The main leaf diseases on peach in Araucaria and Lapa counties, both in the state of Parana, Brazil, are rust (Tranzschelia discolor) and shot hole (Wilsonomyces carpophilus). The first one causes defoliation just after the harvesting, and the second one is always present in the orchards, though its effects are not well known due to the lack of assessment methodology for that disease. This research aimed to develop a diagrammatic scale for shot hole and compare the incidence and severity of leaf diseases in integrated (PI) and conventional (PC) management systems. The shot hole diagrammatic scale was developed in the first year of assessment by selecting leaves with different levels of severity; the minimum and maximum levels of the disease in the fields were established and the other levels were intercalated according to visual accuracy. In order to compare the two production systems - PI and PC, two experimental sites were set in two producing areas (Araucaria and Lapa) with three-year-old commercial peach orchards, cultivar 'Chimarrita', which were evaluated during the 2002/3 and 2003/4 seasons. The PI system was carried out according to techniques recommended for peach PI and the PC was carried out as the system applied by the growers in each area. In order to evaluate the diseases, the incidence and severity of shot hole and rust were quantified in marked branches, from October to April, in two seasons. In addition, defoliation was also determined during the evaluation period. The designed diagrammatic scale established six levels of shot hole severity and can be recommended for the assessment to compare production systems and to monitor the disease in the field. In Araucaria the incidence and severity of shot hole presented inverse behavior between the years, and was lower in the PI system in the first season and higher in the second, whereas rust was less severe and caused less defoliation in the PI system in the first year. In Lapa no differences were observed between the systems in relation to shot hole; as for rust, the conventional management was better. Therefore it is not recommended to reduce pulverization in areas where there is high inoculum of the pathogen.
Prunus persica; Wilsonomyces carpophilus; Tranzschelia discolor; integrated management; rust
