Residues of azoxystrobin, fenhexamid and pyrimethanil in strawberry following field treatments and the effect of domestic washing A. Angioni{*, M. Schirra{, V. L. Garau{, M. Melis{, C. I. G. Tuberoso{ and P. Cabras{ {Dipartimento di Tossicologia, Universita ` di Cagliari, via Ospedale 72, I-09124 Cagliari, Italy {CNR — Istituto di Scienza delle Produzioni Alimentari, Localita ` Palloni, Nuraxinieddu, I-09170 Oristano, Italy (Received 19 April 2004; revised 5 August 2004; accepted 12 August 2004) Residues of the pesticides azoxystrobin, fenhexamid and pyrimethanil were determined in strawberry after field treatment. The effect of ‘home’ washing with tap water and a commercially available vegetable detergent on residue levels was also studied. After treatment, azoxystrobin and pyrimethanil residues on strawberry were on average 0.55 and 2.98 mg kg 1 , respectively, values below the maximum residue level (MRL) fixed by the European Union (2.0 and 5 mg kg 1 , respectively), while fenhexamid residues were on average 2.99 mg kg 1 , which is very close to the MRL of 3.0 mg kg 1 , but some samples were over the MRL. Thereafter, all residues declined, with a half-life of about 8 days (azoxystrobin and fenhexamid) and 4.8 days (pyrimethanil). Washing the fruit with tap water reduced the residues of azoxystrobin and fenhexamid but did not affect pyrimethanil residues. Finally, when fruits were washed with a commercial detergent, greater amounts were removed (about 45% of azoxystrobin and pyrimethanil and 60% of fenhexamid). Keywords: strawberry, gray mould, azoxystrobin, fenhexamid, pyrimethanil, residues Introduction The post-harvest life span of strawberry is very short. Under marketing conditions, strawberry may deterio- rate in a few days due to its high softening rate and susceptibility to decay caused by various pathogens. Among these latter, are gray mould (Botrytis cinerea) which infects the fruit during flowering, remaining quiescent and developing during post-harvest (Bristow et al. 1986); other pathogens are Rhizopus stolonifer (Ehremb ex. Fr.) Vuill and Mucor sp., the major agents of post-harvest decay and incipient infections. These two pathogens are very difficult to suppress. Various strategies for managing the post-harvest decay of strawberry have been investigated (Sutton 1994, Garcia et al. 1995, Spynu 1989, Nigro et al. 2000). However, decay control, on a commercial scale, chiefly employs cultural practices and preharvest fungicide sprays (Aharoni and Barkai-Golan 1987, Blacharski et al. 2001, Legard et al. 2002). In recent years, attention has been focused on food safety. This is especially true for pesticide residues, and degradation rates on strawberries subjected to field treatments (Ahmed and Ismail 1995, Ahamed et al. 1996, Dermibas° 1998, Abad et al. 1999, Falqui-Cao et al. 2001, Stensvand and Christiansen 2000, Wennrich et al. 2001) and post- harvest processing (Will and Kru¨ger 1999). Additionally, there has been increasing interest in novel, broad-spectrum fungicides that have been designated as ‘reduced risk’ pesticides to humans, non-target organisms and environmental resources, which have a different mechanism of action com- pared with other currently registered pesticides for a given crop group (Leroux et al. 2001, Barlett et al. 2002). Among these azoxystrobin (Barlett et al. 2002), Food Additives and Contaminants, Vol. 21, No. 11 (November 2004), pp. 1065–1070 *To whom correspondence should be addressed. e-mail: aangioni@ unica.it Food Additives and Contaminants ISSN 0265–203X print/ISSN 1464–5122 online # 2004 Taylor & Francis Ltd http://www.tandf.co.uk/journals DOI: 10.1080/02652030400010066