using the biology of weeds to leverage weed management chuck mohler cornell university
TRANSCRIPT
![Page 1: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/1.jpg)
Using the biology of weeds to leverage weed management
• Chuck Mohler
• Cornell University
![Page 2: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/2.jpg)
Weeds are plants that thrive in disturbed environments
• For example, in a farm field
• Our crops are mostly annual plants - they live for one season
• We kill off natural vegetation & disturb the soil to make conditions suitable for crops
• But this also creates habitats for weeds
![Page 3: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/3.jpg)
Many ways to be a weed
• Annuals– Summer annuals– Winter annuals
• Perennials– Stationary perennials
• Taproots• Fibrous roots
– Wandering perennials• Bulbs & tubers• Rhizomes or storage roots
![Page 4: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/4.jpg)
Outline
• Two general examples
• Managing perennials through exhaustion of roots and rhizomes
• Choosing an appropriate tillage regimen for depleting a weed seed bank
• A specific example – your choice
![Page 5: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/5.jpg)
Wandering perennials
• Spread by thickened storage roots or by rhizomes (underground stems)
![Page 6: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/6.jpg)
Apical dominance in perennials
Tillage
![Page 7: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/7.jpg)
Shoot above ground
Shoot below ground
New rhizomes
Old rhizome fragment
![Page 8: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/8.jpg)
Management of perennials
• Key is exhaustion of reserves.
• Time shoot removal relative to growth stage
• Shallow roots & rhizomes – chop & bury,
• Deep roots & rhizomes – hit them often
• Competitive crops, frequently cultivated crops, short season crops
![Page 9: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/9.jpg)
Choosing a tillage regimen for managing a weed seed bank
![Page 10: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/10.jpg)
Seeds of most weeds are tiny – why?
• Disturbed environments are risky
• Tiny seeds spread the risk over many offspring
• Seedlings can be small because in a recently disturbed environment they have little competition.
• Seedlings have limited resources
![Page 11: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/11.jpg)
Small seeded species only
emerge if near the soil surface
0
0.2
0.4 Velvetleaf
0
0.2
0.4
Lambsquarters
0
0.02
0.04
0 2 4 6 8Depth (cm)
Redroot pigweed
![Page 12: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/12.jpg)
Seed longevity
Loss per year (%)
Species Cultivated Uncultivated
Lambsquarters 31 8
Annual bluegrass 26 22
Common chickweed 54 32
Common groundsel High 45
![Page 13: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/13.jpg)
Seeds survive better deep in the soil
Depth in soil (inches)
0 2 4 6 8 10
See
d s
urv
ival
(%
)
0.0
0.2
0.4
0.6
0.8
1.0
Velvetleaf
Pigweed
![Page 14: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/14.jpg)
Death near the soil surface
• Seed predation• Wetting and
drying• Freeze-thaw
Dzier włochaty (Harpalus rufipes Dej.) w pełnym biegu.
![Page 15: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/15.jpg)
Plowing vs. minimum tillage?
• Small seeded species with short lived seeds plow them under– Most will die before they find their way to surface
again– Example: hairy galinsoga– Needs to be in the top ¼” to emerge– So if mixed into 8” of soil, the average return time
will be 32 years– But few live longer than 2 or 3 years.
![Page 16: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/16.jpg)
• Large seeded species with long lived seeds keep them near the surface– Their mortality will be greater at the surface– And most that are tilled under will come back to
bother you later– Example: velvetleaf– Emerges well from the top 2” of soil– So if mixed into 8” of soil, the average return time
to the emergence zone is 4 years– 80-90% survival below 4” –
0.85x0.85x0.85x0.85=0.52 so 50+% will make it back into the safe-to-emerge zone before they die
– <20% survival near the surface
![Page 17: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/17.jpg)
Species with small, long lived seeds?
• Lambsquarters
• Wild mustard
![Page 18: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/18.jpg)
Many other examples
• Germination cues – Cultivated fallows – Mulches– Stale seedbed
• Relative size of crop and weed seeds– Management of crop competition
• Plant size distributions– Reduction of weed seed production
![Page 19: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/19.jpg)
“Manage Weeds on Your Farm: a Guide to Ecological Strategies”
Mohler and DiTommaso, SAN
• Ecology of weeds
• Cultural control methods
• Physical control methods
• Farm case studies
• Identification, ecology and management of the 75 worst agricultural weeds in the United States
![Page 20: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/20.jpg)
A specific example
• Most farms have many weeds, but only one or two really problem weeds
• Often need to focus on those
• http://www.css.cornell.edu/weedeco
• http://www.organic.cornell.edu/ocs/index.html
![Page 21: Using the biology of weeds to leverage weed management Chuck Mohler Cornell University](https://reader031.vdocuments.net/reader031/viewer/2022020219/56649e7e5503460f94b817b0/html5/thumbnails/21.jpg)