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RICE FIELD DAY

Rice Weed Control K. Al-Khatib A.S. Godar W. Brim-DeForest S. Johnson

California Cooperative Rice Research Foundation, Inc.

United States Department of Agriculture

University of California

August 26, 2015

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Evaluation of Herbicide Programs for Water-Seeded Rice (Continuous Flood)

#

2

Herbicide program

iiM@IMII Granite GR _ Abolish + Regimpnt + UAN + NIS

Rate (per acret

15lb 1.5qt+0.53oz+ 2% +0.2%

Cerano GrantteGR

121b 151b

Abolish+ Regiment+ UAN + NIS I 1.5 qt+ 0.53 oz+ 2% + 0.2% ~no _121b

4 euii. .. :- 1.51b )Abolish + Regiment+ UAN .+ NIS :'.,' 1.5qt + 0.53 oz+ 2% + 0.2% •

5 I Bolero I 23 lb Regiment + UAN + NIS 0.8 oz + 2% + 0.2%

Boie;,;;: -- ; _ _ __ --,> · 23fb -6 I ,,G_i,i~}i\sc+SuperWham.+

0COC,. '.

15 I RiceEdge c..rano

16 I Shark-+1.ondax SUpe!Wham..: coc Cerano

17 I Shark + Halomax Supe!Wham + coc .GranttaGR + Shad<

1$ I Clincher_ Shark+ Supe!Wham +·COC

l!l C

a ?-~

Flooding

~ 01-June

Seeding ,~ , Rice varieg:

M20¥'(; @120 Ill/acre

231b 6 qt+ 1.25%

:-::12lb &qt+\.25%

151b 6qt+ 1.25%

10 lb+ 1.25%

101b+1.25%

121b 7.5 oz+ 1_.66oz

&qt+ t.25% 12 lb

7.5 oz+ 1.33 oz 6qt+1.25%

151b+ 7.5oz 13oz

4oz_+ &qt+ 1.25%

~

1 lsr 1 Til

005', HU

21sr 1 Til

230AS

41DAS

DOS 4 lsr 2Til

DOS 4 lsr

2Til

_4 lsr 1Til '2Til

Granular applic~tion Foliar application

a Al>. See table See table

(left) (left)

Weed Control (% of untreated control; values for untreated control represent % cover by the respective weed species)

~ ~ € .. .. .. : f 2 0, 'lit' f ~--1-: i ; i .. ~, 1 ~ '~'. Et g ~ ·a:,:,: u>,, a

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.9 EE :I:"' '·O'. ,ca, ,3 I ix: .Cll:> 0" i:i-. IX'. - - 20DAS - !I 40DAS 11 SODAS ~ •1••1•1•1••1•1•1•1•1••••1•1•1

90 I 77 I 74 I 66 10011001100 [ 100 89 ll100l100[ 10l> 100! 100

94 I 79 I 74 I 98 1001100 I 100 1100 1001110011001 95 1001100

97 j 100 l 100 I 100 100[..100,-11001100- 10011100 11_001100 I . -. -95-1100,

99 1100 1100 I 95 10019311001100 10011100 I 83 1100 24 1100

99 1.100 1100 I 99 10011001190'1100 100 I Hoo J 100 J 109 1001100

74 1100 1100 I 99 1001100 1100 1100 1001110011001100 1001100

97;;1100 j 1Qq 1 ~6 I\ 1ooj 100[ 1001100J}\jt19ci!l100J 1oot 100 iiiQ[ 100 86 1100 1100 1100 • - 1001100 I 100 1100 I - I 100111001100 I 100 I - I 1001100

El1 1ga 100 I 93 1100 I 95 1001 90 11001100 10011100 I 82 I 100 85 I 100

90 1 '1{110 68 (;-_;. 1001 51 63 [ 100 100 ll 100 ! 85 so I ::!J:1121100 99 I 83 I 81 I 76 1001100 1100 1100 46 II 100l 100l 100 1001 95

