South: Make time for blackgrass control

Things have changed little since my input last month – the dry weather has continued except a few millimetres of rain a couple of weeks ago.


Early-drilled crops with roots in moisture are growing well, albeit rather slowly, but later cereal crops drilled in the first week of October are standing still and starting to struggle. Rain is forecast for this week and this should restart crop growth before any frosts come.


In the majority of cases, autumn residuals have worked remarkably well despite the dry weather. However, there are some instances where large numbers of blackgrass plants have appeared in the treated fields and will certainly need another mid-season herbicide treatment.


In this instance, take care not to spray before crops have hardened and wait until at least a couple of frosts have occurred. At present crops are tender and subject to crop damage, particularly if a contact type of material is to be used in combination with an aphicide. It is also important to remember that pendimethalin has a limit of 2000g per crop and if using chlortoluron ensure that the variety to be sprayed is tolerant of this chemical.


Oilseed rape crops are at the four- to six-leaf stage. Phoma, which is evident in most fields, is at the 10% threshold level requiring treatment. Use a good product such as Capitan (flusilazole) at the earliest opportunity. Where a PGR activity is required then a product such as Sunorg Pro based on metconazole should be used – indeed a mixture of flusilazole and metconazole is a good option to be considered.


Where blackgrass and sterile brome are a problem then consider waiting until there is adequate moisture before spraying.  Surprisingly no turnip saw fly has been witnessed so far, despite the warm weather.

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