Pittosporum psyllid in NC

Another new pests has turned up around Wilmington, NC. This one on an exotic

Adult Cacopsylla tibiae and characteristic damage to pittosporum. Photo: Matt Bertone, NCSU PDIC.

Adult Cacopsylla tibiae and characteristic damage to pittosporum. Photo: Matt Bertone, NCSU PDIC.

ornamental plant Japanese pittosporum (Pittosporum tobira). The pest, Cacopsylla tobira, is a sucking insect called a psyllid.  Psyllid feeding generally causes deformed leaves. The most common or well-known psyllid in ornamental plants is probably the boxwood psyllid that causes cupped leaves at the end of boxwood twigs. Cacopsylla tobira has only been reported from California in the US. Thus not much is known about the biology, management, or damage of this pest. California has a note on psyllids that infest various crops if you would like to know more about this group. Please take note of strange damage to pittosporum and send suspicious samples to the Plant Disease and Insect Clinic.

Adult Cacopsylla tibiae. Photo: Matt Bertone, NCSU PDIC.

Adult Cacopsylla tibiae. Photo: Matt Bertone, NCSU PDIC.

Look for Hibiscus sawfly damage

This week I found severe damage by hibiscus sawfly.  Larvae and adults were present on

Damage caused by hibiscus sawfly larvae.  Photo: S.D. Frank

Damage caused by hibiscus sawfly larvae. Photo: S.D. Frank

the plants I surveyed. The adults are active throughout the summer. The larvae feed on hibiscus and related plants. The larvae skeletonize leaves when they are young but quickly defoliate plants as they grow. Insecticides for management include bifenthrin, spinosad, acetamiprid, azadirachtin and others listed in this insect note.

Plants around campus were also damaged and I noticed these adults present. Sawflies are actually wasps (Order: Hymenoptera) which is why not all insecticides labels for caterpillars are effective. They are not caterpillars they are wasp larvae. Other sawflies I have reported on are the pine sawfly and rose sawfly both of

Adult hibiscus sawfly. Photo: S.D. Frank

Adult hibiscus sawfly. Photo: S.D. Frank

which I have found at the JC Raulston Arboretum and on Main campus.

Tuliptree scale primer

If you haven’t met tuliptree scale, Toumeyella liriodendri, its high time you did. I found

Tuliptree scales on tulip poplar twig. Photo: SD Frank

Tuliptree scales on tulip poplar twig. Photo: SD Frank

dense patches of it at a local playground the other day. I was tipped off by honeydew, which can mean tulip poplar aphids, but also scales. Tuliptree scales feed primarily on tulip poplar, Liriodendron tulipifera, though it is occasionally found on other trees including Magnolia spp. It occurs throughout the eastern US from New England to Florida.

Unlike many other soft scales in our area, tuliptree scale produces crawlers at the end of summer and into fall. The scales overwinter as 2nd instars on twigs. In spring they develop to adults and produce lots of honeydew throughout the summer. In late summer honeydew production declines as female scale begin producing eggs and crawlers. A single female can produce over 3000 crawlers over three months. This could make control difficult since you cannot target a whole cohort of crawlers with a single application of oil or insecticide.

Honeydew from tuliptree scale supports dozens of other species. Researchers have recorded 93 hymenopteran species that collect honeydew of tuliptree scale and a dozen or so ant species. This is an amazing diversity of creatures that would not be in a tree if these scales were absent. This disproportionate effect of one species on the animal community

Distribution of tuliptree scale as of 1969 from Burns & Donlely 1970.

Distribution of tuliptree scale as of 1969 from Burns & Donlely 1970.

suggests a potential foundational or keystone role. Since these scale produce so much honeydew they can be heavily tended by ants. Ant tending can reduce scale mortality by predators and increase scale abundance.

Tuliptree scale cause considerable damage to trees. They can kill central leaders resulting in bushy plants with codominant leaders. They can kill trees or reduce tree growth rate. High densities of scales can remove more carbon than a tree produces. In this case trees are surviving on reserved energy that is gradually depleted.

Reference: Burns, DP, Donely, DE. 1970. Biology of the Tuliptree Scale, Tourneyella liriodendri (Homoptera: Coccidae). Annals of the Entomological Society of America, 63, 228-235.

 

 

Euonymus scale

Somehow I got this far in the season without posting anything about euonymus scale.