96 1100 1100- 10011 96 ! 1001100 92 I 90

81 I 93 I 91 70 1100

94 I 34 45·1, 76- 100110011001100 - I 1ooll 100 I 100;f100 100! 100

93 I 69 I 74 I 88 10011001100 1100 I - I 10011100 1100 I 100 1001100

96J100 I 68 I 78 1001100110011001 ~ 110011100110011001-:' 1-001100

Weed stage/size

Timing Date 2 4 6

Seeding 03-June X X " .x DOS 04-June

,l'lsr 10-June 1-21 g 21c· x · 2 lsr 14-June 2.5-31 4.5 I 1" 3-41

31_sr_ 16·June 31 2-31 1-2·· : 3-4!' 4 lsr 19-June 41 3-5 I 2-31 >31 21 g

51sr 25-June SJ 5-.71 2-4" >21 · 2-41

23DAS 26-June 5-61 51 3-4' 2-31 3-41

lTil 01-July 1-2Til 2-3Til >S",c... >2-41- 5-61

2Til 06-July 2-3Til 3Til >10" >61 6-81 410AS 14-July 20-25" >18" f ',\?8,1 >81

Crop Response (0 to 100 scale; evaluated two weeks after application)

1''_applicatioQ

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2"" application

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01)J.-010 6_ 0 2' 0 6 I 1 5

Temperature (0 F) Wind speed RH water depth

Water Air (mph) (%) Onches)

surface ... 86 90 4

-.:~3 __ 87 4 69 76 4

~11,· . 82 4 n s2

# Herbicide program Rate (per acre) Timing

11+;;;;;.;;;;;.11 4• i .Butte 7.Sil>" I' 1 lsr 5 I Butte 91b 6 , Butte,' -;,. i ):it:-'.. I.Sib

l,_Grandsl_._.: a ___ n __ cl ____ + ___ S\ll)e!Wham_+COC'. ·f 60Z+6q!+1.25% ............ -·····················---

Butte Granite SC + coc

n .esa112 1!!'l&•e.2

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Crop Response (O 10 100 scale; two weeks after applica1ion)

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I 1" application Ir 2"'ap~(lia\ion I 0 0 0 0

0 1 .o l:3

0 0 L 0 ·1 o.

0 2 2 0

q~TtJ:&91 010 If o,;f 0.1 o I o 0 0 0

Tempera1ure ('F) Wind speed RH water depth

Weed stage/size (mph) (%) (inches) Wa1er Air

Timing Da1e 1 2 3 4 5 6 surface

Seeding OJ.June X X X X J, ,' x', ,X ~- - - - 4 1 lsr 10-June - 1-21 g 21 X X 83 87 -- - 4 1111 01.July 1..ZTII 1-3Ttl 5-61' f ·>61 ¥T 82 ....... 89 1 3fi 2-3"

Abbreviations: lsr = leaf stage of rice, Til = tiller of rice * I = leaf stage; f = flowering; g = germinating, x = not present; - = not recorded

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g

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Flooding

'l,

Ol·June

Evaluation of A New Rice Herbicide (Strada®) [Continuous Flood]

# Herbicide program Rate (per acre) Timing

IIIIIF.lififflillll 21 eerano 1011> DOS

SUpeM/l;,am_ + CCC I c 6 qt+ 1.25% 33DAS

31 Cerano 101b DOS Supel'Wham + Strada + COC 6qt+2.1oz+1.25% 330AS

C Ceratib /', C / 101b 005 4 j Sharf :El ~ ... .. e> il ~ ... ~ ii ~ ·c I! ]l .. 3! 0 .. ... _g 1ii ai g 1ii ~I ;, I t·i ~ ;, i I g $ C ! ~ .3 EE ::, 0 EE 0 "' fl):, a ::; .J "' Cl):, 0 ::;

20DA$ SODAS

• • Ill • II • .. • • • 90 ·o 0 71 - 98 98 100 - :75-92 0 0 74 - 100 98 100 - 92

oo I D'· i> 77 - ,1_00 · .. JlS.·· 85 - so'

Weed stage/size

Timing Date 1 2 3 4 5

Seeding 03-June X X X X X DOS 04-June X X X X X

33DAS 08-July 21il 1-3Til · 2-3Td 2•3Td .. >61

Crop Response (0 to 100 scale; two weeks after application)

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182 application 2"'appfti,alion

