NOXIOUS WEEDS IN PA
110.1. Noxious weed control list, adopted May 19, 1989, amended April 11, 1997, effective April 12, 1997, 27 Pa.B. 1793; amended November 17, 2000, effective November 18, 2000.

The Noxious Weed Control Committee establishes the following noxious weed control list:

(1) Cannabis sativa, commonly known as marijuana.

(2) The Lythrum salicaria Complex: Any nonnative Lythrum including, Lythrum salicaria and Lythrum virgatum, their cultivars and any combination thereof.

(3) Cirsium arvense, commonly known as Canadian thistle.

(4) Rosa multiflora, commonly known as multiflora rose.

(5) Sorghum halepense, commonly known as Johnson grass.

(6) Carduus nutans, commonly known as musk thistle.

(7) Cirsium vulgare, commonly known as bull thistle.

(8) Datura stramonium, commonly known as jimson weed.

(9) Polygonum perfoliatum, commonly known as mile-a-minute.

(10) Puerria lobata, commonly known as kudzuvine.

(11) Sorghum bicolor cv. drummondii, commonly known as shattercane.

(12) Heracleum mantegazzianum, commonly known as Giant Hogweed.

(13) Galega officinalis, commonly known as Goatsrue.

The Department of Agriculture (Department) amends § 110.1 (relating to noxious weed control list) to designate Lythrum salicaria (purple loosestrife), Lythrum virgatum and their cultivars and combinations thereof as noxious weeds and to add Galega officinalis (Goatsrue) and Heracleum mantegazzianum (Giant Hogweed) to the noxious weed control list. The text of this amendment is set forth at 30 Pa.B. 636 (February 5, 2000).

Need for the Rulemaking

There is a compelling public need to protect this Commonwealth's wetland plant and animal populations from the threat posed by nonnative purple loosestrife, cultivars of the plants and cultivars that are combinations of native and nonnative purple loosestrife species.

The addition of Giant Hogweed to the noxious weed control list is necessary to provide the Department needed authority to control and eradicate this nonindigenous plant at the locations in Crawford, Erie, McKean, Venango and Warren Counties where it has appeared. The sap of this plant can cause rashes on the skin of persons with whom it comes into contact.

The addition of Goatsrue to the noxious weed control list will provide the Department needed authority to address the presence of this nonindigenous plant at the Philadelphia area location where it has been detected. This plant is toxic to livestock.

Lythrum salicaria, commonly known as purple loosestrife, is a nonnative wetland plant that thrives in the absence of the insects and diseases that controlled it in Europe and Asia. It clogs waterways, crowds-out native plant species and decreases the population of animals that are dependent upon these native plant species for survival. For this reason the Department placed Lythrum salicaria, commonly known as purple loosestrife on the noxious weed control list in § 110.1. This regulatory change was published at 27 Pa.B. 1704 (April 12, 1997) and became effective on that date.

Since Lythrum salicaria was added to the noxious weed control list, the need to add other Lythrum species and their cultivars and combinations has become apparent. There are many cultivars (cultivated varieties) of purple loosestrife that are listed under species names other than Lythrum salicaria. These other species and cultivars present as great an environmental threat as does Lythrum salicaria. The regulation addresses the threat posed by these plants.

Lythrum virgatum is a source of purple loosestrife cultivars. Like Lythrum salicaria, Lythrum virgatum is a European wetland plant that has been introduced into North America. These two species are very similar, differing in only several minor diagnostic characteristics. The two also cross pollinate freely. For this reason, a number of plant specialists consider Lythrum salicaria and Lythrum virgatum to be the same species. The fact that these plants intercross freely has also helped to blur scientific distinctions between cultivars of the two.

Until recently, the various ornamental purple loosestrife cultivars were thought to be sterile. As such, there would be no danger these plants could naturally cross breed with Lythrum salicaria and pass along genetic traits which might make purple loosestrife an even greater ecological threat than it is already. Recent research, though, has shown that no purple loosestrife cultivar is sterile.

Although most cultivars are self-sterile (that is, incapable of reproducing alone), they produce large quantities of viable seed when functioning as either male or female parents in cross breeding with other cultivars and species of loosestrife. Bees and wasps are effective pollinators of loosestrife, and provide the means for cross pollination, even between plants that are a considerable distance from each other.

