Tom Tiddens – Page 2 – My Chicago Botanic Garden

Pest Alert: Amynthas agrestis (crazy worm or jumping worm)

Unwanted wiggler discovered!

About a month ago, one of our horticulturists called me out to look at a groundcover planting that was being heavily disturbed by worms. At first look, I thought nothing of it—maybe it was increased surface worm activity from all the rain. A couple of weeks later, they were still very active, and the groundcover was actually floating on worm castings! We rolled it up to expose many worms. When I picked up a worm, it flipped out of my hand and wriggled away quickly, snake-like—not like a typical worm.

Since this activity seemed strange, I asked our senior ecologist to have a look at the crazy-acting worms. Coincidentally, he identified them as “crazy worms” (Amynthas agrestis), an invasive worm on his watch-for list that has never been found in Illinois. Samples were sent to the University of Illinois for confirmation, and the Illinois Department of Agriculture and Illinois Department of Natural Resources were informed. Our find has been confirmed—along with another find in DuPage County—and a potential find in Wilmette is being investigated. The crazy worm has been in the United States for many years in many of the southeastern states (and in the Smoky Mountains). In 2013, it was found in Wisconsin. DuPage and our find are the first confirmed for Illinois.

Why is this worm bad?

They out-compete and push out our common European earthworms.
They multiply very quickly.
They devour soil organic matter and drastically change soil structure. This has a huge impact on forest ecosystems as well as on residential and urban ornamental plantings.

How do I identify the crazy worm?

They are found near the soil surface.
When touched, they respond immediately with a crazy flipping and jumping reaction.
They have a fast, snake-like movement.
Unlike a common European worm, they have a milky white flat band (clitellum).
They are 4 to 8 inches long.
A worm may lose its tail when handled.

What should I do if I think I have found the crazy worm?

Report the find to the Illinois Department of Natural Resources or Illinois Department of Agriculture.
To learn more about the crazy worm, just do a Google search on Amynthas agrestis (crazy worm or jumping worm).

Currently there are no treatments recommended for management of the crazy worm. Education and slowing the spread is the current course of action. The crazy worm’s primary means of spread is through the movement of plants with soil.

The Garden is a member of the Sentinel Plant Network, a group that unites botanic gardens in monitoring and providing education on exotic, invasive plant pests and pathogens, and works in partnership with the National Plant Diagnostic Network (NPDN).

If you are a plant and bug person like me, please consider becoming a NPDN First Detector and help be on the lookout for these exotic, invasive plant pests and pathogens. The NPDN offers an online training course to become a First Detector at firstdetector.org. It’s free, and upon completion, you even get a printable certificate!

Pest Alert: Viburnum Leaf Beetle

Viburnum leaf beetle is here, and he’s not a good neighbor!

Yesterday was an exciting (yet worrisome) day for me here at the Garden. We found viburnum leaf beetle here for the first time ever—although his arrival was not unexpected. Two separate discoveries were reported to me within just a couple of hours. One of our horticulturists made a discovery in one location, and one of our trained plant healthcare volunteer scouts found the beetle in another location. Both finds were on arrowwood viburnum (Viburnum dentatum), the beetle’s preferred host (and high on our watch list).

Click here to download the viburnum leaf beetle fact sheet with tips on managing the beetle.

If you live in the area, I suggest you monitor your viburnums for our new foreign friend. The sad thing about this critter is that once he moves in, he will become a perennial pest, just like Japanese beetles.

In ornamental horticulture (your home landscape plants), the viburnum leaf beetle seems to be on the verge of having a great impact in our area, as nearly everyone’s home landscape has viburnum. I’d like to take a moment to review this new critter.

Viburnum leaf beetle (Pyrrhalta viburni)

The viburnum leaf beetle (VLB) is native to Europe and was first found in the United States (in Maine) in 1994. It was first found in Illinois (Cook County) in 2009. In 2012 and 2013, the number of reports increased from Cook County and also from DuPage County. In late summer 2014, there were numerous reports from Cook County and some specifically from neighboring Winnetka, where complete defoliation was reported—only five miles from the Garden!

