The War Against Vine-Weevils
What are Vine Weevils?
The Vine weevil is a beetle that attacks a wide range of plants, both indoors and outdoors, but is especially damaging to plants grown in containers which is why nurseries come under threat. The adult weevils (which are approx 9mm in length) eat leaves during spring and summer, but it is the white, legless grubs (approx 10mm in length) that can cause the most damage over autumn and winter when they feed on plant roots. This damage can result in wilting and plant death. Plants growing in pots and containers, outdoors or under cover, are most likely to be severely damaged by vine weevil grubs.
What are Nematodes?
On our nurseries we tackle vine weevils with Nematodes. They are a commonly used biological control for many plant pests which are watered into pots, trays or open ground. Parasitic nematodes (which are microscopic but resemble worms) seek out suitable hosts by swimming in the thin film of water on soil particles, locating hosts by detecting carbon dioxide and other waste products. Once they find a host, they enter the body cavity and release bacteria (Xenorhabdus). The bacteria kills the host within hours, and the nematodes grow and reproduce within the ‘broth’, which they produce (disgusting we know!). The next generation of juveniles leaves the dead host, and then move in search of fresh hosts. Infected hosts become brown and flaccid, but once dead can be difficult to find in soil. The nematodes can live for 4-5 weeks in the ground.
We apply different types of Nematodes dependant on weather conditions:
• Biobest – Steinernema kraussei (Kraussei system) – cold weather use
• Biobest – Heterorhabditis bacteriophora (B green) – warm weather use
• Nemasys H (Heterorhabitis spp.) From Fargro – warm weather use
They are applied at different times of the year as below:
• March / April and November / December – to kill Larva
• April / May and August through to November – to kill Larva
• April – June – to Kill pupa
Advantages of Nematodes:
• Safe application for user as non-toxic to humans
• Consistent control through extended use
• Reduces amounts of chemicals used on our nurseries
• Fast and effective
Thanks for reading, if you have any questions about this post, or about the products we offer, don’t hesitate to get in touch!