Field Notes: Looking Down on Tree of Heaven

By Katlin Mooneyham and Lori Chamberlin

The City of Winchester and Frederick County are in the midst of an invasion. The spotted lanternfly, a non-native invasive insect, was first discovered in Winchester in January 2018. This pest feeds on more than 70 host plants worldwide and poses a significant threat to multiple Virginian industries. There is still much to learn about the spotted lanternfly, and the Virginia Department of Agriculture and Consumer Services (VDACS) has been working hard to control it within the infested areas.

One method of slowing the spread is treatment of a preferred host, Ailanthus altissima, otherwise known as “tree of heaven”. Smaller trees are killed with herbicide and larger trees are treated with insecticide to kill spotted lanternfly that feed on them. Tree of heaven itself is an invasive species and is widespread throughout Virginia, especially along roads or other disturbed sites.

Knowing the precise location of tree of heaven would greatly facilitate treatment, so Virginia Department of Forestry (VDOF) partnered with VDACS to map tree of heaven in Frederick County and the City of Winchester. The project is supported by Farm Bill funds awarded to VDACS and accomplished with U.S. Forest Service software (Digital Mobile Sketch Mapper). Protocol was based on a 2015 Forest Science paper entitled “Aerial Detection of Seed-Bearing Female Ailanthus altissima: A Cost-Effective Method to Map an Invasive Tree in Forested Landscapes”, and personal communication with forest health professionals from the Pennsylvania Department of Conservation and Natural Resources. This type of survey requires a helicopter in December/January after leaf drop. Female tree of heaven hold onto their seed pods and are visible from above during these winter months.

VAsurveyTOH
Female tree of heaven trees from above (identified by attached brown seed pods).

In January 2020, VDOF forest health staff went up in a helicopter to map tree of heaven. The survey followed pre-determined flight lines spaced at 2,000 feet (1,000 feet of visibility from either side of the helicopter) and flew at an average altitude of 400 feet above ground at a speed of approximately 80 knots. Individual female trees were marked as points, and clusters of trees were marked as polygons. Three VDOF employees conducted the survey — two spotters and a sketch mapper — with minimal Dramamine needed for motion sickness!

Photos: VDOF staff Meredith Bean (emerald ash borer coordinator) and Katlin Mooneyham (forest health specialist) (left) and Jim Pugh (GIS technician) (right) ready for take off!

It will take some time to analyze the data and quantify the results, but general observations fit with our knowledge of this invasive tree species. Tree of heaven is most commonly found along disturbed sites and the highest numbers of trees were observed along train tracks, roadsides, field edges and a quarry in the southern end of the county.

Mapping female trees only gives us data for half of the population, but this winter survey is a quick and easy method to identify tree of heaven clusters to get a better idea of overall distribution. This data will be used by both VDOF and VDACS personnel to identify priority treatment areas and locate areas where the spotted lanternfly may continue to spread.

Paper Citation:
Rebbeck, Joanne, et al. “Aerial detection of seed-bearing female Ailanthus altissima: A cost-effective method to map an invasive tree in forested landscapes.” Forest Science 61.6 (2015): 1068-1078.

NASF Centennial Challenge

Emblem-logo-CC

The Virginia Department of Forestry (VDOF) is excited to participate in the Centennial Challenge put forth by the National Association of State Foresters (NASF) in 2020. Below is the campaign announcement from NASF:

“The National Association of State Foresters is celebrating its 100th anniversary in 2020 with a Centennial Challenge campaign, honoring both the work of the association in providing a unified voice for state and private forestry in the United States since 1920, as well as the tremendous social, environmental, and economic contributions state forestry agencies have made nationwide for over a century’s time.

NASF will be spotlighting state forestry agencies and their work to complete 100-themed challenges regularly throughout the year-long campaign. Keep an eye out for your state’s Centennial Challenge celebration on social media with the hashtags #CentennialChallenge and #NASF100​ or by following the handle @stateforesters on Twitter, Facebook, and Instagram.

Come January 2020, you’ll start to see the nation’s 59 state and territorial forestry agencies’ challenges appearing on a Centennial Challenge interactive map online. In the meantime, for more information about state foresters and their work to conserve, protect, and enhance America’s forests, visit www.stateforesters.org.​”

For the challenge, VDOF has committed to treating 100 ash trees to protect them against emerald ash borer (EAB) — an invasive wood-boring beetle that’s pushing most native species of ash (Fraxinus) trees in Virginia to the brink of extinction. Learn more about EAB in these Storymaps.