It is possible a relatively benign ornamental cultivar of indigenous purple loosestrife could cross breed with Lythrum salicaria and produce a new cultivar of purple loosestrife that combines the native species' tolerance of this Commonwealth's temperature extremes or its ability to thrive in areas other than wetlands with the aggressive growth characteristics and the disease resistant characteristics, or both, of Lythrum salicaria. This is not abstract speculation. Some genetic traits of Lythrum salicaria have already been found in cultivars of purple loosestrife.

Galega officinalis, commonly known as Goatsrue, is a nonnative plant that is on the Federal noxious weed list and is toxic to livestock. Goatsrue is only known to exist in this Commonwealth at an arboretum in the Philadelphia area.

Heracleum mantegazzianum, commonly known as Giant Hogweed, is a nonnative plant that is on the Federal noxious weed list and causes skin rashes on many persons who come into contact with it. The plant is only known to be present in this Commonwealth in Crawford, Erie, McKean, Venango and Warren Counties.

Comments

Notice of proposed rulemaking was published at 30 Pa.B. 636 and provided for a 30-day public comment period.

The sole comment originated from the Pennsylvania Landscape and Nursery Association (PLNA). Although PLNA supports the addition of Lythrum salicaria (purple loosestrife), Galega officinalis (Goatsrue), Heracleum mantegazzianum (Giant Hogweed) and Lythrum virgatum to the noxious weed control list, it expressed concern regarding the addition of the cultivars and combinations of Lythrum salicaria and Lythrum virgatum to that list. Rather than a broad designation of these cultivars and combinations as noxious weeds, PLNA recommended each such cultivar or combination be evaluated and considered individually for inclusion on the noxious weed control list. PLNA offered the opinion there is not ''. . . enough evidence to support that all cultivars, both current and future, should be considered noxious weeds.''

The Department gave careful consideration to PLNA's comment. On balance, the Department is satisfied that all cultivars and combinations of Lythrum salicaria and Lythrum virgatum should be included on the noxious weed control list, and that current scientific research supports this position.

Research conducted in Minnesota has shown that no purple loosestrife cultivar is sterile. All cultivars can produce viable seeds when crossed with other cultivars and species, including Lythrum alatum (winged loosestrife), a noninvasive native of wetlands. The cultivars pose a great risk because, unlike the parent species, they are adapted to grow in drier soils. Continued crossing between cultivars and parent species can lead to new genetic combinations that would allow loosestrife to colonize drier, more upland habitats, making it an even more troublesome weed.

The Department also believes that, even were it inclined to do so, it could not draw a workable regulatory line to exclude any particular cultivar or combination of Lythrum salicaria and Lythrum virgatum from the noxious weed control list. Distinguishing between cultivars of loosestrife is difficult at best. Like-named cultivars may look different and differently-named cultivars may appear identical. This situation would be unworkable for any plant inspector or botanist tasked with making a precise identification of a particular cultivar or combination.

The Department is mindful that certain cultivars or combinations of Lythrum salicaria and Lythrum virgatum are produced and sold commercially in this Commonwealth, and that these plants are not uncommon in ornamental flower gardens. It is satisfied, though, that there are numerous perennial plants that are suitable substitutes for these cultivars or combinations. This Commonwealth's plant nursery industry has been provided several years' advance notice that cultivars or combinations of Lythrum salicaria and Lythrum virgatum would be included on the noxious weed control list, and the Department believes the industry has prepared for this regulation by eliminating stocks of these plants or obtaining suitable substitutes for these plants. The Department views the inclusion of these plants on the noxious weed control list as the first logical step toward reducing the prevalence of these plants in this Commonwealth.

The Department is currently cooperating with the United States Department of Agriculture on a biocontrol project with respect to purple loosestrife. The project involves the release of several different species of beetles that attack loosestrife. Tests have shown these insects capable of drastically reducing loosestrife populations in natural areas, thereby allowing native plants to begin reclaiming these environments. The Department believes it would be self-defeating to allow sale of even a single cultivar or combination of loosestrife while it simultaneously pursues biological control efforts with respect to these plants.

On balance, the Department is satisfied that all cultivars and combinations of Lythrum salicaria and Lythrum virgatum should be included on the noxious weed control list, and that current scientific research supports this position.

This final-form regulation was deemed approved by the House and Senate Committees on October 5, 2000.