Long-lasting Vine Weevil control strategy

For long-lasting protection from black vine weevil, pre-incorporate Lalguard M52 GR into mixes early, is the advice from Sam Rivers, ICL technical manager for controls.

“Left unmanaged, black vine weevil populations can increase rapidly in a single season, causing serious damage to nursery stock,” he warns.  “We recommend a robust IPM strategy combining cultural controls, carefully timed applications of Seeka beneficial nematodes and incorporating the biopesticide Lalguard M52 GR into mixes.”

Persistent spores germinate at 12°C

Based on spores of the soil-dwelling, insect-pathogenic fungus Metarhizium brunneum strain Ma43, Lalguard M52 GR acts by contact, infecting the vine weevil larvae directly. When incorporated into growing media during cooler periods, the spores persist and can still adhere to vine weevil larvae.

“While optimal performance occurs between 15–30°C, the Metarhizium spores start germinating as low as 12°C – delivering reliable, long-lasting protection,” says Sam.

“As spring approaches, overwintered vine weevil larvae begin pupating into adults and, shortly after, egg laying starts.* Lalguard M52 GR spores lie in wait, infecting the new larvae on contact – with mortality occurring within as little as three days, depending on the temperature and larval stage. Importantly, eggs and pupae also show some susceptibility, enhancing overall control.”

When temperatures dip below 12°C

During cooler periods, when temperatures dip below 12°C, the Lalguard spores remain dormant in the background waiting for temperatures to rise.  However, the beneficial nematode Steinernema kraussei (Vine Weevil Seeka CT) can be used in this period, providing reliable control down to 5°C growing media temperature.

Getting the best results

“For best results, Lalguard M52 GR needs to be thoroughly mixed into the substrate to help break the spores from the carrier and ensure even distribution throughout,” says Sam. “For ease of use, it can be pre-incorporated into bespoke Levington Advance mixes, reducing on-site labour and handling.

“Fully compatible with beneficial nematodes, Lalguard M52 GR is organically certified and now firmly established as a cornerstone of effective vine weevil IPM programmes.”

To discuss vine weevil control and plan a robust IPM strategy for the season ahead, contact your local ICL Technical Area Sales Manager.

*all lifecycle stages can be found at any one time in heated glasshouses at +12°C.