Onion thrips management in Wisconsin

Onion Thrips Management
in Wisconsin: 2007
Wisconsin Muck Farmers Association:
Annual Meeting
March 8, 2008
Russell L. Groves
Scott A. Chapman
Department of Entomology
University of Wisconsin
1630 Linden Drive
Madison, WI 53706

Target Pests in 2007: Seed Maggot
Onion Maggot
Delia antiqua
Seed corn Maggot
Delia platura
Maggot Damage

Seed maggot: Management
Cultural
‣Speed up germination:
Early season row cover
pre-sprout, mulch, warm soil
‣Avoid green manure
‣Fly-free periods
Biological
‣Predacious soil beetles
‣Fungal epidemics
Entomophthoraceae
Chemical
‣In-furrow, insecticides (Lorsban)
‣Commercial seed treatments (Poncho)

Next major onion pest:
Onion thrips
larva
Onion Thrips Damage
adult
Onion Thrips,
Thrips tabaci Lindeman
‘silvering’

Onion thrips development and damage
egg
pre-pupapupa
adult
1 st
larvae
2 nd
pupa
Development Stages
• Rasping mouthparts puncture plant surfaces.
• Egg-laying also damages plants.
• Injury appears in streaks rather than spots ‘silvering’.
• Virus vectors (TSWV, INSV, IYSV)
Thrips Damage

Onion thrips: Management
Cultural
Leptothrips
‣ Crop rotation
‣ Overhead irrigation
‣ Sanitation (culls & field borders)
Biological
‣ Predacious thrips
‣ Minute pirate bugs
Chemical
‣ Foliar sprays
‣ Commercial seed treatments
Minute pirate bug

Research Outline: 2007
I. Investigate the potential of insecticide seed treatments
to reduce onion thrips and onion maggot infestations.
II. Evaluate select cultural control practices to delay onion
thrips infestations using wheat straw mulches.
III. Document and evaluate candidate insecticides for the control of onion
thrips and investigate the potential for reduced-risk risk compounds to expand
current labels.
IV. Refine the use patterns of current registrations to improve long-term
control of onion thrips populations.

I. Insecticide Seed Treatments:
Early Season Onion Thrips Control
Treatments
‣ Trigard
‣ Lorsban 15G
‣ Entrust
‣ Poncho 600
‣ Mundial 500
Seed Dynamics
Incotec
Nondestructively sampled
3, weekly sample dates:
‣ 15, 22, & 29 June

I. 2007 Insecticide Seed Treatment
Evaluations 1,2
Product Active Ingredient Rate (amnt/unit)
Trigard cyromazine 5.0 g [a.i.] / 100 g
Lorsban 15G chlorpyrifos 476 g [a.i.] / 1,000
Entrust spinosad 0.3 mg [a.i.] / seed
Mundial 500 fipronil 2.5 g [a.i.] / 100
Poncho 600 clothianadin 0.2 mg [a.i.] / seed
UTC -- --
Note: Products highlighted in yellow were labeled on onion in WI in 2007
1
Experiment arranged as RCBD with 5 replicates.
2
Experimental seed treatments supplied by Seed Dynamics (Salinas, CA) and
Incotec (Salinas, CA).
Note: All have been or are currently in review with IR-4 as seed treatments.

Mean larvae / plant
I. Onion Thrips ‘Suppression’ Using
Insecticide Seed Treatments
12
UTC
Lorsban 15G
Entrust
9
Trigard
Poncho 600
Mundial 500
Action threshold = 5 larvae / plant
6
3
0
7 June 22 June
6 July

Mean adult thrips / trap
I. Early Season, Onion Thrips Ecology
2500
‣ Colonize onion in late June to July
‣ Four to six generations per season
2000
1500
1000
500
Thrips Suppression
Interval
0
145 159 176 189 206 220 237 251 268
May
June
July
August
Sept
Date

