Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Polygonum capitatum (Persicaria capitata); pink knotweed

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

1.02

Has the species become naturalized where grown?

y=-1, n=-1

y

1.03

Does the species have weedy races?

y=-1, n=-1

n

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

See Append 2

1

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

y

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

?=-1, n=0

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

y

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

y

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

y

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

n

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

n

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

y

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

y

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

n

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

n

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

y

4.1

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

n

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

n

5.03

Nitrogen fixing woody plant

y=1, n=0

n

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

y

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

6.03

Hybridizes naturally

y=1, n=-1

n

6.04

Self-compatible or apomictic

y=1, n=-1

6.05

Requires specialist pollinators

y=-1, n=0

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

y

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

1

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

y

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

n

7.04

Propagules adapted to wind dispersal

y=1, n=-1

n

7.05

Propagules water dispersed

y=1, n=-1

7.06

Propagules bird dispersed

y=1, n=-1

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

y

7.08

Propagules survive passage through the gut

y=1, n=-1

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

y

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

8.03

Well controlled by herbicides

y=-1, n=1

y

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

n

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

Total score:

13

Source

Notes

1.01

no evidence

1.02

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

"In Hawaii cultivated on O'ahu , Maui, and Hawai'I, now naturalized in wet forest, open lava fields, and along roadsides, 600-1770m, on Hawai'i."

1.03

no evidence

2.01

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

"Native to the Himalayas and western China"; "In Hawaii cultivated on O'ahu , Maui, and Hawai'I, now naturalized in wet forest, open lava fields, and along roadsides, 600-1770m, on Hawai'i."

2.02

2.03

(1)Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063. (2)http://pss.uvm.edu/pss123/perpolyg.html (3)http://www.suite101.com/article.cfm/222/83872

(1)"In Hawaii cultivated on O'ahu , Maui, and Hawai'I, now naturalized in wet forest, open lava fields, and along roadsides, 600-1770m, on Hawai'i." (2)Soil: constantly moist, tolerates drier if shade, (3)USDA zones 8 and 9

2.04

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

"In Hawaii cultivated on O'ahu , Maui, and Hawai'I, now naturalized in wet forest, open lava fields, and along roadsides, 600-1770m, on Hawai'i."

2.05

USDA, NRCS. 2001. The PLANTS Database, Version 3.1 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

introduced in USA: California, Louisiana, Hawaii

3.01

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

"Native to the Himalayas and western China"; "In Hawaii cultivated on O'ahu , Maui, and Hawai'I, now naturalized in wet forest, open lava fields, and along roadsides, 600-1770m, on Hawai'i."

3.02

http://www.ourgardengang.com/invasive.htm

garden nuisiance

3.03

Singh, R. V.; Arya, M. P. S. (1995) Chemical weed control in Japanese barnyard millet (Echinochloa frumentacea ). Indian Journal of Agronomy, 1995, Vol.40, No.1, pp.51-54, 2 ref.

AB: Chemical weed control in barnyard millet (Echinochloa frumentacea ) was studied in a field experiment conducted under rainfed conditions during the rainy season of 1990 and 1991 at Ranichauri. The herbicide treatments were post-em. application of 0.75 or 1.0 kg/ha 2,4-D Na-salt, and pre-em. application of 0.5 or 1.0 kg isoproturon, 0.075 or 0.1 kg oxyfluorfen and 0.5 or 1.0 kg pendimethalin. The major weeds were Galinsoga parviflora, Polygonum capitatum, Cyperus rotundus, Digitaria ciliaris and Cynodon dactylon . 2,4-D Na-salt at 1.0 kg applied 15 days after sowing gave the maximum barnyard millet grain (15.73 g/ha) and straw (83.50 g/ha) yields. Maximum weed-control efficiency (74.4%) and monetary returns (Rs 3357.7/ha) were also obtained with the same rate of 2,4-D Na-salt.

