Quick way to stop the rot

A RANGE of simple 10-minute tests for fungal plant diseases could increase farmers' profits and reduce the use of fungicides in horticulture.

Growers face significant and increasing problems in maintaining effective disease control. A diseased crop may be saved by treating it with fungicide. But - apart from the cost - the effectiveness of fungicides is falling, and there are legislative and environmental pressures to reduce their use.

'At the same time, factory crop-production methods favour epidemic disease development,' said Stephen Holmes, general manager of Adgen Diagnostic Services, a company set up last month by the Scottish Agricultural College in Ayr to market the new test kits.

At present, diagnosing fungal diseases involves sending a sample to be grown in a laboratory, a process that can take up to two weeks. 'The crop will probably be in the skip by the time the result is obtained,' Dr Holmes said.

Using the Adgen kits, growers will be able to monitor the level of fungal pathogens in their crops very closely. A two-year research programme carried out by the Scottish Agricultural College to validate the kits, which are manufactured by Neogen Corporation in the US, showed that in many cases the fungus was detected before the plants exhibited any signs of damage.

'This means growers do not have to apply fungicides 'just in case',' said Andrew Jackson, Adgen's plant pathologist. If a pathogen is detected, the appropriate fungicide can be used.

Plants can be tested at any point from propagation to point of sale, so garden centres can check plants for disease as they are delivered.

The kits, for which Adgen has sole European marketing rights, will detect phytophthora infestans (best known as potato blight), and pythium and rhizoctonia, which cause rot in the roots and base of the stem, and can afflict most horticultural crops, from geraniums to tomatoes and soft fruit.

There are several species of the three pathogens, and the symptoms are different in each crop. All can lead to complete crop loss, or affect the appearance of bedding plants and ornamentals, making them unsaleable. The kits contain antibodies that will bind only to the antigens produced by a specific fungus.

When this binding takes place, an enzyme is generated that produces a colour reaction. The deeper the colour, the more fungus is present. Colour intensity can be assessed on a scale from 1 to 100 on a meter, allowing growers to judge the extent of disease and measure the effectiveness of any treatment by repeating the test, say, a week later. Tests cost about pounds 12 each, and no special training is needed to use them.

Adgen also sells a kit for detecting the three main fungal diseases affecting grass - dollar spot, pythium and brown patch. Dr Jackson says this could be used in the management of all kinds of leisure grass, from golf courses to public parks.

The company is the agent for the Central Science Laboratory of the Ministry of Agriculture, Fisheries and Foods, which has developed tests for plant pathogens over the past five years, producing antibodies to cereal, potato and sugar-beet viruses.

(Photograph omitted)