Invasive Species Hopscotch

Years ago, the Oregon Department of Agriculture (ODA) responded to a call from a railroad company that reported a worker had been stung by ants. I went was sent to investigate. The train was stopped on a siding in Salem. One of the boxcars contained cotton seed destined for cattle feed. It took me only a few minutes to find red imported fire ants (RIFA), Solenopsis invicta, in the cargo. There were a lot of them. The boxcar was sealed up and fumigated.

RIFA is one of the old-guard invasive species in this country. Native to South America, these ants were introduced to Mobile, Alabama in the 1930s. They have since spread throughout the entire southeastern United States, and in the 1990s, they made the hop to southern California. As their name suggests, fire ants have a powerful sting -- it is painful to humans and fatal to baby birds and newborn animals. The mounds they build interfere with machinery. RIFA is old news in the Southeast, but it is back in the scientific spotlight.

Scott Bauer, a U.S. Department of Agriculture researcher, has been studying the genetics of RIFA. He and his collaborators collected ants from 2,144 RIFA colonies in 11 countries, including newly invaded sites in the Caribbean, Australia, New Zealand, Taiwan, and China. Genetic analysis indicates these new invasions are coming from the United States, not RIFA’s homeland in South America.*

Nik Grunwald at Oregon State University is uncovering a similar hopscotch pattern of spread by sudden oak death (SOD), Phytophthora ramorum. There are three clonal lineages of SOD in North America. One was introduced into California. Another first appeared in British Columbia or Washington, and a third hopscotched here from Europe. Amazingly, scientists haven’t yet found this pathogen’s native range!  It must be pretty inconspicuous at home.

Another invasive species playing hopscotch is the granulate ambrosia beetle, Xylosandrus crassiusculus. Home for this wood borer is Africa and Asia, but it invaded the southeastern United States in the 1970s. In 2004, we caught a bunch of them in The Dalles. They weren’t coming from Africa or Asia; they were hitchhiking in green railroad ties imported from the Southeast. It took us a couple of years to eradicate them.

Secondary invasions may be more important than we realize. Populations of invasive species are often much higher in invaded territories outside their native range and those populations may be pre-adapted for playing invasive species hopscotch.

*Science News. March 26, 2011. Vol. 179(7) pg. 15.

Dan Hilburn

Oregon Gambles with Giant Reed Grass

Oregon has begun a giant experiment with giant reed grass, Arundo donax. Over the next few weeks, truckloads of rhizomes will arrive in Morrow County. The rhizomes will be planted on several hundred acres of farmland in the hopes that 20-ft tall canes will someday be a substitute for coal to run the Boardman Power Plant. If successful, this experiment could be an important step toward a sustainable, carbon-neutral energy supply. That would be a very good thing. If it fails, we could have a major ecological problem. That would be a very bad thing.

Giant reed grass is attractive as a source of biomass fuel because it grows fast, like a weed. In fact it is a serious noxious weed in some places, including southern states like California, Texas, and Florida. The Global Invasive Species Database lists Arundo donax as one of the top 100 worst invasive species in the world http://www.issg.org/database/species/search.asp?st=100ss.  Interestingl,y giant reed grass plantations are the source of clarinet, oboe, and basson reeds.

Why would anyone plant a known noxious weed? That is a fair question. At the Oregon Department of Agriculture (ODA), we are concerned, but we’re also confident that the test phase can be done in a manner that will allow Portland General Electric (PGE) to assess the fuel potential of this crop while ODA and Oregon State University assess it’s weediness. Oregon is on the edge of the range of this grass. It grows well and becomes invasive in warm, wet habitats. Giant reed grass has been sold as a nursery ornamental in the Pacific Northwest for years. It has also been tested as a crop in Prosser, Washington. It has never become invasive here. At this latitude, it doesn’t flower or produce seed.  

We can hope that Oregon is in a zone where giant reed grass will grow under cultivation with human assisstance, but not in the wild where it could be weedy. One good thing about giant reed grass is that it easy to see because it is so tall. So we’re all observers in this experiment. Keep your eyes open. If you see a very tall grass growing most likely in riparian areas, contact us at: 1-866-INVADER or oregoninvasiveshotline.org. Good luck PGE, and good luck Oregon. Roll the dice.

Dan Hilburn

Sterile Butterfly Bush Coming This Spring

Ten new varieties of sterile butterfly bush have been tested and approved. They’ll be available in garden centers in Oregon this spring. I’m going to buy some. They are handsome plants with long flowering periods, and they produce little or no seed. Plant breeders have succeeded in enhancing the desirable features of butterfly bush while eliminating it’s potential to be a noxious weed. Hallelujah!

I suspect gardeners are going to flock to these new varieties like butterflies to the flowers. The pictures are gorgeous, and the plants are more compact with shorter stems and bigger flower clusters.

The Oregon Department of Agriculture (ODA) developed a process in which nurseries can have their varieties evaluated. A 98 percent reduction in fertility is required for approval. The table below shows data for the most recent batch evaluated for Ball Ornamentals. The varieties in bold meet Oregon’s sterility standard. All of the approved varieties are complex interspecific hybrids--in other words, they can’t revert to the original species, Buddleia davidii, that has been the cause of so much concern in the past.

  

Mean fertility of control (fertile) cultivars was 7.32 seeds per capsule. The fertility reported for each cultivar is its relative fertility compared to 7.32 seeds per capsule. Cultivars in bold italics are exempt based on 98% reduction in fertility.

Cultivar                                                                                % Fertility          

FLUTTERBY GRANDÉ™ Blueberry Cobbler Nectar Bush                0

FLUTTERBY PETITE™  Lavender Nectar Bush                                   9.0

FLUTTERBY™ Peace Nectar Bush                                                122

FLUTTERBY™ Pink Nectar Bush                                                  2.0

FLUTTERBY™ Lavender Nectar Bush                                             50

FLUTTERBY PETITE™ Dark Pink Nectar Bush                                  13.1

FLUTTERBY PETITE™ Snow White Nectar Bush                           0.4

FLUTTERBY GRANDÉ™ Peach Cobbler Nectar Bush                     0

FLUTTERBY PETITE™ Blue Heaven Nectar Bush                               5.6

FLUTTERBY™ Mauve Pink Nectar Bush                                           5.9

FLUTTERBY GRANDÉ™ Tangerine Dream Nectar Bush                0.4

FLUTTERBY GRANDÉ™ Sweet Marmalade Nectar Bush               0

FLUTTERBY PETITE™  Tutti Fruitti Pink Nectar Bush                       4.6 

FLUTTERBY GRANDÉ™ Vanilla Nectar Bush                               0

_____________________________________________________________________

More sterile varieties are in the pipeline, and there should be plenty of choice for gardeners in the future. You can find the complete list of the approved varieties at:

http://www.oregon.gov/ODA/PLANT/NURSERY/buddleja_process.shtml.

Breeding out invasiveness is a new concept; I hope it catches on. There are quite a number of other ornamental plants that have weedy tendencies. If would be nice if gardeners could enjoy them now without causing noxious weed problems for future generations.

Dan Hilburn