ASSESSMENT OF PHYTOSANITARY CONDITION OF SOYBEAN AGROCENOSIS IN PRIMORSKIY KRAI

The study was conducted to understand the complex of fungal infections affecting soybeans and monitor their development dynamics in Primorsky Krai to improve pest control systems. The work was conducted from 2020 to 2024. Farms in eight districts (Khankayskiy, Khorolskiy, Pogranichnyy, Ussuriyskiy, Mikhaylovskiy, Kirovskiy, Chernigovskiy and Dalnerechenskiy) were selected to assess the phytosanitary condition of crops, covering a total survey area of 116.1 thousand hectares. Root rots of complex etiology are widespread in Primorskiy Krai. The disease develops epiphytotically, with plant infestation rates ranging from 9.9% to 36.3%. During the research, a complex of leaf spots affecting the crop was identified: septoria leaf spot (Septoria glycines Hemmi.), downy mildew (Peronospora manshurica (Naum.) Syd.), cercospora leaf spot (Cercospora sojina Hara.), ascochyta leaf spot (Ascochyta sojaecola Abramov) and purple cercospora leaf spot (Cercospora kikuchii (T. Matsu & Tomoyasu) Gardner). Among all the pathogens, septoria leaf spot occupied a leading position in the region with an annual development intensity in crops from 20.6 to 34.9%, while the distribution reached 100%. Downy mildew manifested itself with great variability from 0.4 to 7.2%. The level of cercospora leaf spot damage ranged from 2.0 to 4.1%. Ascochyta leaf spot was noted in isolated cases without mass distribution. In 2020 and 2024 the quarantine pathogen purple cercospora leaf spot was recorded with a development rate of 1.5% and 0.4%, respectively. Laboratory phytopathological testing of 298 batches of soybean seeds provided by seed testing laboratories in Primorskiy Krai revealed a high infection load of fusarium and bacterial blight in the seed material.