Weed Control in Vegetable Produ uction Richard Smith, Vegetab ble Crop and Weed Science Farm Advisor, Monterey County

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1 Weed Control in Vegetable Produ uction Richard Smith, Vegetab ble Crop and Weed Science Farm Advisor, Monterey County

2 Why Care a bout Weeds Weeds are not microscopic or small like fungi and insects They can always be pulled out The issue is thei ir impact on crop yield and on the economics of farming

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4 El Pellisco

5 Hours/Acre to Weed Carrots

6 Comparison of Orga anic vs Conventional Leaf Lettuce Pr roduction Costs System Organic 1 Cos sts Percent of $/A Growing Costs Conventional Tourte and Smith, 2004; 2 Tourte and Smith, 2001

7 Weed Clas ssification Annuals Complete lifecycle e in less than one year (from seed to seed d) Winter germinate e in fall and mature in early spring Summer May ger rminate in the fall or spring, but mature in the summer

8 Winter ann uals Nettle Shepherds Purse Groundsel Sow Thistle

9 Summer Annuals Nightshades Purslane Nettleleaf Goosefoot

10 Weed Clas ssification Biennial Live longer than on ne year but less than two. Often overwin nter as a rosette and resume growth in the spring Perennial Live more than one year. Can be woody or fleshy. May have survive as tubers, roots, nutlets, etc. Winter active in th he winter Summer active in the summer

11 Soil Seed Bank Dormant Weed seed Nondormant Germination & Emergence Microbial Physical Physiological Seed degradation Seed Death Tillage & other controls

12 Weed Strategie es Crop Areas Set Seed Quickly Groundsel, Burning Nettle Long lived seed Malva, Burr Clover Large Numbers of Seed Purslane & many others Set seed in surrounding areas and invade from the edges Groundsel, Sow thistle

13 Weed Control Strategies Cultural Mechanical Chemical Biological Few effective oth her than seed viability declinin i ng in the soil over time

14 Cultural Practice es for Managing Wee eds Aggressively control ling weeds in all prior rotations and during the fallow period over the winter Zero tolerance of wee eds going to seed

15 Cultural Practices to Reduce Weed Press sure Field selection Avoidance: Avoiding weedy fields Avoiding weediest time of the growing season (i.e. purslane during June to Sept.) Pre-germination of weeds Use of stale seedbeds Planting vigorous varieties on weediest area

16 No Preirrigation Effects of Preirrigation With Preirrigation Reduces the number of weed seed that are ready to germinate in the top la ayer of the soil Can reduce weed emerg gence in subsequent crop by up to 50% (Shem Tov and Fennimore)

17 Stale Bed Technique: Pre-germinate and kill flush of weeds on shaped beds, prior r to planting cash crop Mulching Cultivation Flaming Liliston

18 Cultural Practices to Reduce Weed Press sure Control weeds that aerial disperse from surrounding areas Not letting weeds go to seed Carrying weeds from the field for disposal elsewhere Crop rotations Deep pp plowing Planting to moisture Use of buried drip irrigation Solarization Mulches Transplants a Cover crops

19 Weeds Around Edge of Field Source of weed i nfestation

20 Carry Weeds Out of Field Purslane in bags carried to edge of field

21 Planting to Moisture

22 Buried Drip Irrigation

23 Solarizat ion Solariz zation

24 Colored mulches

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26 Impact of Cover Crops on Weeds

27 Largest Chickweed Under 3 Cover Crops at 2 Seeding Rates (64 Days Aft ter Planting) Legume/Rye Mustard Rye 1x Seeding Rate 125 lb/acre 10 lb/acre 80 lb/acre 3x Seeding Rate

28 Use of Tra ansplants Transplants open op pportunities for mechanical weed co ntrol Transplants give the crop a head start on the weeds Transplants are more resistant to physical manipulation Transplants are easie er for high tech mechanical weeders to recognize (distinguish from the weeds)

29 Mechanica al Controls Cultivation Plowing

30 Standard cultivation with Knives and sweeps

31 Cultivated Zone Uncultivated Zone 4 wide Cultivated Zone 80% of the bed

32 Typically 80+% of a 40-inch wide bed can be effectively cultivated. The fight with weeds occurs in the uncultivated seedline