0 0 0 0 0 0 0

14 18 5 0 0 0 0

15 11 1 0 0 2 0

12 13 ·?3 91: 0 a ;;.o

Temperature (°F) Wind speed RH

Water Air (mph) (%)

surface

- - -86 90 - --75 80 3.5 5-3

Seeding Granular application Foliar application Abbreviations: DOS = day of seeding lie; DAS, days aft.er seeding rice;Til = tiller of rice ,~ • A • 1 = leaf stage; f = flowering; g = germinating, x = not present , Rice var,,: See table See table M20 (left) (left)

@120 lb/acre

j

0

2

9

6

Water depth (inches)

4

4 3-4

•

Evaluation of Herbicide Programs for Water-Seeded Rice

[Pinpoint Flood]

# I Herbicide program

''*'*'' 2 I RiceEdge 3 I RiceEdge

4 ;:,:,•(·t Granilef!f: ;··

Rate (per acre)

10.lb

101b

1'3 oz :+-2. oi ,. , ,'..

Weed Control (% of untreated controQ

(values for untreated control represent % cover by the respective weed species)

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40DAS SODAS. ·,, · .... ,·.,.' - •••• ss I - l 94 1100 I - I - I - 94 0 100 80 - 0 80 64140198192 - 0 97

1001 - Hbo )00 100 100 100

98 - 99 100 60 97 0 100 100 - 0 100 100 - 98 100 ;:w: 100 .96 - .:.Ci' · 97 99 - 93 100 100 - - 100 90 100 78 0 77 - lfllltaa 100 991991100 100 I 66 I 96 I 79 o I 77

100 1001100 I 80 95190198199 o I 97

weed s1age/size

Timing Date 1 2 3 4 5 6

Seeding 03-Jtlne X X X X X X

31sr 18-June 2-2.51 - 3-41 1-2" 2-31 X 4lsr 20,Jllne 3-41 - 4-51 2-3" 4-51 2-31 · 5 lsr 24-June 41 2-31 51 3-4" «l I 2-41

23DAS 26;-June 5-61 3-41 5-61 4-o" J 4-51 1 Til 01-July 1-2Til 1-2Til 1-2Til 5-61 f >61

. 41DAS 14-July 20" 3-4Td f 18" I >BJ

Abbreviations: DAS, days after seeding rice; lsr = leaf stage of rice, Til = tiller of rice * I = leaf stage; f = flowering; g = germinating, x = not present; -· = not recorded

Crop Response (0 to 100 scale; evaluated two weeks after application)

cc cc 6 'ff 0 g g :, ·2' 2, 2, "' :, "' .,, :, ~ ''o, .,, " O),' ¥ C :s C g, I!! c I!! :ii, !, l-' -g :;; i 'E ~ :;; ii ~ " :;; ,:. 5 '" C a 5 &! ~ m 5 j! ~ bi ~ i a; ID

··1,". application 2"' application 3"' application

0 0 0 0 0 0 0

0 o .. ,co, \i 0 0 0 2

0. 0 0 s 11;:f o 0 a· 0 5 0 o··

~,~1 7 1~1::1 0 5 0 2 II o I 2 4

O:! 9 0 0 11:0 f O 1 0 O.fl .0 J' Q O I .!I. 0 4 I o 4 0 0 o I 4

0 ol, ·\> 0. 0 1 .I 2

Temperature rfl Wind speed RH Water depth Water Air

(mph) (%) (inches)

7 surface

X - -- - - 4 - 74 4 51 0 - - 65 3 44 0 g 79 BO 1 49 3

g .: 87; .95 3.8 39 3.5

4-51 82 89 1 35 3

11-101 75 79 3.1 48 3

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(

RJ E Wednesday, August 26, 2015

Dealing with the Drought

California Cooperative Rice Research Foundation, Inc. University of California

United States Department of Agriculture Cooperating

Rice Experiment Station , P.O. Box 306, Biggs, CA 95917-0306

Rice Weed Control: Herbicide Programs, New Chemicals, and Weed Management (K. Al-Khatib, A.S. Godar, W. Brim-DeForest, J.R. Stogsdill, R. Pedroso, M.F. Galla, B.A. Linquist, L. Espino and R.G. Mutters, UCD and UCCE)

The UC Rice Weed Research Program at the Hamilton road site at the Rice Experiment Station, Biggs, CA includes the performance testing of herbicides, and their mixtures and sequential combinations for the common rice growing systems in California (continuous flood, pinpoint flood, and drill-seeded rice systems). We have also continued testing new products primarily aimed at assisting the rice industry in the registration of new herbicides as options become available. Our efforts seek to assist California rice growers in achieving economic and timely broad-spectrum weed control, preventing and managing issues of evolved herbicide-resistant weeds, and complying with personal and environmental safety requirements.

