AimsThe goal was to determine the effect of temperature, light and incubation period on production, germination and bioactivity of Trichoderma atroviride LU132 against Rhizoctonia solani. Methods and ResultsThe incubation temperatures of 20, 25 or 30 degrees C were assessed on the production of T.atroviride conidia under constant light over a 25 and 50days periods. The resulting conidia were also studied for germination and bioactivity. Conidium production was maximum at 25 degrees C after 20days. The second peak of conidium production occurred at 45-50days. Incubation at 25 degrees C after 15days showed optimum production of T.atroviride LU132. Conidia produced at 30 degrees C gave the greatest germination and bioactivity in comparison with incubation at 20 or 25 degrees C. ConclusionThis study indicates that the temperature at which conidia of T.atroviride are produced affects germination and bioactivity. Formulations based on production of the high conidia yield may not result in optimal bioactivity and there is a trade-off between quantity and quality of T.atroviride LU132 conidia. Conidium production was shown to be a continuous process, and increased under a dark/light regime. This is the first report of bimodal conidium production in a Trichoderma biological control agent (BCA), which is likely to be on 20days cycle, and is dependent on colony age rather than abiotic factors. Conidia produced after 15days are likely to be the most suitable for use in commercial production of this strain as a BCA. Significance and Impact of the StudyMost studies on Trichoderma-based BCA have only shown the effect of culture conditions on the high conidia yield regardless of conidium quality. This study is the first report on conidium quality affected by principal culture conditions for Trichoderma biological control formulations.