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Vulnerable Plants in Your Garden

By: Dr Gareth Evans - Updated: 24 Nov 2012 | comments*Discuss
Pests Fuchsias Hostas Roses Aphids Rust

In the natural world, if there’s a potential free meal going begging, something will always come along to take up the offer. The bottom line is, if it can be eaten, sooner or later, it will be, so present the small army of insect and other pests that lurk in the wild with a well stocked garden and it’s only a matter of time before the chewing starts!

While nothing is safe from their attentions, some kinds of plants are notoriously vulnerable, seeming to act almost like a magnet to attract unwanted visitors to their tender leaves, sap-filled stems or succulent roots. Here’s a quick guide to a few of the most commonly grown and popular varieties that often need a little extra protection, and the threats to look out for to keep them at their best.

Flowers and Ornamental Plants

Lush leaves and tender flower buds offer a ready-made feast for a wide range of pests, and some of our most striking garden favourites are just too tempting to resist.
  • Fuchsias – once they are established, fuchsias tend to be fairly problem-free, but in the early days they are prone to a number of pests and diseases – notably whitefly, so pay particular attention to the undersides of their leaves. A bad infestation can severely damage young, tender plants.
  • Hostas – say “hostas” and slugs and snails have to be your next thought. They simply cannot resist the lush, plump leaves of these beautiful, damp-loving plants, so unless you like hostas with more holes than a Swiss Cheese Plant, effective mollusc control is a must!
  • Michaelmas Daisies – keep an eye out for raised orange/brown spots on the leaves as the first sign of rust; pick off any you do see and use a high potash fertiliser to encourage the new growth. In warm and dry weather, powdery mildew can also become a nuisance – so don’t overcrowd your plants and make sure you keep them properly watered to reduce the threat.
  • Roses – as popular with aphids as much as people, so keep a careful eye out for them and treat accordingly. Black spot is another problem to watch out for – large black/purple spots on leaves and stems which can stunt leaves and severely weaken the plant in serious cases. All varieties and kinds of rose are susceptible to black spot, but fortunately specific treatments are widely available.


Any pest that is named after a particular plant has to be a big giveaway – and when it comes to vegetables, there are plenty that are!
  • Beetroots – watch your plants from May onwards for small leaf blisters, which spread and ultimately turn brown and shrivel. These are the work of Beet Leaf Miners, also known as Mangold Flies, and can seriously retard young plants, so remove any damaged leaves and spray with a suitable insecticide to safeguard your crop.
  • Cabbages – caterpillars come to mind, of course, and between the larvae of the Small Cabbage White, the Large Cabbage White and the Cabbage Moth, it’s a wonder there’s anything left for the Cabbage Root Fly. Big ragged holes in the leaves are an obvious giveaway for the caterpillars, while bluish-tinged leaves that wilt far too readily in the sun suggest the work of the fly.
  • Carrots – the Carrot Fly is the only real pest of these plants, but what a serious nuisance it can be! The big clue to an infestation is a reddish tinge appearing on the leaves and a plant which wilts quickly in the sun. Below ground, holes will be noticeable in the carrot itself as the fly maggots bore into the tissue, often leaving the way open for infections such as the carrot canker fungus to take hold. There are no pesticide treatments available for this problem, so prevention is the only option. Covering the crop in fleece and delaying or avoiding thinning-out can help, and some varieties are now being bred that are partially resistant.
  • Leeks – tunnelling through the tender inside, the Leek Moth’s larvae produce a plant that’s covered in whitish scars as the leaves unfurl, before burrowing down into the body of the leek as they get older, where they can cause extensive damage. Originally more of a problem on the continent of Europe, they are now making much more of a nuisance of themselves in the UK, where there can breed two generations in a year. This is a growing problem for British gardeners and certainly something to keep in mind.
Despite all the hungry little devils just waiting to make a meal of your garden favourites – don’t despair. Vigilance is a major weapon in the ongoing struggle to control pests and knowing what to look for is nine-tenths of the battle and help is at hand. If you do spot any of these signs and symptoms in your own plants, there are plenty of suggestions to be found in the relevant sections of the rest of this site and treatments a-plenty available at garden centres, DIY shops and elsewhere, once you know what you need.

When it comes to protecting your most vulnerable plants, forewarned is definitely forearmed!

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