FRAG-UK have published new guidance of Fungicide Resistance Management in Oilseed Rape.
Click here to download the full document (pdf, 4 pages)
General strategy for managing fungicide resistance
An integrated approach to disease and crop management and hence a strategy for fungicide resistance management should be followed.
Use disease resistant cultivars. Resistant varieties that are not treated with a fungicide may give a higher economic return than a susceptible one that is.
Target fungicides on crops where there is risk of yield loss, using disease forecasts and thresholds where available. Seasonal variation in risk can be large so use local guidance.
Ensure fungicide applications are well-timed and the appropriate dose is used.
Avoid repeated use of the same product or fungicide having the same mode of action. The FRAG -UK website has a database that allows identification of fungicides by mode of action.
Crop residues are the main source of inoculum for phoma and light leaf spot and probably Alternaria spp. Bury crop residues after harvest and prior to emergence of new crops and avoid planting new crops adjacent to the previous year’s stubble. Isolate new crops by 200-500 m if possible.
Sow in late August so that plants are well-grown prior to the onset of phoma leaf spot. Stem canker and light leaf spot are less damaging and easier to manage on plants with large leaves than on small plants
Crop rotations are shortening in response to economic returns from winter oilseed rape and first crops of winter wheat. Alternating wheat/winter oilseed rape cropping has been successful on some farms but may be unsustainable if large areas adopt this rotation.
Biological control with Coniothyrium minitans may be useful after severe attacks of Sclerotinia and reduce the risk of yield loss without resort to fungicides.