Attacking scale and mealybugs

My stag is sick. This is not code for anything rude or crude – my Staghorn Fern has scale.

After watching it suffer and becoming increasingly worried that it was on a downward spiral that couldn’t be stopped, I reached out for help.

It all started when I noticed the plant’s big beautiful leaves turning yellow and falling off. This didn’t happen all at once but over several months. Next, I noticed they were sticky. Fern fronds/leaves are generally not sticky. The final and most obvious clue was that I saw light brown, almost orangish, spots.

This is my first experience with scale. A quick google search told me they are an insect, not a plant disease. Yuck – I have an insect infestation on my stag. I quickly got passed being grossed out and knew I needed to take action.

Enter Josh Hamrick. The Huntington Museum of Art Conservatory Director helped calm my nerves and offered great information. First, he asked for before and current photos. I sent several; sorry about that Josh. After reassuring me, my stag was stronger and smarter than I suspected, he gave me steps to follow to handle the scale infestation.

If you think your plant has scale or mealybugs, which are both common with staghorns and treated in similar ways, you begin by pruning any damaged leaves. The good news is by shedding the sick fronds, the ones that were infected and yellow, my plant was starting to self-heal. So, there was no need for me to prune. It knew to get rid of those leaves so the younger, newer ones could survive.  

Next, it’s time to get up close with the scale. Mix a warm but not hot solution of Dawn dish soap and water. If your stag is mounted, it can be completely submerged in a large bucket or laundry sink filled with the soapy water, then the scale or mealies can be scraped off with your fingers.

My stag is potted and sits on a table, so he suggested I use a washcloth instead of dunking. Because the scale are easily removed if I’m thorough, I can probably get them all in one cleaning session. For mealybugs, this may need to be done several times because they are more mobile and like to hide in nooks that are easy to miss.

Be sure to rinse the plant to remove any soap residue. Hamrick tells me not to worry too much about thoroughly rinsing; Dawn is gentle on most plants and even offers a phosphorous boost. The Dawn will alter the water’s surface tension allowing it to pass into the insects’ respiratory organs, which basically drowns them. This cleaning may not kill them all, but combined with what are removed with the bath, it should get most.

The final step, and one that Hamrick recommends as a houseplant collector and conservatory director, is to give plants a shower. During the warmer months, when plants are moved outside, this happens naturally with rain or even being sprayed with a water hose. 

When the plant collections are brought inside, pests begin to thrive in the warm temperatures and low humidity, especially spider mites.

We know from experience that most plants are weaker indoors, making them less able to fight off pests on their own. Some pests are expected, but a quick shower will help remove not only insects but dust and remanent of air fresheners, candles, incense, and cigarette smoke from the plant.

This might mean literally placing several plants in the shower or laundry tub for a “spa day.” Be sure to use the spray hose or a spray bottle to reach the under the leaves. This works best for thirsty plants who need a good drink, otherwise, the plants could be overwatered.

If soap water sounds like too much, wiping the leaves with rubbing alcohol works. Use a 50-70% strength; anything higher may burn the sensitive or new leaves. This method works but is best done when the plant is well hydrated and you are able to keep it from bright sunlight until the alcohol is evaporated. It never hurts to add the shower to this regimen. Your plants will be happy.

Josh Hamrick has been working with the Huntington Museum since January 2022. He spent his first year working with Dr. Beck as Assistant Conservatory Director until Beck’s retirement in December. He is a West Virginia native who studied ecology/evolutionary biology and parks and recreation management at Marshall University. He has worked for the U.S. Forest Service in California, Casper Mountain Science School in Wyoming, and throughout the Mid-Atlantic and New England states while working on a traveling forest health monitoring crew with the National Park Service. All of this and several years working for the State of West Virginia.

Thank you, Josh. You were responsive and helpful to this panicked gardener, and my stag is on the mend and showing signs of new growth. The Museum is lucky to have such a talent continuing the care of the Conservatory. If you have not had a chance to visit, I encourage you to plan a few hours and treat yourself and a friend to a few hours discovering this gem tucked away in Huntington, West Virginia.