DIFFERENTIAL SUSCEPTIBILITY OF OLIVE VARIETIES TO OLIVE KNOT DISEASE IN ISTRIA

We performed a survey on susceptibility of two olive varieties ‘Leccino’ and ‘Picholine’ to olive knot disease in the area of Pore in the years 2008 and 2009. The incidence of disease was determined by visual inspection of disease symptoms on olives according to recommendations of International Olive Council (IOC). The meteorological data were collected during 2007 and 2008. The damage caused by the disease was evaluated and the area where symptoms appeared was quantified. A rather high frequency of olive knot symptom was determined at all locations investigated. The new infection incidence was lower in 2009 for both varieties probably due to the winter copper treatment conducted. The variety ‘Picholine’ showed higher incidence of disease.