Farmers’ Weekly
© Adas
Robert Hurren is using a free diagnostic test to identify oilseed rape’s most damaging disease in his clients’ crops, allowing him to time fungicide treatments precisely.
The Suffolk-based crop consultant is utilising a service called SpotCheck to assess crops for light leaf spot, the often hard-to-identify disease which can cut yields by 50% in severe cases.Advertisement
Oilseed rape leaves are collected every two weeks through the late autumn and winter and examined under a microscope for the first sub-clinical signs of disease.
“We see it as a valuable tool to time fungicides accurately as it is often a difficult disease to recognise in its early stages,” he tells Farmer Weekly.
See also: Wet weather triggers early onset of phoma in OSR
Free disease test
Mr Hurren is part of the independent East Anglia-based Apex Agronomy group. All seven of its agronomists are members of the Association of Independent Crop Consultants (AICC).
For the fourth year, he is using the free SpotCheck service which is operated by crop consultant Adas, financed by agrochemical giant Bayer and supported by the AICC.
In October the AHDB’s light leaf spot forecast said the disease risk was one of the lowest on record as a dry spring had slowed disease development, although agronomists warn that what inoculum of this wet-loving disease there is present could easily be spread in favourable autumn weather.
Mr Hurren looks after about 2,000ha of oilseed rape across some 30 farms, largely east of the Ipswich-to-Norwich A140 trunk road towards the Suffolk coast.
The starting point for his light leaf spot control strategy is varietal choice
Varieties
Mr Hurren looks for varieties with good disease resistance to light leaf spot and also phoma leaf spot, as this is becoming more important with the move towards early drilling to counter cabbage stem flea beetle attacks.
Oilseed rape varieties are rated on a 1-9 scale for disease resistance in the AHDB Recommended List, with a high figure showing good resistance.
He is looking for scores of 6 or above for light leaf spot and phoma resistance, as early-drilled crops can develop quickly in mild, wet autumns and are more susceptible to disease.
Left to right: Apex agronomists Frankie Pattinson and Robert Hurren, and Suffolk farmer James Porter © MAG/David Jones
“We are looking for varieties with good resistance against light leaf spot and phoma, with preferably a 7 or 8, and not under a 6,” he says.
New hybrid varieties with good resistance to light leaf spot and phoma/stem canker include Aurelia (8 and 8) and Ambassador (7 and 8), while conventional variety Aspire also has good resistance (7 and 6), and all three are turnip yellows virus resistant.
Global Plant Protection News 
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