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Week 5 Discussion
Weedy Traits List

  What traits make a weed successful.  Consider weeds in a broad sense: agriculture, horticulture, turf, lawns, right-of-ways, any space managed by humans for weed control. What traits make them successful?

  Brandon R.

1.  Ability to grow well in dense shade.

2.  Waxy layer on leaves allows chemicals to be shed and not penetrate.

3.  Deep taproot to suvive cultivation.

4.  Growth by rhizomes or stolons to spread out and creep

5.  growing well in compacted soils: areas not fit for turfgrass or other plants; driveway where car tires drive on the grass, or on the shoulder of roads.


Rebecca B.

1.  barbed hooks on seeds to aid in dispersal, ex: Cockleburs

2.  ability to climb to capture sunlight, ex: Poison Ivy

3.  horizontal growth to capture sunlight, ex: Pigweed

4.  horizontal growth to escape mower blades, ex: Dandelions

5.  staggered emergence to survive control messures, ex: Velvetleaf

6.  ability to adapt to salty soils, ex: Green Foxtail in Japan

7.  solar tracking to maximize sunlight, ex: Sunflowers

8.  ability of rhizomes to self-fragment for propogation, ex: Quackgrass

9.  ability to root at stem node where contacting soil (helps to survive tillage type damage), ex: Crabgrass

10.  ability of seeds to survive in soil for years, ex: Velvetleaf (50+ years)

11.  attractive vegetation/flowers so people leave them alone (or even encourage growth for ornamentals), ex: Field Bindweed

12.  tolerance to drying, ex: Quackgrass rhizomes

13.  somatic polymorphism, ex: Quackgrass leaves take on different forms to exploit local resources and conditions

14.  seedlings that immitate crops in appearance, ex: Wild Proso Millet can look like corn

15.  brittleness of plant so as not to be pulled from ground easily

16.  ability to self-fertilize


Brian H.

1.  Germinate at different levels in the soil so preplant herbicides won't effect them.

2.  Germinate at different times of the year again for herbicide and competion reasons.

3.  Ability to tiller such as foxtail or volunteer corn.

4.  Ability to Cross Pollinate

5.  Ability to defend from predators such as a thistle in a pasture ready to get eaten from a cow.

6.  Ability to poison predators from either eating or touching the plant.

7.  Ability to be perennial or biannual.

8.  Ability to grow hairs on leaves to keep the herbicide from contacting the skin such as certain grasses

9.  Disease resistance:

               1.  Ability to resist Phytophora root rot

               2.  Ability to resist Sudden Death Syndrome

               3.  Ability to resist Grey Leaf Spot

               4.  Ability to resist Crown Rot

               5.  Ability to resist Anthracnose

               6.  Ability to resist Common Leaf Spot

               7.  Ability to resist Cyst Nematode

               8.  Ability to resist Stalk Rot

               10. Ability to resist Brown Stem Rot

               11. Ability to resist Pythium

               12. Ability to resist Eye Spot

               13. Ability to resist Rhizoctonia

10.  Ability to resist Drought


Tom P.

1.Ability to grow in low soil fertility situations

2. Ability to grow in wet, marshy soils

3. Fast early season growth

4.Ability to produce vast amounts of seed

5. Large amounts of genetic variability within a population

6.Resistance to triazine herbicides

7.Resistance to ALS inhibitor herbicides

8. Resistance to growth regulators

9.dense hairs on leaves to slow herbicide uptake

10. Ability to adapt to changing environmental conditions (temperatures, length of day, etc.)

11. Ability to florish in both wet and dry soil conditions

12.Ability to hybridize

13. Ability to fill a "niche"

14. Ability to be "plastic" in its growth habits

15.Ability to be dormant during times when control measures are taken

16.Growth habits that provide a head start on the crop ie fall emergence of winter annual weeds

17.Ability to germinate late-after herbicides have weakened

18.Ability to overwelm control measures through sheer numbers ( 90% control of 1000 weeds vs 90% control of 1,000,000)

19. Ability to grow back year after year (perenials)

20.Ability to tiller after initial control measure

21. Ability to produce seed that is the same size as the grain you are trying to grow- helps in dispersal (BNS in soybeans)

22.Ability to germinate after going through an animal's digestive tract- also helps with dispersal

23.Ability to "harden off" prior to a herbicide application

24. Ability to grow taller than competing crop- intercepts more light and shades host crop

25. Weeds that are "biologically similar" to the desired crop-difficult to control because herbicides will damage crop as much as weeds

26.Ability to produce seeds that are distributed by the wind

27.Ability to preduce seeds that can remain dormant for several years

28.Ability to produce seeds that float- easily distributed by water

29. Ability to reproduce in more than one way-seeds, vegetatively,etc.

30.Ability to produce seeds in fruit that are desired by birds and other animals that can carry seed long distances


Brandon B.

