Research from the Horticulture Innovation Fund

Weed management in the nursery industry is one of the most significant costs in the production cycle, yet remains one of the least well-managed elements in the cost-effective production of plants. Reliance on unchallenged chemical industry and/or anecdotal knowledge for weed control decision-making may not be environmentally or economically sound or effective. Information on weed management from international sources is available, but in various locations which are time-consuming to find, and the chemicals used internationally may not be available for such use in Australia.

About the Nursery and Garden Industry Victoria (NGIV) project:

weed project (Download PowerPoint presentation)

Nurseries can undertake weed control experiments of their own, using the information provided in the NGIV guide.

Weed control guide: practical information that growers can use

Literature review - 21 weeds Download PDF in new window (Note: this document does not meet WCAG 2.0 accessibility guidelines)

    General information

    How to conduct a weed trial

    1. Decide which chemical/s or treatments (e.g. coir discs) you want to test.
    2. Use a range of plants that you grow, e.g. an acid-loving plant; a plant that is in the production system for a long time; a strappy plant (monocotyledon); a plant with leaves obscuring the pot surface. This ensures that any adverse reactions are found.
    3. Use a sufficient number of replicates per chemical/treatment. This will mean 10 pots of each plant per chemical/treatment. Ten is the minimum number. If this number is too large, don’t reduce replicate numbers, instead reduce the number of chemicals/treatments tested at once.
    4. Ensure you also have 10 replicates for your “control” pots (i.e. where no chemical/treatment is applied).
    5. Randomise the pots and keep them in this order throughout the trial. This ensures that any effects (such as shading) are spread across all treatments. Numbering pots may help.
    6. Using colour-coded pots per treatment makes for easier application of treatments and avoids losing/misplacing labels. Also ensure that all plants are in the same sized pots.
    7. Inoculate pots with the same amount of weed seed per pot and wait for the weeds to grow to a suitable size before applying treatments.
    8. Set up your trial in a separate part of the nursery so no contamination occurs.
    9. Apply chemical treatments as per the label.
    10. Record results weekly (% weed cover; whether weed is dead or not) – ideally by the same person so no bias occurs. Also note the health of the wanted plant as well as the weed. Use a scoring system for wanted plant health (0 = dead; 1 = unhealthy; 2 = moderately healthy; 3 = very healthy).
    11. Enter all data into Excel to obtain averages for each result.
Disclaimer
OH&S for weed treatments/safe chemical usage/hygiene

The chemicals listed here were correct at the time of research (2020). More current information and the safe use of chemicals is the user’s responsibility. Any listed chemicals or treatments do not imply NGIV or UoM endorsement of a particular product. Similarly, any chemical not listed for control does not imply a criticism of that product. Our aim was not to provide an exhaustive list of herbicides for the control of each crop, but instead to give a couple of examples spanning at least two herbicide groupings so that the necessary and important rotation of herbicide groups can be made to reduce the likelihood of weed resistance to a particular herbicide. Some herbicide groups will show resistance after as few as four years of use (Group B) or more than 20 years (Group I). Herbicide resistance is constantly developing and it is suggested that growers regularly consult the International Herbicide-Resistant Weed Database online for the latest information.

Table 1: The 21 most problematic weeds for the Victorian nursery industry (determined by responses from NGIV grower survey in 2015).

