheita variáveis produtivas e vegetativas, e ao longo do ciclo da videira, avaliou-se o crescimento de ramos e feminelas. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro blocos e cinco plantas por parcela. O aumento da carga de gemas planta-1 resultou em aumento do número de ramos e de cachos planta-1, resultando em aumento da produção por planta e da produtividade. As variáveis vegetativas foram influenciadas pelo aumento da gemas planta-1, observando-se redução do crescimento de ramos e de feminelas. O aumento da carga de gemas possibilitou melhor equilíbrio vegeto-produtivo, com redução do peso de poda, e obtenção do Índice de Ravaz mais adequado para a elaboração de vinhos de qualidade. Em vinhedos que apresentam baixa produtividade e excesso de vigor vegetativo, recomenda-se aumentar a carga de gemas planta-1 durante o manejo da poda invernal.

-The objective of this work was to compare the effect of different times of leaf removal on the vegetative-productive efficiency and on the chemical and physical characteristics of 'Cabernet Sauvignon' clusters in a high-altitude region of the state of Santa Catarina, Brazil. The experiment was conducted in the 2015 and 2016 vintages, in a commercial vineyard, located in the municipality of São Joaquim, in the state of Santa Catarina, at 1,230-m altitude. The treatments consisted of different times leaf removal in the cluster zone, in the following phenological stages: full bloom, buckshot berries, pea-sized berries, veraison, and 15 days after veraison, besides a control without leaf removal. The evaluated variables were subjected to the analysis of variance and compared with the Scott-Knott test, at 5% probability. In a high-altitude region, leaf removal provides more adequate indices for plant vegetative:yield balance. It also increases yield when performed during the pea-sized berry and veraison stages, increases the fertility index when performed during the pea-sized berry stage, and improves the chemical composition of 'Cabernet Sauvignon' grape when performed up to the pea-sized berry stage. The obtained results show the importance of early leaf removal to obtain must with potential for the production of quality wines.

No abstract