Beneficials on farmland: identification and management guidelines (HGCA Summer 2008)

Environment

 


 

The managed habitat created by crops and weeds influences the type and abundance of beneficials. There will be greater diversity, ensuring more robust pest control if habitat structures within the crop are diverse. Allow some weeds to survive, undersow, and use minimum tillage to retain crop residues near the surface. On a larger scale, avoid creating large areas of monoculture and maintain a diversity of crops and uncropped land across the farm.

Overall, aim to have a range of different types of vegetation. Avoid being too tidy. Leave 'scruffy' field corners and piles of rotting wood. Beneficial populations are most damaged by insecticides and molluscicides when they are active within the crop in spring and summer. Insecticide drift during autumn into overwintering areas may also reduce survival.

Adopting Integrated Pest Management (IPM) will ensure that insecticide inputs are only applied when necessary, helping to reduce spray costs and prevent insecticide resistance developing. The main principles of IPM are:

  • Minimise the risk of infestation through cultural means:
    • grow resistant varieties
    • rotate crops to reduce risk to susceptible crops
    • drill when there is less risk of infestation
    • consolidate soils to reduce pest movement.
  • Avoid block cropping that allows pests to spread between fields.
  • Monitor crops and only spray when thresholds are exceeded.

Establishing perennial flower-rich habitats

Seek advice from a seed supplier on suitable species for soil and farm conditions.

Where to sow

Along hedgerows or boundaries with few flowers, beside beetle banks and in field corners. Spread across the farm so that most fields are adjacent to a flower-rich habitat.

Management

Preparing a weed-free environment is vital to successfully establishing these mixtures. Mow regularly up to four times during the first year to prevent grasses from dominating. Mow once or graze in autumn. Remove invading noxious weeds, eg docks and thistles, by spot spraying or weed wiping. Adhere to stewardship regulations or GAEC12.

 

Pollen and nectar flower mixes

What to sow
A mixture of at least three pollen and nectar-rich plants, eg clovers, vetches, birdsfoot trefoil and sainfoin to provide a long flowering period.

When to sow
March-September.

How to sow
Create a fine, weed-free seedbed, drill (1cm) and roll.


Pollen and nectar flower mix
Floristically enhanced grass margin

What to sow
A mix of perennial fine grasses and wild flowers, including:

  • suitable fine grass species, eg common bentgrass, crested dogstail and sheep’s fescue
  • wild flowers, including the most important for hoverflies and parasitic wasps: wild carrot, wild angelica, hogweed, yarrow, common knapweed, rough hawkbit, field scabious, lady’s bedstraw and birdsfoot trefoil.

Species to avoid: aggressive, tussocky grasses, eg cocksfoot.

When to sow
April to October when moisture present.

How to sow
Create a fine, weed-free seedbed, broadcast the seed evenly on the surface and roll.


Floristically enhanced grass margin

Establishing overwintering grassy habitats

Areas of tussock-forming grasses support high densities of overwintering beetles and spiders. They provide a source of alternative prey throughout the year and are a refuge from disturbance.

Management

Little management is needed once grasses have established. To prevent herbicide drift onto sown grasses, create a sterile strip 0.5–1m wide alongside, according to agri-environment regulations. Preferably establish a conservation headland or flower-rich strip adjacent to the grass strip to provide alternative food and some pollen and nectar. This helps diversify the range of beneficials.

 

A combination of techniques also provides nesting cover and foraging habitat for farmland birds.

Beetle banks

Where to sow
Divide large fields (over 20ha) with a beetle bank to ensure beneficials are present across the field as early as possible. More than one bank, spaced 200m apart across the field, may be required in very large fields. When built along contours, they can help slow down run-off.

Construction
In autumn, plough two furrows together to form a raised bank about 0.4m high and 1.5–2m wide. Leave a working gap at either end so that the field can still be worked as a single unit.

What to sow
A mixture of tussock and mat-forming grasses, eg timothy, cocksfoot, red fescue and meadow fescue. Suitable proprietary mixtures are available from most seed companies.

When to sow
Autumn (August-October) or spring (April-May).

How to sow
Hand sowing.


Beetle bank before grasses establish

Grass strip along field margin
Grass field margins/buffer zones

 

Where to sow
Along hedgerows or boundaries, adjacent to flower-rich areas and alongside watercourses.

What to sow
Aim to create an overwintering habitat with a mixture of tussock and mat-forming grasses, eg timothy, cocksfoot, red fescue, meadow fescue and wild flowers. Most seed companies supply suitable proprietary mixtures.

When to sow
Autumn (August–October) or spring (April–May).

How to sow
Ideally drill; hand-sowing is possible.


Beetle bank and flower strip
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