ECOLOGICAL STUDIES SHOW THAT ROADSIDE VEGETATION, IF LEFT UNDISTURBED EXCEPT FOR THE SELECTIVE RENEWAL OF A FEW WOODY SPECIES CAPABLE OF DEVELOPING INTO TREES, IS REMARKABLY STABLE. ANNUALS SUCH AS RAGWEED AND OTHER COMMON WEEDS OF AGRICULTURAL LANDS CAN SELDOM MAKE MUCH HEADWAY AGAINST ESTABLISHED NATIVE PERENNIALS. ONLY WHEN THESE NATIVE SPECIES ARE DISTURBED IS THE GROUND LEFT OPEN TO INVASION BY ANNUALS. TO A CONSIDERABLE DEGREE, WELL-ESTABLISHED GROWTHS OF NATIVE PERENNIALS AND SHRUBS RESIST INVASION BY TREES. ONCE THE UNWANTED TREES AND THEIR ROOT SYSTEMS ARE SELECTIVELY REMOVED, REINVASION IS OFTEN SO SLOW AS TO BE NEGLIGIBLE. IN GENERAL, THE TALLER AND THE DENSER THE COVER THAT CAN BE TOLERATED, THE MORE EFFICTIVELY IT INHIBITS TREE INVASION AND THE LOWER THE MAINTENANCE COSTS DROP. TWO ALTERNATIVES IN ROADSIDE VEGETATION MANAGEMENT EMERGE FROM THE FOREGOING. ONE RETAINS AND WORKS WITH THE NATIVE VEGETATION THAT NATURE HAS EVOLVED FOR THE SITE; THE OTHER REDUCES THE COVER TO SOME TYPE OF SOD-FORMING GRASS BY SEEDING, FREQUENT CUTTING, OR BLANKET SPRAYING WITH AN HERBICIDE DEADLY TO ALL BROAD-LEVED PLANTS. /AUTHOR/