The moldy core has become an important disease in Brazil, no longer considered a secondary disease within the group of summer diseases. The development and fruit shape can be influenced by weather events that occur during the period of pollination and fruit set of apple trees. In addition to other factors such as plant nutrition, management of drives, type of rootstock and scion. The changes in fruits shape these factors can influence the increased intensity of disease. The objective of this study was to relate fruit morphological characteristics with the incidence of moldy core disease in different clones of apple Gala and Fuji cultivars on different rootstocks during the crop season of 2009/10 and 2010/11 in the municipality of Vacaria in the state of Rio Grande do Sul. The experimental design was completely randomized in a factorial 9 x 2 with nine clones of Gala and Fuji and two EM-9 rootstocks and interstock Marubakaido with EM-9. The fruit morphological characteristics evaluated were: relation between fruit length and diameter (L/D), distance between lobes, opening calicinar, calicinar tube length, seed number and class of disease symptoms in carpels. The disease was not identified in any clones of 'Gala' cultivars in both crop season. There was interaction between clones and rootstocks for all fruit morphological characteristics in both crop season 2009/10 and 2010/11. The highest incidence of disease in clones of 'Fuji' showed a positive relationship with the morphological characteristics of fruits with bigger calicinar openness, lower relationship between L/D and greater distance between lobes of the fruit, when compared with clones of 'Gala'. The clone 'Fuji Suprema' grafted on rootstock EM-9 presented 19,33% of moldy core incidence that was significantly higher than 6,67% incidence for rootstock Marubakaido interstock with EM-9. Among the genera of fungi isolated from carpels of apples, Alternaria was the genus with the highest frequency in the proportion of 14 and 20% in 2009/10 and 2010/11 crop season, respectively.
Malus Domestica; opening calycine; Alternaria sp; distance between lobes
