The recent dry spell has enabled uninterrupted planting. Sowing will definitely extend into June but not to the degree that was feared. Despite the warm spell there are still not many emerged crops. Hopefully another week of the same will see this change. Meanwhile, my thoughts turn to aphid and virus control for seed crops.
First Myzus Persicae flights were predicted for early June. The cold spell earlier in the month may have set this back but conditions over the last week have been ideal for aphid multiplication and early flights have been reported across England. At time of writing water and suction traps are not indicating virus pressure but there is a delay in getting results.
As soon as cereal aphid or M. Persicae are recorded spray programs should commence. If M. Persicae is present then neonicotinoid should be tank mixed with a pyrethroid.
I am not advising oils for virus control unless there is a significant virus source. I have seen pronounced reduction in the canopy and subsequent lack of bulking with their use, particularly where crops are slow to establish.
In emerged crops rapid evaporation off the surface of the ridge is reaching 15mm SMD. Most ridges still have adequate moisture to enable the soil to be squeezed into a ball. This will change rapidly as canopies expand and plants pull moisture from the centre of ridge. If the ball starts to crumble at the point where the stolon has started to swell (tuber initation), irrigate 12-15mm within two days to stave off common scab control.
Blight sprays need to commence when the first risk period occurs. New blight strains, Blue A213 and Pink 6, may be active at lower temperatures making reliance on Smith periods a risk. However until you get humidity above 11hours you are at low risk. Alternation of cyazofamid and mandipropamid or cymoxanil will be the preferred option to cover canopy expansion.