Rhodies

Asked March 9, 2015, 6:41 PM EDT

Hello! I noticed my Rhodies are looking beat up! They have small brown spots on the backs of the leaves and the leaves look all pale with larger brown-ringed holes on the front. I'm wondering what this could be! I also noticed similar brown flecks on my daffordils. Any ideas? You guys rock!

Multnomah County Oregon horticulture rhododendrons

3 Responses

Thank you for sending an image along with your question. It’s very likely that the shrub has been attacked by recently arrived invasive insects, azalea lace bugs, insects which specialize on azaleas and rhododendrons plus a few other plants. They don’t damage daffodils though. So, to diagnose their problem please send me an image or two. Please review “Azalea Lace Bug” -- http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/40424/em9066.pdf

Among the keys to successfully battling lace bugs are these:
- Stressed plants appear to be the most common victims. To relieve stress, thin out individual plants to increase aeration, and ease of applying sprays; irrigate every two weeks through our dry months for good health.

- The most effective time for the first spray of the season is right after the insects hatch, usually late April to mid-May, at which time the dark-colored nymphs (youngsters) are clustered on the undersides of the leaves. Youngsters are easier to kill than are adults. (See photo in the above publication.) They hatched earlier than usual this year. But continue to inspect the leaf undersides because 3 or more generations are expected during the growing season.

- Most of the suggested insecticides must thoroughly cover the undersides of the leaves where the insects hide. (See the list below.)
- Repeat spray applications are required during the growing season: June, July, August, with perhaps another in September.

- Don’t spray if the temperature is, or will be, above 80F.

Narrow-range horticultural oil can be applied in Nov/Dec to coat the undersides of the leaves where the eggs are laid in the leaf tissue alongside the midrib.


During the growing season, contact insecticides will temporarily control lace bugs if the product thoroughly coats the insects on the undersides of the leaves. Choose one, then repeat the spray according to label directions: Azadirachtin; insecticidal soap; neem oil, spinosad

Acephate and imidacloprid are several options among systemic pesticides. Follow label directions.

Encore azaleas have been shown to be tolerant of lace bugs in other regions but their value in the northwest remains to be seen.





Thank you so much, Jean! I'm so grateful for your response. Here are the pictures. Think it's those azalea bugs?

I don't see any of the insects in your images. However, the spots on the reverse of the leaves are telltale evidence that the insects were active in the past.