I have scale on my staghorn fern. So far I have been able to keep up with them but is there any other systemic or spray that will work?
Scale insects are the most common pest on a staghorn fern. Our preferred treatment is denatured alcohol applied with a fine brush directly to the insects on the undersides of the fronds. The brown shells on the scale insects protect the from most sprays, but the alcohol may work and if not, manual removal followed by a coating of the whole plant with a malathion spray to resist re-infestation.
If the plant is too badly infested and the leaves are turning yellow, eradication may be impossible.
Courtesy of NYBG Plant Information