Monitoring studies of the occurrence of fire blight pathogen in Kazakhstan and identification of antagonistic microorganisms suppressing its development.

The paper presents data on phytosanitary monitoring of garden cenoses for fire blight in the Turkestan, Zhambyl, and Almaty regions of Kazakhstan. The purpose of this study is to assess the phytosanitary situation in various regions of Kazakhstan, determine the extent of fire blight spread, and isolate and identify the fire blight pathogen. During the study, methods such as hypersensitivity, pathogenicity, and fluorescent simplification-based specific hybridization polymerase chain reaction (FLASH-PCR) were used. It was found that in all the surveyed areas, disease foci were identified. For the first time, the fire blight pathogen was detected on fruit crops such as plum, peach, cherry plum, and quince, as well as on wild apricots. 274 plant samples were collected from which microorganisms were isolated. Isolates related to the fire blight pathogen Erwinia amylovora were identified by methods of hypersensitivity, pathogenicity, and FLASH-PCR diagnostics. Of the 156 isolates of microorganisms isolated from apple tree plant samples, 21 inhibited the in vitro growth of E. amylovora to varying degrees. Isolates 16.2 and 19.2 with maximum antagonistic activity were selected, where the pathogen growth inhibition zones were 52.2 ± 2.58 mm and 45.6 ± 0.55 mm, respectively. Based on the obtained sequence of nucleotides of the 16SpRNA gene site, it was found that the selected isolates with high antagonistic activity belonged to the Pseudomonas genus. In the future, based on these isolates, a new biological product for fire blight control can be created and adapted to the natural and climatic conditions of Kazakhstan.