VDOF’s EAB coordinator Meredith Bean says, “Treating ash trees to protect them from EAB is not always easy, particularly because they tend to grow naturally in wet environments. Our preferred method of chemical treatment is trunk injection of a systemic insecticide product with emamectin benzoate as the active ingredient. Direct injections into the trunk avoids effects on non-target species, unlike bark spray or soil drench treatments with neonicotinoid products. We will continue to treat high-value ash on an individual-tree basis and support landowners and organizations treating on private property through our cost-share program, with the goal to sustain the environmental, economic, and social benefits these trees provide.”

In 2020, we’ll share updates (on social media and here on the blog) about our progress toward our goal of treating 100 ash trees, and we’ll highlight several ash tree stories from across the state. Be sure to follow @stateforesters and @ForestryVA on Twitter, Facebook, and Instagram, and check out #CentennialChallenge and #NASF100​ throughout the year to see how other agencies are responding to the challenge!

 

Field Notes: It’s A Bird, It’s A Plane, It’s A Drone!

by VDOF Forest Health Specialist Katlin Mooneyham

The Virginia Department of Forestry is taking forest management to new heights! The agency has recently purchased three drones and certified three drone pilots (with three more taking the test soon!) thanks to a U.S.D.A. Forest Service Landscape Scale Restoration grant. The use of drones in forestry is a newer field and VDOF is investigating exactly how we can use these tools in forest management. So far, we have successfully used drones for the following purposes: water quality and logging inspections, forest health and fire.

Water Quality and Logging Inspections

For each timber harvest in Virginia, inspections are conducted to ensure water quality buffers are in place and stream crossings are up to code. Using the drone helps in this as it allows foresters to quickly see if things look good or helps to identify potential problem areas. In the picture below, the drone allowed our water quality specialist to see that the buffer meets the required criteria and that the bridge over the stream is correctly placed.

DCIM100MEDIADJI_0174.JPG
Logging inspection using drone imagery

Forest Health

The main way that drones have been used by the forest health program so far is to assess stand-wide issues from above. This “periscoping” technique is utilized when we suspect a problem within a stand and we want to see the full extent of affected tree crowns. We have gone to look at a stand where there was concern for a bark beetle outbreak and also mapped a study area at one of Virginia’s state forests where goats grazed to remove invasive species.

LesesneDrone
Forest Health Program Manager Lori Chamberlin all set for takeoff!

 Fire

Prescribed burns are a key forest management tool and require constant supervision to ensure the fire stays within its boundary. Using a drone with an infrared (IR) camera can make sure that no ember ends up outside the fire line and can tell varying levels of heat within the fire. Using a traditional camera on the drone can also help monitor and show the burned area to any landowners or cooperators that also participate in this management practice.

default
Prescribed fire as it moves
default
Burned area once the fire was complete

 

The Future Use of Drones in Forestry

We are constantly exploring new ways to incorporate drones into forest management. VDOF’s Urban and Community Forestry program as well as our State Forest managers are also looking into how to enhance their work with drones. Technology like this provides the agency a valuable tool to better serve the Commonwealth and help with many aspects of forestry!

Field Notes: Yellow-Poplar Weevil Makes Presence Known in Southwest Virginia

by VDOF Forest Health Program Manager Lori Chamberlin

The yellow-poplar weevil has made its presence known again in southwest Virginia. This native insect generally causes very little damage, but the population increased enough this summer to have a noticeable impact on yellow-poplars in the southwest part of the state. The weevils are black and small, only about 1/8th of an inch long. Since this pest is a weevil, it has a long proboscis, or nose like appendage, that it uses to feed. Though their name implies they feed only on yellow-poplar, they also feed on magnolia and sassafras.

Adult yellow-poplar weevils emerge in early June and feed on leaves until mid-summer. As they feed, they make tiny notches shaped like a grain of rice in the leaf creating brown splotches on the leaf surface. This gives the trees a scorched appearance and may lead to premature leaf drop.

