What Do Weeds Think? RALPH WHITESIDES UTAH STATE UNIVERSITY EXTENSION WEED SPECIALIST

Transcription

1 What Do Weeds Think? RALPH WHITESIDES UTAH STATE UNIVERSITY EXTENSION WEED SPECIALIST

2 What is a Weed? Plant out of place Any plant growing where it is not desired Any plant someone will pay to remove or kill Any plant other than the crop sown Plants that are competitive, persistent, and pernicious. They interfere with human activities and, as a result, are undesirable. (Ross & Lembi)

3 Common Approach What is that plant? How do I kill it?

4 Thoughtful Approach What is that plant? Why is it there? Why is it there now? How do I keep it from being there in the future?

5 Life Cycles and Plant Families ACEAE Annual Winter annual Summer annual Biennial Perennial Simple perennial Creeping perennial

6 Plant Families Asteraceae (sunflower) Zygophyllaceae (caltrop) Convolvulaceae (morninglory) Brassicaceae (mustard) Poaceae (grass) Ranunculaceae (buttercup)

7 Specimen Weeds Common dandelion Puncturevine Field bindweed Quackgrass Crabgrass Shepherd s purse Dyer s woad Bur buttercup

8 Herbicide Nomenclature Pre-emergence Post-emergence Contact Systemic (translocated)

9 Cultural Control/Mechanical Control Competition Tillage Fertilizer Irrigation

10 Management Strategies Annuals Biennials Perennials

11 Management Strategy for Annuals Annuals on the list for today Crabgrass Puncturevine Bur buttercup Shepherd s purse

12 Management Strategy for Crabgrass Digitaria sanguinalis Poaceae native to USA, Caribbean Summer Annual = germinate 55 F Single Large plant = 150,000 seeds seed can survive up to 15 years Objective = prevent seeds

13 Forsythia in bloom

14 Large Crabgrass

15 Large Crabgrass

16 Large Crabgrass siduron 3.71% AKA Tupersan 96.29% inerts

17 Pre-emergence Herbicide Failure

18 Management Strategy for Puncturevine Tribulus terrestris Caltrop Family Summer Annual native to Mediterranean Region One large plant in California produced 576,000 fruits. Assuming 2 seeds per segment = 1,152,000 seeds/plant Germinates all season lives in soil at least 4 years Susceptible to glyphosate, 2,4-D, dicamba Mechanical control = sweep seeds, vacuum seeds, roll old pumpkins, or carpet

19 Puncturevine

20 Military Caltrops

21 Puncturevine Caltrops

22 Mechanical Control of Puncturevine

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24 Bur Buttercup is Not Puncturevine Ranunculus testiculatus Buttercup Family Winter annual Native Southeast Europe

25 Bur Buttercup Flowers

26 Bur Buttercup Seed Pods

27 Shepherd s Purse Management Capsella bursa-pastoris Winter annual mustard Member of mustard family Native of Europe Single plant produces several thousand seeds Remain viable for many years Seeds remain dormant in the dark - mulch

28 Shepherd s Purse Flower

29 Shepherd s Purse Seed Pods and Rosette

30 Management Strategy for Biennials Biennial on the list for today Dyer s Woad

31 Dyer s Woad Isatis tinctoria Native to Central and Western Asia Winter annual, biennial, or short lived perennial Plants produce seeds Seed longevity under field conditions unknown some evidence for 8-10 years

32 Dyer s Woad in Flower

33 Dyer s Woad Seeds

34 Management Strategy for Perennials Perennials on the list for today Common dandelion simple Field Bindweed creeping Quackgrass creeping

35 Common Dandelion Taraxacum officinale Native to Eurasia Simple perennial with fleshy taproot Spread by seed and new shoots from roots Dent-de-lion

36 Dandelion Humor Most gardeners detest them, but the more you try to weed them up, the faster they grow. The taproot is deep, twisted, and brittle. Unless you remove it completely, it will regenerate. If you break off more pieces than you unearth, the dandelion wins. "What's a dandelion digger for?" a dandelion asked. "It is a human invention to help us reproduce," another dandelion replied.

37 Common Dandelion Inflorescence

38 Dent-de-lion

39 Simple Perennial

40 Field Bindweed Convolvulus arvensis Creeping Perennial Native of Europe, North Africa, Asia Reproduces by seed and roots Seed longevity > 50 years

41 Field Bindweed Seed

42 Field Bindweed Flowers

43 Field Bindweed Roots

44 Quackgrass Agropyron repens (Elymus repens) Creeping perennial Native to Europe and Western Asia Reproduces by seed and rootstock (rhizomes and roots) Seed longevity 2-4 years

45 Quackgrass Seed and Leaves

46 Quackgrass Rootstock

47 What are the Annuals Thinking? Seed production Not necessary to develop huge root reserve, plan to die after they produce seed anyway Seed dispersal

48 What are Biennials Thinking? Rosettes Vernalization Seed Production Short-lived perennial

49 What are Perennials Thinking? OK to produce seed, but not necessary Establish significant root reserves Develop brittleness as an ecological advantage Send progeny elsewhere and rebuild root reserve

50 Saltcedar (tamarisk)

51 Salt Cedar on the Freeway

52 Salt Cedar on the Freeway

53 What Should Humans Think About Weeds? Stop annuals & biennials from seeding Recognize apical dominance in perennials Understand Source to Sink in perennials When using herbicides understand selective vs non-selective

54 Apical Dominance

55 Brittleness

56 Herbicide Selectivity

57 Herbicide Selectivity

58 Herbicide Selectivity

59 Herbicide Selectivity Source to Sink Translocation

60 Selective Grass Control in the Landscape

61 Selective Grass Control in the Landscape

62 Selective Grass Control in the Landscape

63 Selective Grass Control in the Landscape

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66 Selective Grass Control in the Landscape Sethoxydim Poast, Segment, others Fluazifop Fusilade II Clethodim Clethodim 2EC

67 Lawn Violet

68 Lawn Violet

69 Vinca major Big Periwinkle

70 Lawn Violet (Viola sororia) and Vinca Triclopyr Garlon 3A (violets are on the label) Carfentrazone Quicksilver Triclopyr + clopyralid Confront