East: Cooler conditions needed after welcome rain

Moist conditions have evened crop establishment of second and later drilled wheats. After the rain, crops that are still emerging through heavy, cloddy seed-beds should be carefully monitored for increased slug activity.  


In winter cereals, dry conditions had reduced the impact of pre/peri emergence residuals. This has been apparent by high populations of volunteer rapeseed. However, following the long-awaited rain, crop volunteers are now clearly affected by the recent uptake of these residuals.  


Recent rainfall and mild temperatures have also prompted rapid grassweed emergence. Where significant grassweed populations have emerged, conditions are now good for sulfonylurea and residual activity.

Atlantis (iodosulfuron + mesosulfuron) applications must be applied at a time that enables the spray to dry on the leaf before the evening dew settles. At this time of year, these opportunities are rare. In marginal conditions, or where resistance could be an issue, good spray techniques are paramount. 

In winter cereals, barley yellow dwarf virus (BYDV) and aphid control should be reviewed on a field-by-field basis. It is worth noting that the Rothamsted Aphid bulletin shows active migration of the bird-cherry aphid (a primary BYDV vector) at the end of October. Consider a final insecticide for BYDV control to any unprotected crops during this time.


High levels of mildew are present in many winter cereals. Infection is most severe in stressed crops, for example, light land barley. In the main, these symptoms are cosmetic and likely to subside in moist, cooler conditions. Although vulnerable, struggling crops may benefit from a mildewicide which will protect new growth. Low levels of yellow rust are also evident on susceptible wheat crops.


Weather forecasts suggest longer spells of rain and cooler conditions from mid-November. In rapeseed, propyzamide applications should be delayed until soil temperatures fall below 10C. It was approximately 12oC on 5 November.


Both propyzamide and carbetamide work best when soils are cool and moist allowing the active ingredients to be held in the top few centimetres of soil where weeds are germinating. Applications should be stewarded to minimise run-off into surface water. In particular, applications to water logged soil should be avoided. During October, phoma infection developed slowly. However, this herbicide application also provides an opportunity to top off phoma control as necessary.

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