session 2: weed reproduction… · session 2: weed reproduction . ... from seeds •plants from vr...
TRANSCRIPT
![Page 1: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/1.jpg)
YOUTH & FAMILIES AGRICULTURE HEALTH ECONOMY ENVIRONMENT ENERGY COMMUNITIES
Session 2:
Weed Reproduction
![Page 2: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/2.jpg)
Annual Weed Success
• Weed seeds often
germinate (or
seedlings emerge)
more quickly than
crop plants
• We need to shift the
balance of power
away from the weed
and to the crop
![Page 3: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/3.jpg)
Annual Weed Success: Why Do Weeds Win?
• Annual weeds make lots of seed, resulting in many individual weeds occurring at the same time
• Even if only one weed/ft2 survives out of perhaps 100 seedlings/ft2, it can replenish the seed bank in a single season
![Page 4: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/4.jpg)
Understanding Germination of Weed Seeds
Seeds respond to light using phytochrome
![Page 5: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/5.jpg)
Understanding Germination of Weed Seeds
Seeds respond to light using phytochrome
![Page 6: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/6.jpg)
Understanding Germination of Weed Seeds
Seeds respond to light using phytochrome
Red light exposure
activates
phytochrome, so
seeds may germinate
![Page 7: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/7.jpg)
Understanding Germination of Weed Seeds
Seeds respond to light using phytochrome
Far red light exposure
inactivates
phytochrome, so
seeds don’t germinate
![Page 8: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/8.jpg)
Understanding Germination of Weed Seeds
• Seeds near or on the soil surface gain red light exposure and germinate
• Deeply-buried weed seeds are not exposed to light (or are exposed to far-red radiation), so they usually do not germinate
Seeds Respond to Light
![Page 9: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/9.jpg)
Understanding Germination of Weed Seeds
• Winter annuals typically germinate under short-day radiation
• Summer annuals typically germinate when days are lengthening in the spring
Seeds Respond to Light
![Page 10: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/10.jpg)
Understanding Germination of Weed Seeds
• Winter annuals germinate in cool soil
• Summer annuals germinate in warming soil, often after a period of exposure to cold temperatures
Seeds Respond to Temperature
![Page 11: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/11.jpg)
Understanding Germination of Weed Seeds
Seeds Respond to Moisture
• Seeds must be imbibed prior to germination
• Many species require a stratification process to leach chemicals from the seed and allow dormancy to break
![Page 12: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/12.jpg)
Annual Weed Success
Every cultivation brings buried seed to the soil surface where they can germinate
![Page 13: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/13.jpg)
Reduced Rate Herbicide Trial—Total Weed Seed Germination Counts
0
2000
4000
6000
8000
10000
Fall Spring Total
Com + Bas
Sen (Hi, PRE)
Com (Hi)
Com + Sen (PRE)
Com + Sen (PRE,POST)
Untreated
![Page 14: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/14.jpg)
Reduced Rate Herbicide Trial—Total Weed Seed Germination Counts
0
2000
4000
6000
8000
10000
Fall Spring Total
Com + Bas
Sen (Hi, PRE)
Com (Hi)
Com + Sen (PRE)
Com + Sen (PRE,POST)
Untreated
![Page 15: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/15.jpg)
Reduced Rate Herbicide Trial—Total Weed Seed Germination Counts
0
2000
4000
6000
8000
10000
Fall Spring Total
Com + Bas
Sen (Hi, PRE)
Com (Hi)
Com + Sen (PRE)
Com + Sen (PRE,POST)
Untreated
![Page 16: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/16.jpg)
Reduced Rate Herbicide Trial—Total Weed Seed Germination Counts
0
2000
4000
6000
8000
10000
Fall Spring Total
Com + Bas
Sen (Hi, PRE)
Com (Hi)
Com + Sen (PRE)
Com + Sen (PRE,POST)
Untreated
![Page 17: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/17.jpg)
• So in this case, return of weed seed to
field would have resulted in:
– Command + Basagran (PRE + POST)
• 3 weeds/m2 (12,000/acre)
– Sencor (PRE)
• 469 weeds/m2 (1.9 million/acre)
– Untreated check
• 8055 weeds/m2 (32.6 million/acre)
Weed Seed Germination
![Page 18: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/18.jpg)
Vegetative Reproduction
• Roots
• Rhizomes
• Stolons
![Page 19: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/19.jpg)
Vegetative Reproduction
• Roots
• Rhizomes
• Stolons
![Page 20: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/20.jpg)
Vegetative Reproduction
• Roots
• Rhizomes
• Stolons
![Page 21: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/21.jpg)
Vegetative Reproduction
•Bulbs
•Tubers
•Rooting
at nodes
![Page 22: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/22.jpg)
Vegetative Reproduction
•Bulbs
•Tubers
•Rooting
at nodes
![Page 23: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/23.jpg)
Vegetative Reproduction
•Bulbs
•Tubers
•Rooting
at nodes
![Page 24: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/24.jpg)
Vegetative Reproduction
Why Does VR Make Sense for Plants?
• Only small portions of vegetative structures are needed for the plant to successfully reproduce
– Sections as small as ¼-inch of a Canada thistle root is sufficient to start a new infestation
– Stem sections only 2 inches long are enough to start a new infestation of Bohemian knotweed
– A single daughter plant crown of creeping buttercup is sufficient to start a new infestation
– Three or more shoots can arise from a single yellow nutsedge tuber
![Page 25: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/25.jpg)
Vegetative Reproduction
Why Does VR Make Sense for Plants?
• Shoots from VR structures have access to
more energy than do seedlings
– They usually grow faster and capture
space more quickly than plants arising
from seeds
• Plants from VR structures are already well-
suited to the environment, having come
from a successfully adapted plant
![Page 26: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/26.jpg)
Vegetative Reproduction
Why Does VR Make Sense for Plants?
• On plants that vegetatively reproduce
themselves, there are usually many shoots
from a single root system
– Controlling the plant means killing not
only all those individual shoots, but also
all the roots that are attached to those
multiple shoots (a difficult task!)
![Page 27: Session 2: Weed Reproduction… · Session 2: Weed Reproduction . ... from seeds •Plants from VR structures are already well-suited to the environment, having come from a successfully](https://reader034.vdocument.in/reader034/viewer/2022042416/5f3199374904265b1373e0d4/html5/thumbnails/27.jpg)
The Next Weed Session Session 1: Biology of Weeds
Session 2: Weed Reproduction
Session 3: Non-chemical Weed Management
Session 4: Chemical Weed Management