Investigation on fungicide residues in greenhouse-grown strawberries

Maximum residue limits (MRL's) for different agricultural food products in Norway are harmonized with EU standards. In field-grown strawberries in Nor way, tolylfluanid has a 7 day quarantine from last application to harvest, while other approved fungicides have 14 days quarantine. Greenhouse product ion of strawberries is newly introduced to the country. Residue levels in s trawberries of the cultivar Korona grown in a commercial greenhouse were in vestigated 4, 7, and 14 days after application of eight different fungicide s at rates recommended by the manufacturers and at half rates. Iprodione, t olylfluanid, and vinclozolin were tested in two experiments, while chinomet hionat, chlorothalonil, imazalil, penconazole, and triadimefon were tested once. For chinomethionat, imazalil, iprodione, penconazole, and vinclozolin , the residue levels were below MRL 2 weeks after application. Application of triadimefon in normal rate gave residues below MRL 14 days after applica tion. However, its metabolite, triadimenol, was above MRL at the same time. Tolylfluanid gave very high residue levels, and except from half concentra tion in the second experiment, all other residue levels were above MRL. Sev en days after application, residues in both experiments were approximately 3 times higher than MRL when normal rate of tolylfluanid was applied. For c hlorothalonil at the recommended rate, the residue level was above MRL at a ny sampling time, while half rate gave residues below MRL 14 days after tre atment. In view of the present results, tolylfluanid, chlorothalonil, and t riadimefon will need longer time from last application to harvest and/or re duced application rates in greenhouse-grown compared to field-grown strawbe rries. In addition or as an alternative, recommended rates could be lowered .