Mn, Mg or Virus Yellows? Magnesium Manganese Virus Yellows (BYV and BMYV) Symptoms of beet yellowing virus (top leaf) and beet mild yellowing virus (bottom leaf) 90 85 95 100 105 Tonnes/Ha Untreated 1 x Fungicide 2 x Fungicide 7.7T 4.8T DISEASE CONTROL The common diseases of fodder beet are Rust and Powdery Mildew but Cercospora, Ramularia and Stemphylium can also affect the crop. Work has shown that the application of at least one fungicide is likely to give yield increases in excess of 10%. If harvest is planned later than November, a second fungicide 3-4 weeks after the first is likely to improve yield further. Rust is favoured by moist weather with temperatures between 15 and 20ºC. Foliar fungicides, with activity against rust, should be sprayed as soon as rust is seen (typically late July). Powdery Mildew is favoured by warm dry weather. Foliar fungicides with activity should be applied at the first sign of the disease (typically late July). Cercospora can be a serious disease. Widespread across Europe, it has recently been causing issues in UK crops. The disease is spread by rainsplash and will infect damp leaves in humid conditions. Some fungicide groups are likely to be more effective than others at controlling this disease. BEET YIELD RESPONSE FROM 1 AND 2 SPRAY FUNGICIDE PROGRAMMES – 7 TRIALS 2009-2014 Source: Bayer Crop Science, British Sugar, Brooms Barn and BBRO; 10 data points, January and February lifting dates. Crop protection: Fodder Beet Late crops of fodder beet need some help from foliar applied nutrients. Our top tips: ✚ Always correct deficiencies and ensure the crop has recovered before applying herbicides. ✚ Apply manganese after herbicide applications – this helps the crop to recover but not the weeds. ✚ DO NOT mix manganese and boron together – they are NOT compatible. MANGANESE DEFICIENCY (also known as ‘Speckled Yellows’) ✚ Shows as inter-veinal yellowing and stunting. Treat as seen or wherever there is a known deficiency. ✚ Can include treatments as routine with herbicides and/or insecticides. ✚ Granular manganese fertiliser treatments are not recommended. BORON DEFICIENCY ✚ Boron deficiency causes ‘heart rot’ or ‘crown rot’ in maturing plants. ✚ Crown rot is more prolific following a wet winter and spring as boron leaches down the soil profile and away from the plant’s reach. ✚ Assess your beet when in the clamp at harvest to determine the amount of crown rot on the farm. ✚ Soil tests can also provide information on the levels of boron available to support growth. MAGNESIUM DEFICIENCY ✚ Magnesium deficiency can be confused with virus infection. Symptoms are visible on older leaves first and tend to show a yellowing from the leaf margins and tips spreading over the whole leaf. Cold wet periods, as well as sandy, acidic and potash rich soils can increase the risk of deficiency. ✚ Although magnesium deficiency is not common in beet, if identified by soil sampling it should be rectified in base fertiliser application. ✚ If visual symptoms are seen then apply foliar sprays. Deficiency also occurs due to root feeding damage from Free Living Nematode (FLN). Treat using a magnesium-based product. Please contact customer services: e: t: 0845 6073322 Please contact customer services: e: t: 0845 6073322 77 CROP PROTECTION 76 CROP PROTECTION