perennial weed management in hay and row crop fields€¦ · cultural tactics: crop management...
TRANSCRIPT
Perennial Weed Management in Row Crops and Perennial Forages
Presented by the PSU Weed Science team:
Dwight Lingenfelter, Extension Associate
Bill Curran, Professor of Weed Science
Annie Klodd, Extension Associate
Perennial Weeds
• Generally live more than two years
• Can reproduce in several ways, beyond just seeds
• Store energy in vegetative structures
Two types:
• Herbaceous
• Woody
Dupont.ca
Progressiveforage.com
Bill Johnson
Types of perennial weeds
Herbaceous- die back every season, then come back next year
Simple- emerge from same
taproot system every year.
- often rely on seeds for reproduction.
Creeping- reproduces and
spreads via vegetative structures
CREEPING
Types of perennial weeds
WoodyContinue growing from same “woody” structure year after year
Some reproduce via vegetative structures (creeping)
Some do not creep - simple
Common problem perennials of the Northeast
Simple Creeping Woody
Chicory Bindweed Brambles
Dandelion Canada thistle Autumn olive
Dock species Groundcherry Multiflora rose
Plantain Hemp dogbane Poison ivy
Pokeweed Horsenettle Sumac
White cockle Ironweed Tree-of-heaven
Wild four-o’clock Japanese knotweed Virginia creeper
Johnsongrass
Milkweed
Mugwort
Quackgrass
Smooth bedstraw
Wirestem muhly
Yellow nutsedge
Perennial Vegetative Structures
Structures that:
- allow the plant to reproduce and grow
- store energy from year to year
Quackgrass rhizomes
Johnsongrass stolon & rhizomes
Stolons - above-ground horizontal stems that root at the nodes to spread the weed.
Rhizomes - below-ground thickened stems that grow horizontally in the upper soil layers.
Yellow nutsedge rhizomes/tubers
Hemp dogbane root buds
Tubers - enlarged rhizomes with compressed internodes located at the ends of rhizomes.
Budding roots - modified roots that can store carbohydrates and grow vertically and horizontally.
Wild garlic bulbs
Jerusalem artichoke tubers
Bulbs – modified leaf tissues that store carbohydrates. Located at the base of the stem, at or below the soil line.
Tubers - enlarged rhizomes with compressed internodes located at the end of ends of rhizomes.
Vegetative Structures are the:
“Energy Reserves”
Energy, or carbohydrate, storage found in vegetative structures
Perennial Broadleaf Energy Reserves:
April May June July August Sept. Oct.
Sto
red E
nerg
y
Canada thistle
“Bud to Bloom”High!
Low…a lot has been moved aboveground.
Hemp dogbane
Dandelion
Milkweed
Importance of Seed Production
• Seed production may be important for spread - new infestations
• Transport within and between fields and longer distances
• Longer lived than vegetative structures• Good news - small plants from seed may
be susceptible to standard controls
Vegetative and Seed Production for Selected Perennials –Prevent seed production
Weed Vegetative Seed
Canada thistle Rhizomes Fairly important
Dandelion Taproot buds Very important
Hemp dogbane Creeping roots Important
Johnsongrass Rhizomes Very important
Nutsedge Tubers Not important
Quackgrass Rhizomes Fairly important
Small plants from seed may be susceptible to standard controls
Herbicide JG HDB MW CT PKW HN
Atrazine 22 100 85 99 84 96
Authority 41 100 64 73 90 65
Canopy 80 100 97 99 96 89
Dual 33 69 75 30 16 28
Lorox 27 58 32 88 36 48
Prowl 38 44 56 34 28 26
Python 76 81 80 98 92 81
Scepter 86 81 77 91 86 80
Metribuzin 76 100 99 100 88 96
Effect of soil applied herbicides on perennial seedlings (% control in greenhouse) –M. VanGessel, Univ. of Delaware
Perennial weeds are a symptom ofmanagement
• Undisturbed habitats
• Grass hay and pasture
• Alfalfa and other perennial legumes
• No-till/reduced-till systems
• Roadside habitats
• Turfgrass/lawns
USDA NRCS
Univ. of TN
Annual tillage –Annual weeds, creeping perennials
Photo courtesy of S. Culpepper, University of Georgia.
