[Pollinator] SF Chronicle: Yellow starthistle menaces flora, fauna

[Jennifer Tsang]

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/01/30/HOEPUKTTJ.DTL


Yellow starthistle menaces flora, fauna


Ron Sullivan, Joe Eaton

Wednesday, January 30, 2008

 
<http://www.sfgate.com/cgi-bin/object/article?f=/c/a/2008/01/30/HOEPUKTTJ.DT
L&o=0&type=printable> The yellow starthistle, Centaurea solstitialis is a
menac...

When you recognize yellow starthistle, Centaurea solstitialis, and you learn
its history and effects, you can scare yourself half to death driving down
Interstate 5 in early summer. Those little yellow flowers blanket miles of
fields.

This pest is familiar along roadsides and "disturbed places" churned up by
plow, bulldozer or cattle. It has few natural consumers or enemies and it
seeds profusely - a large plant can produce nearly 75,000 seeds. Its long
spines are wicked and puncture the eyes and noses of grazers and the skin of
hikers. It's pure hell to extirpate. Starthistle doesn't like deserts, the
coast or anywhere above 7,000 feet, but the rest of California suits it just
fine.

The barbed seeds hitchhike in loads of hay and on the undercarriages of
vehicles. For short-distance transport, they also attach to fur, hair and
clothing.

It pushes out native plants and sucks the moisture out of grassland soil. It
lowers the yield and forage quality of rangelands; though sheep, goats and
cattle will eat it in its young pre-spiny stage, it doesn't approach the
nutritional value of the grasses and other plants that it replaces as it
matures. It contaminates dried hay stocks. Worst is the effect on horses, in
whom long-term starthistle consumption leads to a neurological disorder
called nigropallidal encephalomalacia, or chewing disease. An afflicted
horse develops brain lesions, manifested by involuntary chewing,
lip-twitching and tongue flicking, and may starve. It sounds like an
extremely unpleasant way to go.

It's not good for much, ecologically and biologically speaking, except that
honeybees like it and make it into sweet, neutral honey. Making the best of
a bad thing sounds good.

But there's a downside to the honeybee-starthistle partnership, if you don't
want pastures and meadows full of toxic thistle. A group of entomologists -
John Barthell and Robbin Thorp from UC Davis, Adrian Wenner from UC Santa
Barbara and John Randall of the Nature Conservancy - measured the relative
effectiveness of honeybees versus native bees as starthistle pollinators. At
three California sites, they used mesh to exclude honeybees from starthistle
patches but let native bees in. The honeybee-less thistles had lower than
normal seed set; honeybee pollination approximately doubled seed production.
Barthell and his colleagues dubbed the starthistle and the honeybee
"invasive mutualists" - Old World allies picking up their relationship to
the benefit of both in a new setting.

Yellow starthistle probably got here from its native southern Europe by way
of Chile, contaminating alfalfa seed, around the time of the Gold Rush; the
first confirmed record is from Oakland in 1869. Later introductions came
from Argentina, Italy, France, Spain and Turkestan, whatever that is now. By
World War I the plant was all over the Sacramento Valley. 

It had seized a million acres in the late 1950s, 8 million in 1985, 12
million by the mid-1990s. The San Joaquin Valley, the North Coast ranges and
the Sierra foothills were overrun.

So people familiar with starthistle were both amused and rankled when, early
in January, Forest Service ranger Anne Yost forwarded the following to the
California Invasive Plants Council's e-mail list:

"Yellow Star Thistle Honey comes from an increasingly rare Northern
California wildflower. Not so long ago, the small yellow, fuzzy flowers
dotted roadsides and fields, familiar to all who drove through the
countryside. Now, as the population grows and demands of agribusiness
increase, Yellow Star Thistle has been almost obliterated! Beekeepers ...
vie for hive locations in the last densely flowered areas."

That was from the Moon Shine Trading Co.'s Web site. The same words had been
appearing on its labels for a decade or so. It suddenly changed to a
truncated version when a squad of CalIPC mailing-list readers (disclaimer:
including Ron) sent angry, sarcastic or educational e-mails to the company: 

"Yellow Star Thistle Honey comes from a vibrant wildflower growing
throughout Northern California.

"Not so long ago, the small yellow, fuzzy flowers dotted roadsides and
fields, familiar to all who drove through the countryside." 

It's still a stretch to call starthistle a wildflower, though there is
nostalgia for flowers dotting fields: Now starthistle blankets those fields
instead.

Dr. Joseph Di Tomaso of UC Davis' Weed Science Program had used that label
copy 10 years ago to ask jokingly for a promotion: "I had just started most
of these multiyear [starthistle eradication] projects. That is what made it
so funny. Only three years and I nearly eradicated the plant, according to
the label. Of course, I told the faculty that they were not allowed to go
outside during the summer, lest they find out that the honey ad may not be
accurate."

He adds, "The craziest thing about this is that the labels seem to come from
a company in Winters, Calif. Winters is just west of Davis and is in the
center of YST territory. You could hardly walk out of the printing shop
without bumping into YST." 

Another mailing list member, Forest Service research plant ecologist Jan
Beyers, had a different approach: "I asked them to please look for a truly
native substitute to produce and promote instead." This sounds constructive.
Honey lovers among us might well seek out the products of our unique native
flora. There are aspects of terroir we have yet to explore. 


Resources 


-- UC Davis Yellow Starthistle home page: wric.ucdavis.edu/yst/yst.html.

-- California Invasive Plants Council: www.cal-ipc.org.

Joe Eaton and Ron Sullivan are freelance nature and garden writers in
Berkeley. E-mail them at home at sfchronicle.com. 

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/01/30/HOEPUKTTJ.DTL

This article appeared on page G - 3 of the San Francisco Chronicle

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.sonic.net/pipermail/pollinator/attachments/20080130/10692ca5/attachment.html 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/gif
Size: 4997 bytes
Desc: not available
Url : http://lists.sonic.net/pipermail/pollinator/attachments/20080130/10692ca5/attachment.gif