2017 Rice Insect Control Update - laca1.org...Insect pest management in 2017 •Prepare for the established pests-- Have a plan for managing rice water weevils-- Scout for rice stink

2017 Rice Insect Control Update

Michael Stout, LAES & LCES (interim)Marty Frey, RA, Rice Research Station

Lina BernaolaEmily Kraus

Maisarah SaadJames Villegas

Insect pests in rice: a time of transition?

Established pests

Over the past decade: Invasive pests

Insect pest management in 2017

• Prepare for the established pests

-- Have a plan for managing rice water weevils

-- Scout for rice stink bugs

• Be on the lookout for invasive pests

-- Look for symptoms of Mexican rice borer, South American rice miner, rice delphacid

--Pheromone traps for Mexican rice borer

Rice stink bugOrganophosphates

“old” threshold

OrganophosphatesPyrethroids

“old” threshold

Weeds

Scouting and thresholds• Begin scouting when rice is 50 to 75% heading

• 10 sweeps at 10 different areas

• Avoid hot hours

• First two weeks of heading: 3 bugs per 10 sweeps

• After first two weeks: 10 bugs per 10 sweeps

• Count nymphs as well as adults!

Re-evaluation of stink bug thresholds

• Small field plots of ‘Cheniere’

• Plots assigned to three treatments: no insecticide, high rate of Karate applied every 2-3 days; low rate of Karate applied every ~ 6 days

• At grain maturity, collect 15 panicles per plot

• Hand thresh, separate filled from empty grains

• De-hull filled grains, process to measure peck and broken grains

y = 0.2469x + 1.8628R² = 0.4483

0

2

4

6

8

10

12

0 5 10 15 20 25

Stink bugs per 10 sweeps

% p

eck

Stink bug density vs. % peck, 2015

Each bug: 0.25% peck

y = 0.2704x + 0.3067R² = 0.807

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 5 10 15

% p

eck

Stink bugs per 10 sweeps

Stink bug thresholds: bug density vs. % peck, 2016

Stink bug thresholds: bug density vs. empty grains

y = 0.5656x + 11.762R² = 0.6239

0

5

10

15

20

25

0 5 10 15

% E

mp

ty g

rain

s

Stink bugs per 10 sweeps

These density – damage relationships will allow us to calculate new

economic injury levels/thresholds

Rice Water Weevil Biology

14

Overwintering

Adult feeding

Mating & egg-laying

Root pruning

Flooding triggers

egg laying

Foliar insecticides Seed treatments

Pyrethroids Belay Dermacor CruiserMaxxNipsitInside

What insecticide should I use?

Justification:

If you have a history of rice water weevil or stem borer infestations, probably best to use

seed treatments

Cruisery = -34.03x + 2669.9

R² = 0.5132

Dermacory = -34.12x + 2655.3

R² = 0.9292200

2250

2300

2350

2400

2450

2500

2550

2600

2650

2700

0 2 4 6 8 10 12 14

Relationship between rice water weevil larval

density and rice yield

• Each weevil larva correlated with ~1% loss in yield

• Three larvae per core sample = ~$20 per acre

Plo

t yie

ld

Weevil density

Cruisery = -34.03x + 2669.9

R² = 0.5132

Dermacory = -34.12x + 2655.3

R² = 0.9292200

2250

2300

2350

2400

2450

2500

2550

2600

2650

2700

0 2 4 6 8 10 12 14

Relationship between rice water weevil larval

density and rice yield

• Each weevil larva correlated with ~1% loss in yield

• Three larvae per core sample = ~$20 per acre

Plo

t yie

ld

Weevil density

Threshold = 3 larvae per core sample = density of larvae at which treatment is

justified

0

25

50

75

100

2008 2009 2010 2011

Pe

rce

nt

exce

ed

ing

thre

sho

ld

Year

Proportion of untreated rice with weevil infestations that exceeded threshold, 2008-2011

Threshold = 3 larvae per core, ~$15-$20 loss per acreAverage weevil density = ~11 larvae per core sample

0

25

50

75

100

2008 2009 2010 2011

Pe

rce

nt

exce

ed

ing

thre

sho

ld

Year

Proportion of untreated rice with weevil infestations that exceeded threshold, 2008-2011

Threshold = 3 larvae per core, ~$15-$20 loss per acreAverage weevil density = ~11 larvae per core sample

The majority of rice fields in SW Louisiana will require treatment!

