Weed I.D. and Management

Transcription

1 Weed I.D. and Management featuring 10 common weeds Test your skills Bill Curran Penn State University

2 Weed identification Most people want to know the names of (and how to control) the weeds they encounter or are having problems with Certain weed species can be found around the world, while others grow only in certain regions To ID a weed, it is necessary to understand key features and their differences between species For seedlings or small weeds, use of a hand lens in an area with adequate lighting Accurate weed ID is an important part of an integrated weed management program Seedling weed ID can be very important

3 Weed ID resources Print Weeds of the Northeast Newcomb s Wildflower Guide Common Weed Seedlings of the North Central States Many others Purchasing information for selected weed ID resources Electronic Weeds Penn of State the Northeast Weed Management (~$30) Barnes website and Noble (numerous links) Amazon.com Cornell University Press, [email protected] Weed Science Society of America or by calling website photo herbarium Newcomb s Wildflower Guide (~$15) Weed Identification, Biology, and Barnes Management and Noble CD (~$40) Amazon.com Common WeedEco Seedlings of the North Central States (~$4) Many others or

4 Lifecycles Annual Biennial Perennial

5 Annual weeds Completes lifecycle in <1 year Winter annual germinates in the fall or early spring common chickweed, henbit, shepherdspurse, downy brome, yellow rocket, horseweed, garlic mustard, etc. Summer annual germinates in late spring or early summer lambsquarters, pigweed, foxtail, crabgrass, ragweed, purslane, hairy galinsoga, etc.

6 Biennial weeds Completes lifecycle in <2 years Emerges from seed in early to late summer Overwinters as a rosette then bolts (grows a seed stalk), and sets seed next year common burdock, bull thistle, musk thistle, wild carrot, poison hemlock, common mullein, common evening primrose

7 Perennial weeds Completes lifecycle in >2 years Simple perennial spreads primarily by seed and has a taproot dandelion, plantains, curly dock, pokeweed Creeping perennial spreads by vegetative means as well as seed. May be herbaceous or woody. Herbaceous: quackgrass, Canada thistle, hemp dogbane, purple loosestrife, Johnsongrass, ground ivy, yellow nutsedge Woody: multiflora rose, Japanese knotweed, Japanese honeysuckle, poison ivy, tree-of-heaven

8 Perennial structures These structures allow perennials to spread, produce new plants and overwinter (not all are present on each species) Stolons are above ground horizontal stems that root at the nodes to spread the weed stolons ground ivy, bermudagrass, white clover, strawberries Rhizomes are below-ground thickened stems that grow horizontally in the upper soil layers Canada thistle, quackgrass, goldenrod, Johnsongrass, purple loosestrife rhizomes Tubers are enlarged rhizomes with compressed internodes located at the ends of rhizomes yellow nutsedge, Jerusalem artichoke, potatoes budding roots Budding/creeping roots are modified roots that can store carbohydrates and grow both vertically and horizontally hemp dogbane, milkweed, bindweed Bulbs are leaf tissues modified for carbohydrate storage, located at the base of the stem, at or below the soil line wild garlic, onion, tulips Click here for images of these bulbs tubers

9 Key features and primary characteristics to consider for weed ID Grasses lifecycle habitat ligule auricles sheath shape sheath/blade hairs seed-head seed characteristics root structure Broadleaves lifecycle habitat cotyledon shape leaf shape/texture leaf arrangement stem/leaf hairs venation color floral characteristics root structure

10 Grass and Grasslike Weed ID Key features to look for on grasses Hairlike ligule No Ligule ligule present ligule auricles blade/sheath hairs Not all features will Collar region be present Most ID keys begin with the type of ligule Membranous Auricles and ligule Click on thumbnails for larger image; then click on larger image to return

11 Broadleaf Weed ID Key features to look for: Alternate leaves emerge at different points Leaf or arrangement times on the on stem; stemolder ones are alternate larger. opposite Leaf and/or cotyledon shape Other Various features leaf shapes to consider: leaf margin traits Leaf leaf texture/hairs arrangement First true leaves odor Cotyledons Most seedling keys begin by asking for leaf arrangement, then leaf shape Cotyledons or seed leaves emerge first and are always opposite. Do not confuse them with the first true leaves, which are used to determine leaf shape on most ID keys. Opposite leaves emerge at the same Note point toothed and time and are the same leaf margin size. Click on thumbnails for more information; then click on larger images to return