Here we highlight results from our 2015 field operation for the major rice growing systems used in California. Herbicide program efficacy comments presented here primarily reflect the average visual ratings of four replicates for major weed species approximately 40 days after seeding (DAS) of rice which covers the critical period of competition (30 days). Crop response (stand reduction, stunting and other injury to rice) has also been highlighted wherever relevant.

Continuously-Flooded Rice This system promotes suppression of certain weeds such as barnyardgrass and sprangletop. These two weeds would otherwise be dominant in dry-seeded systems. After seeding rice into a flooded field, a water depth of 4 inches is maintained throughout the season. When late post-emergence foliar applications are needed, water depth is lowered to expose about two-thirds of weed foliage to the herbicide spray, but fields are never completely drained. This year, watergrass (early and late) were the predominant weeds, followed by ducksalad, ricefield bulrush, smallflower umbrella sedge, redstem and sprangletop. All weeds evaluated in our program are susceptible to rice herbicides registered in California, but we discuss and give weed management options for fields with population(s) of resistant weed species.

For this system, several granular into-the-water herbicide products are available for controlling weeds in rice including Bolero, Cerano, Granite, Halomax, Londax, and Shark H20. These herbicides can be

applied early to provide good to excellent control of labelled (target) weeds. As they vary in their target weeds (spectrum of weed control), it is useful to combine two of these herbicides in a program to offer broad spectrum weed control.

POST-applied (foliar) herbicides are often necessary to achieve excellent weed control in rice. The follow-up POST application of herbicides not only extend spectrum of weed control, but also may. help delay and/or manage herbicide-resistant weeds through overlapping activity on the same target weed species. Thus, the choice of POST-applied herbicides is primarily dictated by composition of weed species and the presence or absence of resistant weeds. The rice herbicide options for the foliar application include Abolish, Clincher, Granite SC, Regiment, RiceEdge, Shark H20, SuperWham or Stam, Halomax and Londax.

All Bolero-based programs, with Bolero applied at the 1 leaf stage of rice Osr) offered excellent control (100%) of watergrass, sprangletop and smallflower umbrella sedge. Inclusion of SuperWham at 6 qt/A + 1.25% v/v Crop Oil Concentrate (COC) at 1-tiller stage or Regiment (0.8 oz/A + 2% v/v UAN + 0.2% v/v NIS at 4 lsr) in this program improved (>90%) control of ducksalad; however, neither of these two programs provided more than 85% control of ricefield bulrush. A tank-mix of Granite SC (2 oz/A) and SuperWham (6 qt/A + 1.25% v/v COC) applied at 4 lsr maximized (100% control) the control of ricefield bulrush. Although Bolero-based programs offer excellent control of grasses and ALS- and propanil-resistant smallflower umbrella sedge, a substantial level of stand reduction of rice is observed.

Cerano applied at the day of seeding (DOS) provided good control of watergrass and sprangletop (>90% control) 20 days after seeding (DAS). A foliar application of SuperWham (6 qt/A + 1.25% v/v COC) at 1-tiller stage following Cerano was exceptionally effective in controlling watergrass (100% control), however, the control of ricefield bulrush and smallflower umbrella sedge was poor (99%) control of all

weeds including ducksalad within a week after treatment. With two follow-up applications of Shark H20 (4 oz/A) at 4 lsr and Abolish + Regiment (1.5 qt/A+ 0.53 oz/A + 2 % v/v UAN + 0.2% v/v NIS) at 5 lsr the overall efficacy of this program was excellent (100% control of all weeds). Addition of Shark H20 to the weed management program offers improved efficacy including control of ALS-inhibitor- and/or propanil-resistant sedges; whereas the tank- mix application of Regiment + Abolish provokes synergism on watergrass control and also helps in controlling multiple herbicide-resistant watergrass. This program offers an excellent 'reactive' as well as 'preventive' herbicide-resistant weed management in rice.

