Fungal Isolates Associated with Cuscuta campestris in Kazakhstan: Characterization and Preliminary Screening for Biological Control

Cuscuta campestris Yunck. is one of the most destructive parasitic weeds worldwide, causing substantial economic losses because of its broad host range, prolific seed production, and long-term persistence in the soil seed bank. The limited effectiveness and environmental constraints of conventional control measures have intensified the search for sustainable biological alternatives. This study investigated indigenous fungi associated with C. campestris in Kazakhstan as prospective biological control candidates. During field surveys conducted in southern and southeastern Kazakhstan in 2024–2025, symptomatic dodder plants were collected, and 109 fungal isolates were recovered from stems and seeds, including representatives of Fusarium, Alternaria, and Ascochyta, together with several saprophytic genera. Preliminary in vitro seed assays identified Fusarium proliferatum F6 and Alternaria alternata A5 and A19 as producing the highest percentages of affected seeds, reaching 100% by day 15. No visible disease symptoms were observed in soybean or alfalfa during a seven-day preliminary non-target assay. These findings support further greenhouse, field, and host-range evaluation of the selected isolates and provide a basis for continued development of fungal agents against C. campestris.