Evaluation of Insect Repellents and Barriers as Methods to Control

Cucumber Mosaic Virus of Bell Peppers

Joe NunezVegetable/Plant Pathology Advisor

UC Cooperative Extension-Kern

Cucumber Mosaic Virus

• CMV has been afflicting peppers in Kern County for 5 years.

• Appears most heavily in the southern end of the county near Mettler.

• Some years worst than others. • The earlier it appears in the season, the

more damage occurs. • Is aphid transmitted.

Control of CMV• Essentially none-remove weeds around field

and reflective mulches

• Plants are treated with imidacloprid as seedlings in greenhouses.

• Imidacloprid treatments continue through season.

• Organic fields treated with biologicals.– Lady bug release– Lacewing, etc

Control of CMV

●Even with insecticide treatments, aphids will probe and transmit the virus before it is killed.

•Must prevent aphids from landing on plants.

2008 Trial

1.Control2.Citronella Oil3.Citronella/Clove/Geranium4.Clove/Rosemary5.Garlic Oil6.Garlic/Citronella7.Floating Row Cover8.Silver Reflective Mulch

2009 & 2010 Trial

1. Control2. Black3. Silver reflective4. Silver5. White6. Green7. Red8. Surround Canopy9. Surround Soil

White Control Silver Reflective

Silver Green Red

Surround on Soil Surface

Surround on Canopy

Surround Canopy Surround Soil

Green Mulch

Red Mulch

Black Mulch

White Mulch

0

100

200

300

400

500

600

700

800

gram

s

1. Control 2. Black 3. Silverreflective

4. Silver 5. White 6. Green 7. Red 8. SurroundCanopy

9. SurroundSoil

Total Fresh Weight

cdabc

d

abbc

a ab

d cd

2010

0

10

20

30

40

50

60

70

80

gram

s

1. Control 2. Black 3. Silverreflective

4. Silver 5. White 6. Green 7. Red 8. SurroundCanopy

9. SurroundSoil

Total Dry Weight

Series3

cdab

d

abc

a a

d cd

2010

Yellow Sticky Cards – placed above canopyWeekly aphid and thrips counts

Aphid Trap Counts

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

3/29/2010

4/5/2010

4/12/2010

4/19/2010

4/26/2010

5/3/2010

5/10/2010

5/17/2010

5/24/2010

5/31/2010

Num

ber o

f Aph

ids

1. Control2. Black3. Silver reflective4. Silver5. White6. Green7. Red8. Surround Canopy9. Surround Soil

2010

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

Num

ber o

f Aph

ids

1. Control 2. Black 3. Silverreflective

4. Silver 5. White 6. Green 7. Red 8. SurroundCanopy

9. SurroundSoil

Total Aphids for Season

a

bcdd d

bccd cd

bcd

2010

Weekly Aphid Counts 2009

0

1

2

3

4

5

6

7

8

4/21/2

0094/2

3/2009

4/25/2

0094/2

7/2009

4/29/2

0095/1

/2009

5/3/20

095/5

/2009

5/7/20

095/9

/2009

5/11/2

0095/1

3/2009

5/15/2

0095/1

7/2009

5/19/2

0095/2

1/2009

5/23/2

0095/2

5/2009

Num

ber A

phid

s pe

r Tra

p

ControlFloating coverReflective mulchGreen mulchRed MulchBlack MulchSilver MulchSurround/GroundSurround/CanopyWhite Mulch

0

10

20

30

40

50

60

70

80

3/13/2

0083/2

0/2008

3/27/2

0084/3

/2008

4/10/2

0084/1

7/2008

4/24/2

0085/1

/2008

Wee

kly

Aphi

d Co

unt

1. Control

2. Citronella

3. Citronella/CloveOil/Geranium4. Clove oil/Rosemary oil

5. Garlic oil

6. Garlic oil/Citronella oil

7. Floating Row Cover

8. Reflective Mulch

2008 Aphid Counts

Thrip Counts

0.0

500.0

1000.0

1500.0

2000.0

2500.0

3000.0

3500.0

4000.0

3/29/2

010

4/5/20

10

4/12/2

010

4/19/2

010

4/26/2

010

5/3/20

10

5/10/2

010

5/17/2

010

5/24/2

010

5/31/2

010

Num

ber T

hrip

s

1. Control2. Black3. Silver reflective4. Silver5. White6. Green7. Red8. Surround Canopy9. Surround Soil

2010

0.0

1000.0

2000.0

3000.0

4000.0

5000.0

6000.0

7000.0

8000.0

9000.0

10000.0

Num

ber o

f Thr

ips

1. Control 2. Black 3. Silverreflective

4. Silver 5. White 6. Green 7. Red 8. SurroundCanopy

9. SurroundSoil

Total Thrips for Season

bbcde cde de

a

bcd bcdee

bc

2010

Weekly Thrip Counts 2009

0

200

400

600

800

1000

1200

1400

1600

1800

4/21/2

0094/2

3/2009

4/25/2

0094/2

7/2009

4/29/2

0095/1

/2009

5/3/20

095/5

/2009

5/7/20

095/9

/2009

5/11/2

0095/1

3/2009

5/15/2

0095/1

7/2009

5/19/2

0095/2

1/2009

5/23/2

0095/2

5/2009

Num

ber T

hrip

s pe

r Tra

p

ControlFloating CoverReflective MulchGreen MulchRed MulchBlack MulchSilver MulchSurround/GroundSurround/CanopyWhite Mulch

