For dothistroma needle blight, it appears that a copper fungicide such as Monterey Liqui-Cop would be recommended to protect new needles from infection. There is also a guide below that might help:
When using
When using
Without knowing what disease you are treating for specifically we could not tell you if the Monterey Liqui-Cop would work on the problem you are facing on the Staghorn fern, or what would be the correct mixing rate or retreatment interval would be. You are welcome to try the suggested ornamental rate on the label which is 2 teaspoons per gallon of water, and reapply every 7-14 days to see if this helps. We highly recommend getting the disease properly identified so you can be sure you are treating correctly.
Per product
We recommend that you avoid applications of
