Crop Clinic

The female lays eggs during the summer months (July - September), and bare soil is the preferred  site. Consequently, wheat sown after potatoes, peas, oilseed rape, field vegetables, fallow and set-aside are particularly at risk.

The eggs begin to hatch in January/February and may continue through to mid March. Severe damage is only caused to crops that have yet to form multiple tillers. As a general rule, crops sown before mid-October will be less affected by this pest. Later sown crops which may only have a single shoot at egg hatch, may be completely killed by the grub feeding in the single shoot. 

We have detected significant levels of egg laying by wheat bulb flies in potato fields in 2010. Egg laying will continue up to mid-September, but growers identify now fields going into winter wheat (and spring barley) that are at risk from wheat bulb fly damage.

Treatment thresholds for wheat bulb fly are based on egg counts in soil from fields planned for winter wheat or spring barley.  The threshold for late sown wheat crops is 1.25 million eggs/hectare.

Winter barley is usually sown early enough to withstand any damage.