August 4, 2008
Colo. Releases Bugs to Tackle the State’s Unwanted Plants
By Dan England, Greeley Tribune, Colo.
Aug. 4--Tina Booton keeps a tamarisk tree near her cubicle in the Weld County Public Works Department.Someone with a sick sense of humor could say it was pulled from the ground and displayed as an example to show what happens when you mess with Weld County's weed dictatorship. The tamarisk, after all, is as noxious as they come, a plant that's invaded Grand Junction and other parts of the Western Slope and continues to annoy Weld weeders, too.
Booton, the county's weed division supervisor, is using the plant, pulled a month ago, taped to the front of a cubicle and placed in a small jar of water (they're not savages, after all), as an example -- an example of the plant's strength.
"In that horrible environment, it can still thrive," Booton said with a sigh while pointing out her window in north Greeley near the river. "So just think what it can do out there."
Sometimes it seems tamarisks, and other noxious weeds on the most wanted list, are the dictatorship, not the weeders like Booton leading the fight against them. They're everywhere, they're hardy as heck and they're oppressive, stealing precious habitat and water away from good plants such as cottonwoods (tamarisks can guzzle 200 gallons of water a day, for instance). That hurts wildlife as well because the weeds don't provide the shelter or any food that the good plants give.
But there is hope, and part of it comes from little critters no bigger than your thumb.
Meet the wee warriors.
Weld County unleashed a tiny army of Diorhabda elongata, also called the tamarisk leaf beetle, a couple weeks ago near Fort Lupton as a part of a weed-pulling event. The number released, between 25-50, means it was more ceremonial than anything. But the beetles are being used in bunches in places such as Grand Junction.
They've shown so much promise, this year the state department of agriculture expanded the program to selected sites through the state, and in 2009, officials expect the beetle to be distributed throughout Colorado.
The beetles show just how hard it is to get a wee warrior approved and released, but they also show how effective they can be in controlling noxious weeds as well.
It took 10 years of testing to discover the Diorhabda elongata's passion for tamarisks and learn that the tamarisk is all the beetle eats. That second point, of course, is important, said Dan Bean, director of the Pallisade Insectary for the Colorado Department of Agriculture.
"The first challenge is ensuring that what you're releasing is safe," Bean said. "That's the very first thought. You could introduce a grasshopper that would eat tamarisks, but it would also eat everything else."
Many times, as with this beetle, they have to bring the bug here from overseas because that's how many noxious weeds were established in Colorado. They were introduced from other places, usually overseas, and got out of control. Other times, that means places like Pallisade have to raise the warriors themselves. They have to keep them fed and clean and happy, as if they were raising toddlers (Bean actually prefers to compare it to a dairy farm). They even are one of the few agencies that devotes greenhouse space to raising weeds to feed the bugs during the long, cold winters when the plants all die off.
"They don't take vacations or weekends off," said Bean, sounding like a harried parent describing his children. "The insect growing business is a lot harder than you might imagine."
His agency seems to triple in the summer from seasonal employees hired to go out to fields and collect established populations of bugs so they can be released in other places. That's a lot easier than raising them by hand.
But getting those populations established is challenging. Aphthona flea beetles sometimes work to control leafy spurge, but they didn't seem to work too well in Colorado, Booton said. She was pretty high on Bindweed mites and moths until this hard winter seemed to weaken them. And her dream, finding a critter that could attack Russian olives, is years away, Bean said. Scientists know of about 20 that feed exclusively on the Russian olive, but it's a political issue as well because they aren't nearly as big of a problem in other areas as they are in Weld County (those trees, in fact, are much worse here than the hated tamarisks).
"Some people like it, so there's some opposition to destroying it," Bean said. "People don't want to spend too much time on something that will never be approved."
Still, the Russian olive is listed as a noxious weed in Weld, and the trick is to find a bug that feeds on the just the fruit, so it won't kill the tree, just keep it from reproducing, and there are a few bugs that do that, Bean said, though they are at least a decade away from being released.
Booton is helping to write a nine-county plan for eradicating the tamarisk, and once that happens, she can go for grant money to help. But don't expect her to go after a multitude of tamarisk leaf beetles. The wee warriors are not her first choice to battle weeds. They rarely finish the job. They defoliate weeds, not destroy them.
But the hope comes from the fact that after several years of that, it appears that other methods used to kill tamarisks, such as burning, actually works. So the beetles appear to be a good weapon when combined with other methods. That's soothing considering tamarisks could always become a serious problem in Weld, especially in a bone-dry summer, when other plants are suffering have little left to fight off weeds.
So even Booton thinks about the small army of tamarisk leaf beetles she helped release a couple weeks ago. The odds are against them.
"I do hope they make it though," she said. "It would be nice for them to help us out in the future."
WEE WARRIOR BREAKOUT
--Diorhabda elongata -- Also called the tamarisk leaf beetle, these little critters eat tamarisk trees, and tests have gone so well, officials expect them to be distributed throughout Colorado next year.
--Painted Lady Butterfly caterpillar -- These love to munch on the annoying Canada thistle. In fact some call this critter the thistle caterpillar. They're also considered by many as the most widespread butterfly in the world. The only problem? They don't stick around here for too long and go through cycles like most insects. They are not distributed but do work as a natural agent against thistle.
--Thistle Gall Fly -- This fly forms a gall around Canada thistle. The larvae develops inside the gall.
--Aphthona flea beetle -- These eat leafy spurge and do very well in some parts of the state, although they didn't do too well in Weld County. The beetles don't do as well in parts of the state where the soils are sandy. The state is developing other insects that may do better in these parts of the state and in Weld.
--Bindweed mites and months -- This photo shows the bindweed larvae and moth. The mites are too small. Although the hard winter seems to have weakened them, these are seen as an effective tool against this weed, especially since herbicides don't seem to work as well on the bindweed. Mites also seem to be hurt by heat and dryness, which doesn't bode well for them right now.
--Russian olive -- The next enemy, one of Weld County's worst. What wee warrior will emerge to combat this menace? Stay tuned.
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