Rice Ipm Stout

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

Spectrum of activity: what pests do they control? 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

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

18% 39%

Tolerance is dependent on plant age… Zou et al., Crop Protect. 23: 543 (2004) 0 10 20 30 40 50 60 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 No. of immatures per core, 20 daf Standardized yield Flooded 28 d after seeding Flooded 42 d after seeding

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

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

Rice Ipm Stout

by Natalie Hummel

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