engleski

Influence of treatment period on the olive leaf spot with copper fungicide on the olive oil quality

Fungus Spilocaea oleaginea Cast. causes olive leaf spot disease. Today it is present in the entire world, in all areas of olive cultivation. Experts consider it one of the most widespread and dangerous fungal olive disease. It's safe to say that it is very big and serious problem in almost all Croatian olive-growing areas. The pathogen affects the fertility of infected trees, and its successive occurrences, from year to year, causing degradation of the entire olive trees, especially the younger ones. Specified disease can be controlled by copper fungicides. For a long time it has been considered that olive leaf spot infections can be prevented with only two treatments by copper formulations (September-October and March-April). For effective protection of olives, it takes several treatments in one year. Concentrations of applied preparations must be strictly controlled for possible copper residues in olive fruit and olive oil, which are limited by law regulation (up to 0.4 mg Cu/kg). In years with very warm and rainy autumns, a copper fungicide treatment in the fall is certainly not sufficient. It is necessary to perform at least three treatments. The experiment was conducted in 2009., 2010. and 2011. in an olive grove in Kastel Stari, to determine whether several successive copper fungicide treatment, in the fall, cause accumulation of unallowed Cu concentrations in olive oil. In three years research, the olive trees were treated 3 times in the autumn every 15 days with a copper fungicide (copper oxychloride). After the harvest, the olive samples were processed in a laboratory mill. Chemical and sensory analysis of obtained oils was performed and Cu concentrations in oils were determined by atomic absorption. The results show that chemical and sensorial characteristics of examined oils were not influenced by several consecutive treatments during autumn, period harvesting before. From obtained results it’s evident that unallowed concentrations of cooper were not found in any of analyzed olive oil sample (0.13 to 0.26 mg Cu / kg).

olive leaf spot; copper fungicides; olive oil quality; copper traces in oil

nije evidentirano