Spectra of activityCruiser/Nipsit Dermacor X-100

Pyrethroids very broad spectrum, Belay not as broad-spectrum

For early planted fields without a history of weevils or stem borers, may consider foliars (pyrethroids and Belay)

The question with foliars – when do I treat?

If you have a history of rice water weevil or stem borer infestations, probably best to use

seed treatments

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

0 2 4 6 8 10 12 14 16

We

evil

larv

ae p

er

core

sam

ple

Feeding Scars per plant

Can we predict larval densities by counting adult weevils or feeding scars?

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

0 2 4 6 8 10 12 14 16

We

evil

larv

ae p

er

core

sam

ple

Feeding Scars per plant

Can we predict larval densities by counting adult weevils or feeding scars?

Timing of foliar applications: if weevils are present (adults, scarring) and standing

water is present

But…over the past decade: Invasive pests

South American Rice Miner

• Will the SARM be a problem again in 2017?

--Cannot predict, previous widespread infestation was 2005

• Will seed treatments control SARM?

--Has not yet been tested, because insect does not show up consistently

• What else can be done about SARM?

--early planting, adequate seeding rates

Mexican rice borer now in all rice-producing parishes in Louisiana

Source: Blake Wilson

MRB Range Expansion

2008

2011

2013

2014

2015

2016

Not yet

detected

Calcasieu

Cameron

BeauregardAllen

Jeff.

Davis

Evangeline

Acadia

Vermilion

Laf.

St.

Landry

St.

Martin

Iberia

St.

Martin

St.

Mary

Iberville

WBR

EBR

Pointe

Coupee

Assump.

Stem borer management program

• Use Dermacor X-100 to control weevils and suppress stem borers

• Plant early to avoid severe infestations of borers

• Plow fields in fall/winter to eliminate overwintering habitat

• Use less susceptible varieties

• Scout and use pheromone traps; foliar insecticides if needed

• Silicon soil amendment may reduce borer densities

0.0

2.0

4.0

6.0

8.0

10.0

12.0

Ave

. no

. of

wh

ite

he

ad

Variety

2015

2016

Stem borer infestation (mean whitehead/variety) in Crowley, 2015-2016

Rice delphacid (planthopper) in Texas (2015)

Photo by Pat Porter Photo by Pat Porter

If you see “symptoms” of these invasive pests, contact your county

agent – we need to know how severe and prevalent these problems are

2016 Dermacor trial

• Wanted to test the effectiveness of Dermacorat several rates against rice water weevils and stem borers

• Small rice plots at H. Rouse Caffey Rice Research Station

• Rice water weevils-core samples

• Rice stem borers-infest cut stems in lab at two growth stages

• Lab analysis of chlorantraniliprole levels

0

5

10

15

20

25

30

0 0.25 0.5 0.75 1 2

Wee

vil l

arva

e p

er c

ore

Dermacor rates (relative to label rate)

P < 0.0001

A

B

B B

B B

Dermacor is very effective against rice water weevils…

0

0.5

1

0 0.25 0.5 0.75 1 2

Mo

rtal

ity

Rat

e

Dermacor Rate

SCB Mortality (Vegetative)

0

5

10

15

20

25

30

35

40

45

0 0.25 0.5 0.75 1 2

Mo

rtal

ioty

rate

Dermacor Rates

SCB Mortality: Reproductive

Dermacor also provides protection against stem borers

0

20

40

60

80

100

120

140

160

180

200

0 0.25 0.5 0.75 1 2

Ch

lora

ntr

anili

pro

le (

pp

b)

Dermacor Rates

Chlorantraniliprole Analysis

Reproductive

Vegetative

www.lsuagcenter.com/riceinsects

http://ricescout.lsuagcenter.com/

“Rice Insects Information” website & Rice Scout App

• Information on biology and management

• Pictures

• Links to videos

Mike Stoutmstout@agcenter.lsu.edu

Cell: (225) 892-2972Office: (225) 578-1837

Questions or feedback?