I. Onion Thrips Suppression Summary:
Seed Treatments
‣ Immature onion thrips populations did not exceed
established thresholds
‣ Trigard and Lorsban 15G failed to provide thrips
suppression compared with UTC
‣ Thrips suppression extended over 2 out of 3
successive weeks (Entrust, Mundial).
‣ Suppression level was insufficient to maintain
populations below damaging levels

II. Cultural Practices to Slow / Lower
Early Season Thrips Colonization
A.) Straw Mulches:
Erosion Control Blanket (Straw and Coconut raw
material)
adult thrips
Yellow sticky cards

Mean adult thrips / trap
I. Early Season: Thrips Colonization
A.) Measuring Colonization (thrips colonization):
350
300
250
200
Thrips Suppression
Interval
F=3.92, df = 7, 15, P=0.0763
150
100
50
0
138 145 152 159 166 176 183 189
May
June
July
Date

Mean adult thrips / trap
I. Cultural Practices to Slow / Lower
Early Season Thrips Colonization
A.) Measuring Colonization (thrips colonization):
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
138
145
May
Thrips Suppression
Interval
152
159
166
176
June
183
189
196
July
206
213
220
227
August
237
244
251
259
Sept
268
Date

II. Foliar-Applied Insecticides
2007 Product Evaluations
Product Active Ingredient Rate (amnt/acre)
Warrior lambda-cyhalothrin 1.9 and 3.8 fl oz
Mana - Silencer lambda-cyhalothrin 1.9 and 3.8 fl oz
Lannate LV methomyl 48 fl oz
SpinTor 2SC spinosad 4 and 6 fl oz
*Radiant SC spinetoram 5 and 7 fl oz
**Carzol SP formetanate hydrocloride 0.75, 1 and 1.5 lbs
Movento spirotetramat 5 and 8 fl oz
Agri-Mek 0.15EC abamectin 8 and 10 fl oz
Note: Products highlighted in yellow were labeled on onion in WI in
2007;
*Radiant received a Section 3c label use in November, 2007.
**Carzol was permitted for use in WI under a Section 18, 2007.

II. Reduced Risk Foliar Options
New Registration 2007
Radiant ® SC (spinetoram)
Macrocyclic lactone (spinosad: MoA group 5)
- Use rate 4.5 - 6 oz a.i./a (CPB)
- Control of onion thrips
10-14 14 days persistence (photostability)
Very low impact on beneficials
Low mammalian toxicity

II. Reduced Risk Foliar Options
New Registrations 2009
Movento ® (spirotetramat):
‣ Tetramic acid class (MoA Group 23)
• Use rate 5 – 7 fl oz (Thysanoptera)
• Fully systemic movement (2 directions)
‣ 10 - 14 days persistence
‣ Very low impact on beneficials
‣ Very low mammalian toxicity
‣ IR-4, Review

II. Reduced Risk Foliar Options
New Registrations 2009-10
Agri-Mek
® 0.15 EC (abamectin):
‣ Chlorine channel activators (MoA Group 6)
• Use rate 8 – 16 fl oz (Thysanoptera)
‣ 7-10 days persistence
‣ Very low impact on beneficials
‣ Very low mammalian toxicity
‣ IR-4 In-Review: ‘On-Hold’ (2009-2010) 2010)

Mean number of larvae/plant
II. Foliar-Applied Insecticides for Onion Thrips
Control: 3 dat
16
14
12
10
c
WI Registration
Section 18
Non-registered
Note: Plot sprayed on 7/18 @ 3 dat
threshold of 1 thrips/leaf.
P=0.0245
8
6
4
2
0
UTC
Warrior 1.92
Action threshold = 7.0 thrips / plant
bc
bc
bc
c
c
c
bc
Warrior 3.84
Silencer 1.92
Silencer 3.84
Lannate
SpinTor 6.0
SpinTor 8.0
Radiant 5.0
c
c
bc
b
Radiant 7.0
Carzol (0.5)
Carzol (0.75)
Carzol (1.0)
Movento (8.0)
Movento (12.0)
c
bc
bc
c
Agi-Mek 8.0
Agri-Mek 10.0)
c
Treatment

