Yield loss as they compete for: Increase production costs. Reduce Crop quality

Transcription

1 Weed Management

2 What is a weed?

3 Yield loss as they compete for: Interceptable light, Water, Nutrients. Harbor Pests: Over winter insects, host to diseases and cause infection. Increase production costs. Reduce Crop quality Weed seed contamination.

4 Fertile nutritionally balanced soil: Goose grass, thistle, chickweed, yarrow. Light dry soil: Dandelions, poppy, bramble, shepherd s purse and nettle. Wet soils: Primrose, thistle, dock, comfrey and cuckoo flower.

5 Annual weeds: Complete life cycle in one year. Relatively easy to control. Seeds can remain dormant for many years. Summer annuals (warm season) germinate in spring and grow through summer. i.e. wild oat, foxtail, lamb s quarter, crab grass. Winter annuals (cool season) germinate in fall, live through winter, produce seed in spring. i.e. cheat grass, rye grass, shepherd s purse.

6 Biennial weeds: Germinate in the spring of one year, live vegetatively through winter and flower the following spring i.e. burdock, wild carrot and parsnip, and musk thistle. Perennial weeds: Most difficult to control when established. Warm season weeds i.e. Johnson grass, yellow milk sedge and bindweed. Cool season weeds i.e. bindweed, Canada thistle, wild garlic, curly dock.

7 Dodders (Cuscuta spp.) infest alfalfa, sugar beet, potato and other crop species. Composed of orange or yellow vine strands that smother above ground parts of crop plants. Witch weed (Striga spp.) is a parasite of corn, tobacco, rice, sugarcane and some other small grains. Infected plants are stunted and chlorotic. It grows at the base of infected plants, where it parasitizes the roots of crops.

8 Dodder

9 Witch weed

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11 Weed Giant ragweed Shepherd s purse Large crabgrass Redroot pigweed Common lamb s quarter Life Cycle Summer annual Winter annual Summer annual Summer annual Summer annual Seeds/ Plant Longevity in Soil (Years) 5, , , , , Canadian thistle Perennial 5,500 25

12 Mechanical: Non-selective herbicidal cultivation. Inter-row cultivation. Hand weeding. Cultural: Inter-cropping. Use narrower row spacing. Planting time. Don t introduce them. Biological: Grazing. Insects. Chemical

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14 Row cultivators

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17 Seed Meal

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20 Flame & Steam

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22 By activity: Contact herbicides destroy only the plant tissue in contact with the chemical. Generally, these are the fastest acting herbicides. They are less effective on perennial plants, which are able to regrow from rhizomes, roots or tubers. Systemic herbicides are translocated through the plant, either from foliar application down to the roots, or from soil application up to the leaves. They are capable of controlling perennial plants and may be slower acting but ultimately more effective than contact herbicides.

23 Soil-applied herbicides are applied to the soil and are taken up by the roots and/or shoot of the target plant. Pre-plant incorporated herbicides are soil applied prior to planting and mechanically incorporated into the soil. The objective for incorporation is to prevent dissipation through photodecomposition and/or volatility. Pre-emergence herbicides are applied to the soil before the crop emerges and prevent germination or early growth of weed seeds. Post-emergent herbicides are applied after the crop has emerged.

24 Group 1 : Foliar applied grass herbicides -dims & -fops. Acetyl CoA Carboxytase (ACCase) inhibitors. Herbicide binds to ACCase and disrupts fatty acid synthesis, which leads to membrane degeneration. Examples: Hoelon (diclofop); Fusilade DX (fluazifop); Select (clethodim); Assure II (quizalofop), Puma, Discover.

25 Group 2 : Foliar and soil broadleaf herbicide - imidazilones and sulfonylureas. Acetolactate Synthase (ALS) inhibitors. Herbicide binds to ALS and disrupts synthesis of branched amino acids (valine, leucine & isoleucine), hence inhibits DNA synthesis. Examples: Beyond; Pursuit; Glean; Maverick, Olympus, Osprey, Harmony, Amber, Express, Assert, Peak, Ally, Escort, Telar, etc.

26 Group 3 : Soil applied to control broadleafs and some grasses - Dinitroanalines. Tubulin inhibitors. Herbicide interfers with cell division. Examples: treflan (trifluralin); Prowl 3.3 EC (pendimethalin), Baracade, Solalan, Balan.

27 Group 4 : Foliar applied broadleaf herbicides - Synthetic auxins. Auxin mimicer. Herbicide upsets plant growth regulator balance by mimicing an increase of auxins. Examples: 2,4-D (phenoxy acetic acid); Dicamba (Several - Pyridines), Stinger, Tordon, Milestone, Stinger.