A single application of three-way tank-mix of Clincher (13 oz/A), Granite SC, (2 oz/A), Abolish, (1.5 qt/A) with 2.5% v/v COC applied at 2-3 lsr provided 100% control of watergrass and sprangletop, and an excellent control of ducksalad, ricefield bulrush, smallflower umbrella sedge. This program will not control certain ALS-inhibitor-resistant ricefield bulrush and thiobencarb-resistant watergrass populations; however, it is a good alternative for fields with ACCase-resistant (Clincher-resistant) sprangletop populations. Similar results were obtained when Regiment (0.67oz/A + 2% v/v UAN + 0.2% v/v NIS) or Granite SC (2 oz/A + 2.5% v/v COC) were applied at 3-4 lsr followed by tank mix of SuperWham + Clincher (6 qt/A + 13 oz /A + 2.5% v/v COC) at I-tiller stage.

An excellent control of watergrass, sprangletop and ricefield bulrush, and smallflower umbrella sedge (>98%) were achieved by Clincher (13 oz/A + 2.5% v/v COC) alone at 3-4 lsr followed by a tank mix of SuperWham + Grandstand (6 qt/A+ 8 oz/A+ 1.25% v/v COC) at 1 t-tiller stage or Abolish+ SuperWham (1.5 qt/A+ 6 qt/A 1.25% v/v COC) at 3-4 lsr followed by Granite SC (2.8 oz/A+ 2.5% v/v COC) alone at 1-tiller stage. Grandstand effectively controls ricefield bulrush and redstem, and it is particularly useful when the field has herbicide-resistant populations of these weeds. Abolish is a better choice than Grandstand when ducksalad is predominant in the field.

Drill-Seeded Rice Typically a period of three to four weeks elapses between the first flush and permanent flooding in drill-seeded rice system. This period offers flexibility for herbicide use when proximity to sensitive c:i.rops imposes restrictions to aerial applications. During this period weeds adapted to dryland seedbeds such as barnyardgrass, sprangletop, watergrass and smallflower umbrella sedge become established, whereas aquatic weeds such as ricefield bulrush, ducksalad, and redstem are less favored or eliminated. Thus, this system when alternated with the water-seeded system may be useful for reducing

aquatic weed pressure in water-seeded system, and vice versa. Weeds present in this system were the Eckinochloa complex (early and late watergrass, and barnyardgrass), and smallflower umbrella sedge and sprangletop.

Abolish and Prowl are valuable residual herbicides which provide early weed control up to the start of permanent flood. Both herbicides suppress watergrass and barnyardgrass; however Abolish is more active on smallflower umbrella sedge than Prowl. Regular flushing before permanent flood activates these herbicides and also helps in the establishment of rice. For a delayed pre-emergence application (DPRE) of these herbicides, the rice seed is first drilled into dry soil, the field is then flushed once and then an herbicide is applied onto a moist soil surface. As these pre-emergent herbicides do not provide complete control of weeds, one or two foliar applications of herbicides/herbicide mixtures on emerged weeds are necessary.

The DPRE application of Prowl (2 pt/A) provided 62% control of Echinochloa species and 31% control of smallflower umbrella sedge. Abolish (1.5 qt/A) was less effective on Echinochloa species (43% control) than Prowl; however it was exceptionally effective in controlling smallflower umbrella sedge (99 to 100% control).

All the foliar applications (described later) that followed DPRE application of Prowl provided excellent control of smallflower umbrella sedge (98 to 100% control), thus, providing flexibility in the herbicide program for controlling herbicide-resistant biotypes of this weed.

A foliar application of SuperWham (6 qt/A 2% v/v COC) alone following the DPRE Abolish or Prowl application improved control of Echinochloa species (85 to 90%) compared to its control by DPRE applications alone; however, the control was still not adequate. The DPRE application followed by a tank-mix of Abolish+ Regiment (1.5 qt/A + 0.53 oz/A + 2.0% v/v UAN + 0.2% v/v NIS) at 5 lsr greatly improved Echinochloa control (>97 %). Two foliar applications of Prowl+ SuperWham + Clincher (2 pt/A+ 4 qt/A+ 13 oz/A+ 2.5% v/v COC) at 3 lsr and Shark H20 (4 oz/A) at 4 lsr following the DPRE application provided excellent control (98 to 100%) of Echinochloa species. In this program, the second application of Prowl suppresses Echinochloa emergence for extended period whereas the tank-mix application of SuperWham and Clincher provide overlapping efficacy on emerged barnyardgrass and watergrass. Shark H20 supplements SuperWham for controlling smallflower umbrella sedge (including propanil-resistant biotypes). This is an intensive program for controlling Echinochloa and sedges, thus, it is particularly suitable