Common name

Scientific name

Family

Life cycle

Season

Bittercress

Cardamine flexuosa

Brassicaceae

Annual

Cool

Flickweed

Cardamine hirsuta

Brassicaceae

Annual

Cool

Common mouse-ear chickweed

Cerastium vulgare

Caryophyllaceae

Perennial

Cool

Summer grass

Digitaria sanguinalis

Poaceae

Annual

Warm

Smooth Willowherb

Epilobium billardierianum

Onagraceae

Perennial

Cool

Slender Willowherb

Epilobium ciliatum

Onagraceae

Perennial

Cool

Hairy Willowherb

Epilobium hirtigerum

Onagraceae

Perennial

Cool

Spurge

Euphorbia dallachyana

Euphorbiaceae

Perennial

Warm

Spotted spurge

Euphorbia maculata

Euphorbiaceae

Annual

Warm

Red caustic weed

Euphorbia prostrata

Euphorbiaceae

Annual

Warm

Prickly lettuce

Lactuca serriola

Asteraceae

Annual or biennial

Cool

Cudweeds

Gamochaeta spp.; Laphangium luteoalbum

Asteraceae

Annual or biennial

Cool & Warm

Liverwort

Marchantia polymorpha

Marchantiaceae

Perennial

Cool & Warm

Creeping Oxalis

Oxalis corniculata

Oxalidaceae

Annual or perennial

Warm

Winter grass

Poa annua

Poaceae

Annual

Cool

Pearlwort

Sagina apetala

Caryophyllaceae

Annual

Cool

Pearlwort

Sagina procumbens

Caryophyllaceae

Perennial

Cool & Warm

Chickweed

Stellaria media

Caryophyllaceae

Annual

Cool

Mouse-ear chickweed

Cerastium vulgare

Caryophyllaceae

Perennial

Cool

Prickly sow thistle

Sonchus asper

Asteraceae

Annual

Cool

Sow thistle

Sonchus oleraceus

Asteraceae

Annual or biennial

Cool & Warm

References:

Disposal of weeds:

For Flickweed distance: Vaughn, K.C., Bowling, A.J. and Ruel, K.J. 2011. The mechanism for explosive seed dispersal in Cardamine hirsuta (Brassicaceae). American Journal of Botany 98: 1276-1285.

For compost bin info:

Anon. 2009. Want to keep your compost weed-free? Weed Science Society of America. Accessed 14 August, 2020.

For NIASA composting info:

Nursery Industry Accreditation Scheme, Australia (NIASA). 2018. Best Management Practice Guidelines. Nursery & Garden Industry Australia, Sydney, 7th edition, 224 pp.

For allelopathic properties info:

Yuiqin, C., Hongwei, W., Hongjan, Z. and Wenjing, L. 2009. Allelopathic effects of aqueous extracts from Euphorbia maculata L. on several vegetable species. Chinese Agricultural Science Bulletin 25(2): 81−84.

For resistance info:

Preston, C., Boutsalis, P., Brunton, D., Kleemann, S. and Gill, G. 2018. Herbicide resistance – where are we, where are we going and what can we do about it. GRDC Update Papers.  Accessed 6 October, 2020.

Cudweed:

For reduced germination by covering seed:

Anon. AgPest from agresearch. Cudweeds Accessed 30 September, 2020.

For Gamochaeta pensylvanica paraquat resistance:

Heap, I. 2020. The International Herbicide-Resistant Weed Database online. Accessed 30 September, 2020.

Lactuca:

For seed production and herbicide control:

Wu, H., Shephard, A. and Hopwood, M. 2019. Prickly lettuce ecology and management. GRDC Update Papers.  Accessed 16 September, 2020.

For 2,4-D resistance and glyphosate ineffectiveness:

Burke, I.C., Yenish, J.P., Pittmann, D. and Gallagher, R.S. 2009. Resistance of a prickly lettuce (Lactuca serriola) biotype to 2,4-D. Weed Technology 23: 586-591.

Heap, I. 2020. The International Herbicide-Resistant Weed Database online. Accessed 17 September, 2020.

Sonchus:

For resistance to some herbicides:

Nagalingam, K., Rafter, M., Ireland, K., Hunter, G., Morin, L. and Sathyamurthy, R. 2018. Response of common sowthistle, Sonchus oleraceus to simulated herbivory. In: Australasian Weeds Conference, 9-12 September 2018; Sydney. The Weed Society of New South Wales Inc., p. 33.

For resistance to ALS inhibitor herbicides:

St John-Sweeting, R.S., Preston, C., Baker, J., Walker, S. and Widderick, M. 2010. Genetic diversity among ALS-inhibiting herbicide resistant and susceptible populations of Sonchus oleraceus L. (sowthistle) in Australia. In: Seventeenth Australasian Weeds Conference New Zealand, 32: pp. 281-284.