28 Group 5, 6 & 7 : Foiliar and soil broadleaf (and some grasses) herbicide - Triazines & ureas. Phytosystem II inhibitors Herbicide binds to a pigment in photosystem II and disrupts photosynthesis. Examples: Atrazine, Triazine Sencor (metribuzin); Urea Karmex (diuron).

29 Group 9 : Broad spectrum nonselective herbicide - glyphosate. 5-enol Pyruvylshikimate-3-phosphate synthate (EPES) synthase. Herbicide binds to EPES synthase and disrupts the shikimic acid pathway, which is responsible for producing the precursors of aromatic amino acids. Examples: Roundup, plus other glyphosate.

30 Herbicides are organized into groups based on their site of action. Herbicides in the same group all kill plants the same way. Over use or wrongful application can cause the development of herbicide resistant weeds. Herbicide resistance should not be confused with natural tolerance of some weeds to specific herbicides.

31 Specific weeds can develop resistance to more than one group. Kochia in Idaho are resistant to imidazolinone and sulfonylurea herbicides. This is called cross resistance. Resistance to herbicides with different sites of action can occur. Italian ryegrass in Idaho is resistant to herbicides in 3 groups (Group 1, 2 & 15) This is called multiple resistance.

32 There are currently 397 unique cases (species x site of action) of herbicide resistant weeds globally. 217 herbicides resistant weed species (129 dicots and 88 monocots). Weeds have evolved resistance to 21 of the 25 known herbicide sites of action and to 148 different herbicides. Herbicide resistant weeds have been reported in 63 crops in 61 countries.

33 Roundup Resistant Weeds

34 Herbicide USA Canada U.K. China AACase inhibitor ALS inhibitor Triazines & Urea Roundup Others Total

35 Herbicide USA Australia Canada U.K. China AACase inhib ALS inhibitor Atrazines Paraquat Trifluralin Roundup Others Total

36 Group Herbicide resistant weeds 1 Wild oat and Italian rye grass, Downey broom, Wild oat are resistant to ACCase inhibitor herbicides (e.g. Discover, Puma, Poast, Assure II) 2 Kochia, prickly lettuce, and Russian thistle, Italian rye grass, and mayweed camomile are resistant to sulfonylurea herbicides (e.g. Olympus, Harmony, Express, Pursuit, Beyond, Glean, Amber, Ally) 4 Yellow star thistle is resistant to Tordon 5 Lambsquarter, Kochia, sheperd s purse, Powell amaranth and other pigweed are resistant to Triazines (e.g. Sencor, Velpar) 8 & 26 Wild oat is resistant to Far-Go (Group 8) and Avenge (Group 26)

37 Avoid year-after-year use of the same site of action herbicides. Different chemical families may have the same site of action. Suitable crop rotation Crops have different weed problems, maturity, life cycle etc. Use short-residual herbicides. i.e. ones that do not persist in the soil.

38 Cultivation in row crops can eliminate weed escapes which may be resistant biotypes. Fallow tillage can help eliminate these also. Plant clean seed and avoid bringing weed seeds onto the farm. Accurate farm records. Practice IPM.

39 Herbicide Resistant Canola Roundup (glyphosate) GMO EPSP synthase inhibitor Liberty (glufosinate) GMO Glutamine synthase inhibitor Beyond (imazamox) non-gmo ALS inhibitor

40 Field mustard exists in proximity to canola fields in the PNW

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42 Wheat JGG Hydrid

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44 Canola x weed: Field mustard; wild radish; wild mustard. Wheat x Jointed Goat Grass. Strawberry x wild strawberry. Sunflower x wild sunflower. OTHERS

45 Genotype sensitivity. Weather. Drift, Temperature, Rain Residual in soil. Dependant on soil type, temperature and rainfall. Pesticide formulation. Some formulations are safer than others. Rate of application. Overlaps. Pesticide interactions. Tank clean up.

46 Herbicide injury

47 Bromoxynil - wheat Dicamba - wheat Glyphosate - wheat SU drift - canola

48 Crop Rotation & Plant Back Restrictions Winter Wheat Pea Canola

49 Customary to use Pursuit (imazethapyr) herbicide when growing legumes in the PNW. Pursuit is an imidazolinone class herbicide, interferes with a plants ability to produce acetolactate synthase (ALS). Can not plant traditional canola for 40 months after full rate application of Pursuit.

50 Imidazilone - canola

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