Bakteriozni palež, uzrokovan bakterijom Erwinia amylovora, opisan je kao jedna od najvažnijih bolesti jabuka i krušaka u svijetu. Parazitira na više od 160 biljnih vrsta iz oko 30 različitih rodova. U Europi je prvi puta uočena 1957. godine u Velikoj Britaniji. U Hrvatskoj je otkrivena 1995. g. u Nuštru. Na engleskom se ova bolest naziva „fire blight“ zbog karakterističnih simptoma po kojima dijelovi biljke izgledaju kao da su spaljeni vatrom. U radu su opisani karakteristični simptomi ove bolesti, kao i njen životni ciklus te suzbijanje. Suzbijanje ove fitopatogene bakterije predstavlja veliki izazov u poljoprivrednoj praksi, naročito u uvjetima povoljnim za nastanak i širenje infekcije. Veliki problem pri suzbijanju ove bolesti je to što ne postoji kemijski pripravak za zaštitu bilja pomoću kojeg bi se ta bolest mogla uspješno suzbiti. Dobro djelovanje ima antibiotik streptomicin, ali on kod nas nema dozvolu. Osim toga, u zemljama u kojima se koristio duži niz godina, pojavila se rezistentnost patogena. Upotreba antibiotika, osim njezinog okolišnog konteksta, iziskuje i visoke troškove pa je problem ekonomske opravdanosti također jedan od razloga njegove zabrane. Cilj ovog diplomskog rada bio je provesti difuzijski test za provjeru djelovanja antibiotika streptomicina na fitopatogenu bakteriju Erwinia amylovora uz različite volumene noćne bakterijske kulture. Potvrđena je pretpostavka da je difuzijski test, uz korištenje 50 l noćne bakterijske kulture, prikladan za testiranje antibakterijskog djelovanja streptomicina na spomenutu bakteriju.

Fire blight, caused by bacterium Erwinia amylovora, is described as one of the most important diseases of apples and pears in the world. It parasitizes more than 160 plant species belonging to around 30 different genera. In Europe, it was first observed in 1957 in the UK. In Croatia it was discovered in 1995 in Nuštar. In English, name of this disease ("Fire blight") resembles characteristic symptom by which the parts of the plant appear to have been burnt. The paper describes the characteristic symptoms of this disease as well as its life cycle and control. Control of this phytopathogenic bacterium is a major challenge in agricultural practice, especially in conditions favorable to the onset and spread of infection. A large problem in control of this disease is that there is no chemical plant protection compound that could successfully control the disease. Good effect has antibiotic streptomycin, but he has no permission of use in our country. In addition, in countries where it has been used for long time, resistance of the pathogen has appeared. The use of antibiotics, except its environmental context, also requires high costs, so the problem of economic justification is just one of the reasons for its ban. The aim of this graduate thesis was to conduct a diffusion test for the checking of streptomycin antibiotic activity on the phytopathogenic bacterium Erwinia amylovora by using various volumes of overnight bacterial culture. A hypothesis that the diffusion test, useing 50 ml of overnight bacteria control is suitable for testing the antibacterial activity of streptomycin on mentioned bacterium was confirmed.