3.04

3.05

Bacon, P., P.J. Terry, N. Waltham, & P.Castro S. (1997) An Electronic Atlas of World Weed and Invasive Plants. Version 1.0, 1997. A database based on the original work "A Geographical Atlas of World Weeds" by Holm et al 1979.

Polygonum spp. were listed as serious to common weed around to world.

4.01

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

no description of these traits

4.02

no evidence

4.03

no evidence

4.04

http://www.hort.cornell.edu/gardening/fctsheet/mohonk.html

deer resistant plant

4.05

no evidence

4.06

Pradhanang, P. M.; Elphinstone, J. G.; Fox, R. T. V. (2000) Identification of crop and weed hosts of Ralstonia solanacearum biovar 2 in the hills of Nepal. Plant Pathology, 2000, Vol.49, No.4, pp.403-413, 38 ref.

AB: Common agricultural weeds and crops that grow in the high hills of Nepal were examined following inoculation with biovar 2 of R. solanacearum under natural conditions in the UK and Nepal. Bacterial populations in the roots were determined 1 and 2 months after artificial inoculation, and at various intervals after harvesting infected potato crops under natural conditions in Nepal in 1995. Inoculated roots of the summer weeds Drymaria cordata and Polygonum capitata [P. capitatum ] and the winter weeds Cerastium glomeratum and Stellaria media yielded 102-107 colony-forming units per g root. High populations of the bacterium were recovered from these plants even after partial surface sterilization, indicating that systemic infection had occurred. R. solanacearum populations were recovered from root extracts of 75% of naturally growing D. cordata plants when sampled 3 months after harvest of a potato crop with bacterial wilt. Similarly, root extracts of 25% of P. capitata plants carried the bacterium. No pote

4.07

no evidence

4.08

no evidence [low growing herb]

4.09

(1)Horticopia, Inc. (2002) Horticopia Plant Information. Available at<http://www.hortpix.com/index.html> (2)http://ohioline.osu.edu/hyg-fact/1000/1243.html

(1)"prefers partial shade or partial sun to full sun; soil should be moist to wet" (2)Herbaceous Ornamentals for Shade

4.1

no evidence

4.11

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

"mat-forming perennial herbs from a stout woody root, sometimes rooting at the nodes"

4.12

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

"mat-forming perennial herbs from a stout woody root, sometimes rooting at the nodes"

5.01

terrestrial

5.02

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

"mat-forming perennial herbs from a stout woody root, sometimes rooting at the nodes"

5.03

no evidence

5.04

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

"mat-forming perennial herbs from a stout woody root, sometimes rooting at the nodes"

6.01

no evidence

6.02

Joshi, M.; Joshi, H.; Singh, S. P. (1992) Response of water, temperature and light on germination behaviour of some successional species. Tropical Ecology, 1992, Vol.33, No.1, pp.54-62, 26 ref.

AB: The response of water, temp. and light on the germination of Bidens biternata, Cnicus argyracanthus, Cynoglossum furcatum, Galinsoga ciliata, Oenothera rosea, Polygonum capitatum, Rumex hastatus, Stachys serricea and Viola serpens, collected as seed from the Kumaun region of central Himalaya [Uttar Pradesh] in 1984, was investigated in laboratory experiments. None of the species showed seed dormancy. In each species, increasing water stress decreased the rate and percentage of germination. B. biternata and S. serricea (species of later successional communities) were the most sensitive to water stress, while C. argyracanthus and V. serpens (species of early successional communities) were the most tolerant. Increasing temp. generally had an inhibitory effect on the germination of each species, although C. argyracanthus, O. rosea, R. hastatus and V. serpens (all species of early successional communities) showed wider responses compared to other species. Exposure to red and continuous light promoted germinat

6.03

none reported despite substantial studies on this genus

6.04

no evidence

6.05

no evidence

6.06

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

"mat-forming perennial herbs from a stout woody root, sometimes rooting at the nodes"

6.07

http://www.louisianagardener.com/pages/feats/g-covers.htm

behaves as an annual in frost envirnoments

7.01

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

"naturalized in wet forest, open lava fields, and along roadsides, 600-1770m, on Hawai'i." [along roadsides]