33 Precision Guidan nce of Cultivators Guided d by t he Operator Effective but Slow Old Technology Modern Version

34 Camera Guidance Systems for Cultivators t

35 4 wide cultivation strip

36 3 wide cultivation strip

37 Percent of Weed ds Controlled at Different Cultivat tion Band Widths 2005 Lettuce e Trial No. 1 Cultivation Ba and Width

38 Hours Per Acre to Weed Different Cultivat tion Band Widths 2005 Lettuce e Trial No. 1 Cultivation Ba and Width

39 Removal of Weeds from the High Tech Ideas Seed dline

40 Split Knife Dave Slaughter, UCD

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42 Lower Tech Ide eas for Removing Weeds from the Seedline In Europe where tr ransplanting of vegetables is comm monly used, there is wider use of imp plements that t are capable of removin ng weeds from the seedline

43 Finger Weeders This idea originally came from the US was invented by Company, Michiga an The idea was take en to Europe and further developed d produced by three the Buddingh and refined (now companies) The Europeans cla aim their designs can operate at high her speed

44 Finger Weeders Two sizes and two levels of hardness Softer Harderr Kress Co, Germany

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49 Torsion Frato Corp, Weeder Netherlands

50 Come in Differe ent Sizes 7&9 mm

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52 Transplanted Le ettuce Trial No. 1 Percent Removal of Weeds Small Nettle D ominant Weed Standard 14.5 orange 14.5 yellow 9.5 orange 9.5 yellow Torsion 9mm All cultivation treatments Improved percent removal

53 Transplanted Le ttuce Trial No. 1 Weeding Time hrs/a Standard 14.5 orange 14.5 yellow 9.5 orange 9.5 yellow Torsion 9mm

54 Chemical Wee ed Control for Veget tables Herbicides are an im mportant tool for managing g weeds in vegetable production They greatly reduce the weed population and make subsequen nt hand weeding operations more effic cient

55 Types of Her bicides Used Preplant Fumigants Metam Sodium (Vapam m) Burndown material u sed on beds just prior to planting Glyphosate (Roundup p) Paraquat (Gramoxone e) Carfentrazone (Shark)

56 Types of Her bicides Used Preemergence Applied prior to the emergence of the weed Often applied at seed ding with the crop Pronamide (Kerb) on lettuce Rimsulfuron (Matrix) on tomatoes Can be applied prior to transplanting the crop Metolachlor (Dual Mag gnum) on peppers

57 Types of Her bicides Used Postemergence Applied after the wee eds have emerged in the crop Applied as an selectiv ve over-the-top top application Halosulfuron (Sandea) & rimsulfuron (Matrix) on tomatoes Prometryn (Caparol) on celery Oxyfluorfen (Goal) on Applied as a directed onions Tifl Trifluralin li (Treflan) on tomatoes t spray to the base of the plant

58 Goal 2XL st true leaf 1 st Goal Tender

59 Shepherds h Purse st true leaf 2 nd true leaf 1 st

60 Goal Te ender Weed Bur rn Down

61 Untreated t Goal Tender 1st true leaf

62 Challenges for Chemical Weed Control in Veget table Production Fewer new herbicide es being produced for vegetables Loss of older herbici ide due to economic or regulatory influen ces

63 Year of Regist tration of Key Vegetable Herbicides Trade Name Chemical Representative Crop Year Registered Lorox Dual Magnum Kerb Dacthal Devrinol Caparol Linuron S-metolachlor Pronamide DCPA Napropamide Prometryn Carrots 1966 Potato, Peppers 1976 Lettuce 1972 Broccoli, Onions 1958 Broccoli, Tomatoes 1972 Celery 1964

64 Why few new herbicides? Roundup Ready Corn and Soybeans

65 Why few new herbicides? Resistant weeds may change the situation

66 New Use for Old Herbicides Lorox on Spinach Goal on Broccoli and Onions Prowl H2O on transp planted lettuce Caparol on Carrots

67 Summ mary Weed control in vege etables is accomplished by a combination of strategies: Cultural, Mechanical and Chemical Effective use of all th hese tools assists growers in achieving economical weed control

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