As winter approaches, it is essential to have aphids under control. The key to this is understanding their lifecycle. A lot of heavy rain and windy weather will slow down aphid activity, as will frost, but it will not kill them unless it becomes very cold.
Make sure your winter crops are protected against aphids this year. Damage from aphids occurs in cereals, mainly by transferring the BYDV virus into the plant as it is feeding on it. BYDV can infect wheat, barley and oats. It is reported that BYDV can lead to yield losses of up to 40% in high pressure situations.
Understanding the lifecycle of aphids is important in making decisions to control them. The chief virus transmitting aphid in Ireland is the Grain Aphid (Sitobion avenae) with the Bird Cherry Aphid being less common. The Grain Aphid flies into crops and very quickly (before G.S. 25) produce wingless offspring which can survive on crops through most winters (down to – 8ºC). Numbers increase during mild spells when further BYDV spread may occur.
Warm, moist soil conditions facilitate aphid movement through soil. ‘Green bridge’transmission is most likely in early-drilled crops and in mild, damp autumns. Up to the 1st of November this year this was not as big problem, as in general soil conditions were dry plus the most of this year’s autumn sown crops were drilled with Redigo Deter seed dressing, but with November shaping up to be mild and damp coupled with higher than normal soil temperatures at present it will be advised to spray all September/1st week October sown crops within the first 2 weeks of November.
Any mid-October sown with Redigo Deter should only need to be sprayed once (some may not even require one) before the end of November as the seed dressing runs out of steam which will happen where lower seed rates were used. This is especially important if current the weather pattern continues as it is at the moment as there will be a higher risk from aphids flying in from other fields. Crops sown in late October without any Redigo should have an aphicide applied once crops reaches the 2/3 leaf stage which can be coupled with the herbicide application. A lot of heavy rain and windy weather will slow down aphid activity as will frost but it will not kill them unless it becomes very cold.
Aphids can transfer directly from grass or weedy stubbles, of which, there are plenty of this year to new cereal crops.
It will be important that all crops are sprayed this month to help protect against light leaf spot. Best products to use will be Prothioconazole (Proline) or Tebuconazole based products at around half rates.
It is an opportune time to apply some boron also.
November is also a good month to apply herbicides such as Kerb or Astrokerb to fields that got no herbicide or graminicide thus far, but soil temps need to be down to a consistent 8/9℃. They will also give extra control of troublesome grass weeds like brome and black grass in fields where such problems exist.
|Crop||BYDV Risk||Control Actions||Comments|
|Sept Drilled Winter Cereals||High||Seed treatments followed by Pyrethroid at 2/3 leaf stage followed by Pyrethroid again in early November in low risk scenarios.||Late spraying of previously unsprayed crops can be beneficial e.g. where timings are missed.|
|Oct Drilled Winter Cereals||Medium-High||Seed treatment or Pyrethroid in the 1st week of November.||No second spray needed – even when aphid occurrence is high, there is NO benefit from extra sprays|
|Winter Cereals Emerging after end of Nov||Very Low||No treatment necessary (except in mild winters when aphids are plentiful)||Where pyrethroid fails, consider Chlorpyrifos or Dimethoate (wheat only) Where low seed rates are used (e.g. <125 kg/ha; hybrid barley), very early drilled crops may need 2 pyrethroid applications|
For more information and advice, be sure to contact one of the RED MILLS agronomy team or call into our Agri Super Store in Cillin Hill.
- crop varieties
- parasite control
- seed bed preparation
- tillage farming
- winter barley
- Winter Crops
- Winter Oats
- Winter oilseed rape
- Winter Wheat