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Integrated pest management in the rice system

Incorporating new insecticides

Dr. Michael Stout, LSU AgCenter Department of Entomology

E-mail: mstout@agcenter.lsu.edu

11:15 to noon

Insect pests of rice

Early-season pests• Rice water weevil• Colaspis• South American rice

miner• Aphids/chinch bugs• Armyworms

Late-season pests• Rice stink bug• Stem borers

The “drivers” of pest management decisions in rice

Rice water weevil

Rice stink bug

Insect pests of rice

Early-season pests• Rice water weevil• Grape colaspis• South American rice

miner• Aphids/chinch bugs• Armyworms

Late-season pests• Rice stink bug• Stem borers

“Proactive”approach!

“Reactive”approach!

Adult overwintering

Larval feeding

Mating and oviposition

Adult feeding

Options for control of rice water weevils and other early-season pests

• Dermacor X-100 seed treatment• Cruiser Maxx seed treatment• Adulticidal pyrethroids: Karate, Mustang Max,

Prolex, etc.

The seed treatments cannot be used in water-seeded rice!!!!

Is the use of seed treatments in Louisiana justified?

• More expensive – up to $20 per acre• “Economic threshold” = density of weevil larvae

at which benefits > costs• Yield loss from weevils: 0.5% - 1% per larva• For drill-seeded rice, ~3-5 larvae per core sample• In Dr. Hummel’s demo trials, 2009: 11/12 fields

exceeded this threshold, 11 larvae per core average

• The presence of other sporadic pests further justification

Q: Which of the seed treatments should you choose?

Q: Which of the seed treatments should you choose?

A: it depends on which pests typically infest your fields

Spectrum of activity Cruiser Dermacor X-100

Dermacor X-100 Cruiser Maxx

X Rice water weevil X Rice water weevil

Colaspis X Colaspis

X Stem borers Stem borers

Sucking pests –chinch bugs, aphids

X Sucking pests –chinch bugs, aphids

X Other Leps – fall armwyorm

Other Leps – fall armwyorm

X South American Rice Miner

South American Rice Miner

Spectrum of activity: what pests do they control?

You might consider using Dermacor if…

• Field has a history of heavy weevil infestations or borer infestations

• You are nervous about lack of data on Cruiser at low seeding rates or lack of commercial data for weevil efficacy

You might consider using Cruiser Maxx if…

• You think you may have problems with colaspis

• You are worried about early-season diseases or early season sucking pests (chinch bugs & aphids)

What if you don’t use a seed treatment?

• Foliar (aerial) applications of pyrethroids the other choice

• Pyrethroids cheaper, can be used in water-seeded rice

• All of the pyrethroids are essentially equivalent• If any of the secondary/sporadic pests are

present in the field, pyrethroids will kill• Scouting is necessary

Pyrethroids act by killing adults, thereby preventing egg-laying

X

Timing of insecticide applications for weevil management

• Many adult weevils are present before flooding and additional weevils fly in after flooding

• Females lay eggs in standing water• Females prefer young rice plants for egg-laying

Therefore, most egg-laying occurs shortly after flooding!!!

Apply pyrethroids when adults / feeding scars are

present and fields are flooded

A second application may be needed

Regardless of your choice of insecticides…

Don’t put them in a position to fail!

Agronomic practices to minimize yield losses from weevils:

• Early planting (mid to late March?)• Avoid low seeding rates (e.g., 30 vs. 80)• Delay flood until rice is in mid-tillering (e.g, 42

vs 28 d after planting)• Keep water depth shallow (e.g., 2” vs. 6”)• Avoid high rates of N fertilization

Planting date

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Core samples: 26 days after flooding

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No insecticide+ Insecticide

2006 Experiment

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Flooded 42 d after seeding

Tolerance is dependent on plant age…

Zou et al., Crop Protect. 23: 543 (2004)

What about crawfish?

• All insecticides have wording on their labels prohibiting crawfish culture in rice fields in which the insecticides are used

• What about drift and run-off into ponds?• New insecticides are less acutely toxic to

crawfish than pyrethroids

The “drivers” of pest management decisions in rice

Rice water weevil

Rice stink bug

Rice Stink Bug Damage

Feeding on flowers (non-filled seedFeeding on flowers (non-filled seed))

Remove contents of developing Remove contents of developing kernels (partially-filled seed)kernels (partially-filled seed)

Pecky rice and broken kernelsPecky rice and broken kernels

Photograph by Boris Castro

Photograph by Boris Castro

Rice stink bug management

• Adults can move into fields rapidly after heading

• Adults are the primary damaging stage• Thresholds are important – mere presence of

stink bugs in a field should not trigger spraying• Scout with sweep net• What about natural enemies?

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• Treatments: methyl parathion, malathion (not

recommended), and pyrethroids

Sugarcane borer

Stem borer management

• Scouting begins at green ring, intensifies as early boot approaches

• Look for adults, egg masses, or feeding lesions• No thresholds yet, insecticides targeted at

adults• Pyrethroids• Dermacor has activity

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One Application (at panicle initiation)

Two Applications (one at panicle initiation + 7 days later)

UTC Icon 6.2FS0.035 lb ai/a

Intrepid 2F0.10 lb ai/a

Confirm 2F0.10 lb ai/a

Prolex0.016 lb ai/a

Mustang Max0.0165 lb ai/a

Karate-Z0.040 lb ai/a

Karate-Z0.030 lb ai/a

Mustang Max0.025 lb ai/a

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Management of Sugarcane Borer Infestations in RiceUsing Selected Rates of Insecticides, Louisiana 2004