Disease kit on way

7 February 1997

Disease kit on way

By Robert Davies

IMPROVED diagnostic testing of stem-based diseases in cereals could be available to field consultants in kit form within three years.

So says Dave Parry, leader of Harper Adams Colleges Crop and Environmental Research Centres disease diagnostic team. The patented testing system developed by the Newport, Shropshire-based scientists detects the DNA of pathogens in a soup made of diseased stem tissue and enzymes.

The sample is heated and cooled several times to amplify the path-ogen DNA, which is then extracted using specific chemical carriers.

"At the moment the technique is a valuable research tool, but we hope consultants will soon have access to a kit form that will allow them to diagnose exactly which diseases are present," Dr Parry says.

"Molecular diagnosis is very accurate and can even differentiate between W and R types of eyespot, which cannot be done visually.

"It can be used to identify the presence of the nine main wheat stem diseases, and the extent of each. From this information it is also possible to quantify their effect, and advise the use of specific fungicides. More precise disease control is possible because the most effective product is pinpointed and its application can be better timed."

This will reduce agri-chemical bills and benefit the environment, comments Dr Parry. &#42

Identifying which diseases cause stem browning ensures cereal sprays are well targeted. An acuarte new field kit from Harper Adams could be available in three years, says Dave Parry.


&#8226 DNA technique very accurate.

&#8226 Distinguishes between ninekey stem base diseases.

&#8226 Field kit in three years.

&#8226 Allows better fungicide targeting.

Blight forecast

CERC, in collaboration with Hardi International, is to offer a new on-line computer-based potato blight forecasting service this season. It will use portable weather stations to gather field-specific data to assess accumulated blight risk.

In trials using susceptible variety Bintje, the forecasting model triggered seven sprays a season. A neighbouring farmer growing the same crop in similar conditions used 11 applications to achieve comparable control. Assuming spraying costs £35/ha (£14/acre), a saving of £140/ha (£57/acre) and considerable environmental benefits could be achieved in some years, says senior researcher Peter Jenkinson.

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