UNIVERSITY PARK, Pa. -- Invasive plant species are one of the top environmental threats to Pennsylvania ecosystems, according to a plant scientist in Penn State's College of Agricultural Sciences. But property owners whose land receives no or minimal maintenance can help prevent the spread of these weeds by following several simple steps.

An invasive plant is defined as one that grows aggressively, spreads and displaces other plants in an ecosystem. "Many species now considered invasive originally were introduced intentionally as landscape plants or for other purposes," says Larry Kuhns, professor of ornamental horticulture. "The best insurance against the spread of invasive plants is to avoid their use and to educate others about their use.

"Invasive plants are less of an issue for average homeowners who own small, highly maintained lots of up to 3 acres in size," Kuhns says. "A property owner who has larger tracts of land left in a natural state should be aware of invasive plants."

Kuhns offers some step-by-step advice to homeowners who would like to keep invasive plants in check on or near their property.

--Prevent landscape disturbance. Invasives will thrive in bare soil or tilled earth where native plants have been displaced. "One key to controlling invasives is to protect healthy plant communities," Kuhns says.

--Maintenance plans. Although most homeowners regularly maintain lawns and ornamental gardens, other property areas need maintenance as well. "Meadows should be mowed at least once a year," Kuhns advises. "In woodlands, owners should walk the property and eliminate invasive plants."

--Go scouting. All homeowners should inspect their land every year.

--Remove invasives early. If a homeowner has been scouting vigilantly, most invasive plants can be found when they are small and easily controlled. Kuhns warns that invasives should not be allowed to go to seed. "Digging or cutting out the offending plant is preferred," Kuhns says. "But large plant populations may need to be stopped using a herbicide. Only trained professionals should apply herbicides."

--Replant after weeding. Invasive plants exploit bare soil and unused niches. "If you remove a weed, the invasive plant will come right back unless you substitute another plant," Kuhns says. "It's important to fill niches with plants that will provide seeds for the future."

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EDITORS: For more information, contact Larry Kuhns at 814-863-2197.

Contacts: John Wall jtw3@psu.edu 814-863-2719 814-865-1068 fax