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Controlling the vine weevil (Otiorhynchus) is comparatively easy with nematodes, as long as the right circumstances are observed during application. Here's how it works.
In a nutshell
- Fighting with nematodes alone is often not enough
- Combination with other methods is advisable
- Vine weevils can cause significant damage
- easy deployment
- Larvae are killed by the predators in a short time
Signs of vine weevil
The adult beetles feed mainly, but not exclusively, on the leaves of ornamental plants. For example:
- cyclamen
- Berry
- chrysanthemums
- ivy
- yew
- fuchsias
- geraniums
- pagan
- hydrangeas
- cherry laurel
- tree of life
- medlars
- primroses
- rhododendron
- roses
- grape vines
Other plants can also be affected. The adult specimens show signs of being eaten on the leaves. The larvae, on the other hand, live in the soil and feed on the roots and tubers. Therefore, you should fight the vine weevil promptly. The beetles appear more frequently between May and September. Typical signs are:
- unexplained death of plants
- irregular feeding marks on the leaves
- withered foliage despite good care conditions and the right location
larvae
The larvae are up to one centimeter long. The body is white and appears almost transparent. The head is brown. This makes them comparatively difficult to distinguish from other larvae.
They first feed on root hairs, but later also eat woody sections, tubers and bulbs. The latter can be completely hollowed out by the animals. This damage occurs mainly at the end of summer and early autumn. Therefore, an exact assignment is often difficult.
nematodes
These beneficial insects are roundworms. They are placed in the soil and feed on larvae by penetrating them and killing them from the inside. They help to fight the vine weevil. In addition, they have other advantages. These include, among others:
- simple application
- low price
- Lifespan, even without a host, six weeks
- die on their own without food
- effective against several pests
Source: Bob Blaylock Whidou (date removal), 20100814 175958 FungusOnDeadnematode HarposporiumAnguillulae, edited from Plantopedia, CC BY-SA 3.0
application
The deployment is very easy. All you have to do is follow the steps below:
1. Observe correct temperature: The beneficial insects may only be deployed when the soil temperature is above 12 degrees Celsius. Otherwise, the nematodes will not become sufficiently active to fight the vine weevil.
2. Loosen soil: In order for the animals to be able to penetrate the soil as quickly and deeply as possible, you should carefully loosen the soil in advance with a rake. Be careful not to damage the roots of the plant.
3. Avoid Sun: Full sun can have a negative effect on beneficial insects if they are directly exposed to it. They need a few hours to protect themselves from UV radiation underground. Therefore choose a cloudy day or the evening hours for application.
4. Best time: Depending on the activity of the larvae, it should be used between April and May and between August and September.
5. Keep the soil moist: Otherwise, the animals will dry out very quickly and will not be able to take action against the pests.
Tip: Repeat application every six to eight weeks for effective control of all larvae development stages. Due to the low cost, the pests are safely removed without putting too much strain on the budget.
combination
If you want to combat vine weevils, you should eliminate both the adult beetles and the larvae in a targeted manner. Collect the bugs from the plants and crush or smother them. This reduces the chance of laying eggs again. Bring in the nematodes at the same time to kill any larvae that are already there.
frequently asked Questions
Where can I buy nematodes?The purchase is possible both online and in specialist shops. Garden centers but also garden centers and hardware stores that offer plants are possible sources.
How long does it take for the roundworms to work?This depends on the extent of the infestation, the size of the area and the temperatures. Keep the soil consistently moist, but avoid overwatering. Also, calculate how long the plants will recover. Several weeks or even months must be planned before a visible improvement can be seen.
Why do nematodes need water?Otherwise they will dry out. In moist soil, they can also be more easily and thus more quickly effective and effectively combat vine weevil.