Vine Weevil Control

Vine weevils are common but destructive members of the beetle family. Adult vine weevils are flightless and nocturnal, and feed on the leaves of plants during spring and summer, with grubs feeding on the roots of plants causing significant damage during autumn and winter. 

They are relatively large beetles growing to around 1cm in length. The females lay hundreds of eggs making for substantial infestations in ornamental plants and fruits. They can be particularly damaging to plants grown in containers and are fond of herbaceous shrubs like rhododendrons and hydrangeas. 

Vine weevils are widespread across the UK and are quick to establish in gardens, nurseries and greenhouses. Whilst they can consume large amounts of foliage, adult vine weevils rarely impact the rigour of the plant. 

Identifying Vine Weevil Damage 

The vine weevil larvae however can destroy entire root systems, causing wilting at best or complete plant death at worse. 

Because the adult weevils tend to cause minimal damage to foliage, it can be difficult to detect when there is an infestation. Leaf edge ‘notching’ can be a sign that weevils are present – where the adults eat sections of leaves from the outer edges. 

Unexplained wilting – particularly in container plants - may also be an indicator that vine weevil larvae are present in the soil. 

What is Biological Vine Weevil Control  

Biological controls are non-chemical treatments that rely on the natural enemies of pests. In the case of vine weevil control, the enemy is the nematode, specifically, the species Steinernema kraussei and Heterorhabditis bacteriophora. 

Both these species of nematode are microscopic worms that actively seek out the vine weevil grubs, feeding and multiplying inside them, then infecting them with a bacterium. Once infected, the vine weevil will stop feeding and die. The nematode will then leave the dead vine weevil and go on to seek out more, repeating the cycle.  

Biological vine weevil control is a highly effective, safe treatment that can be used on turf as well as ornamentals. They are safe for pets and other wildlife and the perfect choice for organic gardeners. 

Agrigem offers two different nematode species for the control of vine weevil. Your choice will depend on the soil temperature as both species are highly effective at controlling the larval stages of black vine weevil and other weevil species. Either species can be applied to containers, open soil, beds, borders, and around trees and shrubs. 

Low Temperature Control 

Low temperature control can be used when the soil temperature is between 5°C and 30°C, making them ideal for use earlier in the growing season. This product contains the beneficial parasitic nematode Steinernema kraussei. 

Higher Temperature Control 

High temperature control should be used when the soil temperature is between 12°C and 30°C, making them ideal for later in the growing season. This product contains the beneficial parasitic nematode Heterorhabditis bacteriophora.  

How Many Nematodes Do I Need? 

We sell biological vine weevil control in packs that cover the following areas: 

• 12m²
• 50m²
• 100m²
• 500m²

There are millions of microscopic nematodes in each pack – carefully worked out to ensure accurate application for each specific area listed. Each application of nematodes will provide at least six weeks control of vine weevils. 

Nematodes are supplied as an easy-to-mix powder which needs to be diluted with water before use. Specific dilution rates are shown in the table below.  

How to Apply Biological Vine Weevil Control 

Apply to moist compost/soil using a watering can or sprayer. For both the high or low temperature nematodes: 

When to Apply Biological Vine Weevil Control 

You can apply Steinernema kraussei nematodes when the soil temperature is above 5°C and Heterorhabditis bacteriophora when the soil temperature is above 12°C. This gives broad scope of use from spring through to autumn. 

Nematodes are particularly effective in damp, wet weather. Try and choose a humid or wet day to apply the nematodes. They are UV-sensitive so it is best to avoid applying them on a bright sunny day as they will not survive in these conditions. The best humidity levels are often first thing in the morning or late afternoon.

Can I Store Nematodes? 

Nematodes are perishable and need to be applied quickly after delivery for best results. They can however be stored in the fridge for up to two days. Please note that delivery can take up to two weeks.