Fern Pests and Diseases
Due to the delicate nature of most ferns, one has to be most careful in selecting chemicals or other methods of control for pests and diseases. A good growing environment, producing strong plants, will do much to reduce the incidence of fungal or insect attack.
These can be a considerable nuisance and spoil the appearance of the plants, particularly by the sooty mould which grows on the excreta left by them on the fronds. The best time to deal with these is when the young scale-insects emerge from the parent scale case and search for a suitable feeding spot. Derris liquid (Rotenone) can be used without harm, but a more beneficial preparation is diazinon, on, member of the organophosphorous group of chemicals, which gives a much better degree of success. During the winter months one or two applications of malathion mixed with diazinon in equal proportions will control scale insect.
Can be controlled by spraying with diazinon and malathion.
Mainly appear on Adiantum. Providing no young growth in the pink unfolding stage is present, nicotine shreds may be used as a fumigant, but care must be taken in its use, and rare specimens should not be exposed to the fumes, unless previously known to tolerate the treatment without damage. Diazinon and malathion must not be used on Adiantum.
Slugs and snails
These can be very destructive. A liquid slug-killer applied to benches and staging will give some protection, and slug pellets can be broken and placed in each pot or container.
These are particularly fond of the fern-ally Lycopodium, and eat the centres of the growing spikes, causing them to become blind. Baits can be tried, but general cleanliness is very important.
Glasshouse red spider mite
Although not a prevalent pest of ferns, this does occur and usually can be controlled with diazinon.
This is the main fungal attacker. It causes a lot of harm, and again the Adiantum group suffers most from its ravages if conditions are overcrowded or the atmosphere stagnant. Good plant husbandry should keep the effects of this to a minimum, but if persistent a spray of Benlate may be used.
The frond eelworm
Turns the fronds black. Adiantum again susceptible. These should never be watered from overhead, as this will cause the eelworm to spread rapidly. Badly infected fronds should be cut off and burnt.