for controlling herbicide-resistant populations of grasses and sedges. Similar levels of weed control may be achieved without Shark H20 when Abolish is used as a DPRE application, and Echinochloa and smallflower umbrella sedge are susceptible. Use of Abolish and Prowl in alternate years will add to delaying evolution of resistant Echinochloa species.

New Weed Management Products

RiceEdge® RiceEdge® is a dry flowable mixture of propanil and halosulfuron product delivered by RiceCo, LLC, CA. The herbicide was tested under a continuous flood and a pinpoint flood (drained for one week at the 3-4 lsr). In both trials, it was applied at the highest label rate of 10 lb/A with 1.25% v/v COC at 20 DAS. RiceEdge® provided excellent control (>95%) of watergrass, ricefield bulrush, and smallflower umbrella sedge in both systems. Ducksalad control was often poor (98%) of all weeds including watergrass, ricefield bulrush, smallflower umbrella sedge, ducksalad, and monochoria. These applications provided a broad spectrum of weed control and offered an exceptional level of crop safety. A follow-up application (at I-tiller stage) of SuperWhani + Grandstand (6 pt/A + 6 oz/A + 1.25% v/v COC), Granite SC (2.8 oz/A + 1.25% v/v COC), or Regiment (0.67 oz/A + 2.0% v/v VAN + 0.2% v/v NIS) provided exceptional control (100% control of all weeds including redstem 40 DAS). While stand-alone application of Butte® offers excellent weed control in water-seeded rice, a follow-up application ·or an inclusion of a partner granular herbicide (for example Cerano) will maximize the spectrum of weed control.

Strada® Strada® is a granular formulation of orthosulfamuron (an ALS-inhibiting herbicide) developed by Nichino America. Efficacy of Strada® was tested under a continuous flood in a Cerano-based program in a tank mix with SuperWham or Shark H20 applied at 35

days after seeding (approximately at 2-tiller stage of rice). Cerano (10 lb/A at DOS) followed by a tank. mix of Strada (2.1 oz/A) with SuperWham (6 qt/A+ 1% v/v COC) or Shark H20 (4 oz/A+ 0.25% v/v NIS) provided a very good control of watergrass (>95%) and a fair control of ricefield bulrush (>80%). Smallflower umbrella sedge control was much better (>95%) with the program containing SuperWham than that containing Shark H20 (

Herbicides used and their active ingredient Herbicide % ai lb ai/gal

Abolish SEC (thiobencarb) Bolero Ultramax (thiobencarb) Butte (benzobicyclon + halosulfuron) Cerano 5 MEG (clomazone) Clincher CA (cyhalofop-butyl) Grandstand (triclopyr) Granite GR (penoxsulam) Granite SC (penoxsulam) Halomax 75 (halosulfuron) Londax (bensulfuron-methyl) Prowl H20 (pendimethalin) Regiment (bispyribac-sodium) RiceEdge (propanil + halosulfuron) Sandea (halosulfuron) Shark H20 (carfentrazone) Strada CA (orthosulfamuron) SuperWham! CA (propanil)

84 8.0 15 NA 3+0.64 NA 5 NA 29.6 2.4 44.4 3.0 0.24 NA 24 2.0 75 NA 60 NA 42.6 3.8 80 NA 60+0.64 NA 75 NA 40 NA 50 NA 41.2 4.0

Kassim Al-Khatib, Professor, Department of Plant Sciences, UCD; Amar S. Godar, SRA III, UCD; Whitney Brim-DeForest, PhD Student, UCD; J. Ray Stogsdill, SRA II, UCD; Rafael Pedroso, PhD Student, UCD; Mariano F. Galla, PhD Student, UCD; Bruce A. Linquist, Cooperative Extension Specialist, UCCE; Luis Espino, Farm Advisor, Colusa-Glenn-Yolo Co., UCCE; R.G. Mutters, Farm Advisor, Butte Co., UCCE