PHOTO: Leaf damage to Viburnum dentatum at the Chicago Botanic Garden by viburnum leaf beetle larvae. — Leaf damage to *Viburnum dentatum* at the Chicago Botanic Garden by viburnum leaf beetle larvae.

PHOTO: Viburnum leaf beetle (Pyrrhalta viburni) — Viburnum leaf beetle (*Pyrrhalta viburni*) by Siga (Own work) [GFDL or CC BY-SA 3.0], via Wikimedia Commons

The VLB larva and adult both feed on foliage and can cause defoliation, and several years of defoliation can kill a viburnum. If you live in the area, I strongly suggest you begin monitoring your viburnums for this critter. There are many great university-created fact sheets for VLB that can be found online, or contact the Garden’s Plant Information Service for additional information. Please report new finds to the Illinois Natural History Survey, Illinois Department of Agriculture, or University of Illinois Extension Service.

PHOTO: Plugged cavities on a viburnum twig containing egg masses of the viburnum leaf beetle (Pyrrhalta viburni). — Plugged cavities on a viburnum twig containing egg masses of the viburnum leaf beetle (*Pyrrhalta viburni*). Photograph by Paul Weston, Cornell University, Bugwood.org

Many people ask us: is it true that some viburnums will not be affected by the viburnum leaf beetle?

Viburnum leaf beetles prefer viburnums with little to no hair on the foliage. Plants grown in the shade also exhibit more feeding damage. The University of Illinois Extension has placed viburnums into four feeding categories: highly susceptible, susceptible, moderately susceptible, and most resistant. Viburnum species such as arrowwood (V. dentatum), European and American cranberrybush viburnum (V. opulus, formerly V. trilobum), wayfaringtree viburnum (V. lantana), and Sargent viburnum (V. sargentii) are in the highly susceptible and susceptible categories and can easily be destroyed by repeated infestations of the viburnum leaf beetle. Moderately susceptible species such as burkwood viburnum (V. burkwoodii), blackhaw viburnum (V. prunifolium), and nannyberry viburnum (V. lentago) may exhibit varying amounts of susceptibility, but are usually not killed, depending on the species. Other viburnums, such as Koreanspice viburnum (V. carlesii), Judd viburnum (V. x juddii), and doublefile viburnum (V. plicatum), are resistant to viburnum leaf beetle, will show little or no feeding damage, and are capable of surviving slight infestations. Please contact Plant Information Service at (847) 835-0972 or plantinfo@chicagobotanic.org for susceptibility questions on specific species.

The Garden is a member of the Sentinel Plant Network, a group that unites botanic gardens in monitoring and providing education on exotic plant pests and pathogens, and works in partnership with the National Plant Diagnostic Network (NPDN).

If you are a plant and bug person like me, please consider becoming a NPDN First Detector and help be on the lookout for these exotic invasive plant pests and pathogens. The NPDN offers an online training course to become a First Detector at firstdetector.org. It’s free, and upon completion, you even get a printable certificate!

New Year, New Pests

At the start of every growing season, I get the same question: what are your thoughts as far as garden pests are concerned? Here are my predictions:

First, plants may show signs of cumulative stress from the inconsistent and extreme weather patterns of the past few years: the 2012 drought, followed by the cold winter of 2013-14, and greatly fluctuating seasonal temperatures. These stress factors have an accumulative negative effect on plant health. When plants are under stress, their defense mechanisms are down, and they are much more prone to disease and insect attack, just as people who don’t eat properly and don’t get enough sleep are much more prone to illness. So what can we do? Primarily, just a bit more TLC in the way of cultural care: watering, mulching, pruning, fertilizing, monitoring and managing pests, protecting, and focusing on the more delicate plants in your landscape.

Second, new high-consequence invasive pests will become of concern. We now live with Japanese beetles, which are here to stay; we have experienced the Asian longhorned beetle (which was supposedly eradicated in our area, but I doubt that’s the case); and we are right in the middle of managing the emerald ash borer crisis. So what’s next? Sad to say, there are many other invasive pests to be on the watch for. Two that are literally knocking at our door now are the brown marmorated stink bug (primarily an agricultural concern) and the viburnum leaf beetle (primarily an ornamental landscape concern).

