The withdrawal of the pesticide Chlorpyrifos (trade names including Dursban™ and Lorsban™) means growers will need to take a more integrated approach to pest management, to ensure successful establishment of a

new ley.

Pests such as Frit Fly and Leatherjackets that could previously be controlled by Chlorpyrifos can cause serious losses in established grassland, and can be devastating to new leys if control measures are not taken.

Leatherjackets (Tipula paludosa)

Leatherjackets are the larvae of Crane Flies, which feed on the roots and stems of grass plants at or below ground level. Severe infestations in established grassland can lead to yield losses of more than 5t/DM per hectare whilst attacks in newly established leys are more likely to lead to plant death and crop failure.

Frit Fly (Oscinella frit)

Frit Fly produce 3 generations of larvae a year and are prevalent in almost all grass swards. The small larvae feed on the central shoot of the plant causing tiller death. Loss of tillers reduces yield and persistency in established leys. Attacks in plants at the seedling stage or with low tiller numbers leads to plant death.

Damage to newly sown grass leys by either Leatherjackets or Frit Fly are most likely in the following situations:

• Following established grass or grassy cereal stubbles• In predominantly grassland or mixed arable/ grass areas• In autumn sown leys – particularly mid to late August, and if conditions are warm and damp

• In leys sown with less than a week interval between cultivation and drilling• Infieldswherethereisaprevioushistoryof damage

SamplingafieldtoassessthenumberofLeatherjackets present can help determine the risk level. Indicators of large populations include; birds flockingtofeedonthelarvaeandlargenumbersofadult Crane Flies (Daddy-long-legs) in July/August.

Successfully Establishing Grass in a Post Chlorpyrifos Era

Damage and Importance

Risk Factors

With no chemical pesticides available, damage by these pests can be reduced or avoided by carrying out some/all of the measures below:

• Ploughing in July before reseeding can reduce leatherjacket populations by 50%• Establishing a brassica break crop, such as Interval Rape/Kale Hybrid or Delilah Stubble Turnips between grass crops, removes the pests food source• If sowing grass after grass, leave at least 2 weeks between cultivation and sowing to allow birds to feed on the grubs• Move to spring reseeding• Consider overseeding - sowing into an existing ley may allow seedlings to escape attack as the cover crop provides an alternative food source (Frame et al, 1992)• Increase seed rate to 15-20kg/acre to neutralize any seedling losses• Use Headstart® GOLD treated seed to ensure rapid establishment and vigorous early growth• As with any reseed – soil sample prior to seeding, to ensure pH and nutrient status is correct.

See below for examples of rotations designed to reduce the threat from grassland pests and maximise forage production.

Integrated Pest Management (IPM)

Example Crop Rotations

May June

1st cut silage

1st cut silage

2nd cut silage

Cultivate – leave fallow for >2 weeks

Cultivate – leave fallow for >2 weeks

Cultivate – leave fallow for >2 weeks

Sow Gowrie Swede or Grampian

Kale

Sow Tyfon StubbleTurnip

Sow Delilah Stubble

Turnip or Interval

Forage Rape

Sow LGAN grass ley

Plough – leave fallow for >2 weeks

Plough – leave fallow for >2 weeks

Sow LGAN grass ley

Sow LGAN grass ley

MarchSept _ July AprilAug

= Risk of Pest Damage

Produced by Limagrain UK LtdRothwell, Market Rasen, Lincolnshire, LN7 6DTTel: 01472 371471