Totals Treatment Market Process Total 1. Control 6.7 abc 3.4 10.1 2. Black 7.4 ab 3.4 10.7 3. Silver Reflective 5.5 c 3.5 9.0 4. Silver 8.4 a 3.6 12.0 5. White 6.5 bc 3.2 9.7 6. Green 7.5 ab 2.9 10.4 7. Red 7.3 ab 3.8 11.1 8. Surround Canopy 5.6 c 3.6 9.2 9. Surround Soil 6.9 abc 3.4 10.3

P= 0.0425 0.9167 0.2145 %CV= 17.31 24.09 15.06 LSDp=0.05 1.737 NS NS

2010 Harvest Data

0

2

4

6

8

10

12

14

Kg

1. Control 2. Black 3. Silverreflective

4. Silver 5. White 6. Green 7. Red 8. SurroundCanopy

9. SurroundSoil

Harvested Weights of 12 plants

ProcessingMarketableabc ab

c

abc ab ab

c abc

BBBB’’ss MMaarrkkeettaabbllee WWtt CCuullll WWtt TToottaall MMaarrkkeettaabbllee WWtt TToottaall PPrroocceessssiinngg WWtt TToottaall WWtt.. 11.. CCoonnttrrooll 11 ..1144 00..1122 1166..6611 BBCC 55..5533 BBCC 2222..1144 BBCC

22.. RRooww CCoovveerr 11 ..1166 00..0000 44..9911 DD 22..6666 CC 77..5588 DD

33.. SSiillvveerr RReefflleeccttiivvee MMuullcchh 11..1111 00..0000 1166..4499 BBCC 44..5566 CC 2211..0044 CC

44.. GGrreeeenn MMuullcchh 00 ..7766 00..4411 1188..2266 AABBCC 99..6633 AABB 2277..8899 AA

55.. RReedd MMuullcchh 00 ..6699 00..7766 2222..6688 AA 66..4499 AABBCC 2299..1166 AA

66.. BBllaacckk MMuullcchh 11 ..1155 00..5599 2200..3333 AABB 55..0099 BBCC 2255..1111 AABBCC

77.. SSiillvveerr MMuullcchh 00 ..6644 00..1100 1188..6600 AABBCC 55..5511 BBCC 2244..1111 AABBCC

88.. SSuurrrroouunndd MMuullcchh 00..5555 00..3333 1155..2200 BBCC 1100..8811 AA 2266..6666 AABB

99.. SSuurrrroouunndd WWhhiitteewwaasshh 00..8877 00..2266 1177..8800 AABBCC 66..7755 AABBCC 2244..5555 AABBCC

1100.. WWhhiittee MMuullcchh 00..9955 00..2266 1144..7733 CC 77..0088 AABBCC 2211..8800 BBCC

PP==00..0055 00 ..55777722 00..22114422 00..00000011 00..00445544 00..00000000 %% CCVV 5566..1111 114466..5599 2211..9933 4488..8811 1166..4477 LLSSDD,, PP==00..0055 NNSS NNSS 55..229999 44..554477 55..551166

2009 Harvest Weights (lbs)

Harvest Dates

06/04/08 06/17/08 06/25/08 Total 1. Control 9.1 lb 28.3 14.7 52.2 ABC 2. Citronella 4.8 21.7 16.0 42.5 CD 3. Citronella/Clove/Geranium 6.0 27.5 16.4 49.9 ABCD 4. Clove/Rosemary 4.4 27.3 17.1 48.9 BCD 5. Garlic Oil 5.7 30.0 18.2 54.0 AB 6. Garlic/Citronella 7.7 23.1 20.1 50.9 ABC 7. Floating Row Cover 6.5 16.1 17.7 40.4 D 8. Reflective Mulch 9.6 26.6 24.1 60.2 A P=0.05 0.2547 0.1434 0.5756 0.0831 %CV= 47.43 27.01 35.38 17.20 LSD, P=0.05 4.702 9.969 9.402 12.625 LSD, P=0.10 10.450

lb lb

2008

Conclusions from 2010 Trial

• All mulches, plastic or kaolin clay, can reduce aphid flights into peppers.

• Silver reflective, Silver & Kaolin clay on canopy reduce thrips populations in plant canopy.

• Silver, Green & Red mulches increase plant growth of peppers.

• CMV was not a problem in 2010

Summary for the 3 year study

• Reducing aphid flights into pepper fields reduces the incidence of CMV.

• Reducing incidence of CMV increases yields.

• Plastic mulches, especially silver reflective, are very effective at reducing aphid and thrips populations in a field.

• Red and Green plastic mulch increase plant size and pepper yields.

Summary for the 3 year study

• Kaolin clay as a mulch may be less expensive, easier, and more environmentally sound method to reducing aphid populations.

• Botanical oils sold as insect repellents are not effective.

Thanks to:

Valprado FarmsMike ValpredoRick MartinezOmar Martinez

California Pepper Commission