12 1. Key features Heart-shaped leaves and cotyledons Toothed leaf margins Stems and leaves densely hairy Lifecycle Summer annual

13 2. Key features Leaves are lacy and hairy Opposite leaf arrangement Spoon shaped cotyledons Pollen an allergen Lifecycle Summer annual

14 3. Key features Lanceolate shaped cotyledons and true leaves Opposite then alternate leaf arrangement White mealy substance on leaves Prolific seed producer Lifecycle Summer annual

15 4. Key features Opposite, egg-shaped to triangular leaves with toothed margins Stems and leaves are hairy Flowers have yellow centers with outer white petals Lifecycle Summer annual Ontario Weeds UMass Coop. Ext. Virginia Tech Coop. Ext.

16 5. Key features Ovate leaves with some hairs and pointed tip Toothed edges on leaves Purple color on under-leaf Black/purple berries when mature Lifecycle Summer annual

17 6. Key features Opposite, broadly ovate/egg-shaped leaves Light green color Single row of hairs on stem Small white flowers Lifecycle Winter annual

18 7. Key features Hairlike ligule Short hairs on blade (upper surface) Lifecycle Summer annual

19 8. Key features Hairlike ligule Long hairs on blade near collar Flat stem Purplish-red color near base Lifecycle Summer annual

20 9. Key features Membranous ligule Hairy blade and sheath Finger-like seed head Lifecycle Summer annual

21 10. Key features No ligule Triangular stem Shiny blades Lifecycle Perennial

22 1. Velvetleaf Key features Heart-shaped leaves and cotyledons Toothed leaf margins Stems and leaves densely hairy Lifecycle Summer annual

23 Velvetleaf (Abutilon theophrasti) Summer annual Native to India Reproduces by seed Emerges from mid May through June Densely hairy on both leaf surfaces (velvety) Flowers are circular cup-shaped disks that contain multiple seed Seed can remain viable for up to 50 yrs.

24 Velvetleaf management Prevent competition and seed production Seed dissemination via crop seed, manure, equipment (combines) Reduce tillage (no-till) Thrives in fertile cultivated soils Plowing encourages velvetleaf Velvetleaf can emerge from over an inch deep Rotate to hay crop to prevent seed production

25 2. Common ragweed Key features Leaves are lacy and hairy Opposite leaf arrangement Spoon shaped cotyledons Pollen an allergen Lifecycle Summer annual

26 Common ragweed (Ambrosia artemisiifolia) Summer annual Native to the U.S. Common in many crops and other areas Leaves are lacy and hairy Reproduces by seed Each plant produces about 3000 seeds Seeds can remain viable up to 40 years Prolonged emergence period in some areas Pollen a major contributor to allergies

27 Ragweed management Prevent competition and seed production Seed dissemination via crop seed, manure, equipment (combines) Include hay in crop rotation Ragweed does not tolerate repeated mowing Reduced and no tillage systems help lessen germination

28 3. Common lambsquarters Key features Lanceolate shaped cotyledons and true leaves Opposite then alternate leaf arrangement White mealy substance on leaves Prolific seed producer Lifecycle Summer annual

29 Common lambsquarters (Chenopodium album) Summer annual Native to Eurasia Reproduces by seed 72,000 seeds/plant Seeds can remain viable for many years in the soil Emerges from mid-april to mid-june Common in all tillage systems

30 Lambsquarters management Prevent competition and seed production Seed dissemination via crop seed, hay, manure, equipment (combines) Tillage system less important Most seeds germinate within top ½ inch Moldboard plow can bury seed Seed longevity reduces effectiveness Rotate to hay crops to prevent seed production Can be a problem seeding year

31 4. Hairy galinsoga Key features Opposite, egg-shaped to triangular leaves with toothed margins Stems and leaves are hairy Flowers have yellow centers with outer white petals Three-toothed ray flowers Lifecycle Summer annual Ontario Weeds UMass Coop. Ext. Virginia Tech Coop. Ext.

32 Hairy galinsoga (Galinsoga ciliata) Summer annual Called Quickweed Native to Eurasia Reproduces by seed 5,000-10,000 seeds/plant Seeds can remain viable for several years in the soil Emerges from April to July Flowers from June to late Fall More common in tilled systems and a serious problem for vegetable crops UMass Coop. Ext.