Find more information on identifying and dealing with emerald ash borer on our website, and in our previous posts on EAB.

In ornamental horticulture (your home landscape plants), I feel the viburnum leaf beetle is on the verge of having a great impact in our area, as nearly everyone’s home landscape has viburnum; I’d like to take a moment to review this new critter.

Viburnum leaf beetle (Pyrrhalta viburni)

The viburnum leaf beetle (VLB) is native to Europe and was first found in the United States in 1994 in Maine. In 2009, it was first found in Illinois (Cook County). In 2012 and 2013, the number of reports increased from Cook County and also from a new county, DuPage, as well. In late summer 2014, there were numerous reports from Cook County and some specifically from our neighbor Winnetka, where complete defoliation was reported—only five miles from the Garden!

The VLB larva and adult both feed on foliage and can cause defoliation, and several years of defoliation can kill a viburnum. We have not yet found VLB at the Garden but have been monitoring our viburnums closely. If you live in the area, I strongly suggest you begin monitoring your viburnums for this critter. There are many great university-created fact sheets for VLB that can be found online, or contact the Garden’s Plant Information Service for additional information. Please report new finds to the Illinois Natural History Survey, Illinois Department of Agriculture, or University of Illinois Extension Service.

Emerald Ash Borer: Sad But True, Part 3

Last week, a college biology professor in Ohio announced he had found evidence that the emerald ash borer (EAB), an invasive insect decimating the continent’s ash trees, is also attacking white fringetrees (Chionanthus virginicus).

PHOTO: White fringetree in bloom. — White fringetree (*Chionanthus virginicus*) in bloom

In August he found the telltale D-shaped exit holes on a fringetree near his home. When he investigated further by peeling back the bark, he found feeding galleries and live borers. He had the borers positively identified morphologically as well as with DNA tests conducted by the USDA’s Animal and Plant Health Inspection Service (APHIS). He also found evidence of EAB activity on fringetrees in three other locations in Ohio.

The recent discovery marks the first time EAB has been found completing its life cycle on anything other than ash in the United States.

The finding adds an alarming new element to the EAB story:

Researchers have been wondering whether the host range for EAB could be wider than just ash. That theory had seemed unlikely up to now but is proven with the fringetree discovery. There has already been a lot of research investigating other possible hosts, and with the new discovery, there will likely to be more.
Is the insect adapting? This is a scary thought!
Will EAB kill fringetrees as it does ash, or just cause damage? So far the invasive insect appears to only be damaging—not killing—fringetrees.
Has EAB moved to fringetrees because EAB populations are locally so high? If the buffet is crowded at the “prime rib station,” it seems logical that “meatloaf station” may get some visits.
What will happen when ash tree populations dwindle? Will the EAB population die back, or just move to a secondary host (the meatloaf, as the prime rib is gone) and/or develop a completely new palate?

PHOTO: A D-shaped exit hole left by EAB. — This D-shaped exit hole was left by a mature emerald ash borer as it exited this host tree.

The Ohio professor’s find was not all by luck; he had reason to focus on the white fringetree. Laboratory studies have shown that the adult EAB will feed on the foliage of other tree species in the same family as ash—the olive family, or Oleaceae. Members include ash (Fraxinus), fringe tree (Chionanthus), lilac (Syringa), forsythia, privet (Ligustrum) and swamp privet (Forestiera). Literature from Asia, the homeland of the EAB, indicates other secondary EAB hosts.

The Chicago Botanic Garden has 42 fringetrees; all have been inspected and show no signs of EAB activity. Even a fringetree that is 25 feet from an ash tree that was heavily infested with EAB shows no signs. If you have a fringetree, you should inspect it for signs of EAB. These include dieback starting at the upper limbs of the tree, new growth on the lower trunk, and small, D-shaped holes where the larvae have exited through the bark. Emerald ash borer larvae can kill a mature ash tree in two to three years by destroying the tree’s vascular system.

