Get one step ahead of vine weevil – plan now

It’s that time of year again, planning for the 2025 season is well underway and growers are working to get ahead while they still have a little bit of precious time on their hands. As such, it’s the perfect time to start thinking about how to control vine weevil on your nursery this season.

In the past, it was generally easier to control this devastating pest with chemical control options that were both long lasting and highly effective. While we now have an effective growing media incorporated bioinsecticide Lalguard M52, it is part of the overall solution – we still need to plan a robust IPM programme to keep vine weevil successfully under control.   

Vine Weevil Larvae

Which nematode?

There are two species of beneficial nematodes predominantly used for controlling vine weevil larvae, Heterorhabditis bacteriophora – Vine Weevil Seeka, and Steinernema kraussei – Vine Weevil Seeka CT.  While both are highly effective, it’s important to know the pros and cons.

Seeka works best at temperatures above 12°C, while Seeka CT (cold tolerant) continues to work well down to 5°C, but costs slightly more. When applied correctly, both can be super effective. However, it is a numbers game (beneficial nematodes vs larvae), so doubling up applications on the most vulnerable crops is a good strategy to follow.

Vine weevil favourites

Attracted to a wide range of plants, the vine weevil adults favour species such as Euonymus, Rhododendrons, Heuchera, Sedums and Cyclamen. Knowing this, Seeka applications can be targeted more effectively – ie potential hotspots treated more than once.

While the adult beetles home in on their favourites, they also feed and move through less desirable crops, indiscriminately laying eggs.  So, while targeting hotspots, it is strongly advisable to treat every plant on your nursery, particularly when you consider a single beetle can lay over 500 eggs.

We can now start to plan our season-long programme.

In outdoor grown crops, March* is the perfect time to start targeting over wintered larvae with the first application of the cold tolerant Seeka CT (>5°C).  Given average minimum March temperatures are around 6°C, we recommend applying Seeka CT in mid to late March, targeting susceptible crops.

In April*, when temperatures have risen sufficiently, switch to the more cost-effective Seeka (>12°C) making sure to apply it to every plant on the nursery.

Conversely in autumn, when the newly laid eggs start to hatch, make a broad application of Seeka (>12°C) in early September*, ideally treating all plants on the nursery.

Then, as temperatures fall in October*, apply Seeka CT (>5°C) to highly susceptible species.

Get one step ahead

So, to programme in your vine weevil control programme for the season ahead, speak to your Technical Area Sales Manager now.

*Intended as approximate guide – check growing media temperatures. 

Please note: In heated crops, vine weevil larvae can be present at any time of year.  If applying Seeka in warm months, maintain pot moisture levels and apply on dull days. Nematodes are extremely UV light sensitive and require moisture.