Transcript Document

Thrips Management in Blueberries
Oscar E. Liburd
Entomology and Nematology Department
University of Florida
Background
Flower thrips, Frankliniella spp.
 Adults 1/16 of an inch
 Yellow-orange coloration
 Wide host range, rapid
colonizers
 Multiple generations per
year
 Travel along wind currents
Background - Thrips Lifecycle
Female
Male
Pupa
non-feeding
Larval
feeding
Flower-thrips species
97%
1%
Western
Florida
flower thrips
1%
Other
1%
Eastern
Goals (2005)
1) Track the movement of flower thrips into blueberry
fields
2) To correlate thrips population with blueberry flower
development
3) To evaluate reduced-risk and conventional
insecticides for control of thrips in blueberries
Tracking the movement of flower thrips
into blueberry fields
• 2 Farms were selected
• Each farm had 49 sampling
stations (white sticky traps)
• Traps were collected every
other day for 25 days
• Correlated the number of thrips
caught on traps with flower
development
Relationship between flower development
and movement of thrips
40 - 50%
0 - 5%
Day 5
day 3
6
0
5
10
15
20
25
6
5
Y Data
4
4
Y Data
0
5
10
15
20
25
30
35
5
3
3
2
2
1
1
0
0
1
2
3
4
5
6
7
X Data
0
0
1
2
3
4
5
6
7
X Data
Day 3
Max 5 thrips/trap
Day 7
Max 25 thrips/trap
Movement of thrips into blueberry fields
80 – 90%
70 - 80%
day 15
6
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
> 100
5
4
Y Data
Day 16
3
2
1
0
0
1
2
3
4
5
6
7
X Data
190 thrips/trap
day 13
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
5
Y Data
4
3
2
1
Fruit formation
day 21
6
0
5
10
15
20
25
30
35
5
Day 21
4
Y Data
6
3
2
0
0
1
2
3
4
5
6
7
1
X Data
Day 13
100 thrips/trap
0
0
1
2
3
4
5
6
7
X Data
35 thrips/trap
Results
Size of thrips populations in relation to flower phenology
Percentages of opened flowers
1
10
70
90
20
250
 x 13.68  2
0.5  

 2.53 
Average # of Thrips captured
f(y)  4.16  192.9  e
x column 1 vs y column 1
200
Col 1 vs Col 2
150
100
50
0
0
5
10
15
20
25
Days after blooming
R = 0.9908; F = 107.8; df = 3,9; P < 0.0001
Questions
Q. When do I spray for thrips?
Ans. It depends on several factors including history
of farm
If you have a history of high thrips population you
should begin to spray when 5% of the flowers have
opened
If your farm usually experience low thrips
population, you can wait until 50% of the flowers
have opened to begin your spraying program
Q. What should I spray?
Average increase in thrips
population
Pesticide efficacy
2
2004
1.5
1
0.5
0
Assail
Average population increase rate
results
3
2.5
SpinTor
Novaluron
GF968
Knack
Calypso
Malathion
2005
2
1.5
1
0.5
0
Actara 25 WG
Diamond .83EC
Assail 70W
TD 2480
SpinTor 2SC
Malathion 5EC
Effect of SpinTor on thrips
population over 48 hours
Mean # of Thrips
30
20
10
0
Untreated
24 Hours
Hours after Application
48 Hours
Question
Q. What is the relationship between thrips numbers
and injury?
Thrips Injury
Hand pollination
Thrips release
Flower protection
Fruit formation counting
Flower protection
Thrips Injury
fruits
0 thrips /flower
Thrips Injury
Oviposition Injury
(5 to 10 thrips / flower)
fruits
Thrips Injury
Fruit dehydration
20 thrips /flower
Thrips Injury
% of fruit formed
75
70
Average ± S.E.M.
65
60
55
50
0
5
10
15
No. of thrips per flower
20
25
Thrips Injury
oviposition
Style
Petals
• 2 blueberry
species in FL
Fruits
• 250 flower per
species
Ovaries
• 27°C and 80% RH
• 15 days
Average No. of thrips
emerging / 10 flowers
Thrips Injury
16
14
12
10
8
6
4
2
0
oviposition
a
b
c
Petals
Ovary
Style
c
Fruit
Flower tissues
F = 19.16; df = 3,46; P < 0.001
Conclusions
• Flower-thrips reduce the quality and quantity of the
blueberries
• 7 days after bloom the initiation of hot-spots are defined
• Thrips are present in blueberry fields for about 25 days
from flower opening to ‘petal fall’
• In cases where there are high populations of thrips,
insecticides could be more effective if applied when the
hot-spots are defined (5-10 days after bloom)
•
Assail, Diamond and Actara have shown to be
significantly more effective than Malathion in
controlling thrips population in blueberry fields
Acknowledgements
• Florida Blueberry Growers Association (FBGA)
• Michigan Blueberry Growers Association (MBG)
• Florida and Georgia blueberry growers
• Southern Region EPA grant #: X8-96424405-0
• Small Fruit and Vegetable Lab at UF