Although four years have passed since the State of Arizona's Advisory on Invasive Species published its "invasives" lists and eradication plans, gross vegetative violators persist in the Northland like Cheat Grass and Tamarix. Unchecked invasions persist like the Siberian Elm (Ulmus pumila) thickets, rending asphalt and concrete in old parts of Flagstaff. Some, less evident but occasionally attractive, like the Field Bindweed (Convolvulus arvensis), creep along Espee Road's flats north of Williams.

This war has fronts all over Arizona's Highlands. Scotch Thistle (Onopordum acanthium) thickets mar the first half-mile of Airport Road north of Williams. Parking lots and open areas from Milton to Cosnino itch with Diffuse Knapweed (Centaurea diffusa). Ravenna Grass (Saccharum ravennae) infests creek-side hills and canyon edges from Wet Beaver Creek to upper Chino Wash. A gnarled Saltcedar tree (Tamarix ramosissima) is poised in a yard along Seligman's Old Route 66, ready to flush its seeds into the Verde River's upper watershed with the next monsoon downpour.

So, what is one to do?

One, if you own property or are a renter with a desire to help, learn to identify the plants and eliminate them or pay someone to cull them for you. If you discovered bedbugs in your boudoir, you'd call an exterminator. Well, advancing infestations of knapweed demand the same quick action.

Two, pick your battles. Some were lost a long time ago and fighting them isn't worth it. The eradication of Bermuda grass (Cynodon dactylon) from Oak Creek's courses is like trying to spray the moon with a water hose. But those biennial invasive thistles, the tap-rooted mustards like Sahara Mustard (Brassica tournefortii), those scratchy "Russian thistles" (the Salsola genus) and the clumping invasive grasses like bromes and lovegrasses, are all well worth your ammunition.

Three, pick your weapons. To cut off young, tap-rooted thistles, saltcedars and mustards, use a sharpened spade or garden hoe. To weaken Siberian Elms and the stoloniferous invasives like Mellilotus, use focused applications of commercially available glyphosphates like "Round-Up." They're effective on young plants, and when applied sparingly on targeted plants, you can avoid collateral damage to neighboring plants. Keep the nasties's seeds from germinating next year with pre-emergents (organic ones, like corn gluten meal, are proven safe and effective). And, when you encounter invasions of resilient, deep-rooted foes, like Field Bindweed, smother them. Drown the infestation under a tough crust like cardboard and pile on a thick layer of mulch, and eventually the plant's reserve of buds will die from light-starvation.

Four, time your attacks strategically. It's best to attack a taprooted invader while it's still young. Pull or cut that tap root before it can store sufficient sugars to launch a comeback. Pull them after wet weather. With hand-in-glove while the ground is still moist, pull them up whole and easily. If you're facing a stand of mature plants, eliminate them before they drop seed for the year. A schedule that pulls the mustards and bromes on snow-free days in March and April, digs the thistles and knapweeds in May and pulls your Russian Thistles by mid-July is just about right.

And, five, reach out, there's help. Lots of information is available, and brigades of helpers are standing by. Coconino County provides a model of one of its eradication success stories at its official Web site. Fort Valley's growing neighborhoods have undertaken extensive eradication campaigns that are showing good results. The Master Naturalists' blog offers an excellent summary of regional efforts at biological eradication and physical removal methods, in addition to excellent photos of many of the region's invasive plants. Arizona's "Advisory on Invasive Species" has published its statewide plan to identify and eradicate invasive species. And volunteer groups, like the county's graduating Master Gardeners and its "Youth Works" corps can provide both brawn and brains. Contact numbers and links for all of these are listed below.

Contacts and Links:

Arizona's official "Invasives" identification and eradication plan: http://www.governor.state.az.us/AIS/

"Non-native Invasive Plants of Arizona:" http://cals.arizona.edu/pubs/natresources/az1482.pdf

Master Gardener hotline: (928) 774-1868, Ext. 19

Youth Works: Contact Judy Chapman for pine needle raking (928) 226-5426

Steve Shields is a Master Gardener Volunteer. Dana Prom Smith, a Master Gardener volunteer and coordinating editor of the Master Gardener Column for Coconino County Cooperative Extension, can be contacted at stpauls@npgcable.com. For more information about the Master Gardener Program, call Hattie Braun, Coordinator of the Master Gardener Program, at 774-1868, Ext. 17, or visit our Web Site: highelevationgardening.arizona.edu.