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Excerpts from recent issues of Invasive Plant Newsletter

These news items pertain to events in New Hampshire, Vermont or in the Upper Valley region.   These articles have been organized by topic [and date], and are culled from an irregular newsletter published by the Upper Valley Purple Loosestrife Coalition.

General news about invasive plants
Local community  initiatives about invasive plants
News about Purple Loosetrife and bio-control program
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General News On Invasive Plants

Proposed Rule Making on Noxious Weeds in VT: A Complex Process
Comments and questions should be submitted by February 16, to 

Scott Pfister                                                    Phone: (802) 828-3481 
VT Dept of Agriculture, Food and Markets     FAX: (802) 828-2361 
116 State Street, Drawer 20 Montpelier
VT    05620-2901 

Some of you may wish to submit comments on the following list, on the proposed criteria, or perhaps suggest additions/deletions for the list. 

The following criteria were developed with assistance of the ad-hoc VT Invasive Exotic Plant Committee: 

  • as determined by a pest risk assessment, the invasive plant targeted must pose an actual or anticipated threat to a substantial agricultural, forestry or environmental interest and/or the general public. However, the absence of complete biological knowledge of a pest will not necessarily prohibit the adoption of a quarantine. 
  • establishment of a quarantine for a specified invasive plant is likely to contribute to the objective of preventing introduction or for limiting spread and/or severity. 
  • no substitute or alternating mitigating action will accomplish the same pest prevention purpose. 
  • the economic and/or environmental benefits outweigh the economic and/or environmental costs associated with the quarantine. 
The list includes 33 species, including 
upland plants: goutweed, tree-of-heaven, garlic mustard, oriental bittersweet, Japanese knotweed, common buckthorn, glossy (European) buckthorn, Bell's honeysuckle, Japanese honeysuckle, Amur honeysuckle, Morrow's honeysuckle, Tartarian honeysuckle, black swallowwort and pale swallow wort. 
aquatic plants: yellow flag iris, common reed (Phragmites) , purple loosestrife, flowering rush, frogbit, hydrilla, E.Indian hygrophila, fanwort, Brazilian elodea, parrot feather, variable- leaved milfoil, Eurasian watermilfoil, yellow floating heart, curly leaf pondweed, four types of salvinias and water chestnut. 

This list is similar to one in circulation, entitled Vermont Invasive Exotic Plant Fact Sheet Series, dating from Spring, 1998. It has additions to the old list of the salvinias and the swallow-worts; and the notable omissions of Japanese barberry, European barberry, Norway maple, Russian and Autumn Olives -- which were on the original list. 

Scott Pfister notes that the quarantine process has many steps: Currently, he is seeking input on the criteria that were used to list plants and if the proposed plants meet the criteria. Once comment has been received, he will draft the proposed rule and submit it to the Interagency Committee on Administrative Rules (ICAR). This is the start of the formal rule making process. If accepted by ICAR, the proposed rule will go out for public comment and public hearings will be held. The department will then need to respond to all public comment and amend the rule as appropriate reflecting the public comment. The rule then goes to the Legislative Committee on Administrative Rules (LCAR). This committee consists of legislators that review the public comment and vote as to whether the rule meets the intent of the law that authorizes the rule. [1/01]

NH Invasive Species Committee Working on a Draft List 
The NH committee met in December with Les Mehrhoff, from Torrey Herbarium at UConn. Mehrhoff has been active in forming the New England Invasive Plant Committee, and in drafting assorted criteria and lists for discussion. In January, the group adopted criteria similar to those used in Connecticut. It has also assembled lists from 14 states/provinces in the north-east, noting the frequency of species listed and is reviewing some of the more commonly listed plants for possible inclusion in a preliminary NH list. [1/01]

