The caterpillar challenge facing UK horticulture

A growing problem that growers can't afford to ignore

If you've been working in UK horticulture for any length of time, you'll know that caterpillars are rarely far from the conversation. Whether it's the tell-tale ragged holes in leaves, skeletonised foliage, or the frustration of a crop that looked fine on Monday and looks very different on Friday, the damage caused by Lepidoptera larvae is a challenge that growers across the country have to deal with season after season.

The range of species that affect ornamental crops in the UK is wide. Caterpillars from species including angle shades moth, carnation tortrix, and various noctuid moths regularly cause damage to a broad range of pot and bedding plants. And with the milder winters becoming more common than in previous years, the pressure isn't always confined to the warmest months, coupled with populations not naturally controlled in winter with lower temperatures.

Limited options, increasing pressure

For professional growers, the challenge isn't just identifying the pest - it's having the right tools to deal with it effectively. The UK has a relatively narrow range of approved insecticides for caterpillar control in ornamentals, and options with genuinely systemic or long-lasting activity have historically been in short supply.

Many products available offer contact activity, which requires precise timing and thorough coverage to be effective - and in a busy nursery environment, that isn't always straightforward. Biological controls such as Bacillus thuringiensis (Bt) have a role to play in IPM programmes, but they come with their own limitations: narrow windows of activity, sensitivity to environmental conditions, and a need for repeat applications. For high-pressure situations or where populations are already established, growers need something more robust. Add to this the growing pressure on resistance management - rotating modes of action to prevent caterpillar populations from adapting - and it becomes clear that having a diverse toolbox is not just beneficial, it's essential.

The need for a new solution

With more species to contend with, tighter margins, and higher consumer expectations for quality, growers need products that work quickly, last well, and fit into responsible pest management programmes. What the UK ornamentals sector has been missing is a product that combines fast action with residual protection, and that can be used with confidence within an IPM strategy.

That's about to change. Sempliance, a new insecticide from Syngenta, brings a new mode of action and a fresh approach to caterpillar control for ornamental growers.  

--- Sempliance is approved for use on ornamental plants grown in pots greater than 10cm in diameter in Great Britain and Northern Ireland. Always read the label before use.