ORNAMENTALS AND TURF

From: Steve Frank, Extension Entomologist

Rose Sawflies

I found these sawflies on knockout roses this week in Georgia. I also found some on my roses in Raleigh that were slightly smaller. They are probably the curled rose sawfly, Allantus cinctus, but I am waiting on a positive identification. In any case you can look for damage to leaves by these and other sawflies. Small larvae typically skeletonize the leaves. Larger larvae consume entire leaves. Scout for this damage and also for feces which are a sure sign of something feeding on your plants. If infestations are large a contact insecticides such as a pyrethroid or acephate can be applied. Conserve is also labeled for sawflies. Small infestations in home landscapes could be managed with horticultural oil or insecticidal soap.

Tiny rose sawfly larva on knockout rose leaf. Photo: S. D. Frank.

Azalea Lace Bugs

Azalea lace bugs (Stephanitis pyrioides) are one of the most damaging pests of evergreen azaleas. They overwinter as eggs in azalea leaves and begin hatching in Spring. This is actually late compared to some other years, but I found the very first ones yesterday. I found them near HVAC units that blow hot air behind our administration building. This is my monitoring spot for azalea lace bugs because they always hatch here first. In addition the high temperature always leads to greater abundance and damage, too. This is a great example of how high temperature increases advances pestphenology and increases development rate leading to more generations per year.

Azaleas planted next to HVAC equipment that blow hot air. The azaleas always get lace bugs first and worst. Photo: S. D. Frank.

Control is best targeted early in the season when nymphs are present for two reasons. First, nymphs are easier to kill than adults and if you kill nymphs before they mature and lay eggs you have a better chance of clearing up the infestation. Second, the longer azalea lace bugs are on your plant the more damage they do. On evergreen azaleas this damage sticks around for a long time so plants may be permanently damaged. So scout your azaleas and get those lace bugs cleared up before damage occurs. 

Photo: S. D. Frank.

Juniper Scale Crawlers are Active

Juniper scale, Carulaspis juniper, attacks some of the most commonly used plants in ornamental landscapes including all Juniper species, but also cypress species and false cypress. There is one generation per year in which females fill up their armored cover with eggs in spring from which crawlers hatch and look for new feeding sites. Infestations can lead to foliage that becomes yellow or brown and generally less lustrous than normal. Large infestations can cause the tips of branches to die and the plant to become sparsely foliated. Isolated infestations can be pruned off of plants. Natural enemies will often keep scale below damaging thresholds. However, in environments where natural enemies are not abundant control may be necessary. Horticultural oil will smother crawlers. Other chemicals such as dinotefuran (Safari), acetamiprid (TriStar), and pyroproxifen (Distance) and others can be used to manage infestations. More information on armored scale management can be found at:http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/note157/note157.html.

Heavy infestation of juniper scale on Leyland cypress. Adult females are white and round with a yellow center and resemble a fried egg. Photo: S. D. Frank.

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.