What are Beneficial Nematodes?

Beneficial Nematodes are a great natural way to attack such pests as grubs, black vine weevil, leather jackets and many more. Nematodes are tiny microscopic worms that live in the soil that attack other soil dwelling insects. They kill the other insects by entering through a body opening; once inside they release a bacterium which will kill the insect within 48 hours. Once the nematode is finished it will then reproduce and find its next victim. Beneficial nematodes are totally safe to be used around children, pets and plants of any kind.

Halifax Seed is pleased to have it’s own line of beneficial nematodes; Blackvine Weevil Killer, Grub Killer and Leatherjacket Killer. They are available late spring and fall for appropriate application times.

Blackvine Weevil Killer (Steinernema kraussei)

Vine weevils are beetles that have a long thin snout and are approximately 8-14mm (1/4 - 1/2 inch) in length. They are dull brownish-black and cannot fly. All adults are female and lay hundreds of white eggs (approx. 0.8mm in diameter and are round). They rapidly turn brown as they mature. The larvae are ‘C’ shaped and legless, with a small head. The larvae feed and grow throughout late summer and autumn. During winter their growth slows as temperatures decrease and feeding activity also decreases. As the temperature rises in spring, the larvae’s activity starts to increase again causing more and more root damage. Eventually the larvae stop feeding and pupate (early spring) and quickly hatch into adults, and so they cycle continues. Outdoors, the adults emerge in early summer (June) and lay their eggs immediately, starting their year long life cycle again. Finding and destroying the adults is difficult as they are nocturnal, quick moving and play dead once disturbed. The adults eat plants in summer and autumn, leaving distinctive crescent-shaped notches on leaves. The vine weevil grub (larvae) is far more of a danger to plants that the adults. The young larvae feed on plant root systems, initially on small fine outer roots, but progressively attacking the more important main roots as they grow bigger. To keep a minor problem at bay, one autumn treatment should be adequate. However, for a serious infestation, treat in the spring and again in the autumn. When treating in pots take care that the pots are not allowed to dry out.

Grub Killer (Heterohabditis bacteriophora)

White grubs are the larval stage of the June Beetle. Grubs are cream colour and about 1.5cm (0.6”) in length, have distinctive legs, and are found in the root systems of plants and lawns. June beetles have a 3-year life cycle. Adults overwinter in the soil and emerge to lay eggs in late May to early June. After eggs are laid, white grubs are present and begin feeding on grass roots. They then lay dormant deep in the soil before moving to the surface in the spring and continue to feed. In the fall, they again go deep into the soil for the winter and again return to the surface the following spring. At that time, the grubs feed for only a few weeks before pupating and changing to beetles. The beetles, however, remain inactive in the soil until the next spring before taking flight. The life cycle is then complete and a new generation is started. The second year grub stage is the most damaging due to the size and appetite of the grub. Apply to moist lawns during late summer to early fall. This is when the young grub larvae are active and the temperature is above 12 degrees Celsius. Immediately after applying the nematodes, water the grass well so the nematodes are washed into the soil to reach the root zone where the grubs will be. Keep the lawn well watered for at least two weeks.

Leatherjacket Killer (Steinernema faltiae)

Leatherjackets are the larval stage of the crane fly. The larvae are about 2.5cm (1” long), greyish black in colour, legless and with no distinct head. During summer, leatherjackets can be seen in the soil. In late August, the adult crane flies emerge form the soil and start to lay eggs. Within about two weeks, the eggs hatch into leatherjackets and overwinter in the soil. In spring, the larva feed on grass roots. In June the leatherjackets stop feeding and pupate the soil until fall when they emerge as adults, mate and lay eggs. The adult crane fly completes its lifecycle after laying eggs. In late summer gardeners may see clouds of adult crane flies emerging form lawns in the early morning; this is a sure sign of a leatherjacket infestation. When you see the crane flies in your garden (towards the end of August) you will know that in a few days they will be laying eggs. Apply nematodes when the young leatherjackets are active in the soil, this is typically late summer to early fall.

Tips for successful results:

  • Area to be treated must to moist prior to application. After a heavy rain is best. Area must be kept moist for at least two weeks after application.
  • Avoid applying nematodes in sunny conditions. Apply in evening or when overcast.
  • Use the entire package at once and immediately after mixing
  • If using a sprayer make sure it has been cleaned and rinsed well. Removed screen from the sprayer. Use only sprayers that have not had pesticides used in them; residue can be harmful to nematodes.
  • Apply prior to expiry
  • Check soil temperature for your area. Ideal temperature at application is 5 degrees C (41F) for Blackvine Weevil Killer and 12 degrees C (54F) for Grub Killer and Leatherjacket Killer.

Directions for applying:

  • Mix contents of package in at least 4 liters of lukewarm water then apply mixture with a hose end sprayer to affected area or add 1/2 liter of the mixture to an 8L watering can and filled with water to apply to area.
  • Apply to moist lawns when the soil temperature is appropriate for the type of nematode you have and water them in well. The nematodes need to be washed in well so that they reach the root zone where the insect you are looking to treat lives. Make sure the lawn does not dry out after applying nematodes. Keep the lawn well watered for at least two weeks.

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