Control Agent for Multiflora Rose, Slowly Advancing Eastward
Introduced from Asia over the past 200 years, and once encouraged for wildlife cover and soil stabilization, multiflora rose has grown into one of the most frequently listed of the noxious weed plants in the Northeast. At a recent meeting in Great Barrington, John Randall (TNC's weed expert, from UC-Davis) reported on a disease called rose-rosette (RRD) which causes multiflora rose to die within two to five years of infection. The disease, also called "witches broom", is caused by a virus which is vectored by a tiny mite, Phyhllocoptes fructiphylus; both the disease and mite are considered native. The virus seems endemic in the south and west, and was first observed attacking rose plants in 1983 in Kansas, had reached Ohio by 1987 and now known to have reached Pennsylvania. Since multiflora rose provides rootstock for many cultivated roses, the disease may cause problems for some, particularly hybrid tea cultivars. The virus can be introduced, by grafting infected buds onto healthy plants, using a protocol outlined in a technical paper on the topic: AH Epstein , JH Hill, FW Nutter : Augmentation of Rose Rosette Disease for Biocontrol of Multiflora Rose. Weed Science, 45, pp 172-178, Jan-Feb 1997 . 
Several websites discuss this disease:    and                        [2/01]

Norway Maple, an Effective Invader of Undisturbed Forest
Norway maple has been a favorite shade tree for more than a century. In the article The Myth of the Resilient Forest: Case Study of the Invasive Norway Maple , Rhodora, Vol.102, No.911, pp 332-354, 2000, Sara Webb and others report on the effective invasion of a mature oak-beech-sugar maple forest in NJ by Norway maple (Acer platanoides). Norway maples have existed in the Drew Forest Preserve back to at least 1915 along with the other species, probably established in replacing pasture. Among the larger trees (DBH > 5 cm), Norway maple ranked near the top in abundance among all study plots. 

Understory stem densities provide another picture, however: Norway maple seedlings out compete other shade tolerant species: Norway maple understory had low diversity and a preponderance of Norway maple seedlings. Sugar maple and beech had significantly higher diversity in the understory, but Norway maple seedlings still accounted for 81% of all woody seedlings beneath sugar maples and 80% of seedlings beneath beech trees. The tree does not require the forest edge to initiate invasion, although recruitment from adjacent landscape plantings does accelerate its progress. The article concludes that the plant is clearly a threat to forest diversity, and to the preservation of native wildflowers and shrubs, which the tree out-competes. 

A "wild" section of Central Park (The North Woods) had suffered the same experience as the Drew Forest; a concerted effort to remove Norway maple trees and seedlings has resulted in a surprising recolonization by native species. A similar observation of Norway maple dominance in understory is reported in recent (winter 2000-2001) edition of The Land Steward, a newsletter of the Finger Lakes Land Trust. In an informal survey of tree species in Fall Creek gorge in Ithaca NY, 60 specimens of 12 native trees were found; but three invaders were represented in amazing numbers --- 50 seedling ailanthus, 238 Norway maples, two dozen glossy buckthorns. The solution to this problem is certainly tough -- remove those trees present and prevent future invasions. [2/01]

Towards A Native-Grass Seed Mix for New England 
Currently, commercial seed mixes often contain non-native grasses, such as tall fescue, orchardgrass, and Kentucky bluegrass. These non-native grasses have been widely used in our area, are well established, have many useful attributes in some applications (say, for forage or lawns), but also have notable vigor and quite a competitive advantage when compared to native warm season grasses. Native warm seasons grasses have many positive attributes which are preferred to maximize resource conservation objectives on some sites. 

Currently, native grass seed supplies often come from the mid-west or other areas, where the seed may be genetically different than the native grasses found here in the North East. Of our native species, the only commercially available cultivars from the Northeast are 'Niagara' big bluestem and 'Tioga' deertongue, two warm season grasses. There are no selected and tested cultivars currently available of our native cool season grasses. 

To remedy this problem, the Plant Materials Program of the NRCS* has collected specimens of 10 native cool season grasses (collected from 178 sites), and 8 warm season grasses (with samples collected from 90 sites). The cool season species to be investigated include: Poverty oatgrass, Canada bluejoint, Bottlebrush, Canadian wildrye, Virginia wildrye, Riverbank wildrye, Hairy wildrye, Drooping woodreed, Stout woodreed, and Crinkled hairgrass. Seed was collected from sites within New England, NY and PA. 

These 268 seed samples will be evaluated at the NRCS Plant Materials Center in Corning, NY. The selected collections then will be tested at several sites within the region, and assessed for qualities such as root structure, plant survival, growth response, phenology, and biomass. Depending on the results of this assessment, final selection will be made for release to commercial production, to form the basis of regional native seed mixes for use in many conservation and farm plantings such as permanent wildlife cover, disturbed lands reclamation, forage, and possibly biofuel cropland. The project is expected to take from 5 to ten years until completion, with successful species made available during that time frame. 