Since the yellow-poplar weevil is a native pest in the eastern United States, control is usually not warranted. Natural predators of the weevil normally regulate the population and keep it below damaging levels. Outbreaks of the weevil tend to occur every few years when weevil populations surpass natural predators. During outbreak years, tree damage may be unsightly and alarming, but is mostly just cosmetic and does not cause long-term harm to the trees. There have been six VDOF documented outbreaks in the last 25 years, all primarily in southwest Virginia. This year, reports of this pest came from Roanoke, Bedford, Buchanan and Russell counties. VDOF forest health staff conducted an aerial survey on July 2nd and mapped damage in Bedford, Botetourt, Roanoke, Montgomery and Floyd counties. Yellow-poplar weevil damage appears to be widespread throughout the western region this year, but it is patchy and scattered throughout the landscape.

In heavily infested areas, you may see these weevils crawling on top of vehicles or falling on people walking by. They are often mistaken for ticks, but don’t worry, the yellow-poplar weevil doesn’t harm humans!

IMG_3312

Field Notes: White Pine Monitoring in Western Virginia

By Forest Health Specialist Katlin Mooneyham

Eastern white pine is a species commonly found in forests in the western part of the state. In Virginia, eastern white pine is grown for wood production, Christmas trees, holiday garland and ornamental plantings.

In 2006, former VDOF Forester John Wright noticed that white pines were declining in his work area in Highland County. He called the forest health program manager at the time, Dr. Chris Asaro, out to collect samples. They observed trees with browning needles, crown thinning and dieback, resinosis (streaking of resin), and canker (open and exposed tissue) development on the trees. Upon closer inspection, tiny fruiting bodies or “eyelashes” were noticed on the main trunk, and branches and small round shiny dots were seen within cankers. Samples were sent off to a pathologist with the USDA Forest Service and it was determined that there was a small scale insect (round dot) called Matsucoccus macrocicatrices and a fungal pathogen (eyelashes) called Caliciopsis pinea. It is unknown what the exact interaction is between the two causal agents, but the work of both has led to this decline being labeled a complex.

IMG_0830
Caliciopsis pinea under magnification on a white pine branch
IMG_0833
Matsucoccus macrocicatrices under magnification on a white pine branch
DSCN0990
Symptomatic white pine in western Virginia

As Dr. Asaro started to see more symptomatic white pine, he decided to set up long-term monitoring plots to record the health and general conditions of these trees in western Virginia. Four sites were set up, one in each of the following counties: Bath, Highland, Augusta and Grayson. Within each site, four plots were established to collect data. Both the scale and pathogen have been found at each plot, and overall white pine health has been monitored since 2012.

Tree mortality in a forest is a natural process and part of natural thinning as trees mature and start to compete with each other for resources. This baseline mortality for eastern white pines in Virginia was determined to be between 12 and 14 percent. However, initial results from our VDOF white pine monitoring study indicate that there is some white pine mortality above normal baseline levels, most noticeable on smaller-sized trees. To better understand if/how this impacts larger trees, more data will need to be collected.

This spring, the VDOF Forest Health staff will return to these sites and take annual measurements. These measurements will be added to the current data set to help better understand the big picture of what is going on with this white pine scale/pathogen complex. Additionally, samples of scale and fungus will be collected and sent to researchers at the University of Georgia where they are studying the interactions between these two damaging agents (scale and fungus), as well as developing better survey techniques to continue monitoring white pine health.

Forest Health: A Small But Mighty Pest

The southern pine beetle (Dendroctonus frontalis) (SPB) is a small, seemingly innocuous beetle that brings new meaning to the phrase “small but mighty.” These beetles are known as the most destructive native forest insect in the Southeastern United States. While a single adult beetle is only about 1/8 inch long, the ability to aggregate quickly means these tiny insects can overtake a pine tree’s defenses in a short period of time. All species of southern pine are targets for SPB but favorite hosts include loblolly, shortleaf, Virginia and pitch pine.SPBpic1

Females emerge first in the spring and fly to a suitable host where they bore into the tree and start creating their infamous “S”-shaped galleries in preparation for laying eggs after mating. Shortly after, they emit a pheromone (think seductive bug perfume) and the masses begin flocking to the suitable host tree. Each female is prolific with her egg production, producing upwards of 150 eggs over the course of her life! These eggs are laid in the galleries where the developing larvae then feed on the inner bark. As trees are killed or fill up with beetles, the outbreak spreads to neighboring trees and continues until suitable host material is no longer found or control measures are taken.SPBpic2

Historically, outbreaks of these destructive insects have been cyclical, occurring on average every five to seven years. Since they are native, they have a predator complex which helps control the populations and regulate outbreaks. However, since the early 2000s these outbreaks have been less common and almost non-existent here in Virginia. Many factors may contribute to the decrease in southern pine beetle abundance, including more intensive silvicultural practices, genetically improved trees and forest fragmentation.

