Understanding and Managing Walnut Botryosphaeria/Phomopsis...
Transcript of Understanding and Managing Walnut Botryosphaeria/Phomopsis...
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Themis J. Michailides
D. Morgan, J. Moral, D. Felts, R. Puckett, M. Luna
U N I V E R S I T Y O F C A L I F O R N I A
Kearney Agricultural Research and Extension Center &
University of California Cooperative Extension
Quad-County Walnut Institute, Stockton – 15 March 2016
Cooperators: J. Hasey, R. Buchner, B. Coates, K. Pope, K. Anderson, J. Grant,
and D. Lightle: UCCE Sutter/Yuba/Colusa, Tehama, San Benito, Yolo/Solano, Stanislaus, San
Joaquin, and Butte/Glenn counties, respectively
Understanding and Managing Walnut
Botryosphaeria/Phomopsis Canker and Blights
(Influence of El Niño on the Sleeping Giant)
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Winter 1982-1983 “El Niño storms”
Winter 1994-1995 “winter storms”
Winter 1997-1998 “El Niño storms”
El Niño winters in California (1982 through 2015)
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The Bot disease started in 1983, probably in the oldest
pistachio orchard in the State (Butte Co., CA)
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Winter 1982-1983 “El Niño storms”
Winter 1994-1995 “winter storms”
Winter 1997-1998 “El Niño storms”
El Niño winters in California (1982 through 2015)
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1995
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Winter 1982-1983 “El Niño storms”
Winter 1994-1995 “winter storms”
Winter 1997-1998 “El Niño storms”
El Niño winters in California (1982 through 2015)
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Bot epidemic of 1998
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… because of Botryosphaeria blight
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Winter 2015-2016 “El Niño?
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Botryosphaeria /Phomopsis of walnuts in Spain
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Symptoms we expect to see in walnut orchards
in an El Niño year in California
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Latent infection of fruit:
Blighted fruit and pathogen isolation from kernels of walnut fruit
inoculated with Lasiodiplodia citricola
0.0
20.0
40.0
60.0
80.0
100.0
120.0
5/12 5/22 6/1 6/11 6/21 7/1 7/11 7/21 7/31 8/10 8/20 8/30 9/9
Brighted fruit
Isolation from kernel
Lasiodiplodia citricola
bc
aba
abc
abc
c
bc
B
A
AB
A
B
BB
A
0.0
20.0
40.0
60.0
80.0
100.0
120.0
5/12 5/22 6/1 6/11 6/21 7/1 7/11 7/21 7/31 8/10 8/20 8/30 9/9
blighted fruit
Isolation from kernel
Neofusicoccum parvum
c
a
bcbc
cc
ab
AB
BCABC
BCC
ABC
A
B
%
Date of 2015
Blighted fruit
infected kernels
May Sept.
Infe
ctio
n (
%)
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Infection of intact fruit in the orchard
Fruit
Infect spurs/shoots
All Botryosphaeria
& Phomopsis
species
Peduncle
Fruit
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Spurs with cankers covered
with sporulation (pycnidia)
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Susceptible walnut cultivars
Ashley
Chandler
Howard
Tulare
Vina
Serr
Hartley
Payne
Dixon
Livermore
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Distribution of
“Botryosphaeria” spp.
in walnut orchards
Botryosphaeriaceae
Phomopsis
N. mediterraneum =
widespread
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Lasiodiplodia spp.
Diplodia seriata
Botryosphaeria dothidea
Neofusicoccum spp.
Neoscytalidium**
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Perithecia Pycnidia
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Oozing pycnidia
Rain:
Oozing pycnidia of Botryosphaeria on walnut spurs
0
water water
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The majority of spores will be
released within 30 minutes
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Spores of Botryosphaeria
they germinate within 1.5 hours wetness!
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Germination under adverse (wet/dry/wet)
conditions and surviving mechanisms
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Botryosphaeria spread
rain & moving water in the orchard +++++++*
air (airborne ascospores) ++
pruning equipment +
insects ?
