Apply nematodes against vine weevil

Once you have pests like the vine weevil in your garden, it is often difficult to get rid of them. A simple, biological way to control the vine weevil is to use nematodes.

This article provides simple hints and tips on using nematodes to control vine weevil. These are particularly up to mischief at night and leave characteristic feeding marks on plants such as rhododendrons, roses, clematis or strawberries. More problematic than the unsightly feeding marks are the beetle larvae, which damage plant roots.

Detect weevil infestation

If a garden is infested with vine weevils, this can usually be recognized relatively easily by the semicircular feeding spots, the so-called bay feeding, on the leaves of ornamental plants such as rhododendrons. The real problem for the plants is not the nocturnal beetle, but its larvae. The larvae live in the soil, where they eat the roots of the plants and often even peel off the bark on the root neck. The plant is cut off from the supply of water and nutrients and can die. Therefore, you should start fighting the vine weevil as soon as you discover it.

Nematodes against vine weevil: timing

During the year there are two phases when it is advisable to control vine weevils with nematodes: in spring from April to May or in late summer between August and September. The condition is that the soil temperature is above 12 °C for a few hours a day. These recommendations result from the life cycle of the beetle and the temperature requirements of the nematodes. In order to achieve complete control, it makes sense to treat once in spring and once in late summer. Suitable nematodes are only effective against vine weevil larvae and pupae, but not against vine weevil beetles or eggs. Early treatment kills the pupae and then the newly hatched larvae in the fall. After application, the first larvae of the vine weevil die within7 days from. Since the nematodes continue to multiply in the insects, the success of the control increases over time, so that a suitable long-term effect is achieved depending on the severity of the infestation.

Which nematodes can be used against vine weevil?

An example of nematodes that are effective against both pupae and larvae of the vine weevil are our Plantura HB nematodes against vine weevils and grubs. HB nematodes are tiny roundworms of the species Heterorhabditis bacteriophora, approximately 0.6 mm in size. In the soil, they look for the larvae and pupae of the pests and penetrate them. There the nematodes continue to multiply and kill the infested larvae or pupae. Eventually, the nematodes leave their host and infest other larvae.

Tip: In addition to controlling vine weevils, HB nematodes can also help control grubs that cause lawn damage.

Because HB nematodes only specialize in a few pests, they pose no threat to warm-blooded animals, humans or plants. So you don't have to worry about the nematodes spreading unintentionally in your garden. As soon as the work of the nematodes is done, i.e. there are no more pupae and larvae of the vine weevil in your garden, the number of nematodes continues to decrease. However, HB nematodes can also form more long-lived outlasting forms, so that a certain long-term protection remains.

Note: There are other nematodes that are suitable for controlling vine weevils. Nematodes of the species Steinernema kraussei mainly parasitize larvae, whereas Steinernema carpocapsae attack the adult beetles. However, HB nematodes are the most commonly used because of their effectiveness.

Apply nematodes against vine weevil

The application of our HB nematodes against vine weevils and grubs is easy and requires no special equipment. However, a few points should be considered: Because nematodes are sensitive to UV light, they should only be applied in the morning or evening and when the sky is overcast. The required soil temperature of 12 °C is important for effective reproduction of the nematodes and thus for successful application.
When storing nematode preparationsnote that these are living organisms. Bring the beneficial insects out as soon as possible after receipt. Stored in the refrigerator, nematodes can be kept for a maximum of 6 weeks.

Application instructions for vine weevil nematodes:

1. Moisten dry soil.
2. Stir the contents of the pack into 10 L of water.
3. Further dilute the mixture according to the number purchased and the area to be treated, as indicated in the application recommendation. If necessary, divide between several watering cans or mix in several steps one after the other.
4. Stir the mixture vigorously, otherwise the nematodes will settle to the bottom.
5. Pour the finished mixture into a caster or nematode sprayer and spread evenly.
6. Rinse immediately after application with at least 1 L of water per square meter to flush any nematodes from plants into the soil.
7. Do not allow the treated soil to dry out for at least the following 4 weeks as the nematodes need moist soil to survive.

Note: The information given relates primarily to our Plantura HB nematodes against vine weevil. There may be different application instructions for other products.

If you're not just struggling with the vine weevil in your garden, you can read more about nematodes as beneficial insects in our special article.