33 Galinsoga management Prevent competition and seed production Seed dissemination via crop seed, hay, manure, equipment (combines) Most common in tilled soil Most seeds germinate within top ½ inch Moldboard plow can bury seed Seed longevity an issue? Rotate to winter grains, hay crops, and cool season summer annuals to prevent seed production

34 5. Eastern black nightshade Key features Ovate leaves with some hairs and pointed tip Toothed edges on leaves Purple color on under-leaf Black/purple berries when mature Lifecycle Summer annual Note: Seedlings often confused with pigweed. Also it can be confused with groundcherry

35 Eastern black nightshade (Solanum ptycanthum) Summer annual Native to the Americas Reproduces by seed Plant flowers and produces berries (100 seed/berry 1000 berries/plant Seeds can remain viable for several years in the soil All plant parts are considered poisonous Emerges from mid-may to late-june Most common in tilled fields

36 Nightshade management Prevent competition and seed production Seed dissemination via crop seed, hay, manure, equipment (combines) Reduced till biggest problem Most seeds germinate within top ½ inch Moldboard plow can bury seed Seed longevity reduces effectiveness Rotate to hay crops or winter annuals to prevent success and seed production

37 6. Common chickweed Key features Opposite, broadly ovate/egg-shaped leaves Light green color Single row of hairs on stem Small white flowers Lifecycle Winter annual Note: can be confused with mouseear chickweed and some speedwell species

38 Common chickweed (Stellaria media) Winter annual Native to Europe Reproduces by seed 3,000-5,000 seeds/plant Emerges from late- August to spring Common in winter annual crops, perennial forages, and no-till tillage systems

39 Chickweed management Prevent competition and seed production Seed dissemination via crop seed, hay, manure, equipment (combines) More common in no-tillage or winter grains Most seeds germinate within top ½ inch Moldboard plow can bury seed Seed can remain viable for several years Rotate to later summer annual crops to prevent success

40 7. Giant foxtail Key features Hairlike ligule Short hairs on blade (upper surface) Lifecycle Summer annual

41 8. Yellow foxtail Key features Hairlike ligule Long hairs on blade near collar Flat stem Purplish-red color near base Lifecycle Summer annual Foxtail seed heads giant green yellow

42 Giant foxtail and Yellow foxtail (Setaria faberi) (Setaria glauca) Summer annuals Native to Eurasia Prolific seed producers Giant foxtail 10,000 seeds/plant Yellow foxtail 6,500 seeds/plant Emergence from early May through June Yellow foxtail can sometimes emerge later Foxtail seed heads giant green yellow

43 Foxtail management Prevent competition and seed production Seed dissemination via crop seed, manure, equipment (combines) Bury seed with tillage Optimum germination depth is about ½ inch Giant foxtail seed short-lived, yellow longer Can be successful in tilled and no-till systems

44 Foxtail Management (cont.) Crop competition helps suppress foxtail growth Rotate to winter grains Maintain competitive hay crops Control by regular mowing

45 9. Large crabgrass Key features Membranous ligule Hairy blade and sheath Finger-like seed head Lifecycle Summer annual Note: Smooth crabgrass is similar to L. crabgrass but it is generally smaller, hairless, and has a bluish appearance

46 Large and Smooth crabgrass (Digitaria sanguinalis)(d. ischaemum) Summer annuals Native to Europe Germinate from mid spring to mid summer (often after crop has emerged) Prolific seed production Tolerates hot, dry conditions Opportunistic weeds Not competitive when shaded Large crabgrass generally more common than smooth in agronomic crops

47 Crabgrass management Prevent seed production and spread Seed dissemination via crop seed, manure, equipment (mowing) Plant crop as early as possible Grow competitive early shading crops Can thrive in conventional and reduced tillage systems Watch for late emergence Prevent seed production when possible

48 Yellow 10. nutsedge Key features No ligule Triangular stem Shiny blades Lifecycle Perennial

49 Yellow nutsedge (Cyperus esculentus) Perennial monocot (not a grass species) 3-sided base (triangular in cross section) Shiny, yellowish-green, narrow, grass-like leaves Native to N. America and Eurasia Reproduces by tubers (primary means), rhizomes, and seeds Thrives in various crop settings and soils Ag, horticulture, nursery, turf crops Well-drained, sandy soils to damp/wet soils Infestations often start in wet areas

50 Yellow nutsedge management In general, nutsedge is not very competitive; dense infestations can cause problems Prevent spread of nutlets Clean soil clods, etc. form tillage equipment before leaving infested field Fall tillage can provide some benefit

51 Questions?