Among the four soils studied under laboratory conditions, only one was accepted by the RMS to study the route and rate of degradation in soil of tricyclazole. Indeed, because of the poor mass balances, which may be due to a poor quality of the extraction method (SWE: subcritical water extraction), three soils out of four were not accepted (US loam, US clay loam and Italian loam). According to the results for the aerobic Italian sandy loam soil, tricyclazole degrades slowly (from 97.6% of AR at 0 DAT to 88.7% of AR at 120 DAT). A non-transient minor metabolite not characterized reached 8.4% of AR at 14 DAT. Mineralisation and NER of tricyclazole are low (maximum of 1.9% of AR at 120 DAT). The Italian sandy loam soil was also studied under laboratory anaerobic conditions. Tricyclazole degrades from 91.2% at 0 DAT to 70% at 120 DAT for the whole system. Low amount of 14CO2 and NER were analysed (respectively maximum of 0.1% and 4.7% of AR). In an indicative photodegradation study conducted at very high dose compared to the intended uses, tricyclazole is very slowly degraded.