Harnessing optimal growth conditions for improved biocontrol of parthenium weed using mycoherbicidal fungi

<italic>Parthenium hysterophorus</italic> is an invasive weed causing significant ecological, agricultural, and health-related issues worldwide. This study aimed to optimize various growth parameters to enhance the colony development and sporulation of fungal isolates for effective management of <italic>Parthenium hysterophorus.</italic> During field surveys, four fungal isolates were isolated from infected <italic>Parthenium</italic> leaves, and the fungal isolates were identified as <italic>Alternaria alternata</italic> and three different strains of <italic>Alternaria macrospora</italic>, based on morphological, cultural, and molecular analyses. To maximize the growth and efficacy of these fungal isolates, experiments were conducted to determine the optimal conditions for temperature, pH, and incubation time. The results revealed that the ideal conditions for maximizing colony diameter and sporulation were 28 °C, pH 7, and 6–9 d of incubation. Surface and contour plots highlighted the interaction effects of these factors, confirming that deviations from these conditions resulted in reduced colony growth. ANOVA results indicated that all main factors and their interactions had a significant impact on colony development, underscoring the importance of maintaining precise control over these variables. Optimizing these growth parameters is essential for enhancing the efficacy of fungal isolates as biocontrol agents. The findings provide a foundation for scaling up fungal biomass production and field application, offering an environmentally sustainable alternative to chemical herbicides. This work advances the development of effective biocontrol strategies to manage <italic>Parthenium</italic> weed while promoting safer and more sustainable agricultural practices, thereby reducing dependence on harmful chemical herbicides.