Pests in Winter Wheat – Sept 2019

Wheat bulb flies will be laying eggs through to late September.  Growers are strongly advised to consider an assessment of egg numbers from early-September in fields planned for wheat, particularly in light of the unavailability of chlorpyrifos as an egg hatch treatment which only leaves a seed treatment as a control option.  Note that this season is the last chance to use fludioxonil + tefluthrin seed treatment, which can no longer be used after 31st August 2020.

Fields, particularly at risk, are those currently in potatoes, field vegetables and fallow that will be sown with wheat (or spring barley next year).  Identify fields potentially at risk now and be prepared to get them sampled in early September.  Contact your local agricultural consultant or agronomist to arrange for soil samples to be taken before the field has been cultivated.  Soil samples should be taken from early September onwards and advice will be provided on whether the crop will benefit from the use of a seed treatment to mitigate the impact of wheat bulb fly grubs when they hatch in February 2020.

Photo credit: ADAS

Initial results from our wheat bulb fly egg counts this autumn indicate a risk to later sown wheat crops going in after potatoes.

The following options are available to growers:

• Use decoy areas – fields with areas of bare soil that are not planned for cereals – these can divert flies away from fields planned for wheat/spring barley
• Do nothing if egg counts are below damaging levels (relies on having an egg count assessment)
• Sow earlier rather than later if egg counts are at borderline threshold levels (relies on an egg count assessment)
• Sow seed treated with fludioxonil + tefluthrin or cypermethrin

If egg counts are known, then there are several informed choices that can be made.