*rain, dew, sprinkler irrigation
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Conditions for infection events
Presence of inoculum
Rain: at least 1/4”
Temperature: ≥ 50°F
Presence of susceptible tissues
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Cankers associated with pruning wounds
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Post-pruning inoculation date
contr
ol
0 d
ay
3 d
ay
1 w
eek
2 w
eek
3 w
eek
4 w
eek
8 w
eek
12 w
eek
16 w
eek
Ave
rag
e c
an
ke
r le
ng
th (
cm
)
0
2
4
6
8
10
12
14
16
de
a
abc
a
ab
abc
cd
e
cde
bcd bcd
bb
Susceptibility of pruning wounds of 1-, 2-, 3-, & 4-
year-old wood to infection by Bot
Pruning on 9 & 10 Feb 2015
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Prune branch
Walnut branch
Walnut branches
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Age of inoculated shoots
1 year 2 year 3 year 4 year
Ave
rag
e c
an
ke
r le
ng
th (
cm
)
0
2
4
6
8
10
12
14
16
a
a
b
b
Susceptibility of pruning wounds to infection by Bot
as affected by age
Pruning on 9 & 10 February 2015
5-6 inches
up to 2 inches
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Control
Quadris T
op
Merivo
n
Merivo
n+V
itiS
eal
Abound
Ave
rag
e c
anke
r le
ng
th (
cm
)
0
2
4
6
8
10
b
ab
a
b
ab
Neofusicoccum parvum
Treatment of pruning wounds with fungicides and
then inoculation with Neofusicoccum parvum
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Fruit scars when walnuts drop
Leaf scars
Wounds in the field during 1) the season,
2) at harvest and 3) postharvest
*
*
*
*
Canker
Peduncle
scars
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Infection Courts of Botryosphaeria and Phomopsis
During the season:
Wounds from hail, freeze,
sunburn, wood peckers
Pruning wounds
Scale wounds
Walnut blight lesions
At harvest:
Scars from peduncles
Fruit wcars
Leaf scars
Mechanical wounds
Postharvest:
Peduncle scars
Leaf scars
Husks (remaining on the tree)
Pruning wounds
Wounds from freeze damage
Injuries from wood peckers
Other type of injuries
p
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Leaf scar infections
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Injuries (wounds) by walnut scale & Botryosphaeria
More than 50% of necrotic
lesions had Botryosphaeria spp.!
Injuries from scales
Necrotic lesions
walnut scale
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Management of Botryosphaeria canker
and shoot blight:
2. Cultural control: Sanitation: prune infected
shoots to remove cankers and reduce spore inoculum;
avoid wetting the tree canopy.
Best control…
Integrated disease control: Use all of the above
(1 + 2 + 3).
1. Assessment of Bot inoculum risk: BUDMON, or CANCERED SPURS (… in progress).
3. Chemical control: Apply fungicide sprays.
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BUD MONitoring (= BUDMON) Technique
Results in 6-7 days
BOT
% of buds with Bot
Bud collection:
February/March
BOT
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Sanitation by pruning
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Walnut prunings
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Bot survival in chipped wood
0
20
40
60
80
100
120
% V
iab
ility
Unchipped Chipped
Pre
sence o
f pycnid
ia w
ith v
iable
spo
res
c/o Katherine Pope, UCCE Yolo /Solano
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Botryosphaeria …………. 40%
Phomopsis ……………….. 30%
Botryosphaeria + Phom.…. 20%
No pycnidia……………..…..10%
Botryosphaeria ……..…0%
Phomopsis …………….. 0%
Botryosphaeria + Phom.. 0%
Compost
90%
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Montgomery fungicide efficacy 2014 seasons
– all treatments
Blighted shoots (%)
0 2 4 6 8 10 12 14
ControlLuna Sensation 5 oz
ViathonQuadris Top
FontelisPh-D
Badge + ManzateLuna Experience 6 oz
Fontelis + TebuconLuna Experience 10 oz
PristineEXP 1
Luna Sensation 7.6 ozEXP1 + EXP 2
EXP 1 + EXP 3K Phite + Latron
Fontelis + OR009K Phite
Ph-D + TebuconQuash
Merivon aaaaa
abab
ababab
abababab
abab
abcabc
abcbc
c
Effects of fungicides on Botryosphaeria in Chandler
walnut shoots/spurs (Butte Co.) - 2014
SPRAYS: May 8, June 12, and July 10
4X
Blighted spurs (%)
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Black kernels
Brown kernels
No discoloration
Isolations on agar media
Nuts at harvest
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Effects of fungicides on Botryosphaeria in Chandler
walnut (black and brown kernels) (Colusa Co.) - 2014C
ontr
ol
Luna E
xperience (
1)
Luna E
xperience (
2)
Quadris T
op (
1)
Quadris T
op (
2)
Merivon (
1)
Merivon (
2)
Fonte
lis+
Tebucon (
1)
Fonte
lis+
Tebucon (
2)
Bo
trysp
ha
eri
a s
pp
. (%
)
0
2
4
6
8
10
a
ab ab
ab
bbb
b
b
Black kernelsBrown kernels
Contr
ol
Luna E
xperience (
1)
Luna E
xperience (
2)
Quadris T
op (
1)
Quadris T
op (
2)
Merivon (
1)
Merivon (
2)
Fonte
lis+
Tebucon (
1)
Fonte
lis+
Tebucon (
2)
Bo
tryo
sp
ha
eri
a s
pp
. (%
)0
2
4
6
8
a
ab abab
b
abab
b b
Black kernels Brown kernels
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Efficacy of four calendar sprays of fungicides in a Chandler
walnut orchard in Butte Co. (Sacramento River) - 2015
Blighted spurs (%)
0 1 2 3 4 5 6 7 8 9
ControlFontelisMerivonFracture
Badge-Manzate Pro StickPh D
Luna SensationQuash
Fontelis + TebuconazolQuadris Top
ViathonLuna ExperienceFontelis + Vintre
IndarFont-Teb>QuadTop>Font-Teb>QuadTop
Fontelis + AboundPh D + Tebuconazol
Pristine a
aa
ab
ab
ab
abab
abcabcabc
bcd
abcd
abcdabcd
abcd
bcd
abcd
bcdcd
d
SPRAYS: May 12, Jun 11, Jul 10, Aug (4X SPRAYS)
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Leaf wetness model (LWM) where rain exceeded
threshold in a Chandler walnut orchard in Butte
County
Temperature, °C
5 10 15 20 25
Lea
f w
etn
ess,
ho
urs
0
10
20
30
40
50
60
High Risk
Medium Risk
Low Risk
April 8-9 (8 mm)
April 24-25 (18 mm)
Sept. 16-17 (3 mm)
sprayed
sprayed
sprayed
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Various timings of Merivon® fungicide in a Chandler
walnut orchard in Butte Co. - 2015
Blighted spurs (%)
0 1 2 3 4 5 6 7 8 9
Control
Merivon: bloom
Merivon: bloom, post-harvest
Merivon: bloom, May, June, July, post-harvest
Merivon: May, June, July
Merivon: post-harvest
Merivon: May, June, July, post-harvest
Merivon: April 9, 26; Sept 17--leaf wet
Merivon: bloom, May, June, July a
ab
abc
bcd
e
cde
cde
cde
de
Leaf wetness model
Standard calendar
Standard calendar+postharvest
Bloom + Standard calendar
SPRAYS:
Calendar: May 12; Jun 12; Jul 10 = 3X
4X
5X ?
