DevelopingDeveloping a Weed Control Strategy in a Weed Control Strategy in

Transplanted Bell Peppers with Transplanted Bell Peppers with

Preemergence Herbicides Preemergence Herbicides for Californiafor California

Michelle Le Strange and Richard SmithMichelle Le Strange and Richard SmithUniversity of California Cooperative ExtensionUniversity of California Cooperative Extension

Farm Advisors in Tulare and Monterey CountiesFarm Advisors in Tulare and Monterey Counties

Weed Control Challenges Weed Control Challenges field grown peppers without plastic mulchfield grown peppers without plastic mulch

Peppers compete Peppers compete

poorly with weeds poorly with weeds

for the first 40 to 60 for the first 40 to 60

days following days following

transplanting.transplanting.

Peppers may be Peppers may be

subject to weed subject to weed

pressure by both pressure by both

winter and summer winter and summer

annual weeds.annual weeds.

2007

Issues with weed control in Issues with weed control in

California field grown peppersCalifornia field grown peppers

Several perennial Several perennial weeds are weeds are problematic.problematic.

Registered Registered preemergentpreemergentherbicides have herbicides have gaps in spectrum of gaps in spectrum of weeds controlled.weeds controlled.

Very few postVery few post--emergent herbicides emergent herbicides registered.registered.

2007

As a result of these challenges weed management is a significant

cost of production.

Growers can easily spend $400/Acre

On herbicide application, mechanical cultivation,

and hand hoeing.

Black Nightshade

(Solanum nigrum)

Difficult to control weeds in CaliforniaDifficult to control weeds in California

Hairy NightshadeHairy Nightshade

((SolanumSolanum sarrachoidessarrachoides))

Also Also cutleafcutleaf nightshade nightshade

and and groundcherrygroundcherry. .

Common purslane (Portulaca oleracea)

Pigweeds (Amaranthus sp.)

Redroot pigweed

Tumble pigweed

Also Prostrate pigweed

Puncturevine (Tribulus terrestris)

Difficult to control perennial weeds in CADifficult to control perennial weeds in CA

Yellow nutsedge (Cyperus esculentus)

Purple nutsedge (Cyperus purpurea)

Field bindweed (Convolvulus arvensis)

No currently registered layby herbicide is effective against field bindweed.

Little Mallow (Malva parviflora)

No currently registered layby herbicide is effective against malva.

Weed Control Materials Registered for Weed Control Materials Registered for

Transplanted Peppers in CaliforniaTransplanted Peppers in California

PreplantPreplant

ParaquatParaquat

Roundup Roundup

MetamMetam SodiumSodium

Shark (Shark (carfentrazonecarfentrazone))

Scythe (Scythe (pelargonicpelargonic acid)acid)

PreplantPreplant -- PreemergencePreemergence

TreflanTreflan & & Prowl HProwl H22OO

Dual Magnum Dual Magnum (24c)(24c)

GoalGoal1,21,2

Post TransplantPost Transplant DevrinolDevrinol

LaybyLayby DacthalDacthal

Prowl HProwl H22OO

Dual Magnum (24c)*Dual Magnum (24c)*

PostemergencePostemergence PoastPoast

Select Max (Select Max (clethodimclethodim))

SandeaSandea

11-- Preformed beds up to 30 days prior to transplanting, must workPreformed beds up to 30 days prior to transplanting, must work beds beds

22-- Applied to shaped beds and tarped (approved in 2004)Applied to shaped beds and tarped (approved in 2004)

Field Research ObjectivesField Research Objectives

To develop a To develop a weed control strategyweed control strategy for for peppers with preemergence herbicides peppers with preemergence herbicides applied applied

-- At PLANTINGAt PLANTING

and/or and/or

-- At LAYBYAt LAYBY

that provide weed control throughout the that provide weed control throughout the growing season.growing season.