7.02

(1) Kadner, R.; Eckart, G. (1992) Trials with new hanging basket, bedding and balcony plants. [FT: Neue Ampel-, Beet- und Balkonpflanzen im Versuch.] Gartenbau Magazin, 1992, Vol.1, No.4, pp.66-68
(2) Mans, C. C.; Hattingh, D. A. (1992) Evaluation of permanent groundcovers at Everdon Estate, Natal. [FT: Evaluering van permanente grondbedekkers te Everdon-Landgoed, Natal.] Yearbook - South African Avocado Growers' Association, 1992, Vol.15, pp.94-96

(1) AB: Fifty selected species and numerous cultivars were evaluated at Erfurt during summer 1991 for their suitability as hanging basket or balcony plants. Notes are given on the following species deemed appropriate for hanging baskets: Brachyscome [Brachycome ] melanocarpa, Erigeron karvinskianus, Lotus berthelotti, Cuphea hissopifolia [C. hyssopifolia ], Polygonum capitatum and Tradescantia fluminensis . Mixtures of species/cultivars (3 for hanging and 12 for balconies), recommended on the basis of their flower production, self-pruning, growth, weather tolerance and overall appearance, are listed.
(2) AB: Three permanent ground covers, viz. Arachis glabrata , Polygonum capitatum and Lippia canescens [Phyla nodiflora ], were compared in an orchard of avocado cv. Hass on Duke 7 rootstock. Trees were planted in Jan. and the ground cover species planted in Oct. (after the removal of all grass and weeds). Controls were left with natural cover. Cost of establishment and management, speed of growth, competiti

7.03

no evidence

7.04

(1)Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp. p.1063.

(1)peduncles with purple glandular hairs.; "Nuts dark redish brown, trigonous, ca 2 mm lomg, apex beaked, the surface somewhat striate, glossy."

7.05

http://pss.uvm.edu/pss123/perpolyg.html

other areas)

7.06

http://www.africanbirdclub.org/feature/bullfinh.html

seeds consumed by granivorous birds [granivores kill seeds]

7.07

http://lamar.colostate.edu/~secarney/USDA_Grant_2002.html

possess elaiosomes [ant disperesed]

7.08

no evidence of being consumed [perhaps incidentally by ungulates]

8.01

(1)http://www.suite101.com/article.cfm/222/83872 (2)personal observation

(1)Seeds are the typical nutlets of a dark reddish brown (2)many-seeded dense floral heads

8.02

no evidence

8.03

Singh, R. V.; Arya, M. P. S. (1995) Chemical weed control in Japanese barnyard millet (Echinochloa frumentacea ). Indian Journal of Agronomy, 1995, Vol.40, No.1, pp.51-54, 2 ref.

Chemical weed control in barnyard millet (Echinochloa frumentacea ) was studied in a field experiment conducted under rainfed conditions during the rainy season of 1990 and 1991 at Ranichauri. The herbicide treatments were post-em. application of 0.75 or 1.0 kg/ha 2,4-D Na-salt, and pre-em. application of 0.5 or 1.0 kg isoproturon, 0.075 or 0.1 kg oxyfluorfen and 0.5 or 1.0 kg pendimethalin. The major weeds were Galinsoga parviflora, Polygonum capitatum, Cyperus rotundus, Digitaria ciliaris and Cynodon dactylon . 2,4-D Na-salt at 1.0 kg applied 15 days after sowing gave the maximum barnyard millet grain (15.73 g/ha) and straw (83.50 g/ha) yields. Maximum weed-control efficiency (74.4%) and monetary returns (Rs 3357.7/ha) were also obtained with the same rate of 2,4-D Na-salt.

8.04

(1)http://www.maasnursery.com/groundcovers6.htm (2)http://www.cvwd.org/lush&eff/lsh&ef39.htm

(1)Good ground cover for uncultivated areas (2) No traffic

8.05

no evidence