Euonymus scale

Euonymus scale on a heavily infested leaf. Photo S.D. Frank

Maybe because this is the first year I have not been conducting research on it or writing papers about it. Euonymus scale has three generations per year in North Carolina the first of which occurs around May. It is best to treat euonymus (or any) scale in the crawler stage. So if you forgot in the spring or didn’t get sufficient control (or were waiting for an alert from me) you still have a chance. Crawlers are active at sites on campus and in Raleigh neighborhoods. In the first generation crawlers come out all at once but become less synchronized in second and third generations. Thus you may find all developmental stages present at this time. There are a number of products that can be used to treat armored scale. You can read an article in Nursery Management about scale control here. Our research (published here) has found neonicotinoids Safari, Flagship, and TriStar to be very effective and also plant growth regulators Distance and Talus. Note that imidacloprid is not labeled for, or effective against, armored scale. Please check the updated insect note for recommendations http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/note15/note15.html

Columbine leafminers

The first round of flowering is about over for my native columbine, Aquilegia canadensis. Columbine is a great early spring flower that flowers profusely and spread easily by seed. Spring bees and humming birds visit columbine flowers particularly in early spring when it is one of the only flowers present.

Heavily mined columbine leaves. Photo: SD Frank

Heavily mined columbine leaves. Photo: SD Frank

The columbine leafminer, Phytomyza aquilegivora, overwinters as pupae. Adults emerge in early spring and oviposit in new columbine leaves. Small white maggots mine the leaves creating white or grey serpentine pathways. Often entire leaves are discolored. Larvae pupate after about 10 days on the underside of leaves. Columbine leafminer has at least 4 overlapping generations per year in North Carolina. There are at least 13 species of parasitoids that become more abundant as the summer progresses.

Braman et al. (2005) reported that the native species, A. canadensis, is more resistant to leafminers than many other species of cultivars. Removing and destroying infested leaves before adults emerge may help reduce damage to subsequent leaves. Leafminer control is often best to left the parasitoids become established and just accept some damage. If you are a grower than there are several insecticides available to help reduce leafminer damage.

Lots of Lacewing Larvae

Green lacewing larvae are common predators of several soft-bodied arthropods pests such as scale insects, spider mites, aphids, thrips, and eggs of pest insects. They are useful in biological control because of their generalist and voracious feeding habits.

Lacewing egg on stalk on oak bark. Photo: SD Frank

Lacewing egg on stalk on oak bark. Photo: SD Frank

Lacewing larvae have large pincer mouthparts that they use to penetrate bodies of prey, paralyze them, and suck out their insides. They use these mouthparts to devour several hundred prey per week. Lacewings are known to be cannibalistic if they cannot find any other food source. This is probably one reason they deposit their eggs individually on long hairs that suspend them above the leaf surface out of reach. You can find these eggs very easily just by searching leaves of trees and bushes. They are even more common on plants with lots of prey.

Lacewing larvae on spicebush leaf. Photo: SD Frank

Lacewing larvae on spicebush leaf. Photo: SD Frank

Some but not all green lacewing larvae develop a camouflage cover which hides them from their prey and predators. These are called debris-carrying lacewing larvae because they pick up plant debris, lichen, and remains of their prey and attach it to their back. This camouflage makes them difficult to recognize by prey, natural enemies, and the

Debris carrying lacewing larvae on maple trunk. Photo: SD Frank

Debris carrying lacewing larvae on maple trunk. Photo: SD Frank

inexperienced human eye. Often they will appear to be a cluster of tree lichen until you notice it start to move. This time of year when flatid planthoppers are producing lots of cottony fluff I see lacewings covered in the same cottony fluff. On a hike in Umstead State Park last week I found half a dozen. Debris carrying lacewing larvae are easy to find. Just look for little mounds of debris moving around the top of leaves.

Debris carrying lacewing larvae covered in flatid fluff. Photot: SD Frank

Debris carrying lacewing larvae covered in flatid fluff. Photot: SD Frank

The ones covered in flatid fluff are bright white and stand out against leaves. They remain larvae for two to four weeks then pupate and emerge as winged green lacewing adults. Adult lacewings are not predators and primarily feed on plant nectar. The adults are commonly attracted to lights at night and can often be found around your home.

New armored scale for NC

Gloomy scale, Melanaspis tenebricosa, infests nearly every urban red maple in the Southeast. It devastates trees so we (mostly Adam Dale and Elsa Youngsteadt) spend a lot of time studying why gloomy scale is so abundant on urban trees and how to manage it. The obscure scale, Melanaspis obscura, is common on pin oaks and several other tree species.

Melanaspis deklei on wax myrtle. Photo: Al Hight, NCSU

Melanaspis deklei on wax myrtle. Photo: Al Hight, NCSU

Now we have another Melanaspis species to contend with. This one, Melanaspis deklei, infests native wax myrtle, Myrica cerifera. It has been reported from Florida with occasional reports further north. In the last several years my colleague J.C. Chong at Clemson has found increasing number of infestations in the landscapes of coastal communities in South Carolina. Wax myrtle is one of the most common plant species in ornamental landscapes particularly near the coast. M. deklei has not been reported in North Carolina until now. As with many new or rare pests this one was noticed by a landscape professional and Extension Agent in New Hanover County who reported several dead and dying wax myrtles and sent pictures and samples to the NCSU Plant Disease and Insect Clinic.

