ACUTE OAK DECLINE (AOD) NEW COMPLEX DISESE ON HOLM OAK (Quercus ilex L.) AND POSSIBILITIES OF SPREAD ON OTHER OAK SPECIES IN CROATIA

The paper presents an overview of current knowledge on Acute Oak Decline (AOD), a polymicrobial disease that was recently discovered in Croatia (in 2021) on the Pelegrin peninsula (island of Hvar). In the last few years typical symptoms have appeared on holm oak trees: dieback of the top of the tree crown, followed by appearance of longitudinal cracks in the bark and black tissue necrosis in the form of black necrosis under the bark. At a later stage, swollen lesions with exit holes of insects on tree stems appear, and after 3-4 years tree dies. The disease spreads from tree to tree, resulting in mass dieback. The causes of tissue necrosis under the bark are pathogenic bacteria Brenneria godwinii, Gibbsiella quercinecans and Lonsdalea britannica, and their possible vectors are jewel beetles Agrilus sulcicolis and A. olivicolor. AOD has so far been described in the United Kingdom, Latvia, Spain, Iran and Swit-zerland. The specificity of the first AOD finding in Croatia is that holm oak as a native species has a special significance for the Mediterranean forests, and for the first time other species of jewel beetles that have not been found as AOD vectors have been detected. The risk of AOD transition to conti-nental pedunculate oak and sessile oak forests is particularly concerning, because unlike all previous AOD findings in the world, pedunculate and sessile oak forests in Croatia are the only ones that have been exposed to constant attacks of oak lace bug (Corythucha arcuata) for years. The possible syner-gism of oak lace bug with AOD could be extremely dangerous. Therefore, the prompt application of protection measures, especially preventive ones, together with the importance of scientific research is emphasized.