Mountain laurel is a pretty flowering shrub that zone 5 through 9 gardeners like to use for screening, borders, and other yard elements. Unfortunately, there are a number of pests of mountain laurel that you will have to contend with if you want to grow this beautiful shrub.
This shrub is a great plant for shady yards and forest gardens, but there are a few bugs that eat mountain laurel. Be aware of all the possible mountain laurel insects that may infest so that you can take steps to prevent and manage as needed:
Lace bug – If you see pale, mottled discoloration on your mountain laurel’s leaves, it may be lace bug that is sucking the sap out of them. This is one of the most common of mountain laurel insects and is small and square shaped.
Weevil – Weevil larvae attack the roots of mountain laurel, which causes the leaves to turn yellow first, and ultimately the leaves and branches to die. The adult bugs fed on the leaves, leaving notches along the edges.
Rhododendron borer – This is a small, pale larva that bores into stems and overwinters there. The boring damages stems and leaves scars. You may also see little piles of sawdust where they have entered a stem.
Mulberry whitefly – Whitefly nymphs may infest the undersides of your mountain laurel leaves, so turn them over to check for infestation. Whiteflies are sap-sucking insects that quickly stress plants in large numbers.
To manage pests on your mountain laurel, start by giving it the best growing conditions; a healthy plant will be better able to resist pests and damage. Use compost in the soil, but don’t apply too much fertilizer. Keep it well watered during the growing season, using mulch to retain moisture.
If you see signs of pests, there are some steps you can take to manage infestations. Lace bugs are often easy to spot, and you can remove these manually for minor infestations. For a bigger problem, use an insecticide on the affected leaves. Whitefly control usually requires use of an insecticide.
For weevils, which drop from leaves when disturbed, you can lay down a cloth, shake the branches of the shrub, and collect the fallen insects. You can also use a plant barrier like tanglefoot to keep adult weevils from climbing up to eat the leaves. To manage larvae at the roots, use a pathogenic nematode or an appropriate pesticide.
To manage a borer infestation, kill the larvae in their bore holes. You can do this manually with a hook or knife, or you can inject an insecticide into the holes you find with sawdust beneath them. Seriously damaged stems should be removed and burned. Adult borers can be caught with a black light trap.
Note: Any recommendations pertaining to the use of chemicals are for informational purposes only. Chemical control should only be used as a last resort, as organic approaches are safer and more environmentally friendly.
What causes little brown spots on the shrub?
This is likely fungal leaf spots.
Symptoms generally appear in summer but will remain on the plant through winter and can still be appearing in spring.
Leaf blights also cause browning leaf patterns, they differ in that the spots will forms together and the entire leaf will turn brown and drop.
Control is generally with good care and sanitation.
Clean up any dropped leaves and discard of. This helps the spores from spreading.
Good care of the shrub with proper sunlight, air circulation, and fertilizer schedule will help manage these diseases.
Chemical treatment is generally not necessary, but a fungicide can be applied.
|Plant Habit:||Shrub |
|Life cycle:||Perennial |
|Sun Requirements:||Full Sun |
Full Sun to Partial Shade
Partial or Dappled Shade
Partial Shade to Full Shade
|Water Preferences:||Mesic |
|Soil pH Preferences:||Very strongly acid (4.5 – 5.0) |
Strongly acid (5.1 – 5.5)
Moderately acid (5.6 – 6.0)
Slightly acid (6.1 – 6.5)
|Minimum cold hardiness:||Zone 4a -34.4 °C (-30 °F) to -31.7 °C (-25 °F) |
|Maximum recommended zone:||Zone 9b |
|Plant Height :||5 to 15 feet (1.5-4.5m)|
|Plant Spread :||5 to 15 feet (1.5-4.5m)|
|Fruiting Time:||Late summer or early fall |
Late fall or early winter
Blooms on old wood
|Flower Color:||Pink |
|Bloom Size:||1"-2" |
|Flower Time:||Spring |
|Uses:||Will Naturalize |
|Wildlife Attractant:||Bees |
|Toxicity:||Other: All parts of plant are toxic. |
|Propagation: Other methods:||Cuttings: Stem |
The Common Mountainlaurel has a native range from southern Maine down to northwest Florida, most of Alabama, parts of Mississippi, much of Kentucky & Tennessee, and eastern & southern Ohio, in swamps, meadows, and upland woods in acid soils ranging from draining wet to dry. It is slow growing of about half to 1 foot/year. It has smooth, glossy, leathery leaves about 3 to 4 inches long, borne alternately or in whorls. It bears white to pink star-like or bell-shaped or bowl-shaped flowers in flat-topped large terminal clusters in June with a nice fragrant scent. It bears little dry, brown fruits of 5-valved capsules from September until March. It has a brown to red-brown scaly-furrowed bark much like Pieris. It has a dense, shallow, fibrous root system and is easy to transplant. It is sold many nurseries in the East and some in the Midwest. In landscapes it can do well if it is planted in a shrub border or bed with mulch around it and shelter from winds, heat, and drought. I've seen a good number do poorly and even die out in landscapes in its native range because of some bad factor. It can be temperamental.
Connecticut and Pennsylvania's state flower.
"How to Know the Wildflowers" (1922) by Mrs. William Starr Dana has a lot of interesting information about this plant. First, as to its name, Kalmia was named by Linnaeus after Peter Kalm, one of his pupils. Another name for the plant, Spoonwood, came from its use by the Indians for making eating utensils. It is said that the wood is of fine grain and takes a good polish. The name Calico Bush may have come from the markings of the corolla which might suggest the cheap cotton prints sold in stores.
The shrub was highly prized and carefully cultivated in England. According to the author, Barewood Gardens (then the home of the editor of the London Times) was celebrated for its specimens. The English papers would announce the flowering season and the estate would open for visitors to come view the flowers. The author apparently had trouble convincing the head gardener of the estate that in parts of America, "the waste hillsides were brilliant with its beauty every June."
The author also points out that this is not the laurel of the ancients which was a symbol of victory and fame, although its leaves are similar in appearance. The leaves of Kalmia latifolia were said to be poisonous and supposedly used by the Indians for suicidal purposes. There was also a popular belief that the flesh of a partridge that had fed upon its fruit would become poisonous.