The last big southern pine beetle occurrence noted in Virginia was first detected in 2012, and had become a full outbreak by 2014. This took place on Chincoteague National Wildlife Refuge. The U.S. Forest Service observed the outbreak in 2016 from the air, and documented an average of 46 active SPB spots per thousand acres of host type. The average spot size calculated to be 1.5 acres. When a ground check was done, all spots visited had active adult, larvae and eggs, indicating that the population was still thriving. This area was hit particularly hard due to many factors: most of the pine was over-mature, overstocked and stressed from saltwater intrusion leading to a beetle buffet, ripe for the picking!

Unfortunately, no control efforts were enacted and the population continued to spread and the outbreak ultimately died out on its own. VDOF Forest Health staff flew the impacted area in October of 2018 and mapped 475 acres of pine mortality.

SPBpic3SPBpic4

To monitor populations and predict future beetle spots, each year VDOF Forest Health sets up traps that are baited with pheromones mimicking the ones produced by females and stressed trees throughout the state. Trapping starts in spring, around the time that beetles would start looking for suitable trees. Last year, we trapped in 10 counties, placing a total of 24 traps around the state. VDOF foresters and Virginia Department of Conservation & Recreation employees sample each week and VDOF Forest Health sorts the contents, counting the number of SPB caught as well as their associated natural predator, the clerid beetle. The good news for Virginia is that our SPB population levels continue to persist at low and static levels! We will continue to monitor these insects and their activity (or lack thereof!) and trapping efforts are planned for spring of 2019.

Forest Health: A Winter Pest Survey

Each month, Field Notes will bring you news from our forest health team. We kick off 2019 with a focus on winter activities and the hemlock wooly adelgid.

What do forest entomologists do in the winter? We look for hemlock woolly adelgid! The Forest Health program staff at VDOF surveys for many forest pests throughout the year, but the hemlock woolly adelgid is unique in that it is most active and visible during late fall and winter months. This invasive insect has been killing hemlock trees in eastern North America since its introduction into the United States in the 1950s. The tiny adelgid insects crawl along hemlock branches in search of a suitable feeding site, and settle at the base of needles where they insert their piercing sucking mouthparts into the plant tissue. They feed on the tree’s nutrients and produce a white ovisac, or covering, around their body for protection. If you ever see small white “cotton balls” on your hemlock tree, you probably have hemlock woolly adelgid.

hemlockwao
Hemlock woolly adelgid ovisacs on eastern hemlock

Most hemlock trees in Virginia are found in the western region, but there is an isolated population of hemlock situated east of the species’ major range at James River State Park in Buckingham County. In December 2018, VDOF visited this stand to assess the health of the hemlock trees and monitor the hemlock woolly adelgid population. While many hemlocks near the river still look healthy, there has been significant decline of hemlock trees further upland. Overall stand health was rated “fair” in comparison to the “good” rating just two years ago. Surprisingly, however, hemlock woolly adeglid populations appear quite low. The winter of 2017/2018 saw some extremely low temperatures which may have reduced adelgid populations. Bad news for adelgids, but good news for hemlocks.

mooneyham
Katlin Mooneyham, VDOF Forest Health Specialist, beat sheet sampling for L. nigrinus beetles

What kills adelgids beside cold weather? Beetles! Small predator beetles have been released as biological control of the hemlock woolly adelgid on federal and state lands throughout Virginia by various universities and federal agencies over the past decade. In 2005, Laricobius nigrinus beetles were released at James River State Park to control the hemlock woolly adelgid and hopefully preserve the population of hemlocks within the park. L. nigrinus is native to pacific northwestern North America and has been thoroughly screened and tested to ensure it is not a threat to non-target species. Since the release, the stand has been monitored to assess the population change of the beetles and the adelgid over time. The presence of L. nigrinus is determined by beat sheet sampling- a fun technique in which you shake a branch over a large white sheet attached to a cross frame and then identify all the beetles than fall from the branch onto the sheet. This sampling is done on dozens of hemlock trees and typically lasts about an hour. L. nigrinus beetles are very small and difficult to detect, but we found 6 adult beetles during our visit in December. These six beetles indicate the population of L. nigrinus is surviving and feeding on hemlock woolly adelgid which gives us a glimmer of hope for our hemlock trees.

