Monday, December 2, 2019

Those Poor Raphs...

Horticulture Hotline 12/02/19
By Bill Lamson-Scribner

Yes, once again, it is time for The Holiday Festival of Lights at James Island County Park. I know many of you are new to the area. This is a “must do” event. I have been to many other light shows and none of them have even come close. You have to experience it for yourself!

The grass is going dormant and the insects are moving deeper, so once again (do they ever slow down), the moles are very visible. Stop by a Possum’s for the three prone approach handout for the best results at controlling this pesky mammal.  

After all these years, the Indian Hawthorn, Raphs or Raphiolepis have been really suffering. Raphs have been plagued with leaf spot for years, and I’m always surprised to see them in a landscape especially a newer one. It seems like right after the Red Tips (Photinia) were virtually wiped out by Entomosporium leaf spot, the diseased began attacking the Indian Hawthorn.  Indian Hawthorn and Red Tips are in the same plant family as roses (Rosaceae). 

When dealing with a plant that is very susceptible to a leaf spot disease, I like to think of several different factors:
1.      Is this plant worth keeping in the landscape or should I replace it with another plant that is not susceptible to disease.
2.      Is this plant worth spraying ever 14 – 28 days to keep it in my landscape?  To keep an Indian Hawthorn alive, it needs a life-support system.  The plant must be sprayed at least monthly or it will get leaf spot again.
3.      What cultural practices can I do to help relieve the pressure of the disease?  The removal of fallen foliage (sanitation) is key when dealing with a leaf spot disease.  Having a healthy soil, as determined by a soil test, is also very important because a stressed plant is more susceptible to disease.  Providing the correct amount of water preferably through a drip system, so the plants are not over-watered or drought stressed.  Proper fertility as determined by the soil test is also important.  Use nitrogen fertilizer very sparingly in small amounts because flushes of new growth are more susceptible to leaf spot.  Choose “resistant” varieties such as “Olivia”.    This does not mean that this plant will never get this disease; it is just more resistant to the disease. If I was planting something new, I would stay away from any of the Raphiolepis plants and use something proven to be a little less maintenance. Mulch like Cotton Burr Compost will help prevent splashes of water drops that could spread the disease.  Also this mulch will lower the watering needs of the plants. Bioscience products like KeyPlex should be considered. KeyPlex will thicken the cuticle of the leaf making more resistant to the disease as well as more drought resistant. Pruning for good air movement.
4.      What control products will work best on this disease?  If you decide to spray, be prepared to spray often.  Honor Guard, Banner, Dithane (Mancozeb), and Kocide are good choices. These products should be used in rotation and according to label. I like the lime-sulfur idea or lime-copper spray for the reason that the original Lamson–Scribner invented this product in an effort to save the French wine crop in the late 1800’s. He called it Bordeaux mix (unfortunately Bordeaux mix is not available anymore). When spraying these chemicals, an appropriate surfactant should be used. Certain surfactants work better than others with particular products.

I’m in yards all the time and this disease is the most common disease I see in our Lowcountry landscape. I usually recommend replanting the area. I can understand spraying roses all the time. Indian Hawthorn – ah, not so much.

Always read, understand and follow product label. The product label is a Federal Law.

Bill Lamson-Scribner can be reached during the week at Possum’s Landscape and Pest Control Supply. Possum’s has three locations 481 Long Point Rd in Mt. Pleasant (971-9601), 3325 Business Circle in North Charleston (760-2600), or 606 Dupont Rd, in Charleston (766-1511). Bring your questions to a Possum’s location, or visit us at You can also call in your questions to “ The Garden Clinic”, Saturdays from noon to 1:00, on 1250 WTMA  (The Big Talker). The Horticulture Hotline is available 24 / 7 at