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Onion thrips management in onions

Zsofia Szendrei

Professor & Extension Specialist

szendrei@msu.edu

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Outline

Onion thrips management and action thresholds

Plastic mulches

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Onion thrips damage

Silvery shine
Rasping on leaf surface
Similar to disease symptoms

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weeks

1

2

3

4

5

6

7

8

9

Onion thrips management without using threshold

9 weekly sprays

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Insecticides applied at insect threshold

Using thresholds saves unnecessary insecticide application

weeks

1

2

3

4

5

6

7

8

9

Movento

Minecto-Pro

0.6-1 thrips/leaf

1.1-2 thrips/leaf

Movento

Minecto-Pro

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Insecticides applied at insect threshold – 4 sprays total

Using thresholds saves unnecessary insecticide application

weeks

1

2

3

4

5

6

7

8

9

Movento

Minecto-Pro

0.6-1 thrips/leaf

1-2 thrips/leaf

Movento

Minecto-Pro

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Insecticides applied at insect threshold – 4 sprays total

Using thresholds saves unnecessary insecticide application

weeks

1

2

3

4

5

6

7

8

9

Movento

Exirel

0.6-1 thrips/leaf

1.1-2 thrips/leaf

Movento

Exirel

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Insecticides applied at insect threshold – 4 sprays total

Using thresholds saves unnecessary insecticide application

weeks

1

2

3

4

5

6

7

8

9

Movento

Radiant

1 thrips/leaf

3 thrips/leaf

Movento

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Insecticides applied at insect threshold – 4 sprays total

Using thresholds saves unnecessary insecticide application

weeks

1

2

3

4

5

6

7

8

9

Movento

Radiant

1 thrips/leaf

3 thrips/leaf

Movento

2 applications 1 week apart
Non-ionic surfactant, 0.5% v/v

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Using thresholds can save unnecessary insecticide application

Recommendations to scouts and growers:

before making an application determine the average number of thrips on your onions, do this in multiple locations in your field

compare insect numbers to threshold

most insecticides – 1 thrips/leaf

Radiant – 3 thrips/leaf

check the weather forecast: hot, dry spells will help numbers rise quickly, but cool, wet weather will keep numbers low

YouTube video on scouting

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Onion thrips management guidelines for onion

Movento

WARNING: Agri-Mek and Exirel should NOT be used in a sequence with Minecto Pro

Start

Finish

Exirel

Radiant

Agri-Mek

Movento

Action Thresholds

*Use 1.1-2.0 thrips per green leaf except Movento/Senstar use 0.6-1.0 thrips per leaf or pre-bulbing

If avg. thrips per leaf is 1.1-2.0:

Exirel @ 13.5-16 fl oz/acre
Radiant SC @ 8-10 fl oz/acre
Other products at highest rate

If avg. thrips per leaf is ≥ 2.1:

Exirel @ 20.5 fl oz/acre
Radiant @ 8-10 fl oz/acre

Radiant

Exirel

Agri-Mek

+

Radiant

Exirel

Radiant

Exirel

Lannate + Warrior

Minecto Pro

Brian A. Nault

Christy A. Hoepting

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Organic insecticide options and disease interactions

Entrust is the best OMRI option, no other classes available
Thrips facultatively transmit numerous onion diseases

7 fl oz / ac

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Plastic mulches in onion production

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Weed suppression

Increased yield

Moisture retention

Mulches have many benefits

Temperature regulation

Insect repellent

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How do mulches and insecticides compare?

Can we combine strategies?

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Onions transplanted onto mulches

Transplanted at 2-3 leaf stage
Onions placed in two rows

8 inches apart

Irrigation line between the two rows
Watered weekly

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Mulches

Control- bare ground

Black

White

Silver

Red

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Mulches

Control- bare ground

Black

White

Silver

Red

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Onion insecticide program

May

June

July

August

May 17th: transplanting

June 6th

June 14th

July 11th

July 18th

August 18th:

scouting ended

Insecticides applied with Syl-Tac 1% v-v

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Temperature: above and below mulch

Control- bare ground

Black

White

Silver

Red

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Silver mulch performed similarly

0.8 thrips/leaf

= thrips

0.5 thrips/leaf

= thrips

0.7 thrips/leaf

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Silver mulch performed similarly

0.8 thrips/leaf

= thrips

0.5 thrips/leaf

= thrips

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Red mulch reduced thrips numbers

0.8 thrips/leaf

62% LESS thrips

0.3 thrips/leaf

= thrips

0.7 thrips/leaf

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Red mulch reduced thrips numbers

0.8 thrips/leaf

62% LESS thrips

0.3 thrips/leaf

= thrips

0.7 thrips/leaf

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Black mulch performed similarly

0.8 thrips/leaf

= thrips

0.8 thrips/leaf

61% MORE thrips

1.3 thrips/leaf;

= control, no spray

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White mulch did not control thrips

0.8 thrips/leaf

x 2.4 MORE thrips

1.9 thrips/leaf

x 2.75 MORE thrips

2.2 thrips/leaf

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Color	Brand	Price per foot	Website
Black	KenBar	$0.20	Harris Seeds
White	KenBar	$0.40	Harris Seeds
Silver (Diamond)	Viagrow	$1.00	Home Depot
Red	KenBar	$0.67	Harris Seeds

Mulch information

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Acknowledgements

Vegetable entomology lab members
Southwest Michigan Research and Extension Center
USDA Specialty Crop Block grant, MI Onion Committee

Visit our lab website: https://vegetable.ent.msu.edu/