Leaf emergence is faster than ever as high temperatures push growth rates
The heavy rain of the last week has been very welcome for autumn-sown cereals. Crops have been drilled in excellent conditions and with high soil temperatures, emergence has been even and rapid.
Crops have never looked as well for this time of the year and contrasts dramatically with the last few autumns. Leaf emergence and tiller numbers are driven by temperature, with a leaf emerging every 12 days when temperatures are 10C.
Each extra leaf can be expected to produce a tiller bud. The recent weather has been well above 10C.
The excellent seed quality of the 2013 harvest is an added bonus. Seed bed conditions have seldom been as good and growers are amazed at the speed of emergence of crops sown. The downside of this is obviously possibly greater problems with aphids leading to yellow dwarf virus and higher levels of take all, greater disease pressure in the autumn and higher lodging pressure.
Advanced crops of barley wheat or oats should have already received an aphicide. Any early winter barley treated with Redigo Deter will require an aphicide towards the end of October/early November.
Warm, moist soil conditions facilitate aphid movement through soils. 'Green bridge' transmission is most likely in early-drilled crops and in mild damp autumns. Aphids transfer directly from weedy stubble to new cereal crops. The ITCA aphid traps show very high aphid levels.
While it appears that there is currently a relatively low level of pyrethroid resistance in the grain aphid, it is important to remember that this is becoming an issue and should be monitored carefully. If aphid activity remains high after spraying, there should be a follow-up treatment.