scales found in walnut: identification, life cycles ... · scales found in walnut: identification,...
TRANSCRIPT
Scales found in Walnut: Identification, Life Cycles, & Management Timing
Dani Lightle UCCE Farm Advisor, Glenn, Butte & Tehama Cos. February 6, 2015
Botryosphaeria lesions under walnut scale
Scale populations are increasing
Photos: T. Michailides
Outline:
1. Scale species common in walnut
2. Scale lifecycles
3. Management timings and options
Most common scale species: walnut scale
Daisy-like scalloped margins
Most common scale species: walnut scale
Tree symptoms with high populations: • Branch dieback • Splitting bark • May appear water stressed
Frequently encountered scale species:
European fruit lecanium Frosted scale
Rounded, army-helmet shape
European fruit lecanium versus frosted scale:
Identical most of the year White waxy coating on Frosted scale only during March-April
Lesser common scale species:
San Jose Scale Circular with raised ‘nipple’
Lesser common scale species:
Italian Pear Scale
San Jose Scale Circular with raised ‘nipple’
Associated with Lichens
Generic scale lifecycle: eggs
abundantnature.com
Generic scale lifecycle
Unhatched eggs
Generic scale lifecycle
Eggshells
Generic scale lifecycle
Crawlers
Generic scale lifecycle: crawlers
Adult spider mite
Scale crawler
Generic scale lifecycle: nymph development
Lose: ‒ Legs ‒ Eyes ‒ Antennae
Gain: + Scale cover + Rudimentary eye
spots (if male)
Generic scale lifecycle: females versus males
Female: no eye spots, legs, or antennae Male: eye spots, penile sheath
Generic scale lifecycle: females versus males
Adult male: Winged, flies to females
Walnut Scale Lifecycle
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Walnut Scale Males
Crawlers
Males
Crawlers
Development Nymph
Development 2nd instar
• 2 generations per year • Overwinter as 2nd instar nymph
Adult females
Frosted Scale / European Fruit Lecanium Lifecycle
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Eggs
Rapid
growth
into
adults Frosted Scale
2nd instar 2nd instar
1st instar rs Crawlers Crawlers
• 1 generation per year
Frosted Scale / European Fruit Lecanium Lifecycle
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Eggs
Rapid
growth
into
adults Frosted Scale
2nd instar 2nd instar
1st instar rs Crawlers Crawlers
• 1 generation per year • Overwinter as 2nd instar nymph
Managing scale: in-season monitoring
Have monitoring tapes out by early May
Double-sided tape
Check regularly with a hand lens
Managing scale: in-season monitoring
Scale tape under more powerful magnification
Often high densities at margins of tape
Scale Monitoring: Red Bluff 2014 – Walnut Scale
0
10
20
30
40
50
60 A
vg. #
of
Cra
wle
rs /
Day
Average Number of Crawlers per Day
Scale Monitoring: Red Bluff 2014 – Walnut Scale
0
10
20
30
40
50
60 A
vg. #
of
Cra
wle
rs /
Day
Average Number of Crawlers per Day
0
10
20
30
40
50
60 A
vg. #
of
Cra
wle
rs /
Day
Average Number of Crawlers per Day
Aug. 23rd Assail, 8oz/ac
Scale Monitoring: Red Bluff 2014 – Walnut Scale
0
10
20
30
40
50
60 A
vg. #
of
Cra
wle
rs /
Day
Average Number of Crawlers per Day
Aug. 23rd Assail, 8oz/ ac
Sep. 22nd Harvest
Scale Monitoring: Red Bluff 2014 – Walnut Scale
0
1
2
3
4
5
6
7
8
Avg
. # o
f C
raw
lers
/ D
ay
Average Number of Crawlers per Day
Aug. 23rd Assail, 8oz/ ac
Sep. 22nd Harvest
Scale Monitoring: Red Bluff 2014 – Frosted Scale
Managing scale: treatment timings & options
Timings: Delayed dormant (bud swell until flowering) Crawler stage - research suggests may be more effective timing
Managing scale: treatment timings & options
Timings: Delayed dormant (bud swell until flowering) Crawler stage - research suggests may be more effective timing
Organic treatment options: Organic option: oils -Don’t apply when dormant! Narrow range oils during summer: -Watch for phytotoxicity
Managing scale: Current Research into Control Options Lead researchers: B. Van Steenwyk, C. Wise, J. Hasey
Methods: • 4 replicates in Vina walnuts • Each tree monitored with sticky tape -- March 25th – June 2nd - First crawlers: April 23rd • Treatments applied:
- Post Delayed Dormant – April 8 - Crawler stage: May 6
Study treatments
Treatments: Post Delayed Dormant (April 8): Centaur 70 WDG Seize 35 WP Crawler Stage (May 6): Movento 2SC Assail 30SG Assail 30SG Brigadier 2EC Closer 2SC Centaur 70 WDG Untreated check
Rate Form/ ac: 46.0 oz 5.0 oz 9.0 fl. oz 9.6 oz 5.3 oz 12.8 fl. oz 5.75 fl. oz 46.0 oz ---
Results: Mean Crawlers / Day: May 12 – June 2, 2014
0
5
10
15
20
25
Untreated check
Centaur 70 WDG
(delayed dormant)
Seize 35WP (delayed dormant)
Assail 30SG Assail 30SG Movento 2SC
Brigadier 2EC
Closer 2SC Centaur 70 WDG
Mea
n c
raw
lers
/ cm
/ d
ay a a
a
bc
c
b
(5.3 oz/ac) (9.6 oz/ac)
a
d
bc
0
1
2
3
4
Untreated check
Centaur 70 WDG
(delayed dormant)
Seize 35WP (delayed dormant)
Assail 30SG Assail 30SG Movento 2SC
Brigadier 2EC
Closer 2SC Centaur 70 WDG
# liv
e sc
ale
/ cm
ab
c c
bc
c
a
bc
c c
Results: Live Scale / cm: Jan 21, 2015
(5.3 oz/ac) (9.6 oz/ac)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Eggs
Rapid growth
into adults
Walnut Scale
Frosted Scale
Males
Crawlers
Males
Crawlers
Nymph development
2nd instar
Nymph Development 2nd instar
2nd instar
1st instar Crawlers Crawlers
0
10
20
30
40
50
60
Avg
. # o
f C
raw
lers
/
Day
Aug. 23rd Assail, 8oz/ ac
Sep. 22nd Harvest
Scale Monitoring: Red Bluff 2014 – Walnut Scale
0
2
4
6
8
Avg
. # o
f C
raw
lers
/ D
ay
Aug. 23rd Assail, 8oz/ ac
Sep. 22nd Harvest
Scale Monitoring: Red Bluff 2014 – Frosted Scale