Staghorn Fern with black spot and yellowing leaves

[RikoAus]

 

  

 

Hi all,

I am a newbie starting out in gardening. Recently I obtained three Staghorn Ferns and I’ve board mounted them two weeks ago. Just last week I start to notice black spot on the staghorn looking leaves and they are spreading. One of the leave started to yellow and today it seems the black spots have taken over the entire leave.

After reading some online post, it appears my stags are infected with fungi. I’ve purchased the Hortico Insect + Disease control (roses and flower) to treat the black spots. I’ve also cut down my watering, only misting the stag last weekend and the sphagnum moss now feels dry. 

Should I

1) cut away the really infected leaves?

2) cut away any leave that shows even a small sign of black spot to prevent the spread

3) switch to another fungicide ?
4) resume the watering? 

I am also wondering the part the leaves are growing out from the base appears to be dark brown/black, are they normal sign for a stag?

thanks for reading this far and I look forward to the responses. 

Regards,

Dave

[MitchellMc]

Welcome to the Bunnings Workshop community Dave (@RikoAus). It's brilliant to have you join us, and many thanks for your question about a disease on Stag horns.

I recommend removing the affected leaves, then bag them and placing them in the hard rubbish bin. Give this fungicide a chance to work. Only water the sphagnum and not the leaves. It's fine to mist the leaves a healthy Stag horn, but if a disease is present, I'd refrain from it.

You should probably also isolate the plant to reduce the chances of the disease spreading to your other one.

Let me mention a couple of our horticulturalists, @Noelle and @Adam_W, to get their thoughts.

Mitchell
 

[Noelle]

Hi @RikoAus 

I agree with Mitchell's recommendations especially regarding the watering. The blackening of the 'shield' from which the leaves arise is an indication that the sphagnum moss has been kept too moist. It looks like, from your photos, that you have put quite a lot of sphagnum behind each plant. Only a very small amount is needed - just enough to provide some moisture while the plants establish and attach themselves to the backing boards but not enough to cause issues like rotting and fungal infections.

The plants would benefit from removing quite a bit of the sphagnum, tightening the ties if needed and leaving only a small cavity behind each into which you can place banana skins and other compostible materials that will break down and provide some nourishment for the staghorns, without holding too much moisture.

As the ferns grow, observe the fishing line ties to ensure they are not cutting into the shield - pantihose or a soft and wider material tie would be preferable to minimise potential damage. In time, the ties can be removed entirely.