Emerging pests of rice: Stem borers and apple snails Blake Wilson Field Crops Entomologist
LATMC Rice Breakout Session February 14, 2020
Rice stem borer complex
Sugarcane borer Mexican rice borer Rice stalk borer Diatraea saccharalis Eoreuma loftini Chilo plejadellus
Rice stem borer complex Lep.: Crambidae, Snout moths
Sugarcane borer Mexican rice borer Rice stalk borer Diatraea saccharalis Eoreuma loftini Chilo plejadellus
1 Non-crop grass hosts
Johnson grass Brome grass
Vasey grass Annual rye grass
Host preferences: Choice tests
1.0
Rice 0.8
0.6
Johnsongrass 0.4 Vasey grass
Sugarcane 0.2 Rye grass Brome MRB ovipositionpreference
0.0
Old Old Old Old
Young Young Young Young Young Young
Intermediate Intermediate Intermediate Intermediate Intermediate Intermediate
Beuzelin et al. (2011) ; Reay-Jones et al. (2007)
Host suitability
0.100
0.075
0.050
0.025 MRB LarvalMRB Survival
0.000
2 Rice stem borer complex
Stem Borer Management
• Begin scouting in late tillering • Pyrethroids can be applied with fungicides for sheath blight • Once white-heads are present, losses have already occurred Stem borer injury to leaf sheath
Stem borer injury in rice
White heads
3 MRB Range Expansion
Rapides Avoyelles Vernon
2008
Evangeline 2011 Beauregard Allen St. Pointe Landry Coupee EBR 2013 WBR
St. 2014 Jeff. Acadia Martin Calcasieu Iberville Davis Laf. Ascen. 2015
St. 2016 Iberia James Assump. Cameron St. Vermilion Martin 2017 St. Mary 2018
Terrebonne Not yet detected
High whitehead density
4 Average whitehead density at Crowley Station 2015-2019
6
5
4
3
2 Whiteheads/m2 1
0 2015 2016 2017 2018 2019
Cultural Control: Stubble Management
• Reduce overwintering habitat
Cultural Control: Stubble Management
18 20 cm 15
12 40 cm 9
6
No. stem borersNo. m2 / 3
0 E. loftini D. saccharalis
Data from Beuzelin et al. 2012
5 Cultural Control: Early planting
9 A A 8 A 2018 A 7 6 2019 5 4 B 3 B BC B B Whiteheads/m2 2 C B C 1 0
2018: F = 35.8, df = 3, 105; P < 0.001 2019: F = 33.8, df = 5, 105; P < 0.001
Varietal resistance
12 A 10 2018 A 8 2019 A
6 B 4 BC B BC BC Whiteheads/m2 B B 2 C B
0
2018: F = 35.8, df = 3, 105; P < 0.001 2019: F = 35.8, df = 5, 105; P < 0.001
Insecticidal Seed Treatments
6 Insecticidal seed treatments (ISTs)
–Dermacor X-100 (chlorantraniliprole) –Controls: RWW, armyworm, borers –Fortenza (cyantraniliprole) – Controls: RWW, Armyworm? Colsasipis? –Cruiser (thiamethoxam) –NipsIt Inside (clothianidin) –Controls: RWW, colaspis, aphids, – chinch bugs, thrips
Seed treatment trials 2019 –10 Treatments combinations –Early planted (March 22) and late (May 2) –Stand counts (not presented) –3 cores/plot taken at 4 and 5 weeks after permanent flood –Whiteheads and yield data
Seed Treatment Combination Trial 2019 35 30 Early planted A A 25 A Late Planted AA A 20 B B 15 B B RWW/Core 10 B B B B BC 5 C CC C C 0
Early: F = 39.5, df = 9, 27; P < 0.001 Late: F = 21.3, df = 9, 27; P < 0.001
7 Seed Treatment Combination Trial 2019
7 Early planted 6 Late planted 2 AA A 5 AB AB 4 AB 3 AB
2 B B B B
Whiteheads/m B 1 0
Early: F = 1.3, df = 9, 30; P = 0.287 Late: F = 21.3, df = 9, 27; P < 0.001
Seed Treatment Combination Trial 2019
11000 Early planted 10000 Late planted 9000 8000 A A AB 7000 A AA 6000 AB B B B 5000
Yield (lbs/acre) Yield 4000 3000
Early: F = 1.1, df = 9, 30; P = 0.392 Late: F = 21.3, df = 9, 27; P < 0.001
Relative yield loss 2019 –Unprotected (RWW and borers) –RWW only (Prevathon sprayed) –Borers only (Fortenza + Cruiser) –Protected (Dermacor X100)
–Early planted (March 29) and late (May 17)
8 Relative Yield Loss Trial 2019
30 A Early planted 25 Late planted A A 20 A 15
10 B B RWW larvae/coreRWW 5 B B 0 Protected Weevils only Borers only Unprotected
Means from 3 corers per plot at two sampling dates
Early: F = 57.8, df = 3, 12; P < 0.001 Late: F = 27.7, df = 3, 12; P < 0.001
Relative Yield Loss Trial 2019 12 Early planted 10 A Late planted A 8
6
4 A Whiteheads/m2 2 A B B B B 0 Protected Weevils only Borers only Unprotected
Early: F = 57.8, df = 3, 12; P < 0.001 Late: F = 27.7, df = 3, 12; P < 0.001
Relative Yield Loss Trial 2019
Early planted Late planted
8000 A A 7000 A 6000 B B B B B 5000
4000
3000
Yield (lbs/acre) Yield 2000 B 1000
0 Protected Weevils only Borers only Unprotected
Early: F = 15.4, df = 3, 12; P < 0.001 Late: F = 3.7, df = 3, 12; P < 0.044
9 Foliar insecticidal control - 2018 Applied 35 days after permanent flood 6 A 5 4
3 B 2 BC
Whiteheads/m2 1 C C 0
P < 0.001
Foliar insecticidal control - 2018
10 9 33 Days after flood A 8 A 7 22 Day after flood A A 6 5 4 3 2 B B B B Whiteheads/m2 B B 1 0
P < 0.001
Apple Snails Recorded high densities in rice and crawfish in Vermilion Parish
Impacts to rice likely minimal, research is on-going.
10 Apple Snails
Crawfish will be impacted
Apple Snail Distribution
*Estimated from detections in rice/crawfish farms
Slow the Spread
Mermentau and Vermilion rivers and tributaries are infested Check surface water irrigation sources for presence of snails
Source crawfish stock from uninfested areas
Egg masses can be transported on boats or other equipment
Report new infestations to AgCenter extension agents
11 Chemical Control
Copper Sulfate is Effective
2 ppm (≈8 lbs crystals/ acre-ft) in rice
Not safe for crawfish!
Crop Oil Reduces Egg Hatch
12 Questions? Blake Wilson [email protected] 985-373-6193
Call me or your extension agent with any questions.
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