For using both cultural and chemical control:

Chauhan, B.S., Widderick, M., Werth, J. and Cook, T.2015. Northern IWM Factsheet Common Sowthistle (Sonchus oleraceus L.): Ecology and Management. The State of Queensland, Department of Agriculture and Fisheries, 4 pp.

For description:

Widderick, M. and Walker, S. 2009. Management of common sowthistle. Fact Sheet. Department of Employment, Economic Development and Innovation, Queensland Government, 4 pp.

Cardamine:

For self-fertile:

Mandáková, T., Marhold, K. and Lysak, M.A. 2014. The widespread crucifer species Cardamine flexuosa is an allotetraploid with a conserved subgenomic structure. New Phytologist 201: 982-992.

Vaughn, K.C., Bowling, A.J. and Ruel, K.J. 2011. The mechanism for explosive seed dispersal in Cardamine hirsuta (Brassicaceae). American Journal of Botany 98: 1276-1285.

For herbicide resistance:

CABI. 2020. Cardamine flexuosa (wavy bittercress). In: Invasive Species Compendium, Wallingford, UK. CAB International. Accessed 15 August, 2020.

For clubroot host:

Tanaka, S., Mizui, Y., Terasaki, H., Ito, S.I. and Sakamoto, Y. 2006. Distribution of clubroot disease of a cruciferous weed, Cardamine flexuosa, in major isolated islands, Hokkaido and Okinawa in Japan. Mycoscience 47: 72-77.

Epilobium:

For ID:

VicFlora (2020). Flora of Victoria, Royal Botanic Gardens Victoria.  Accessed 11 September, 2020.

Western Australian Herbarium (1998–). FloraBase - the Western Australian Flora. Department of Biodiversity, Conservation and Attractions.  Accessed 11 September, 2020.

For dispersal:

Agriculture Victoria. 2020. Victorian Resources Online - Giant Willow Herb (Epilobium hirsutum). Accessed 11 September, 2020.

For seed number produced and germination temperatures:

Altland, J. 2007. Northern willowherb control in nursery containers. Oregon, USA: Oregon State University.

For not sole reliance on herbicides:

Altland, J.J. (nd) Northern willow-herb management Oregon State University.  Accessed 11 September, 2020.

For glyphosate tolerance:

Western Australian Herbarium (1998–). FloraBase—the Western Australian Flora. Department of Biodiversity, Conservation and Attractions. Accessed 11 September, 2020.

For resistance to several herbicides:

CABI. 2020. Epilobium ciliatum (northern willowherb). In: Invasive Species Compendium, Wallingford, UK. CAB International.

Cerastium:

For chemical control:

Turf Tips. (nd) Mouse-ear chickweed. Accessed 14 September, 2020.

Stellaria:

For reproduction and pests:

CABI. 2020. Stellaria media (common chickweed). In: Invasive Species Compendium, Wallingford, UK. CAB International.  Accessed 16 September, 2020.

For info on pests and herbicides:

Wilen, C.A. 2006. Chickweeds. Pest Notes. Publication 74129. University of California, Davis. Agriculture and Natural Resources. 4 pp. Accessed 16 September, 2020.

For ALS-inhibitor herbicide (Group B) resistance:

Kudsk, P., Mathiassen, S.K. and Cotterman, J.C. 1995. Sulfonylurea resistance in Stellaria media [L.] Vill. Weed Research 35: 19-24.

Sagina:

For rooting at nodes:

Richardson, F.J., Richardson, R.G. and Shepherd, R.C.H. 2011. Weeds of the South-East. An Identification Guide for Australia. 2nd edition. R.G. & F.J. Richardson, Meredith, Victoria.

For coarse substrate:

Altland, J. (nd). Pearlwort control with preemergent herbicides. Oregon State University. Accessed 14 September, 2020.