Reduced-till –Simple perennials & small-seeded annuals
Photo: S. Culpepper, University of Georgia
Pokeweed Pigweed (small-seeded annual)
Photo: Ohio State Weed Guide
White cockle roots
No-till fields & pastures –Woody & herbaceous perennials and biennials
Autumn Olive in pasture. Photo: WV Univ.
Photo: WV Univ.
Perennial Weed Biology Summary
Lifecycle • Live more than two years• Herbaceaous [simple, creeping], and woody• Vegetative structures: Reproduction & energy
storage.
Plants can be targeted when energy reserves are lowest (bud-bloom & fall)
Seed production is still important for some simple perennials
Perennial weeds depend on land management
Next up:Successful management of
perennial weeds
Row crops
Grass hay and pasture
Alfalfa
Management is most successful with an integrated approach
Prevention• Stop weeds before they become established
Cultural• Includes crop rotation, competitive crop varieties, soil fertility,
crop competition, planting density, planting date, routine field scouting, ensiling weed-infested crops, etc.
Mechanical• Use of physical techniques such as hoeing, mowing, plowing,
cultivating, digging, mulching
Biological• Involves the use of other living organisms such as insects, diseases,
or livestock to control certain weeds
Chemical• Herbicides - convenient, economical, effective when used in
combination with other tactics
Progressiveforage.com
Integrating tactics for perennial weed management
Selecting tactics:• Design program based on what is best for the particular
weed species and farm operation
Consider weed biology:• Target perennials during certain times of year for best
control
Fall
Early summer
Cultural –Crop Rotation
Cultural tactics: Crop management decisions that improve weed control
Selecting crop rotations to aid in perennial weed mgmt:• Breaks weed lifecycles – stops certain weeds from dominating
• Adds options for tillage & mowing • Mowing - Perennial forages and winter grains
• Tillage - Summer annual crops
• Adds herbicide options
• Small grains create better herbicide timing (early summer, fall)
Perennial Broadleaf Susceptibility
April May June July August Sept. Oct.
Root Energy or Susceptibility to Systemic Herbicide
“Bud to Bloom”
ReservesSusceptibility
Movement to roots
Mechanical –Tillage and Perennial Weeds
• Perennial weeds are more common in no-till (undisturbed) areas
• Tillage disrupts vegetative growth – esp. simple & woody perennials
• Deep tillage more effective than shallow
• Fall tillage better than spring, but carries environmental concerns
Follow tillage with winter cover crop
Part of integrated strategy:
• Chisel plow and disking alone can increase spread of creeping perennials
• Tillage alone is generally inadequate and should be used selectively and with other tactics
In no-till fields:
If not tilling, perennial weed management relies more on cultural tactics, herbicide, and possibly
biological control like grazing.
Moldboard Plow
High Residue Cultivator
Chisel Plow
Vertical tillage
Most potential for perennial control
Tillage – good or bad for thistles?
• Mold board plow will bury roots deep
• Chisel plowing in fall will expose taproots• Good or bad result depends on timing.
