Presentation on theme: "Know Your Weeds How to Control Undesirable Plants (i.e. Weeds) OLLI May 2, 2013."— Presentation transcript:
Know Your Weeds How to Control Undesirable Plants (i.e. Weeds) OLLI May 2, 2013
Think its a weed? 1.Identify plant 2.Determine biology / life cycle Winter annual, summer annual, perennial 3.Determine method(s) of management or leave it and enjoy it Hog potato C.V. Community Church
Lets test your knowledge – can you identify the following weeds? Pay attention to the biology / life cycle.
Information you should know before you can effectively manage weeds …….
Summer and Winter Annuals Summer annual - germinates from seed in spring and early summer; matures in summer; produces seed in fall and dies with first frost Winter annual - germinates from late summer through early spring; grows in winter and dies in late spring or early summer when temperature exceeds 85 °
Perennials Some flourish in cool months and go dormant at onset of summer heat, others grow actively in summer and are suppressed with frost. Roots can be rhizomes, stolons, fleshy tap roots, corms or tubers.
Management Methods Mechanical (pull, mow, till, etc.) Cultural (burn, solarize, seed bare ground w/ competitor like cool or warm season grass, or mulch) Biological (animals, insects) Chemical (herbicides)
Mechanical Annuals (weeds reproduce from seed) – Cut before they go to seed. – If in bloom, cover w/ plastic bag before pulling to keep seeds from spreading. – Cut (weed eater)or mow before going to seed. Mowing sometimes ineffective because plants flower too close to soil. Perennials (grow from roots each year) – If hand digging, do so when soil is moist; pieces of root often break off and sprout new plants.
Cultural Solarize to kill seeds and roots in heat of summer (use clear plastic). Mulch – at least 3 can prevent annuals, not perennials like Bermuda grass. – Organic: bark, chipped trimmings, wood debris, lawn clippings, compost, etc. Straw not recommended; could have weed seeds. – Synthetic: landscape cloth, rocks, etc. Plastic not recommended.
Biological Animals Chickens, goats, sheep, etc. graze to control weeds. Insects Introduced insects can control noxious weeds but will never eradicate; should be done by professionals.
Pre-emergent Herbicides Work best on annual weeds Can control perennial species prior to establishment Warm season weeds (e.g. tumble weeds) – apply in Spring Cool season weeds (e.g. filaree) – apply in Fall
Post-emergent Herbicides Selective – only kill targeted weeds –read product label Non-selective – kill all vegetation touched by herbicide
Got all that? Theres more…
Herbicides: Contact and Systemic Contact herbicide – Use on annuals or non-flowering biennials (only kills green tissue contacted by the spray, not the roots) Systemic/translocator herbicide – Use on perennials to kill the root – Apply when weeds actively growing – Best when weeds are small – Does not prevent new weeds
What about….. Corn gluten meal? – Can work as a pre-emergent on seeds, but it is nitrogen, so timing is critical Household vinegar? – Household vinegar is 5% acetic acid & not an approved herbicide; 10% is better for killing weeds
Read Product Labels Product may contain more than one herbicide e.g. glyphosate (systemic - slow) & diquat (contact - fast) Labels will specify residual impact to soil, but be cautious of run-off, ground water impacts, etc. May need stronger application in cooler weather Caution: chemical sterilents should not be used in residential landscapes
How would you manage - Pull, trash, burn, etc. -Pre-emergent in spring (before germination) -Hand pull -Post-emergent -Plant more desirable species that compete with weeds } } Russian thistle - summer annual
Resources Plant ID – Weeds of the West – Plants of Arizona – Extensions Native & Naturalized Plant Database Herbicide Information – Read product labels