In addition, the agency is currently developing selections of these warm-season grasses: switchgrass, indiangrass, prairie cordgrass, big bluestem, little bluestem, seaside bluestem, broomesedge, and deertongue. 

* Natural Resources Conservation Service -- formerly the Soil Conservation Service, a branch of the USDA, with offices in most counties.    [2/01]

Montshire Native Grass Experiment -- a Great Success, to be Extended
A previous (June) newsletter reported that the new Quinn Preserve at the Montshire Museum is home to an experiment run in cooperation with the VT-NH regional group of the Natural Resources Conservation Service (NRCS) of the USDA . Earlier this summer, the site didn't look too hopeful (as some of these grasses are slow to germinate), but finally all varieties did germinate and grow: Indian Grass, Eastern Gamagrass, Tioga Deertongue, Switchgrass, Little Bluestem, Big Bluestem and Side Oats Grama. The seed mix also included Black-Eyed Susan. The season ended with a magnificent display of feathery bronzed grasses, accented by the tall tassels of big bluestem. Some blue vervain has kindly volunteered itself in the plot. The NRCS folks came to see the grass plot, and declared it a success. These grasses are growing on land once crowded with invasive shrub honeysuckle and glossy buckthorn plants. Buckthorn seedlings (which can easily be hand-pulled when small) are re-appearing at a heavy rate, and will probably need monitoring for several years. However, the museum folks intend to extend the area covered by the experiment, and push back the invasive plant frontier. [11/00]

Garlic Mustard Making Inroads -- Plainfield, Hanover, Thetford and Hartland
For those of you who haven't yet encountered Garlic Mustard (Alliaria petiolata), be on the lookout, and remove at its first occurrence! The plant is a biennial, but spreads at a fantastic rate, and can tower over its neighbors if given a start. (Check this website for more information.). 

At the New England Wildflower Society's sanctuary on River Rd in Plainfield NH, Chris Mattrick, rare plant curator and invasive plant lead attacker for the NEWFS, reports that volunteers collected 37 50-gallon bags of garlic mustard over a two day period at the end of May, just when the plant was beginning to set seed. The group worked on a larger area than last year, but only collected 2 more bags this year than last. He's not sure what this means - but feels that the quantity was no worse this year than last. When Chris came to NEWFS in 1995 and visited the sanctuary then, he did not note Alliaria in the species list. He first noted the plant in 1997 and by 1998 it was a big problem and spreading. The first control effort was 1999, so now we have the data from 1999 and 2000. Other problem species of note at the site - both Celandine (Chelidonium majus ) and Aegepodium (Bishop's weed or goutweed) are definitely on the increase in the area, especially on the river side of the road.

Garlic Mustard has also been found next to a construction site on Buck Rd in Hanover, and seems to be associated with hay bales used to retain runoff silt -- probably a gift from the place which grew the hay. Weed-free hay (straw) is much more expensive. This suggests yet another requirement for construction sites and their enforcement. There has been an honest effort to pull all the garlic mustard plants in the Buck Road area, but the site will have to be monitored for several years to be certain it has been contained. Apparently the plant has also appeared in Thetford, near Geary Road. The NH Nature Conservancy sent out a crew to tackle the plant on Hart Island in Hartland where it has recently appeared (along with the Black Swallow-wort which is a perennial problem in the area). [6/00]

A Market for Japanese Knotweed Revealed by CA Floral Designer 
Recently, the Hanover Garden Club was treated to a demonstration by Trace Robinson, a noted California designer. Part of the program was devoted to "modern" floral design, and in three arrangements, she made use of Japanese Knotweed. She had removed the leaves from the plant, and in one arrangement used varying lengths of cut tubes of the stem (with the membrane at each joint punctured) packed endwise into a low container -- the tubes made elegant and excellent supports for floppy roses; in other designs, she wired longer lengths of the plant stem (which does look like bamboo) into a trellis-like support for tall arrangements. Beware -- the cut tubes can sprout roots (at the ridged joints in the stalk) when placed in water. Don't dispose of the stalks in your compost or leave on the ground! [6/00]

