JJ BECK¹, SJ STEWART², L ETIENNE³, C BASSIN³, C THOMAS⁴, SJE WEST⁴, A ABEL⁵, E SCHURMANN⁵, P OROSZLAN⁵, M EHRAT⁵ and U GISI³

¹Novartis Crop Protection, Biotechnology and Genomics Center, 3054 Cornwallis Road, Research Triangle Park, North Carolina 27709 USA; ²Immunovation, PO Box 13342, Research Triangle Park, North Carolina 27709 USA; ³Novartis Crop Protection Ltd, Agrobiology Research Station, CH-4108 Witterswil, Switzerland; ⁴Novartis Crop Protection UK Ltd, Whittlesford, Cambridge CB2 4QT, UK; ⁵Novartis Pharma Ltd, BioAnalytical Research, CH-4002 Basel, Switzerland

Background and objectives
Our crop disease diagnostics program is based on developing assays for detecting crop pathogens to facilitate product support for Novartis fungicides. Disease diagnostics are used as a tool for optimizing crop inputs, to demonstrate product stewardship, to practice integrated pest management (IPM) and to work towards sustainable agriculture. Assays are targeted to diseases which are difficult to identify based on visual symptoms. Samples can be tested in a core laboratory or in the field depending on the assay used and the desired information. The results generated help growers decide if fungicide application is appropriate.

All our assays are pre-symptomatic in detection, that is they identify the presence of the pathogen before the onset of visible disease symptoms. In addition, these assays provide a tool for identifying the diseases without the problems of traditional disease diagnosis and the isolation of the pathogen. Novartis diagnostics is an ongoing program to support our customers' needs with the applicable solutions.

Results and conclusions
Diagnostic assays have been developed using two immunological formats. Pathogen-specific antibodies have been formulated into the conventional microtiter plate format known as enzyme linked immunosorbent assays (ELISA). These assays are very routine to use and are currently being used worldwide; however, these assays require a laboratory for analysis. More recently, the antibodies used in our ELISA have been integrated into a format intended for field use. The onsite format[1] requires no laboratory equipment and can be performed in minutes. The onsite assay results have shown good correlation with our ELISA results.

We have also developed diagnostic assays using polymerase chain reaction (PCR) technology[2]. By targeting a pathogen-specific gene, highly specific PCR primers have been developed which amplify DNA only from the targeted pathogen. These assays are highly sensitive, inexpensive to develop and are very specific. As with our onsite assays, the PCR results correlate well with our existing ELISA assays.

PCR tests are performed pursuant to licensing arrangements with the Perkin-Elmer Corporation under patent rights owned by F. Hoffman-LaRoche Limited and Hoffman LaRoche Incorporated.

References
1. Stewart SJ, Jehan-Byers R, 1996. Proceedings Brighton Crop Protection Conference: Pests and Diseases, pp.215-220.
2. Beck JJ, Beebe JR, Stewart SJ, Bassin C, Etienne L, 1996. Proceedings Brighton Crop Protection Conference: Pests and Diseases, pp.221-226.