X Do not chisel plot thistle right before planting a crop –taproots will re-sprout along with the crop
Could chisel plow before winter, exposing roots to freezing to kill them
Mechanical –Mowing• Removes tops to prevent seed formation
• Depletes underground food reserves
• Aids growth of desirable vegetation –grasses/legumes
Challenges:
• Not effective on some species –simple perennials
• Repeated mowing necessary for complete control – often not practical except in alfalfa
• Certain livestock grazing practices can target specific perennials
• Examples:• Goats consume poison ivy and multiflora rose
• Sheep in fall, on Canada thistle, followed by fall herbicide
• Intensive, low-frequency cattle
• Carefully consider challenges
Biological-Livestock grazing on perennials
Progressiveforage.com
Herbicides and Perennials
• Soil-applied – may have some impact on seedlings, but rarely established plants
• Foliar applications – necessary for vegetative control
• Timing is very important, but doesn’t always line up with crop
• June-early July & fall
Control of Hemp Dogbane depends on application timing and rate: Roundup – year after application
0
10
20
30
40
50
60
70
80
90
100
Vegetative Bud Early Flower Full Flower
% c
on
tro
l (8
/1)
1.5 pt
2 pt
3 pt
4 pt
J. Doll, U of Wisc.
Pokeweed: Effect of glyphosate application timing on control
0
10
20
30
40
50
60
70
80
90
100
mid May early June mid June early July mid July late July mid Aug
% C
on
tro
l
Time
2012
2013
K. Patches, Penn State (2012/2013)
Crop Rotation and Herbicide Timing – when to apply
• 1 to 3 weeks prior to planting or after harvest:
• Apply systemic herbicide to actively growing perennials
• Fits better with fall-seeded small grain or alfalfa planting or…
• After winter wheat harvest
Example – Best Case ScenarioIntegrate Cultural, Mechanical, Chemical tactics
Early summer: Follow ryelagewith competitive annual forage
Early July: harvest topgrowth. Allow forage & weeds to regrow
Mid-August: harvest topgrowth. Allow forage & weeds to regrow
Late summer: Apply systemic herbicide (2,4-D + dicamba)
Greencoverseed.com
• Combines crop competition (Cultural), mowing (Mechanical), and herbicide (Chemical)
Perennials of Row Crops
• Common problems: Canada thistle, pokeweed, dandelion, horsenettle, hemp dogbane, Johnsongrass, others
• Simple and creeping herbaceous
• Most problematic in no-till – less disturbance
• Can be competitive in corn, soybean, and small grains
• Suppression often depends on herbicides
Table 2-12. Herbicide effectiveness on perennial broadleaf weeds in corn2017 Mid-Altlantic Field Crop Weed Management Guide
Table 4-12. Effectiveness of postemergence herbicides on perennial broadleaf weeds in soybean (based on seasonal control)
2017 Mid-Atlantic Field Crop Weed Management Guide
B
AAB
D
CC
C
AB AB AB AB
0
10
20
30
40
50
60
70
80
90
100
% c
on
tro
l
p < 0.0001
E
C
Glyphosate important for pokeweed control in soybean
(visual rating), 12WAA, 2012/2013.
Perennials Weeds of Grass Hay and Pasture• Common problems: Canada thistle,
horsenettle, smooth bedstraw, dock species, multiflora rose, others
• Simple, herbaceous, and woody
• Presence often depends on grazing and mowing management and age of stand
• More herbicide options
• Control dependent on mowing, fertility mgt., and herbicides
Table 6-11. Relative effectiveness of grass pasture, hay, and CRP grassland herbicides.2017 Mid-Atlantic Field Crop Weed Management Guide
Perennial Weeds of Alfalfa
• Common problems: dandelion, plantain, dock species, white cockle, others
• Mostly simple perennials that tolerate mowing
• Presence often depends on mowing management and age of stand
• Control depends on mowing, herbicide, and crop rotation
Table 6-5. Relative effectiveness of herbicides on weeds and crop tolerance in legume forages.
2017 Mid-Altlantic Field Crop Weed Management Guide
Roundup Ready AlfalfaExtension Publication: Agronomy Facts 65
http://extension.psu.edu/publications
• Benefits: good weed control, wide harvest intervals, greater potential for no-till, other
• Challenges: alfalfa-grass mixtures, concern for resistant weeds, more expensive seed
• Refer to fact sheet for more details