2004 2004 -- 20082008

CA Weed Control Trials in PeppersCA Weed Control Trials in Peppers

Field Trials Field Trials Central Coast Central Coast (Santa Clara and Monterey Counties)

San Joaquin Valley San Joaquin Valley (Fresno County)

Materials evaluated included:Materials evaluated included: Dual Magnum Dual Magnum (S-metolachlor)

Chateau Chateau (flumioxazin)

Goal Tender Goal Tender (oxyfluorfen)

Outlook Outlook (dimethenamid)

Prowl H2O

Devrinol Devrinol ((napropamidenapropamide)) oror DacthalDacthal (DCPA)(DCPA) Standards

Goal Tender Goal Tender ((DowAgroDowAgro Sciences)Sciences)

Goal Tender applied to Goal Tender applied to

shaped beds 30 days shaped beds 30 days

prior to transplanting.prior to transplanting.

Goal Tender less Goal Tender less

tendency to lift off the tendency to lift off the

soil and damage young soil and damage young

pepper plants.pepper plants.

Goal 2XL Goal TenderGoal 2XL Goal Tender

2 lb/gal 4 lb/gal2 lb/gal 4 lb/gal

RegisteredRegistered

Concerns with Goal Treated Beds Concerns with Goal Treated Beds

without Incorporationwithout Incorporation

Leaf crinklingLeaf crinkling

but can causebut can cause

necrotic spottingnecrotic spotting

and leaf deathand leaf death

as wellas well

Dual Magnum Dual Magnum ((SyngentaSyngenta))

When we started the current label was very When we started the current label was very restrictive and we are working with Syngenta restrictive and we are working with Syngenta to improve the wording and the allowed to improve the wording and the allowed usage (i.e. restricted to bell types and atusage (i.e. restricted to bell types and at--planting applications).planting applications).

It is registered for a 60 day PHI and, if we It is registered for a 60 day PHI and, if we could work out details on the wording of the could work out details on the wording of the label, it would be an important tool as a layby label, it would be an important tool as a layby application.application.

Dual Magnum Dual Magnum ((SyngentaSyngenta))

Now available is an INDEMNIFIED 24c label for Now available is an INDEMNIFIED 24c label for

Dual Magnum in peppers, onions, celery, and Dual Magnum in peppers, onions, celery, and

spinach.spinach.

Growers can only obtain this label by going to Growers can only obtain this label by going to

the the SyngentaSyngenta sponsored website and sponsored website and

registering as a user. registering as a user. httphttp://://farmassist.comfarmassist.com

This agreement affords This agreement affords SyngentaSyngenta protection protection

from unreasonable liability. from unreasonable liability.

Outlook Outlook (BASF)(BASF)

CurrentyCurrenty this product is not registered for use this product is not registered for use

in peppers. We are working with BASF to in peppers. We are working with BASF to

determine application method (over the top determine application method (over the top

versus directed spray), timing, and versus directed spray), timing, and

application rate. application rate.

We have noticed excellent weed control, but We have noticed excellent weed control, but

crop phytotoxicity may be a problem.crop phytotoxicity may be a problem.

Chateau, Chateau, BroadstarBroadstar ((flumioxazinflumioxazin)) ((ValentValent))

This product provided excellent weed control. This product provided excellent weed control. BUT Crop PHYTOTOXICITY is a PROBLEM.BUT Crop PHYTOTOXICITY is a PROBLEM.

We worked with We worked with ValentValent Corp. to determine Corp. to determine application method (spray versus granule), application method (spray versus granule), timing, and application rate for a couple of timing, and application rate for a couple of years.years.

We stopped testing it but then resumed last We stopped testing it but then resumed last year in conjunction with water repellent year in conjunction with water repellent adjuvantsadjuvants to increase selectivity. to increase selectivity.

