Teasel: Why Is It Here and How Do We Get Rid of It?

Reid J. Smeda and Diego J. BentivegnaUniversity of Missouri

Cut-leaf teasel (Dipsacus laciniatus L.)

• Exotic- Invasive weed

• Declared Noxious in Missouri, Iowa, Colorado and Oregon

• Dipsacus is derived from the Greek word 'dipsakos', which means thirst

(USDA)

A sheepish beginning

Origin Introduced as a “crop” to New England from France in

1780’s; “teaseling” wool Abandoned in 1800’s; mechanization Movement follows interstate highway corridor Desirable as a dried flower

Teasel in Argentina, 2009

Biology

Deep taproot : Extracts nutrients and water from deficient soils

Leaves: large, opposite, and sessile with deep serrations Prickly stem and spine in the mid-rib of the leaves

Biennial, with emergence in fall and spring

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Emergence of teasel in Missouri (Data 2003-2004)

Seedling (2 months)

Rosette(12 months)

Pre-flowering (1 month)

Seed

Development (3 months)

Total above ground Biomass

Plants capable of growth late into year

Taproot (DW)

Reproductive Phase (Stem – Seedheads)

Methodology Fifteen plants growing alone and in a group (2 plants within 60 cm) were randomly selected in two locations and two years

Regression used to estimate seed production

Number of seedheads, seed production of the primary seedhead, and total seed production per plant was evaluated

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xAlone Group

Primary Seedhead

Total Seed Production per Individual Plant

Summary of seed production study Seed production is more than five times greater than was registered in other locations (Werner 1975, Glass 1991) Seed production was affected by location, year, and growth habit Principal seedheads produce more than 1000 seeds

Maximum seeds produced per plant was 33,000 First viable seed produced 12 days following first flowers on primary seedhead

Seed persistence study 150 seeds were put in pots in 09/04 in New Franklin and Columbia (Bradford); 5 pots harvested each spring, summer and fall. Tetrazolium test was done to assess the viability.

If we don’t want teasel, what do we do about it? Fire= insufficient fuel to burn through infested areas (Solecki 1993) Biological= slow and doesn’t have natural enemies in USA (Rector 2006) Mechanical= - immature seeds complete maturation in stem - plants regrowth (Solecki 1993)

Chemical= most cost effective (Missouri Vegetation Management Manual 1997)

5 months

Mowing

Mowing (15-30 July) Frequency (one time) Height (12 cm)

08/18/04

Determine the optimum timing to mow bolting plants:

10/04/04

12/18/04

Plant mowed above 12 cm at the beginning of July

Flowering on 10/04/04

What about control practices?

Determine the efficacy of herbicides on teasel rosettes as well as residual activity on new emergence

Herbicides

Herbicides treatmentsMode of action Herbicide Rate (kg ai ha-1) Time

- Untreated -- --

AA biosynthesis Glyphosate 2.52 Fall and Spring

Growth regulator

Dicamba + Diflufenzopyr 0.29 Fall and Spring

2,4-D 1.68 Fall and Spring

2,4-D + Triclopyr 1.68 + 0.84 Spring

2,4-D + Picloram 1.68 + 0.45 Spring

2,4-D + Clopyralid 1.68 + 0.32 Spring

Acetolactate Synthase

inhibitors (ALS)

Metsulfuron Methyl 0.008 Spring

Imazapyr 0.84 Spring

Sulfometuron methyl 0.11 Spring

Sulfosulfuron 0.11 Spring

Cell Membrane Disrupters

Paraquat 0.94 Spring

Soil pH= 5.9-7.6

Soil OM= 1.8 -2.9%

Wind speed: < 4 mph

Air temperature> 8.5C in Fall> 15C in Spring

Environmental conditions

At 2, 4 and 8 weeks following applications, teasel plants were visually evaluated for injury

A scale of 0 to 100 was used: 0 = no effect and 100 = plant death

Residual activity was evaluated in two 0.3 x 0.3 m areas in plots of selected treatments by counting seedlings through the year