1.  ability to form a rosette -- able to grow back from mowing

2.  adaptibility to herbicides -- after long term use

3.  allelopathic chemicals

4.  large amount of foliage to compete for sunlight

5.  rapid growth

6.  variable seed dormancy rates

7.  able to produce an abundance of seeds

8.  parachute structure on dandelion seeds for seed dispersal

9.  poisonous liquids to prevent animals from eating the plant -- Eastern black nightshade 10.  variable germination times throughout growing season

11.  Deep taproot to compete for water

12.  ablitiy to surpass crops in height to compete for light

13.  adaptability to all land types

14.  Can grow in soil lacking nutrients needed for the favored plant

15.  Plant genetic engineering -- volunteer Round-up ready corn in Round-up ready beanfield

16.  ability to form seed head at low mowing heights -- poa annua (1/8")

17.  ability to grow in tight spots like cracks in cement -- clover, knotweed

18.  large fibrous roots to absorb water

19.  ability to survive flooding

20.  hardened stems to resist animal damage -- smartweed


Vicky R.

1.  Effective seed dispersal habits.

2.  High seed production.

3.  Long lived seed.

4.  Some weeds have numberous underground tubers on the end of rhizomes.

5.  Natures way of bringing about natural sucession.

6.  Herbicide resistance

7.  Adaptive to low sunlight conditions.

8.  Weed seeds may be mixed in with crop seed.

9.  Ability to regenerate from fragments.

10.  Easy cross pollination by wind or insects.

11.  Have exploitative root systems.

12.  Many have ability to grow in compacted soils (knootweed)


Brett S.

1.  Velvetleaf- Very competitive, well adapted in agroecosystems, seed bank longevity, adaption to physical stress, disease resistant, growth plasticity, competitive ability in many habitats, and resistant to herbicides.

2.  Crabgrasses- adapted to drier habitats, ability to root at its stem nodes, stems grow horizontally, able to reroot after being ripped up by tillage.

3.  Johnsongrass- tall plant, starting to adapt further north.

4.  Common Lambsquarters- Very competitive, adaptive weed, can get a toe-hold (root) just about anywhere, can reproduce offspring with limited resources, does well in corn fields, competitive for both nutrients and water.

5.  Common Milkweed- very competitive, with large leaves, infests most types of crops. Field Bindweed- climbing capabilities, to capture light

6.  Field Pennycress- grows vegitatively, and quickly bolts up.

7.  Jimsonweed- contains poisons, adapts to survive whatever it takes

8.  Hemp Dogbane- extensive rootstocks, can store seed in ground for long period of time.

9.  Foxtails- biodiversity, competitive ability, tolerance to stess, herbicide resistant.

10.  Quackgrass- growth habitat and herbicide resistant adaptations, Rhizome adaptions to survive in agriculture fields.


Jessica U.

1.  foul odor that some weeds give off to keep people and animals from bothering them;

2.  thorny seed covering as in cockleburs protect the seed from harm and help scatter the seeds;

3.  some plants seem to have a camouflage as they perfectly blend in with the surroundings and are rarely noticed;

4.  one last thing is the way a weed often survives damage such as a hail storm or a lawn mower, the damage can be devastating to gardens and crops but weeds seem to just bounce right back as if they were saying "try again!"


Nick H.

1.  Morphological and physiological similarity to crop

2.  Timing of seed maturity to coincide with crop harvest

3.  Resistance or tolerance to chemical herbicides

4.  Resistance to mechanical control; regeneration from rhizomes or other vegetative propagules

5.  Seed dormancy, longevity in soil; discontinuous germination over long periods of time

6.  High relative growth rates in seedling stage

7.  High rates of photosynthesis

8.  Rapid development of exploitative root systems

9.  Rapid partitioning of photosynthate into new leaf area production

10.  Rapid vegetative growth to reproductive phase

11.  Special "weapons" for interference

12.  Freedom from environmental constraints, high capacity for acclimation to changing environment


Sam K.

1.  1. Morphological and physiological similaity to crops.

2. Timing seed maturity to coincide with crop harvest.

3. Rapid partitioning of photosynthate into new leaf area production.

4. Freedom from environmental constraints.

5. Deep root system that will regrow when pulled.

6. Mimic other plants.

7. Bad taste to animal that eats weeds

8. begins germination process in digestive tracts of animals.

9. Hard seeds cover for protection.

10. Long and short dispersal ability.

11. Self-compalatibility but not autogamy or apomixy.

12. Continous seed bank for later gerination

13. Ability to store excess energy for later use.

14. Ability to slow matabolism rate until able to reach energy source.

15. Special weapons for interference


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