Melanaspis deklei on wax myrtle. Photo: Al Hight, NCSU

Melanaspis deklei on wax myrtle. Photo: Al Hight, NCSU

M. deklei has 3 generations per year in SC. It feeds primarily on stems and branches and causes canopy thinning, branch dieback, and eventually large canopy gaps or plant death. Similar to gloomy scale, crawlers emerge for over a month which makes control difficult. Little else is know about M. deklei biology. No effective management tactics have been identified. Applications of horticultural oil can decrease abundance a little but systemic neonicotinoids have shown no effect. A recent paper on insecticide efficacy appeared in the Journal of Agricultural and Urban Entomology.

Dead and dying wax myrtle infested with Melanaspis deklei. Photo: Al Hight, NCSU

Dead and dying wax myrtle infested with Melanaspis deklei. Photo: Al Hight, NCSU

Just a week or two ago I reported on crape bark myrtle scale as a new exotic pest that is working its way toward NC. Now we have a new (probably native) pest of another common landscape plant.

 

Cottony fluff from flatids

This time of year many species of plants host flatid plant hoppers that produce a cottony

IMG_1790 mass. These are vert evident as you look around most yards, forests, and other habitats. Just look for bright white stems then go dig in and you will find plant hopper nymphs that are yellow, white, or green. They really do not do any damage but do attract a lot of attention. In some cases they are tended by ants.

Daylily leafminers

Just a brief update that daylily leaf miners have been active for about three weeks in DSC02337Raleigh. They started slow but are really hammering some plants. Last year every daylily I saw had damage.

This is a relatively new pest to the US. You can read more in an earlier post. We are conducting some efficacy work this year to figure out good control options.

Keep alert for a new crape myrtle pest

Most folks realize that international commerce delivers a steady stream of new pests on our shores. You probably also realize by now that I rarely deliver good news. One of the newest pests to plague urban trees is the Crape myrtle bark scale, Eriococcus lagerstroemia. It is not yet in North Carolina but it is probably coming.

The first detection of Crape myrtle bark scale in the US was just outside Dallas, Texas in 2004. Since then it has spread throughout much of Texas. It has also spread to Arkansas, Louisiana, Oklahoma, and Tennessee. This is a worrisome development because the climate of Tennessee is similar to many parts of North Carolina suggesting this pest is not limited to warmer areas of the South. Just last week it was found in Georgia.

Crape myrtle bark scale on crape myrtle in Dallas. Photo: SD Frank

Crape myrtle bark scale on crape myrtle in Dallas. Photo: SD Frank

Female scales produce fluffy white filaments that cover their body. In spring they produce eggs beneath their body then die. Tiny crawlers hatch from the eggs, settle in their new spot, and begin producing white filaments. They have at least 2 overlapping generations in Arkansas and probably more in warmer areas.

At low density, crape myrtle bark scale feeds in rough areas around branch collars but as the population increases all the bark may be covered. These scales are most often noticed because trees become covered in black sooty mold. At first many people assume this is from crape myrtle aphids so the scales may go undetected. If you notice unusually heavy honeydew and sooty mold on crape myrtles take a closer look at the bark.

Since this is such a new pest in the US we do not have a good idea how to manage it. Drench applications of neonicotinoids have provided some control in Texas. However, since crape myrtles flower continually and attract a slew of pollinators this may not be the best option. Insect growth regulators such as pyriproxyfen and buprofezin are effective for many other scales and may be a good option. Horticultural oil, especially the heavier dormant rate, can reduce scale abundance also.

But control is not our biggest concern in North Carolina. We should be most concerned about this pest getting into our nurseries and landscapes to begin with. Sedentary pests like this often spread on infested nursery stock or when someone moves here and brings a sentimental plant along with them. We just analyzed the Raleigh street tree database and found that crape myrtles are the most common tree. When I was in Dallas last fall the crape myrtle trees lining streets of downtown and tony residential neighborhoods looked terrible. They were black and crusted with scales. Stumps indicated that many had already been removed.

So what is my message for North Carolina urban forests? First, this is another great reason to buy locally. So far you can be pretty sure crape myrtles from North Carolina will be scale free. The larger message is that it may be time to stop planting so many crape myrtles. Each one you plant is likely, at some point, to require extensive (and expensive) pest management . Diversify.