AA Biosynthesis

Membrane disrupters

Growth regulators

Acetolactate synthase

Treatments Time Highway Fairground Bradford Moberly

GlyphosateFall 30 def 23 cd 28 b 28 b

Spring 43 bcd 88 b 59 b 65 b

Dicamba + Diflufenzopyr

Fall 34 cde 19 d 25 b 20 b

Spring 43 bcd 53 b 49 b 56 b

2,4-DFall 24 efg 6 d 13 c 15 c

Spring 31 de 36 b 25 b 49 b

2,4-D+Triclopyr Spring 48 bc 50 b 38 b 50 b

2,4-D+Picloram Spring 53 b 49 b 51 b 55 b

2,4-D+Clopyralid Spring 39 bcd 39 b 35 b 42 b

Metsulfuron-methyl Spring 15 fg 29 c 16 c 16 c

Imazapyr Spring 16 fg 31 c 11 c 14 c

Sulfometuron-methyl Spring 13 gh 23 c 23 c 18 c

Sulfosulfuron Spring 0 h 6 e 1 c 5 c

Paraquat Spring 95 a 95 a 86 a 88 a

Evaluation 2 Weeks after treatment

Treatments Time Highway Fairground Bradford Moberly

GlyphosateFall 95 a 90 a 96 ab 100 a

Spring 85 abc 98 a 93 ab 100 a

Dicamba + Diflufenzopyr

Fall 100 a 96 a 100 a 100 a

Spring 95 a 100 a 100 a 100 a

2,4-DFall 89 ab 96 a 66 d 83 b

Spring 95 a 100 a 76 cd 100 a

2,4-D+Triclopyr Spring 98 a 100 a 86 bc 100 a

2,4-D+Picloram Spring 100 a 100 a 100 a 100 a

2,4-D+Clopyralid Spring 100 a 100 a 100 a 100 a

Metsulfuron-methyl Spring 100 a 100 a 100 a 100 a

Imazapyr Spring 100 a 100 a 100 a 99 a

Sulfometuron-methyl Spring 64 c 81 b 78 cd 98 a

Sulfosulfuron Spring 0 d 9 c 3 e 33 c

Paraquat Spring 70 bc 88 b 100 a 100 a

Evaluation 8 Weeks after treatment

Accumulated emergence after 210 days of herbicides treatments for year 2005.

Remote Sensing Remote sensing consists of the acquisition and recording of information about an object or interest target without touching it

Advantages: Non destructive measurement Objective periodical data Large spatial distribution

Growth regulator

Acetolactate Synthase

Data Collection and Pre- ProcessingBradford Research & Extension Center Highway I70 (Miles 89-93)

Hyperspectral, 2006(63 bands)

Multispectral, 2007 (4 bands)

Determine the best band for cut-leaved teasel

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Teasel Grass Bare soil Tree

Blue Green Red Infrared

Normalized Difference : (G-T)/G

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Bands

2006 2007

2006 2007 Change

Teasel 8.5% 13% +4.5%

Grass 78.4% 74.5% -3.9

Bare Soil 11.8% 3.3%Grass death -8.5

Others 1.3% 7.8 +6.5

* Means within a column followed by the same letter are not statistical different. T test p>0.05

Percentage of Cut-leaved Teasel Control and Grass Cover Visual in June 2007

Treat Fall 2006 Spring 2007

Teasel Grass Cover

Rosette SeedlingsTall

FescueCanada Wildrye

1 Triclopyr Triclopyr 16.3 C 31.3A 66.3 A 67.5 A

2 Metsulfuron-methyl

Dicamba 73.8 B 66.3 A 80 A 84.8 A

3 Dicamba Dicamba 98.8 A 58.8 A 70 A 78.8 A

4 Aminopyralid Aminopyralid 100 A 63.8 A` 82 A 79.5 A

5 Metsulfuron-methyl

Metsulfuron-methyl

92.5 B 40 A 67.5 A 65 A

What do we know now?

Teasel stores resources in the taproot to catapault plants into reproduction

Teasel has two important peaks of above ground growth

Seed production is greatest when plants invade new areas; seeds reach viability quickly following initial flowering

Herbicides can reduce the number of existing plantsand imazapyr reduces the emergence

Mowing below 12 cm precludes plant flowering; plants remain alive and flower the following year

Plants emerge during 2 distinct periods in Missouri

Remote sensing can identify teasel; combination of herbicides and seeding desirable grasses is most effective strategy

Chester McWhorter (USDA weed scientist)

“I have spent the last 16 years of my career working on johnsongrass, and I can report that johnsongrass is a bigger problem today than when I began.”

-1991

I have worked on teasel for about 8 years and cannot say populations are in decline!

Questions

Questions?