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Question
yellow dots on staghorn
yellow dots on staghor  
QUESTION: Why am I seeing yellow dots appear on my staghorn leaves older and younger leaves.

ANSWER: There could be many reasons for yellow dots to appear.  From the one photo you sent me, based on the location, shape, and distribution of the dots, it appears to be oedema (or edema).  This occurs when the plant undergoes dry / wet cycles.  If it dries to the point that it loses turgidity (becomes limp) then the re-hydration causes some cells to explode and die (those are the yellow ones).

The preventative measure is by maintaining constant moisture.  Though staghorns are very drought resistant and do not require frequent irrigation,  if they ever become limp or droopy then they are probably too dry.

Other potential causes may be pest related (look for scale under the leaf), fungus related, or nutrition related.  It is hard to ascertain without more information.  However, from the photo, the overall health of your plant looks very good.  So unless it appears to spread and become unsightly, I would not take further measures at this time.

Thanks for your question and feel free to follow up for additional or more detailed advice.

DC



---------- FOLLOW-UP ----------

QUESTION: I accept your answer as correct, as we have had lots of rainy days over the last several weeks in Dallas. I have the plant getting morning sun until around 1pm, shade the rest of th day. I am hoping that is not too much su? What fertilization should I he using on the plant?

Answer
Your plant will tell you if it is getting too much sun.  Check it at full noon.  If it looks droopy and unhappy, then it is getting too much sun!  From the photo, it does not look like it is.  But as I mentioned, the spots may be indicative of daytime stress with high sun and heat early and then late rain.

For Staghorns that are grown outside (under a tree), there is usually no need for additional fertilizer, as they can capture decomposing leaves, insects, etc.  Many people give their plant half a cut-up banana (wit the peel) in spring and fall (this is both a novelty and a useful natural way to assure potassium and other crucial nutrients).  If your staghorn in on a screened porch where it does not capture random organic debris, I would suggest feeding twice a year with a couple of tablespoons of any multi-purpose commercial fertilizer.  Just spread the granules in the crown and root zones of the plant, not all in one place.

Best of success!

DC  

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Dan Carmi

Expertise

I can answer all types of questions regarding ferns: their physiology, life cycle, taxonomy, culture (for both the professional and hobbyist), home and garden application and care, site suitability, and more. I can also answer questions in the fields of greenhouse production, foliage plants, and houseplant care, along with questions in the general field of ornamental horticulture. I may be able to identify fern and foliage plants by photo, but I am unlikely to be able to do it by description (though I will never turn down a challenge). I am not an expert in crop, field, and agronomic production. I am not an expert on annuals, perennials, tree & shrub crops.

Experience

I am a horticulturist with a formal education and twelve years experience in commercial fern and tropical foliage production. I also served as Adjunct Professor of Horticulture at Florida Southern College.

Organizations
Florida's Nursery Growers and Landscape Association: current member and Action Chapter Board Member 2006-2008.

Education/Credentials
I have a BSc in Environmental Horticulture / Business from Florida Southern College, specializing in Greenhouse Management and Production.

Awards and Honors
FNGLA Action Chapter President's Award 2006-2007, numerous academic awards 2001-2005.

Past/Present Clients
Through my place of employment, I serve hundreds of commercial growers across the country and beyond.

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