Home Gardening techniques When to use nematodes for pest control

When to use nematodes for pest control

Vine weevils
Heuchera completely severed at the roots by vine weevil grubs

Temperature’s the key for good results

Keeping on top of pests organically is one hell of a job but nematodes can be the answer to your prayers – but what are they and how do you use them?

Nematodes are tiny organisms living in the soil, sea or freshwater and feed on bacteria, fungi, protozoans and other nematodes. Depending on the species, they can be beneficial, feeding on garden pests.

BASF, which makes Nemasys, is the only specialist nematode production facility in Britain. Plan what you need now for the year, order online and they’ll be sent out when needed (as living things, they have to be sent out ‘fresh’).

Nemasys has products to control:

  • Slugs
  • Vine weevils
  • Chafer grubs
  • Carrot and cabbage root fly
  • Leatherjackets
  • Cutworms
  • Onion fly
  • Ants
  • Scarid fly
  • Caterpillars
  • Gooseberry sawfly
  • Thrips
  • Codling moth

How to use nematodes

Simply mix with water and apply from a watering can with a coarse rose or sprayed onto the foliage and soil, depending on the variety.

There’s no need to keep children or pets away and as biological controls, they can be used by organic gardeners.

Nemaslug nematodes. Picture; BASF
Nemaslug nematodes. Picture; BASF

Nemaslug: apply March-October

There are usually two overlapping generations of slugs, with peaks of egg laying in March-April and September-October.

Each slug lays up to 300 eggs, in up to 50 separate batches, so each cubic metre of soil can contain about 200 grown slugs.

The best time to target them is when they are newly hatched, so nematodes are able to attack them before they are in sight, unlike slug pellets.

Use every six weeks throughout the growing season to keep on top of the slimy pests.

Biological Vine Weevil Killer. Picture; BASF
Biological Vine Weevil Killer. Picture; BASF

Nemasys Vine Weevil Killer: apply March-October

Vine weevils are my nemesis, wrecking Heucheras, strawberries, Rhododendrons and many other plants in my garden. The adult beetles eat foliage, leaving irregular notches in leaves.

It’s the horrible C-shaped cream larvae that do the real damage. They stay in the soil over winter and sever roots, leading to death.

Nemasys Vine Weevil Killer targets the larvae while they are still in the soil, and kill them before they have a chance to cause damage. Use every four weeks throughout the growing season for best effect.

Nemasys nematodes. Picture; BASF
Nemasys nematodes. Picture; BASF

Nemasys Fruit and Vegetable Protection: apply April-October (depending upon pest)

A mix of nematode species to target a broad range of pests:

  • Carrot and cabbage root fly, leatherjackets, cutworms, onion fly, ants, scarid fly: April-August.
  • Caterpillars, gooseberry sawfly, thrips: May-October.
  • Codling moth: September-October.
Biological Chafer Grub Killer. Picture; BASF
Biological Chafer Grub Killer. Picture; BASF

Nemasys Chafer Grub Killer: apply August-October

Chafer grubs are cream, about 15mm in length, and have distinct legs. They burrow deep into lawns during the winter, where they lie dormant before surfacing in spring as beetles.

The grubs attack grass roots, resulting in slow growth and yellow patches. Wildlife can also create damage by digging the turf to search for the grubs.

Apply between August and October to dramatically reduce the chafer grub population.

Biological Leatherjacket Killer. Picture; BASF
Biological Leatherjacket Killer. Picture; BASF

Nemasys Leatherjacket Killer: apply August-October

Leatherjackets are about 25mm in length, with greyish black, legless bodies and no distinct head. They are the larval stage of the crane fly, which appears towards the end of August and lays eggs which hatch within two weeks and immediately start to feed on grass roots.

Apply Nemasys Leatherjacket Killer when the leatherjackets are still young and active in the soil, throughout late August to the end of October.

Biological No Ants. Picture; BASF
Biological No Ants. Picture; BASF

Nemasys No Ants: apply April-September

Yellow ants build nests in lawns, red ants are aggressive and can sting and black ants can nest anywhere.

Apply Nemasys No Ants to runs and nests from April-September.

All of the above are available from stockists online.

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Mandy Watson is a freelance journalist and an incurable plantaholic. MandyCanUDigIt grew from the tiny seed of a Twitter account into the rainforest of information you see before you. Gardening columnist for the Sunderland Echo, Shields Gazette and Hartlepool Mail and editor of the Teesdale Mercury Magazine. Attracted by anything rebellious, exotic and nerdy, even after all these years. Passionate about northern England and gardens everywhere. Falls over a lot.

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