Mean number of larvae/plant
II. Foliar-Applied Insecticides for Onion Thrips
Control: 14 dat
60
50
40
a
WI Registration
Section 18
Non-registered
Note: Plot sprayed on 7/18 and 7/24.
P

Examples of Suggested Sequences
(Note: IF Carzol receives Section 18)
1a. Early maturing onion varieties
Product Threshold # Sprays
Carzol SP 1-3 thrips/leaf 2
Radiant SC 3 thrips/leaf 1-2
Lannate LV 1 thrips/leaf 0-2

Examples of Suggested Sequences
(Note: IF Carzol receives Section 18)
1b. Early maturing onion varieties
Estimated
Product Threshold # Sprays
SpinTor 2SC 1 thrips/leaf 2
Carzol SP 1-3 thrips/leaf 1-2
Lannate LV 1 thrips/leaf 0-2

Examples of Suggested Sequences
(Note: IF Carzol receives Section 18)
2a. Late-maturing varieties
Product Threshold # Sprays
Carzol SP 1-3 thrips/leaf 2
Radiant SC 3 thrips/leaf 2
Lannate LV 1 thrips/leaf 0-2
OP/pyrethroid 1 thrips/leaf 0-2

Examples of Suggested Sequences
(Note: IF Carzol receives Section 18)
2b. Late-maturing varieties
Estimated
Product Threshold # Sprays
SpinTor 2SC 1 thrips/leaf 2
Carzol SP 1-3 thrips/leaf 2
Lannate LV 1 thrips/leaf 2
OP/pyrethroid 1 thrips/leaf 0-2

Insecticide Control Failures in Wisconsin
are more Frequent Because…
‣ Populations in Wisconsin may be resistant, similar to
populations in other locales.
Environmental conditions become hot and dry.
Spray coverage may be inadequate.
Application threshold adjustments.

IV. Increasing Spray Coverage
‣ Randomized Complete Block: (Warrior EC, Carzol SP)
‣ Application Volumes:
30, 60, & 90 gpa
‣ Nozzle Types:
XR Teejet® Extended Range Flat Fan Tips (FF)
TwinJet® Even Flat Spray Tips (DFF)
Turbo Teejet® Wide Angle Flat Spray Tips (TU)
Conejet® Visi-flo® Hollow Cone Spray Tips (HC)
HC
FF
DFF
TU

Mean number of larvae/plant
IV. Increasing Spray Coverage
35
30
d
Carzol SP: 1.0 lb / acre
25
20
Note: Plot sprayed on 7/13 and 7/20
threshold of 1 thrips/leaf.
15
10
5
0
UTC
c
b
bc
Action threshold = 8.5 thrips / plant
a
a a a a
30 60 90 30 60 90 30 60 90 30 60 90
HC
FF
DFF
TU
bc
bc
b
bc
Gallonage / Nozzle Tip

Mean number of larvae/plant
IV. Increasing Spray Coverage
35
c
Warrior EC: 3.84 fl oz / acre
30
25
20
bc
bc
Note: Plot sprayed on 7/13 and 7/20
threshold of 1 thrips/leaf.
bc
bc
abc
bc
bc
15
10
ab
a
a
ab
ab
Action threshold = 8.5 thrips / plant
5
0
UTC
30 60 90 30 60 90 30 60 90 30 60 90
HC
FF
DFF
TU
Gallonage / Nozzle Tip

Acknowledgements
Wisconsin Muck Farmers Association
• Dean Kincaid Farms, Palmyra, WI
• Anders Huseth
• Dan Selje
• Daryl Sanderson
• Beth Novak
• Corrine Wade
Questions