Local Invasive Plant Initiatives

Canaan: Dave Barney, who has been concerned with monitoring water quality at Goose Pond, reports finding a total of five scattered small stands of purple loosestrife near the pond or Little Goose Pond and one in a garden on Goose Pond Rd. All have been removed, neighbors of those plants have been informed, and our color brochure will be distributed in a spring mailing. These measures are very important, for when there are just a few plants it is possible to stop a loosestrife invasion (the plant has three morphs, and to produce viable seeds, each plant must be crossed with one of the other two types) [11/00]

Lebanon:  When the city's Site Plan Regulations were revised about four years ago (in 1996), one provision was introduced to help slow the introduction of invasive plants.  The City of Lebanon now requires that invasive plants cannot be used to satisfy landscaping requirements. The list of exotic invasive plants includes the following 22 species (several of these are no longer sold at nurseries, but many are still for sale): Acer plantanoides (Norway maple ) ; Aedopodium podagraria (Bishopsweed or goutweed ) ; Ailanthus altissima (Tree-of-heaven); Ampelopsis brevipedunculata (Porcelain berry); Berberis thunbergii (Japanese barberry); Berberis vulgaris (European or common barberry); Celastrus orbiculatus (Asian Bittersweet); Coronilla varia (Crown vetch); Cytisus scoparius (Scotch broom); Elaeagnus angustifolia (Russian olive); Elaeagnus umbellata (Autumn olive); Euonymus alata (Burning bush) ; Euonymus fortunei (Climbing euonymus, wintercreeper); Hedera helix (English ivy); Lonicera japonica (Japanese honeysuckle); Lonicera maackii (Amur honeysuckle); Lonicera morrowii (Morrow's honeysuckle); Lythrum salicaria (Purple loosestrife); Phragmites (Common reed); Rhamnus cathartica (Common buckthorn, tallhedge); Rhamnus frangula (European buckthorn, Glossy buckthorn); Rosa multiflora (Multiflora rose, baby rose)  [4/00]

News About Control of Purple Loosestrife

Purple Loosestrife Collapse at Several Bio-control Sites 
In NH, at two bio-control release sites near Nashua, the purple loosestrife population has collapsed. A site near Bedford NH is near collapse. In VT, the site at the Rutland Airport has collapsed and you can find photos of this on the VT purple loosestrife webpage. ( You can also find the 2000 Report on Purple Loosestrife Bio-control Program.

At most of these sites, the beetles were released four years ago. The term "collapse" doesn't mean that purple loosestrife is eradicated at these sites. It does mean that the leaf-eating beetles (Galerucella pusilla or G. calmariensis ) have reached sufficient numbers and that the plant is being suppressed by the beetles. The plants are weakened, but some will survive. The beetles should remain a presence, to help keep loosestrife numbers in check in the future. [11/00]

Bio-Control Programs in NH and VT -- Area Activities in summer 2000 
In Vermont, beetles were released in White River Junction opposite the fire station (the large loosestife patch visible from I-89, near VA hospital), and at the boat launch in Springfield. So far, all Vermont sites have been monitored by state employees. 

In NH, beetles were released at five sites in the Upper Valley: Reed's Marsh WMA in Orford (near boat launch), Wilder WMA in Lyme, Wilson's Landing boat launch in Hanover and on private property in Enfield (Mascoma Lake) and in Lyme. In the case of Wilson's Landing, both the Hanover Conservation Commission and Select Board gave approval for the beetle release; and neighbors submitted a letter of support for the bio-control initiative. At each of these NH sites, there is an individual responsible for monitoring the site for the next three years, who will share data with the state, the landowner and the local conservation commission. Both states are planning to have citizens rear and release beetles next summer. [11/00]

Weevil Release
Vermont had permission to release the root-eating weevil (Hylobius transversovittatus) this year, and this happened at two sites, one of which was Reed's WMA in Orford NH (on the river side of the marsh). The VT Audubon Canoe Campers (who last summer helped us map the loosestrife on the upper stretches of the Connecticut River) this summer did the painstaking weevil release: cut the stem of a loosestrife plant, insert one weevil egg, and then cap the stem with clay. Lori Cragin, bio-control coordinator for VT, directed this effort. Lori says that the15 campers took half a day to "plant" about 200 weevil eggs.  [11/00]