Field Notes: Be Thankful for the Good Bugs!

by Forest Health Specialist Katlin Mooneyham

Here in the forest health program at VDOF, we spend a lot of time talking about bad bugs and how to kill them. Much of our time working with landowners and other forestry professionals is spent identifying pests, giving management recommendations and, in some cases, even treating trees against a variety of problematic insects. The emerald ash borer, an insect that originates in Asia, received a lot of our attention this year. Gypsy moth, a pest from Europe, typically makes an appearance each year in early spring and caused moderate damage in 2018. We also can’t forget our newest invasive insect, the spotted lanternfly! This pest showed up in the state in January of 2018 and has been the source of much attention and control efforts ever since. Sometimes it is exhausting trying to keep up with these invaders as they make themselves at home in our forests!

Given it is the holiday season, a time to be thankful for all that we have, I want to shift focus off these nuisance species, and celebrate the good bugs. They don’t often get the credit they deserve, even though they are constantly working hard in the background controlling the “bad bugs”. When these “good bugs” (also called natural enemies) control populations of pest insects, this is called population regulation.  This phenomenon involves a fluctuation of populations that cycle between the high population of an insect pest and the subsequent increase of natural enemy populations. Eventually the natural enemy controls the pest below injury level and to a point where the pest population is less than that of the natural enemy population. In natural systems where both species are native, these population dynamics fluctuate back and forth and remain in balance so long as the ecosystem is not altered (Stevens 2010) (see figure 1).

Figure 1:Nov20

Insects that act as natural control agents can fall in to two different categories- predators and parasitoids, though natural control also encompasses fungi, bacterial and viral pathogens of invertebrates. Predators are insects that rely on their prey as a food source. Sometimes only a certain life stage of an insect is predacious; the larvae may be predators while the adult stage feeds on nectar. Other species are predacious their whole lives, controlling pests constantly! Parasitoids are awesome insects that don’t harm humans, but parasitize other insects when they are young and then are free living as adults. They can parasitize and use their hosts for food or can use them exclusively for homes while they develop! Either way, they ultimately kill the host they rely on. Take away message here- Mother Nature is awesome and clearly there is a lot in the natural world to be thankful for!

One of our favorite native predators here in Virginia is the checkered clerid beetle, Thanasimus dubius (Figure 2). This species is a native predator of the southern pine beetle (SPB), the most destructive native insect in the southeastern U.S. Both the adult and larval stages of this predator feed on all life stages of southern pine beetle, as well as many other native pine beetle species in Virginia. In the VDOF forest health program, we trap annually for SPB and clerid beetles and use the number of clerid beetles as an indicator of SPB population status. If we catch more clerid beetles than SPB, as we have the past few years, we know that the SPB population is at low and static levels and the predators are controlling the SPB.

Figure 2:

cleridbeetle
Credit: Gerald J. Lenhard, Louisiana State University, Bugwood.org 

An amazing native parasitoid found in the woods of Virginia is Megarhyssa nortoni, a lovely wasp that looks terrifying but is actually specially adapted to find larvae of a horntail grub underneath bark (Figure 3). She probes the wood trying to catch the scent of the fungi that horntail cultivate. Once she finds a suitable spot, she drills into the tree laying an egg on or near the horntail grub. Once her egg hatches, it consumes the entirety of the horntail grub, killing it.

Figure 3:

wasp
Credit: Steven Katovich, USDA Forest Service, Bugwood.org 

These two examples represent only a very small portion of the natural control going on in our forests around us. All of our native pests are controlled by natural agents that keep the pests from reaching destructive levels for too long. Non-native pests can be so damaging in the U.S. because they arrive without natural predators to keep them under control and they are effectively at a buffet in our forests and ecosystems. So let us toast our good bugs this holiday season and be grateful for all they do in our forests around us!

Happy Holidays from the VDOF Forest Health Program!

Literature Cited:  Stevens, A. (2010) Dynamics of Predation. Nature Education Knowledge 3(10):46