ORNAMENTALS AND TURF
From: Steve Frank, Extension Entomologist
Gloomy Scale Crawlers are Active
Gloomy scale, Melanaspis tenebricosa, is an armored scale that is found on maples and other tree species. It becomes very abundant on landscape maples and can cause branch dieback and tree death in some cases. It is not unusual to find trees with nearly 100% of their trunk covered in scale. Street trees are particularly prone to gloomy scale. I have never found one that didn’t have it! Crawlers of this scale are active now and can be seen on bark and under scale covers. Control of this scale is complicated be-cause crawlers emerge over 6 to 8 weeks so it is impossible to treat all the crawlers at once with horticultural oil or other contact insecticide. This is as opposed to scale such as euonymus scale in which all crawlers are produced within a narrow window of two weeks or so. However, horticultural oil can still be applied to kill gloomy scale. We have tested several products against gloomy scale with mixed results. None provides consistent high levels of control. Products including Safari, TriStar, and Distance can provide some suppression. It is important to note that imidacloprid (e.g., Merit) is not effective on armored scale. More information on armored scale control can be found here (http://www.ces.ncsu.edu/
Gloomy scale on a maple branch. Photo: Steve Frank.
Crapemyrtle Aphids
Crapemyrtle aphids are one of the most common pests of crape myrtle, but rarely require treatment. Small populations are present in Raleigh and have been building over the past couple weeks. Feedings by these aphids result in leaf yellowing and distortion, leaf drop, and honeydew deposits which of course lead to sooty mold. Crapemyrtle aphids are generally kept in check by natural enemies. When scouting for them I often find almost as many lacewing eggs, lady bug larvae, and other predators as aphids. Interestingly, there are no known parasitoids of this exotic aphid. A variety of chemicals are available should these aphids reach unacceptable levels in nurseries or landscapes. Some of the same chemicals recommended for aphids such as imidacloprid can be applied as a drench to protect against Japanese beetles later in the year. For more information on this pest including control options, visit http://ecoipm.com/ and Ornamentals and Turf Insect Note ENT/ort-31 at http://www.ces.ncsu.edu/depts/
For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.