Bell Pepper Herbicide Studies

Monterey

April 15

May 15

Baron

40 bed x 25

74 gal/A

June 16

Sprinkler to drip

Pacheco silt loam

Aug 19

Fresno

March 15

April 15

Jupiter or Indra

2(40) x 70

30 gal/A

May 30 mid June

Sprinkler to furrow

Panoche clay loam

Aug 1-15

Methods

Preplant Goal Tender:

Transplant Peppers:

Variety:

Plot size:

Water volume:

Layby herbicides:

Irrigation:

Soil type:

Harvest:

---------Untreated

7.00Dacthal 75W1.50Devrinol (standard)

7.00Dacthal 75W0.094Chateau - Broadstar

0.60Outlook 6.00.094Chateau - Broadstar

1.43Dual Magnum 7.620.094Chateau - Broadstar0.125 lb ai/A per 250 lbs

7.00Dacthal 75W0.60Outlook 6.0

0.60Outlook 6.00.60Outlook 6.0

1.43Dual Magnum 7.620.60Outlook 6.0

7.00Dacthal 75W0.50Goal Tender 4F1

0.60Outlook 6.00.50Goal Tender 4F1

1.43Dual Magnum 7.620.50Goal Tender 4F1

7.00Dacthal 75W1.43Dual Magnum 7.62

0.60Outlook 6.01.43Dual Magnum 7.62

1.43Dual Magnum 7.621.43Dual Magnum 7.62

Lbs a.i./ALayby ApplicationLbs a.i./A

Transplant Application

Plot size: Two 40-inch beds x 70 row

4 replications

2007

UNTREATED

2007

Weed control ratings (1-10 scale)

Crop phytotoxicity ratings (1-10 scale)

