Finally decent amounts of rain are allowing crops to fully emerge and with the relatively warm sunny weather, grow away well.
Bare patches in oilseed rape have by and large filled in with a lot of new, small plants. After last year’s experiences hopefully they will make it through the winter. I have seen a few myzus persicae in some crops so be aware of these as they can transmit the Turnip Yellow Virus.
Other pests seen, apart from slugs which have now come to the surface after the rain, include a few cabbage root aphid larvae on some roots of large rape plants, turnip sawfly larvae and some plants near hedgerows with clusters of mealy aphids. None of these are at threshold levels but nonetheless are interesting to find. I have also heard that a further generation of leaf miner flies have been seen.
A young trainee I have with me spotted the first leaf with phoma I have seen this year so if conditions remain mild vigilance will be needed. A 10% threshold trigger should be used if this is reached, especially on the smaller plants.
Pre-emergence herbicides applied to early-drilled crops are having mixed success at the moment. Some will need a little longer before any thoughts of follow up sprays are acted on. Rain has only just activated them and a I feel it will be a little longer before decisions will be made.
Blackgrass that is beyond two leaves and showing no symptoms will need to be addressed sooner rather than later with regard to Atlantis application. Beware of complicated tank mixes if applying to lush crops particularly in barley – a hardening off period should be observed before application.
Several bird cherry aphids have been seen in the last few days so untreated crops are at risk of barley yellow dwarf virus.