Use of streptomyces for biocontrol of pests and virus mitigation in tomatoes in arid zones

The “greening” of crop production technologies is fundamental to the modern concept of phytosanitary optimization of agroecosystems. Environmentally friendly plant protection products based on actinobacteria, with their novel mechanisms of action and high physiological and biochemical potential, are of particular interest. While soil streptomyces are technologically scalable, have long shelf lives, and are field-friendly, their effectiveness can vary due to limited knowledge of the properties of introduced actinobacteria. This study is the first to establish the in vivo biological effectiveness of Streptomyces carpaticus RCAM04697 for biocontrol of insect pests and reduction of phytovirus damage in open-field tomatoes in the Astrakhan Region. The study aimed to investigate the virucidal and antifungal properties of S. carpaticus RCAM04697 suspensions and extracts, and to evaluate their impact on tomato yields under arid conditions. The S. carpaticus RCAM04697 strain was isolated from brown semi-desert soils of the Astrakhan Region. Field trials demonstrated that treatment of tomato plants with a seven-day culture suspension of S. carpaticus RCAM04697 exhibited high virucidal activity against three phytovirus isolates: cucumber mosaic virus (75.3%), tomato mosaic virus (69.1%), and tomato bronzing virus (82.5%). Maximum antifungal activity was also observed with S. carpaticus RCAM04697 suspension on day 14 after the third treatment, reaching 87.5% against A. crassivora, 86.9% against A. gossypii, and 86.6% against A. fabae, indicating a sustained antagonistic effect. Bacterization of the open field tomatoes with the S. carpaticus RCAM04697 strain resulted in a 2.9-fold yield increase compared to the control. These findings suggest that S. carpaticus RCAM04697 possesses significant potential for developing biological products with virucidal, antifungal, and phytoregulatory properties for open-field tomato protection.