Antibody test does the trick

6 March 1998

Antibody test does the trick

AN ANTIBODY-BASED test to detect triazole fungicides and help growers determine how much protection remains on the crop has been successfully developed by Central Science Laboratory. Antibodies have already been produced for tebuconazole (as in Folicur), and it is hoped others will soon follow, according to Simon Oxley of the SAC.

"The test is very sensitive, and can detect the fungicide at levels below one part per million," says Dr Oxley. "This means we can easily detect fungicide concentrations likely to be present in field crops."

The test is specific to tebuconazole, and has been checked beside expensive laboratory methods used for detection. "We were pleased with the repeatability of the results from small leaf samples. This suggests that testing a few leaves should prove an accurate way of measuring the fungicide present in the field."

The antibodies have been used against a wide range of other triazoles, but react only to tebuconazole, he reports. "This is important as we do not want false reactions from other inputs. There is an obvious disadvantage in that the test is specific to one fungicide, but the long-term goal is to develop similar antibodies to other popular triazoles, and produce kits which can detect a range of fungicides."

Work is underway by Adgen, a spin-off business of SAC, to produce a prototype field kit using the tebuconazole antibodies. "For this we anticipate the farmer will collect leaves, soak them overnight in a bottle of extraction liquid, and conduct the test the following day. It should take about 2Omin."

Interpreting the finding can be done in two ways. The result can indicate the dose of fungicide left in the leaves. This can then be used by the grower or adviser to decide on the appropriate dose for follow-up treatments.

Alternatively, it could be used to indicate the risk to the crop from a particular disease. This risk analysis will be based on the results of field trials underway as part of the project, and backed by the vast amount of information from HGCA research.

projects aimed at developing the full-blown decision support system, known as DESSAC, explains Dr Oxley.

"Any commercial test will be made as straightforward as possible to use and interpret.

"We are very pleased with the progress made so far, and are grateful to the HGCA for its support. Looking ahead we are keen to do further research to widen the range of fungicides to include some of the new strobilurins recently approved in the UK.

"By detecting a wide range of fungicides in crops and interpreting the results, we hope to help growers manage diseases in a more cost-effective way."

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