Find more information on identifying and dealing with EAB on our website, and in our previous posts, Signs of Emerald Ash Borer, and Emerald Ash Borer: Sad But True, Part 2.

As the world has become less fragmented by ease of transportation, more exotic, high-consequence plant pests and pathogens like EAB have entered—and will continue to enter—the country. Other exotic plant pests and pathogens we are watching for at the Garden include the following: viburnum leaf beetle, Lymantria dispar asiatica moth, brown marmorated stink bug, Asian longhorned beetle, thousand cankers disease, plum pox virus, chrysanthemum white rust, sudden oak death, and so on; most are already in the country. Vigilance and education are the key to managing and slowing the spread of these foreign invaders.

If you are a plant and bug person like me, please consider becoming a NPDN First Detector and help be on the lookout for these exotic plant pests and pathogens. The NPDN offers an online training course to become a First Detector at firstdetector.org. It’s free, and upon completion, you even get a printable certificate!

The Plant Doctor Is in the House

A couple years ago, in early spring, I got the kind of call that puts a “plant doctor” like me on edge. “Come look at the roses right away,” someone said. In my 25 years at the Chicago Botanic Garden, no one has ever called me to say, “Hey, Tom, come look at the roses; they look great today!” I’m in charge of plant healthcare at the Garden, so when I pick up the phone, there’s usually a problem.

I got the call about the Krasberg Rose Garden following a string of very damp nights that meant trouble—a white fuzz had spread over all the roses. The fuzz was a destructive pathogen that produces mycelium, or fungal spores. It can happen pretty much overnight. We ended up managing the problem, but it was scary to start off a season like that. Roses are tricky, prone to a lot of diseases and insect problems. Our friends at the Missouri Botanical Garden lost all their roses to a virus called rose rosette disease.

I don’t just get calls about diseases or pests such as the emerald ash borer. I get called to the Butterflies & Blooms exhibition if the staff is worried about a larva or to the Elizabeth Hubert Malott Japanese Garden if there’s a raccoon problem. I like to say that I’m sort of like a CSI detective when it comes to plants. If a plant is failing, I try to find out why and what it needs. I look at the buds, the stem, the trunk, the root flare, the soil, and the plant’s history over the years.

PHOTO: Tom Tiddens poses with a cardboard coyote cutout, used to deter varmints from veg. — Tom Tiddens and a plant healthcare specialist’s best friend head out to play fetch.

I also work with the horticulturists on preventive care, including watering, pruning, weeding, and fertilizing. When I see a problem in the early stages, I’m very patient and tolerant. I like to see if Mother Nature might take care of it—maybe a hard rain will wash away any aphids or the ladybugs will get rid of the pests, for instance.

People ask me how I track the health of more than 2.6 million plants here. I have two great plant healthcare specialists who work with me, and I really rely on the horticulturists—they’re my eyes out in the field—and my volunteer team, which includes a lot of master gardeners. Every week, I give the volunteers a map and checklist marked with target plants and pests. So a typical volunteer assignment, for example, would be to check the spirea bushes in the Sensory Garden for aphids.

PHOTO: Bagworms infect a pine. — From bagworms…

PHOTO: Rust infects a fruit and leaf. — …to rust…

PHOTO: Black spot infects rose foliage. — …to black spot on roses, Tom Tiddens treats them all.

The average home gardener doesn’t have to be so methodical. Gardening shouldn’t be a chore. I like to keep things simple at home. I don’t like weeding, and I avoid using a lot of perennials or groundcovers. I like having a nice woodchip mulch bed and a mulching lawnmower. It’s the same thing with fall leaves. Everyone bags up all the leaves. Nope. I raise my mulching lawnmower, and I just grind them into the lawn.

Register now for a certificate class with Tom Tiddens, plant health care supervisor and certified arborist. From July 21 to August 28, he will teach Plant Health 2 with Kathie Hayden, the Garden’s manager of plant information service.