IMPORTANCE OF OILSEED RAPE DISEASE CONTROL

• Oilseed rape is a profitable crop, with buoyant prices and good yields creating attractive gross margins.
• Growers are focusing on improving their yields, especially as the average yield in the UK (of around 3 t/ha) is considerably lower than that achieved in Germany (around 4 t/ha) and well below the theoretical maximum potential (of 6-7 t/ha).
• Attention to detail is required throughout the life of the crop including varietal choice, good establishment, timely removal of weeds, prevention of disease and pro-active growth manipulation.
• The recent increase in the oilseed rape area has lead to shorter rotations and more block cropping, so there is a higher disease pressure in those crops next to last years rape stubble.
• Emerging oilseed rape crops are facing another high disease risk this year, with Phoma leaf spots already being seen in advanced crops and on volunteers. It is a very early year for disease.
• Triazole fungicides such as metconazole and tebuconazole have additional growth regulation benefits and are widely used to create a robust plant that will survive and thrive the autumn/winter and create a canopy that will optimise yields.

Very Early Risk of Phoma

• Phoma can reduce yields by up to 50% and its control must start in the autumn in order to prevent the canker symptom developing in the spring. Autumn fungicide treatments prevent the fungus from spreading down the leaf to the leaf axil and then to the stem.
• The infection threshold is 10-20% of plants infected, regardless of the number of spots seen. The lower threshold is used on smaller plants and susceptible varieties. Last year over 95% of rape was infected by Phoma.
• A two-spray fungicide programme starting in the autumn is the usual approach. The first spray should be applied within two weeks of the symptoms being seen.
• Phoma infections are much earlier this year and crops should be inspected from the end of September onwards.

Problems With Light Leaf Spot

• Light leaf spot is the predominant disease in the North, the West and in Scotland as it flourishes under cool, moist conditions.
• Light leaf spot can reduces oilseed rape yields by 40 %.
• Last year over 46% of the crop suffered from this disease.
• The threshold for spraying is 25% of plants infected at stem extension, but it is advised to incubate plant samples in a polythene bag for 1-2 days to determine infection levels.
• The most cost-effective spray timing is in the late autumn from November onwards, but it is often difficult to see the symptoms at this time.

Arma Enhances Oilseed Rape Fungicide Performance

The performance of triazole oilseed rape fungicides, including Folicur (tebuconazole), Caramba/Sunorg Pro (metconazole), Plover (difenoconazole), Punch C/Sanction/Genie (flusilazole), Proline (prothioconazole) or Prosaro (prothioconazole + tebuconazole), can be enhanced by the addition of the adjuvant, Arma.

Arma in mix with oilseed rape fungicides;

• improves disease control and increases yield.
• boosts growth regulatory effects.
• helps to retain and spread the fungicides onto the waxy oilseed rape leaf surface.
• improves placement of fungicides onto the plant.
• helps penetration into the plant where it is needed.
• works at low temperatures.
• ensures the most robust fungicide performance.
• ensures maximum performance in tough conditions.