Prolonged cooler weather has reduced aphid pressure in cereal crops. That said where aphids are already present in crops they will continue breeding at an increased rate for every degree over 3 °C therefore growers will continue to be vigilant and ensure crops are well protected to limit their risk of BYDV. Secondary spread of aphids will occur once 170 accumulated day degrees occur above the threshold of 3 °C
Blackgrass is emerging in later drilled crops and at the end of winter, we will be able to assess how many plants have survived pre-emergence herbicide applications. Follow up contact acting herbicide applications should be planned and it is important to remember that these herbicides require active growth to be most effective. Recent cool temperatures have slowed crop growth right down and crops will be monitored for signs of growth occurring before application.
Septoria tritici and powdery mildew are now being found quite widely in winter wheat crops but generally on older leaves. Yellow rust is not currently being found and recent cold weather will have delayed the progress of the disease further. However following changes in yellow rust populations, the disease is likely to be more prevalent in some varieties which we would not expect.
Powdery mildew and net blotch have been widely reported in crops of winter barley. Consider treatment for powdery mildew in susceptible varieties if the disease is found on the last fully expanded leaf.
Remember that the last date for use of propyzamide is approaching (31st January) and that carbetamide can be used until the end of February. Check soil conditions and weather forecast before application to minimise movement into water.
Peach–potato aphids, the vectors of turnip yellows virus (TuYV) are still being caught in low numbers, and are commonly being found in central, eastern and southern England in winter oilseed rape - especially where the crops have not had a Biscaya or Plenum treatment yet. It is likely that the effect of TuYV on yield will decline the later the crop becomes infected, but it is unknown if there is a cut-off date after which the impact is minimal.
Phoma leaf spotting has increased dramatically following many rain events. Where crops have not already been treated, a fungicidal application is advised to safeguard yield potential. Phoma protection is increasingly important where crops are small as passage of the disease into the stem causing canker happens much quicker in small crops.
Light leaf spot is now likely to be the priority for most crops. Reports of lesions appearing in crops are beginning to come in, including those crops that have received an autumn fungicide.
Numbers of cabbage stem flea beetle larvae being found in crops is very variable. The pest is present in Lincolnshire, but generally below threshold, whereas much higher numbers are being found in the south. Insecticides have been shown to be effective against larvae right though until February, but these should not be applied unless the threshold is exceeded.
Avian flu H5N8 has been confirmed in a flock of farmed breeding pheasants in Lancashire. A Surveillance Zone has been put in place around the infected premises to limit the risk of the disease spreading. Defra have urged poultry keepers to remain vigilant, with measures requiring domestic birds to be housed and kept away from wild species, remaining in place until at least the end of February.
The NFU have accused Sainsbury’s of pursuing an “anti-meat” agenda, following the announcement that the retailer is working with Oxford University and the Wellcome Trust to encourage people to eat less meat and more greens.
Defra is in the process of revising the NVZ designations that will apply from 2017 to 2020. Farmers are reminded that they have just 28 days from being notified if they want to make a challenge. Check whether your NVZ status is part of the proposed changes at WIYBY search map tool