Break Crops

Root crops are valuable as a break crop between grass leys due to the risk of frit fly which can cause considerable damage to autumn grass reseeds or even devastate a new ley. Frit fly lay their eggs on or near grass plants. On hatching the larvae tunnel into the centre of the grass plant eating out the heart and killing the whole plant. Larvae can also migrate up from the remains of the ploughed decaying sward to infest the new ley. Direct drilled (slot seeded) reseeds can be particularly at risk as the larvae find it easy to migrate from the decaying vegetation to the seedlings often in the same slot. Breaking the cycle by establishing a fast growing summer break crop, the frit fly is unable to continue its life cycle.3

Most at risk from frit fly damage:

• Ryegrass leys, particularly Italian though perennial also suffer significantly
• Autumn or late summer sowings especially crops sown in mid-August
• Direct drilled reseeds
• Grass to grass sowings
• Grassy stubbles
• Fields with a previous history of damage.

If possible, leave a long gap between ploughing and reseeding grass, ideally 6 – 10 weeks but a minimum of 2 weeks to reduce the frit fly source.