Farmers carrying out grasslandrenovations this autumn are being reminded of the importance of treatmenttiming to control damaging frit fly populations.
Frit Fly is the number one pest fordamage potential when establishing new grass leys, explains Brent Gibbon,Regional Business Manager (west) at Dow AgroSciences. Tillers which have thepest feeding on them will show the classic deadheart symptoms, a yellowcentral leaf, by which point it is often too late to treat, he says.
Noting that there is an increasedrisk of attack when planting a new grass ley following a previous grass ley,Brent says the larvae can move from tiller to tiller, surviving for up to sixweeks in ploughed soil. The fly lays its eggs on the underside of the leaves,the maggots then hatch and burrow into the centre of the shoot to startfeeding.
There are no visible signs of thepest or its larvae until it is too late and the damage is done to the tiller.Chlorpyrifos is the only effective treatment against frit fly, however it canonly be used once per calendar year so timing of application is key, andresponsible use when applying it is essential in order to comply with stewardshiprequirements as set out by Say NO to DRIFT, warns Brent.
In an ideal world it would beadvisable to leave a six week interval between ploughing and sowing, hecontinues. However, this is clearly not always possible, so we recommend thebest time to apply the active is at or around emergence. An application ofchlorpyrifos will stop the larvae in their tracks, stopping them hatching andpreventing further damage to the tiller.
This crucial insecticide is currentlyunder threat due to regulatory pressure. The Say NO to DRIFT stewardship grouphas been working hard to increase awareness and further encourage uptake of thechlorpyrifos stewardship guidelines use low drift nozzles and increasedbuffer zones across the whole industry in order to retain availability ofchlorpyrifos.