Pest Control for Indoor Ferns
The most important method of control, particularly if you intend to use mechanical and biological remedies, is the early recognition of pests.
Once the entire plant is covered in scale insects, it will be very difficult to gather them all by hand without merely spreading some of the young insects, Once spider mite colonies have become established over the entire plant and have formed dense webs, predatory mites will never gain the upper hand. With ferns that are cheap to buy and commonly available on the market, you should probably consider whether it is worth your while using plant protection agents or large amounts of your own time and energy in combating pests rather then simply discarding that particular plant and replacing it with a healthy one. However, once you have decided to attempt the rescue of a much-loved specimen or a precious older plant, you should carry out the treatment rigorously in order to prevent renewed infestation.
The appearance, symptoms and control of the five most frequently occurring pests in ferns are summarised in the table on the right. In addition to these pests, leaf blotch eelworm may occasionally occur and, in small, conservatories or glass cases, you may come across the occasional slugs and snails.
Leaf blotch eelworm: You will recognize an infestation by the dark brown to black patches on leaves that are clearly delimited by the leaf veins. Cut off infested fronds and if the symptoms persist, destroy the entire plant.
Slugs and snails: Usually, they only eat the leaves at night. Inthey scrape off the undersides of the leaves and allow the upper-side to remain as a transparent layer. Slugs and snails that eat ferns do not leave behind any tell-tale slime trails so proof of their presence is not always obvious. Collect the snails early in the morning or stand small dishes filled with beer around your plants.
The most common pests on indoor ferns :
Aphids mainly infest young shoots and rob them of nutrients by sucking the sap from them. This results in poor growth and crippled leaves. The honeydew excreted by the aphids may lead to an infestation with sooty mould fungus.
Remedy: Rinse the aphids off with water; employ useful predatory insects or biological or chemical agents.
Gnats (Diptera, Sciaridae)
These are small, black gnats that run across the surface of the compost and fly up when you water. The larvae live in the compost and eat the roots. Infestation is encouraged by water-logging.
Remedy: Catch the gnats by hand or with the help of yellow tags; avoid water-logging; ensure adequate ventilation.
Symptoms are silvery, shiny patches and black excrement on the leaves. The insects are rarely visible as they live on the undersides of leaves and in other sheltered places and are very quick. They damage the plants by sucking the sap.
Remedy: Use useful predatory insects or chemical plant protection agents.
Symptoms are brown-scaled insects on leaves, stalks and rhizomes. They rob the plant of nutrients and cause disturbances in growth. Colonies of sooty mould fungus appear on the excreted honeydew.
Remedy: Scratch off the insects; treat with synthetic insecticides or with tar oil.
Minute spider-like creatures, mostly on the undersides of leaves. Yellow patches will appear on the leaves. Dense webs with heavy infestation are encouraged by too low humidity and too warm a position.
Remedy: Employ useful insects; spray with biological plant protection agents or synthetic acaricides.