Stay Alert for Phoma and Light Leaf Spot signs in Oilseed Rape This Month

According to a number of agronomists in the UK, growers are now reporting signs of Light leaf spot in winter OSR crops, as well as disease threats from Phoma, in recent days. Therefore, fungicide treatments may be required if disease pressure remains or increases in the coming weeks for both these damaging diseases.

The end of the prolonged dry spell in August helped to set back Phoma infections in many crops, however with higher rainfall periods from mid-September through October, along with relatively mild temperatures last month, this has increased Phoma disease pressure.

If temperatures remain relatively mild for the time of year, it will be conducive to increasing Phoma symptoms and disease transmission from the leaves will take place more rapidly, leading to a risk of more damaging stem canker symptoms taking hold in crops. The later appearance this autumn of Phoma in OSR crops may cause both diseases to hit crops at the same time (Light leaf spot, which normally appears later than Phoma), and to peak together.

After assessing disease risk, growers may be able to target both diseases with one careful fungicide timing if disease level risks warrant an application, in which case product choice will be crucial.

Fungicide products containing prothioconazole and tebuconazole can offer strong and cost-effective control of Light leaf spot and Phoma in the late autumn period. These options can also be aligned with metconazole-based products if growth regulatory activity is required to reduce canopy size and manage very forward crops ahead of the winter. Growers should also consider the variety risk scores for Light leaf spot and Phoma, as even relatively high score ratings may not fully protect the crop. Any fields with varietal ratings below 7 should be considered first for fungicide applications to help protect those crops.

Clayton can offer a number of cost-effective fungicides for autumn disease control in OSR, including;

Clayton Navaro (125g prothioconazole + 125g tebuconazole) View Product

Clayton Tuskar (250g prothioconazole) View Product

Clayton Tebucon 250EW (250g tebuconazole) View Product

View our Autumn OSR Product Guide:

Additionally, to moderate forward crop growth in autumn, Clayton can offer;

Clayton Nascar (30g metconazole + 210 g mepiquat) View Product

a versatile PGR for use in winter oilseed rape. Metconazole based products have a growth regulatory effect on oilseed rape that can be highly beneficial to over-developed forward crops ahead of winter.

For further advice or support, please contact Will Ridgwell (Will@claytonpp.com) or Jessie Boden (Jessie@claytonpp.com).