Aphid and Thrips Management
in Desert Lettuce
Aphids in the Desert
Total Aphid Complex
Harvest Densities
800
(% reduction compared with
untreated check)
Aphids/Plant
800
Untreated
Mean Aphids / Plant
Admire 12-16 oz
600
600
400
400
200
200
(96)
(96)
(94) (97)
(98)
(97)
(91) (95)
(99)
(98)
(92)
0
0
93
94
95
96
97
98
99
00
01
02
03
What happened
in 2003
Foxglove
Aphid, Aulacorthum
solani
?
• Mild Winter – one of the warmest
Januarys on record in Yuma.
• An increase winter / spring lettuce
acreage not treated with Admire ?
• Emergence of the Foxglove aphid as a
pest of lettuce
Lettuce Aphid
Foxglove Aphid
Green peach Aphid
Nasonovia ribisnigri
Aulacorthum solani
Myzus persicae
Lettuce Aphid
Foxglove Aphid
Green peach Aphid
Nasonovia ribisnigri
Aulacorthum solani
Myzus persicae
Avg. Aphids / Plants
Avg. Aphids / Plants
Avg. Aphids / Plants
o
Temperature ( F)
Foxglove Aphid in Head Lettuce
75
70
65
60
55
50
75
70
65
60
55
50
Average Daily Temperature
20
16
2000-2001
2001-2002
2002-2003
20
2000-2001
16
12
12
8
8
4
4
0
0
20
Wet date
Oct 11
Nov 1
Nov 15
Dec 1
Dec 15
20
2001-2002
16
16
12
12
8
8
4
4
0
0
2002-2003
300
300
250
250
200
200
150
150
100
100
50
50
0
0
20
Nov
3
Dec
17
Dec
Oct 10
Oct 28
Nov 15
Dec 3
Dec 13
1
Jan
14
Jan
28
Jan
11
Feb
25
Feb
11
Mar
25
Mar
Oct 10
Oct 29
Nov 14
Dec 3
Dec 12
Will Foxglove Aphid Continue to be a Desert Pest?
Celery
Beans
Brassicas
Peas
Citrus
Potato
Melons
Pecans
Ragweed
Purslane
Pigweed
Ground cherry
Shepards purse
Silverleaf nightshade
Lambsquarter
Dandelion
Keys to Economic Aphid Management
Acyrthosiphon lactucae
Early detection of
colonization
Proper ID of species
Treat when populations
begin to colonize plants
(1- 5% infestation)
Use Insecticides at
effective rates
Effective Insecticides for Aphid Management
Admire
Provado
Endosulfan
Dimethoate
Orthene
MSR
Fulfill
Assail (CA)
Season-long *
7-14 d
7-14 d
10-14-d
Head lettuce; 21 d PHI
Head lettuce; 28 d PHI
7-10 d
7-14 d residual
* Higher rates in late Nov-Dec plantings for foxglove aphid
Population Dynamics
Onion Thrips
(3%)
Western Flower
Thrips
(93%)
Avg. Temperature (oF)
Thrips Population Dynamics in Head Lettuce
80
80
70
60
60
50
250
50
2002
Sept 17
Oct 10
Oct 29
Nov 14
Dec 3
Dec 12
2002
200
150
Mean Thrips / Plant
70
2003
250
200
150
100
100
50
50
0
0
-60
250
-40
-20
0
20
40
60
80
100
250
2003
200
200
150
150
100
100
50
50
0
0
12
Oct
1
Nov
21
Nov
11
Dec
1
Jan
20
Jan
9
Feb
1
Mar
21
Mar
8
Apr
Thrips Sampling
•
Determining presence
and abundance
•
Initiating Control
•
Evaluating Control
•
Research
Direct Visual Counts
Beat Pan
Absolute Estimates
Counting All Thrips on Plant
using a Plant Wash Technique
Population Dynamics of Thrips in Head Lettuce
2003
Oct 29th
1000
750
750
Beat Pan
Direct counts
Plant Wash
500
1000
500
250
250
0
0
Nov 14th
1000
1000
750
750
500
500
250
250
012
Oct
1
Nov
21
Nov
11
Dec
1
Jan
20
Jan
9
Feb
1
Mar
21
Mar
0
Beat Pan Counts (n=27)
~ 20 % of what was actually on plant
Plant Wash (Total Thrips / Plant)
1200
1100
1000
900
800
700
600
500
400
300
200
Y= -22.3 + 5.0x
R2 = 0.85
100
0
0
50
100
150
200
Beat Pan (Total Thrips / plant)
250
Direct Visual Counts (n=27)
~ 12 % of what was actually on plant
Plant Wash (Total thrips / Plant)
1200
1000
800
600
400
Y= 24.5 + 8.3x
R2 = 0.73
200
0
0
20
40
60
80
100
120
Direct counts (Total thrips / plant)
140
Thrips Damage ?
Thrips Damage on Romaine
UTC
Caged
Leaf Position
Thrips Damage ’scarring’ in Romaine
17 adults/ plant
42 larvae / plant
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
Cages
0
1
2
Damage Rating
3
231 adults/ plant
1122 larvae / plant
4
Untreated
0
1
2
Damage Rating
3
4
Weekly Sprays
Caged Plants
Thrips Damage ’scarring’ in Romaine
Leaf Position
203 adults/ plant
390 larvae / plant
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
231 adults/ plant
1122 larvae / plant
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
7-day Spray Interval
0
1
2
Damage Rating
3
4
Untreated
0
1
2
Damage Rating
3
4
Rib Bronzing
Leaf Position
Thrips Damage ’Rib bronzing’ in Romaine
17 adults/ plant
42 larvae / plant
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
Cages
0
20
40
60
Rib Bronzing
(% of leaves)
231 adults/ plant
1122 larvae / plant
80
100
Untreated
0
20
40
60
Rib Bronzing
(% of leaves)
80
100
Key to Economic Thrips Management
Early detection of
thrips populations
“A few probably
means a lot”
Treat before thrips
larval populations
become established
Use Insecticides at
effective rates
By ground when possible
Western Flower Thrips
in Lettuce
What Rate of Success®
Should I Use For Thrips?
What Rate of Success® Should I Use For Thrips?
Head Lettuce
100
10 DAT#2
A
LAR
% Control
80
LAR
LAR
LAR
100
80
60
60
40
40
AD
AD
20
0
20
AD
AD
Success
Success
6 oz
10 oz
Success
5 oz
Mustang
4 oz
Lannate
0.7 lb
Mustang
4 oz
0