2007

Goal Tender Worked! Fresno June 1, 2005

Fresno - July 13, 2005

Goal TenderOutlook

Dual Magnum Goal TenderDual Magnum Goal Tender

OutlookOutlook

OutlookOutlook

DualDual

MagnumMagnum

Fresno: Outlook stunting persisted to harvest August 23, 2005

Fresno - Goal Tender & Dual Magnum

August 23, 2005

Weedy check

0.71.0----

Untreated - weedy

6.70.7----

Untreated - weeded

8.88.20.0947.00

FlumioxazinFb Dacthal

8.89.70.0940.60

FlumioxazinFb Outlook

9.07.70.0941.43

Flumioxazinimpregnated on fertilizer

Fb Dual Magnum

7.09.70.607.00

OutlookFb Dacthal

8.510.00.600.60

OutlookFb Outlook

8.310.00.601.43

Outlook 6.0Fb Dual Magnum

8.81.00.507.00

Goal Tender1

Fb Dacthal

9.31.50.500.60

Goal Tender1

Fb Outlook

8.71.30.501.43

Goal Tender 4F1

Fb Dual Magnum

9.710.01.437.00

Dual MagnumFb Dacthal

8.510.01.430.60

Dual MagnumFb Outlook

9.69.81.431.43

Dual Magnum 7.62Fb Dual Magnum

67DAT

24DAT

a.i./ AcreTreatments

Weed ControlWeed Control

RatingsRatings

31.520.9----

Untreated weedy

107.578.4----

Untreated weeded

89.065.30.0947.00

FlumioxazinFb Dacthal

112.379.40.0940.60

FlumioxazinFb Outlook

84.457.50.0941.43

Flumioxazinimpregnated on fertilizer

Fb Dual Magnum

31.921.00.607.00

OutlookFb Dacthal

66.241.80.600.60

OutlookFb Outlook

65.547.20.601.43

Outlook 6.0Fb Dual Magnum

89.166.00.507.00

Goal Tender1

Fb Dacthal

116.091.60.500.60

Goal Tender1

Fb Outlook

97.662.60.501.43

Goal Tender 4F1

Fb Dual Magnum

89.561.01.437.00

Dual MagnumFb Dacthal

103.571.31.430.60

Dual MagnumFb Outlook

112.277.61.431.43

Dual Magnum 7.62Fb Dual Magnum

Total FruitMarketable a.i./ATreatments

Yield of PeppersYield of Peppers

Lbs/plotLbs/plot

Peppers

never

recovered

2008 Fresno Pepper Trial2008 Fresno Pepper Trial

Pepper Variety - INDRA 10.5 inch spacing

lbs ai/A rate/A 6 plots lbs ai/A rate/A 6 plots

1 untreated 1 untreated

2 handweeded 2 handweeded

3 Dual Magnum 1.4 1.5 pt 43 ml 3 --------

4 Outlook Lo 0.5 10.7 oz 19 ml 4 --------

5 Outlook Hi 1.0 21.4 oz 38 ml 5 --------

6 Prowl H2O Lo 0.75 1.5 pt 45 ml 6 --------

7 Prowl H2O Hi 1.5 3.0 pt 90 ml 7 --------

8 Dacthal 7.0 9.3 lb 254 gr 8 --------

9 Dual Magnum 1.4 1.5 pt 43 ml 9 Dual Magnum 1.4 1.5 pt 43 ml

10 Dual Magnum 1.4 1.5 pt 43 ml 10 Outlook Lo 0.5 10.7 oz 19 ml

11 Dual Magnum 1.4 1.5 pt 43 ml 11 Outlook Hi 1.0 21.4 oz 38 ml

12 Dual Magnum 1.4 1.5 pt 43 ml 12 Prowl H2O Lo 0.75 1.5 pt 45 ml

13 Dual Magnum 1.4 1.5 pt 43 ml 13 Prowl H2O Hi 1.5 3.0 pt 90 ml

14 Dual Magnum 1.4 1.5 pt 43 ml 14 Dacthal 7.0 9.3 lb 254 gr

15 Outlook Lo 0.5 10.7 oz 19 ml 15 Outlook Lo 0.5 10.7 oz 19 ml

16 Outlook Hi 1.0 21.4 oz 38 ml 16 Outlook Lo 0.5 10.7 oz 19 ml

17 Outlook Lo 0.5 10.7 oz 19 ml 17 Outlook Hi 1.0 21.4 oz 38 ml

18Outlook Lo &

Prowl H2O Lo 0.5 & 0.75

10.7 oz &

1.5 pt

19 ml &

45 ml 18 --------

19Outlook Hi &

Prowl H2O Lo 1.0 & 0.75

21.4 oz &

1.5 pt

38 ml &

45 ml 19 --------

20Outlook Lo &

Prowl H2O Lo 0.5 & 0.75

10.7 oz &

1.5 pt

19 ml &

45 ml 20Outlook Lo &

Prowl H2O Lo 0.5 & 0.75

10.7 oz &

1.5 pt

19 ml &

45 ml

21Outlook Hi &

Prowl H2O Lo 1.0 & 0.75

21.4 oz &

1.5 pt

38 ml &

45 ml 21Outlook Hi &

Prowl H2O Lo 1.0 & 0.75

21.4 oz &

1.5 pt

38 ml &

45 ml

22 Outlook Lo 0.5 10.7 oz 19 ml 22 Dual Magnum 1.4 1.5 pt 43 ml

23 Outlook Hi 1.0 21.4 oz 38 ml 23 Dual Magnum 1.4 1.5 pt 43 ml

24 Outlook Lo 0.5 10.7 oz 19 ml 24 Dacthal 7.0 9.3 lb 254 gr

25 Outlook Hi 1.0 21.4 oz 38 ml 25 Dacthal 7.0 9.3 lb 254 gr

Layby application - Directed spray

2008 Bell Pepper X Preemergence HerbicidesApril 18 - At Planting application - applied post transplant, over the top

2008 Bell Pepper X Preemergence Herbicides

Transplanted April 18, 2008

Photo on June 3

June 19, 2008

July 10, 2008

August 4, 2008

August 4, 2008

OUTLOOK - Method of Application - 2008

At planting

OVER the topAt planting

DIRECTED Spray

Pre-Transplant

OVER the top

DevelopingDeveloping a Weed Control Strategy in a Weed Control Strategy in

Transplanted Bell Peppers Transplanted Bell Peppers

with Preemergence Herbicides for Californiawith Preemergence Herbicides for California

A work in progress ...A work in progress ...

AcknowledgementsAcknowledgementsCalifornia Pepper Improvement FoundationCalifornia Pepper Improvement Foundation

California Pepper CommissionCalifornia Pepper Commission

UC West Side Research & Extension CenterUC West Side Research & Extension Center

B and T Farms, GilroyB and T Farms, Gilroy

Thank youThank you