New ambrosia beetle marching across the US

Nursery growers have been struggling with ambrosia beetles for decades. In the southeast it is

Scopes-eye view of camphore shot borer fresh from a trap mixed in with granulate and other ambrosia beetle species. Photo: Andrew Ernst, NCSU.

Scopes-eye view of camphore shot borer fresh from a trap mixed in with granulate and other ambrosia beetle species. Photo: Andrew Ernst, NCSU.

primarily the granulate ambrosia beetle, Xylosandrus crassiusculus. In the Northeast and Midwest the predominate species is Xylosandrus germanus. These are tiny beetles that make tiny albeit lethal holes in trees. 

In the past several years a new species has been detected in several states including Florida, Tennessee, North Carolina, and just last month Virginia. This is the camphor shot borer, Cnestus (used to be Xylosandrus) mutilatus, and it is BIG. At least by ambrosia beetle standards this one makes holes as big as a pencil instead of then tiny 2mm holes made by other species. You can find out all about it in a thorough publication from University of Tennessee.  

We trap at 5 -10 nurseries every year around Johnston County, North Carolina. In 2011-2013 we captured 1 or 2 camphor shot borers each year. This year we captured about a dozen from at least 3 different nurseries. So it is here to stay and will probably become more of a problem over time. 

Camphor shot borer in a twig photographed by Matt Bertone, NCSU.

Camphor shot borer in a twig photographed by Matt Bertone, NCSU.

Advertisements

Mimosa webworm

Mimosa webworms are active in Raleigh. I saw initial webbing just a week or so ago but

Small web in a mimosa tree. Photo: SD Frank

Small web in a mimosa tree. Photo: SD Frank

now they are in full swing. These are annual pests of mimosa trees which many people consider pests in their own right. However, if you are you of the many folks who love mimosa trees sans messy caterpillar webbing then it is time for action. The best way to prevent heavy infestations and extensive webbing is to prune out the nest when they are small. Moths overwinter as pupae attached to tree trunks, buildings, or other sheltered locations. The adults emerge in June or so to lay eggs on mimosa and honey locust trees. Caterpillars feed within the webbing for several weeks before pupating. There are multiple generations per year. Most insecticides available for caterpillar control will also control

Mimosa webworm. Photo: SD Frank

Mimosa webworm. Photo: SD Frank

mimosa webworm but remember that contact is difficult since they live in waterproof webs. In most cases mimosa webworms will not reduce the health or growth of their rapidly growing hosts. They also don’t seem to eat all the seedlings that pop up all over my yard from the tree next door. http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/note07/note07.html

Imported willow leaf beetle

Imported willow leaf beetle (Plagiodera versicolor) adults are metallic blue. This time of

Imported willow leaf beetle. Photo: SD Frank

Imported willow leaf beetle. Photo: SD Frank

year adults and larvae are feeding on willows. The adult beetles overwinter outdoors under bark or in leaf litter. They and emerge from hibernation sites in spring around the time willows start getting leaves since adults prefer new leaves. Females lay pale yellow eggs that hatch into voracious larvae. Adults and larvae skeletonize leaves which can give trees a brown cast as damaged leaves crisp in the sun. In some cases though they can eventually defoliate trees like the one I saw walking to work today. Insecticides labeled for leaf feeding beetles such as spinosad, imidacloprid, and chlorantraniliprole can be used if needed. Unfortunately, these beetles are here to stay so efforts to prevent any

Imported willow leaf beetle eggs. Photo: SD Frank

Imported willow leaf beetle eggs. Photo: SD Frank

damage to willows is in vain. High populations that cause complete defoliation pose a risk to tree health and may warrant management. Otherwise some damage is inevitable so go out and look at the beautiful beetles.

 

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.

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.

 

Emerald Ash Borer Information

I added a webpage just to post information about emerald ash borer.  I will add to it as more information become available.

The ultimate source for EAB information is the website EmeraldAshBorer.info which is a collaborative effort of the USDA Forest Service, Michigan State University, Purdue University and Ohio State University.

There are insecticide treatments that will help protect trees from emerald ash borer. See “Insecticide Options for Protecting Ash Trees from Emerald Ash Borer

There are a few products available to homeowners for protecting ash trees. But there are many considerations before committing to protecting a tree.  See the “Emerald Ash Borer: Homeowner Guide to Insecticide Selection, Use, and Environmental Protection