Water Garden Plant Diseases and Pests

Water Garden Plant Diseases and Pests

If they are planted in the correct positions, pond plants are only rarely infested with diseases and pests.



Powdery mildew can occasionally be observed. It likes to infest shrubs around the edge of the pond, for example meadowsweet (see p. 42). Plants which are growing in a position that is too dry are more likely to be affected. The proximity of other plants susceptible to mildew, like roses, may provoke infestation. Only complete removal of the infested plants will serve in a case of serious attack, so that other plants do not become infested too.


Water-Garden-Plant-Diseases-and-Pests Iris rust

Iris rust (Puccinia iridae) is a fungus which attacks certain Iris species. This fungus forms yellow-orange spots on the leaves. The species most likely to be infested are those that prefer a moist position and are being grown in a dry one. The best procedure is to destroy the infested plants and to plant new ones in a more favourable position.



Various water butterfly may prove unwelcome guests around a pond as hungry caterpillars• can cause considerable damage to water-lilies. They bite shield-shaped pieces out of the edges of water-lily leaves and build a cocoon in which the larvae pupate until metamorphosing into their adult form. The marks of their voracious feeding are clearly visible on the water-lily leaves. Healthy water-lilies can cope with these parasites. If they should get out of hand, however, simply collect the caterpillars or cocoons by hand or remove the eaten leaves. Please do not use any pest control agents as they are very toxic and would damage the pond.


Galerucella nymphaea

Another pest that attacks water-lily is Galerucella nymphaea. This beetle is dark brown and about 1 — 2 cm (1/2 — 3/4  in) long. It lives along the edge of the pond and eats various pond plants but lays its eggs only on water-lily leaves. The larvae create tunnels in the leaves but there is rarely much damage and the beetle generally appears only in large colonies of water-lilies. In a garden pond, it is a simple matter to collect the beetles and larvae by hand.


Slugs and snails

Garden slugs and snails are ancient enemies which will sometimes penetrate the marginal zone of a pond. They will keep away if the marginal zone is kept consistently moist and will hardly ever inflict much damage along the edge of the pond. If they get out of control, simply collect them by hand. Never use toxic slug pellets or any similar product which might end up in the pond.


If frogs, toads or newts decide to make a home in or around your pond, you will find that they are a great help in keeping down the insects and other undesirable pests — but not, of course, if you fill the water with poisons!

12. December 2010 by admin
Categories: Disease Control, Pest Control, Water Features | Tags: | Comments Off on Water Garden Plant Diseases and Pests


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