Archive: Frit Fly

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Look out for Frit Fly this autumn

If you sow a grass to grass reseed in the autumn, the establishing grass (and cereal) seedlings are vulnerable to damage from a number of pests, but most damaging are probably Frit Fly larvae, says Francis Dunn from Field Options.

The pest is 2-3mm long and burrows into the stem base of tillers. It is endemic in established grassland and mature plants can cope with losing a few tillers, but establishing seedlings may only have one shoot – an attack is then terminal.

Look out for yellow shoots. The newest leaf dies and can easily be pulled out of the leaf sheath at the point where the larvae have bitten off young leaf. There is a range of resistance. Italian Ryegrasses are more susceptible than Perennials and Timothy is rarely damaged. Good seedbed consolidation is beneficial - grass establishes faster and pest mobility is reduced. If you have symptoms, discuss using an appropriate insecticide with your agronomist.

To avoid Frit Fly damage, you either need a 5-week fallow period or use chlorpyrifos-based insecticide immediately after sowing. In future, it is hoped the industry will offer perennial Ryegrass varieties with resistance to Frit Fly and other insect pests, based on selections of naturally occurring endophytes. These are saprophytic fungi which contain low levels of alkaloids which potentially kill the larvae.