Euphorbia:

Agriculture Victoria. 2020. Victorian Resources Online - Spotted Spurge (Chamaesyce maculata). Accessed 16 August, 2020.

Molinar, R.H., Cudney, D.W., Elmore, C.L. and Sanders. A. 2009. Spotted spurge and other spurges. Integrated pest management for home gardeners and landscape professionals. Pest Notes. University of California, Davis, Publication 7445: 4 pp.

Liverwort:

Altland, J. and Krause, C. 2014. Parboiled rice hull mulch in containers reduces liverwort and flexuous bittercress growth. Journal of Environmental Horticulture 32: 59-63.

England, J. and Jeger, M. 2006. Liverwort gemmae dispersal: the effect of overhead irrigation and its influence on gemma production. Proceedings of the Sixtieth Annual Meeting of the Northeastern Weed Science Society 60: 24 (Abstract only).

Lewis, L.R., Behling, E., Gousse, H., Qian, E., Elphick, C.S., Lamarre, J.F., Bêty, J., Liebezeit, J., Rozzi, R. and Goffinet, B., 2014. First evidence of bryophyte diaspores in the plumage of transequatorial migrant birds. PeerJ 2: e424.

Mathers, H. n.d. “Weeds just want to have fun!!!” or why are these 10 common container weeds so common: Part 1. 11 pp.

Oxalis:

Doust, L.L., MacKinnon, A. and Doust, J.L. 1985. Biology of Canadian weeds. 71. Oxalis stricta L., O. corniculata L., O. dillenii Jacq. ssp. dillenii and O. dillenii Jacq. ssp. filipes (Small) Eiten. Canadian Journal of Plant Science 65: 691-709.

Flora of Victoria. Oxalis corniculata.  Accessed 14 August, 2020.

Wada, S., Altland, J., Mallory-Smith, C. and Stang, J. 2006. Effect of dolomitic lime rate and application method on substrate pH and creeping woodsorrel establishment. Journal of Environmental Horticulture 24: 185-191.

Digitaria:

For seed info, cultural and organic control:

Anon. AgPest from agresearch. Summer grass, Digitaria sanguinalis.  Accessed 6 October, 2020.

CABI. 2020. Digitaria sanguinalis (large crabgrass). In: Invasive Species Compendium, Wallingford, UK. CAB International. https://www.cabi.org/isc/datasheet/18916 Accessed 6 October, 2020.

Hwang, S.J., Shin, D.H. and Kim, K.U. 1997. Identification of biologically active substances from lilac (Syringa vulgaris L.). Korean Journal of Weed Science 17:334-344.

Molinar, R.H. and Elmore, C.L. 2010. Crabgrass. Integrated pest management for home gardeners and landscape professionals. Pest Notes. University of California, Davis, Publication 7456: 5 pp.

Nam, S.J., Kim, K.U., Shin, D.H. and Hwang, S.J. 1997. Identification of biologically active substances from Ginkgo biloba L. Korean Journal of Weed Science 17: 421-430.

Wang, Y.H., Ma, Y.L., Feng, G.J. and Li, H.H. 2018. Abiotic factors affecting seed germination and early seedling emergence of large crabgrass (Digitaria sanguinalis). Planta Daninha 36: e018166895, 10 pp.

For resistance:

Heap, I. 2020. The International Herbicide-Resistant Weed Database online.  Accessed 30 September, 2020.

Preston, C., Boutsalis, P., Brunton, D., Kleemann, S. and Gill, G. 2018. Herbicide resistance – where are we, where are we going and what can we do about it. GRDC Update Papers.  Accessed 6 October, 2020.

Poa:

For seed production:

CABI. 2020. Poa annua (annual meadowgrass). In: Invasive Species Compendium, Wallingford, UK. CAB International.

For year-round germination:

Anon. AgPest from agresearch. Poa annua. http://agpest.co.nz/?pesttypes=poa-annua Accessed 2 October, 2020.

For herbicide resistance:

Heap, I. 2020. The International Herbicide-Resistant Weed Database. Accessed 2 October, 2020.