Biocontrol Science and Technology (2002) 12, 371±380 Monitoring of Biocontrol Agents Based on Trichoderma Strains Following Their Application to Glasshouse Crops by Combining Dilution Plating with UP-PCR Fingerprinting METTE LU È BECK and DAN FUNCK JENSEN Department of Plant Biology, Plant Pathology Section, Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark (Received for publication 2 July 2001; revised manuscript accepted 3 December 2001) Universally primed (UP) PCR analysis was used to characterize strains of Trichoderma spp., which constitute the active ingredients of commercial products for biocontrol of phytopathogens . Several UP primers were able to generate distinct and reproducible Wngerprints for each strain, allowing them to be di Verentiated from a collection of other Trichoderma spp. strains. In order to test whether the UP-PCR method in combination with dilution plating could be useful to detect and enumerate propagules of biocontrol strains of Trichoderma spp. when applied on a commercial scale, sampling was carried out in three commercial glasshous e operations. Dilution plating was carried out using a semi-selective medium and a number of the Trichoderma spp. recovered were subjected to UP-PCR analysis with one selected UP primer. The results showed that the method could be used to identify the isolates from the biocontrol products applied in the di Verent glasshouses. Furthermore, it was found that a biocontrol strain also colonized an untreated bench in one of the glasshouses. The combined methods enable veriWcation of the active ingredient concentration, facilitating monitoring establishment and spread of the Trichoderma strains. Keywords: universally primed-PCR Wngerprinting, BCAs , monitoring, Supresivit TM , TRICHO- DEX TM , Binab T TM , Promot TM , Bio- Trek22G TM , biological control, eYcacy INTRODUCTION In Denmark, and in the EU in general, many chemicals previously used for control of various plant diseases have been withdrawn from the market for environmental and safety reasons. Thus, the need for other strategies for disease management is urgent, and biological control is becoming an attractive alternative. In Denmark, for example, it is estimated that biological control of diseases is used in 30% of the glasshouse area producing ornamentals (Enkegaard et al., 1999). The active ingredients of several commercial products for use against soilborne diseases are represented by strains of Trichoderma spp., which are Correspondence to: M. LuÈbeck.Tel: + 45 35 28 33 05; Fax: + 45 35 28 33 10; E-mail: mette.lubeck@plbio.kvl.dk ISSN 0958-3157 (print)/ISSN 1360-047 8 (online)/02/030371-10 © 2002 Taylor & Francis Ltd DOI: 10.1080/0958315022012815 8