2X
1X
3X
1X
4X
Bloom: Apr 9 = 1X; Postharvest: Nov 3 = 1X
3X
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Best-timing of a single spray of Merivon® in a
Chandler orchard in Butte Co. - 2015
Merivon: blo
om
Merivon: M
ay
Merivon: June
Merivon: July
Merivon: A
ugust
Merivon: post: h
arv
est
Blig
hte
d s
purs
(%
)
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
a
a
ab
ab
ab
ab
Best
timing
SPRAYS: Apr 9 (bloom); May 12; Jun 12; Jul 10; Aug 10; Nov 3 (PH)
Nonsprayed = 8%
Postharvest (PH)Bloom
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www.ipm.ucdavis.edu
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Efficacy of registered fungicides against Botryosphaeria
canker and blight of walnut
Quash…………
Merivon…….…
Pristine ……….
Quadris Top…..
Switch…………
PhD…..……….
Viathon………..
K-Phite ………. Luna Experience
Luna Sensation
Fontelis
Manzate
metconazole
fluxopyroxad+pyraclostrobin
boscalid + pyraclostrobin
difenoconazole + azoxystrobin
cyprodinil + fludioxonil
Polyoxin-D
tebuconazole + phosphite
Polyphosphite
fluopyram + tebuconazole
fluopyram + trifloxystrobin
penthiopyrad
copper-mancozeb
++++
++++
+++
+++
++++
+++
+++
++++
+++
++
+++
++
Fungicide Active ingredient Efficacy
http://www.ipm.ucdavis.edu
Efficacy: + = poor: ++++ = excellent
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Orchards - Heavy infection (>50%): Prunings need to be chipped and they may be
left in the orchard; apply 3-5 fungicide sprays ((bloom, May, Jun, July, and postharvest).
Orchards - Moderate infection (21% - 50%): Prune or hedge these orchards first
and then move into heavily infected orchards; prunings need to be moved out of the
orchard; at least 3 sprays (bloom and June spray, & July – depending on weather
conditions).
Orchards – Light infection (6% - 20%):
Prune or hedge these orchards first and then move into more infected orchards;
prunings need to be moved out of the orchard; two sprays (bloom and mid June to early
July).
Orchards – Very light infection (1% - 5%): Prune infections and destroy them out
of the orchard; no spray(s) needed, unless it rains.
Orchards – No infection: no Botryosphaeria yet (0%): Prunings can be chipped
and left in the orchard; no spray(s) are needed.
Scenarios for sanitation & sprays
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For best management we need all: a) assessment of
inoculum risk; b) sanitation; and c) fungicide sprays.
Sprays during May through July/August reduce
Botryosphaeria (confirmed in 2014 & 2015).
Bloom sprays and postharvest sprays seem to reduce
disease (we need to repeat in 2016).
Sprays after a rain/infection event seem to be very effective
(we need to repeat in 2016).
The best-timing spray seems to be around mid-June to
early/mid July (we need to repeat in 2016).
CONLCUSIONS
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Acknowledgments
Thank you
UC Kearney Agricultural Research & Extension
Center
David Morgan
Dan Felts
Yong Luo
Ryan Puckett
Juan Moral
& farm advisors
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0%
2%
4%
6%
8%
10%
12%
14%
16%
18%
20%
L as iodiplodia
c itricola
Neofus icoccum
parvum
Neofus ic oc cum
mediterraneum
C ontrol
With s cales
No s cale
Treatment
Pe
rce
nta
ge o
f w
aln
ut bra
nch
es infe
cte
dEffect of walnut scales on infection of walnut
by Botryosphaeriaceae (cv. Vina)
3 weeks after inoculation60-75% more shoots were infected when scales were
present than when scales were not present
Inoculation
Without wounding – spore suspension
Shoots w/
scales
a
b
a
b
a
b
Shoots w/
scalesShoots w/
scales
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