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Doug GublerDepartment of Plant PathologyUniversity of California, Davis
FOOTHILL GRAPE DAYMAY 18,2016
log-normal, then probit transformations
Powdery MildewErysiphe necator
Disease epidemiology/ Pathogen biology
Pathogen negatively effected by direct sunlight
Reduces sporulation, spore germination, infection and lesion expansion
Pathogen negatively effected by high temperatures
Reduces spore production
Reduces spore germination rate
Reduces infection rate
Affects reproduction rate
Grapevine Powdery Mildew
Effects of Moisture
Optimum RH is 65%
No effect of higher RH
Effect of RH is overcome by temperature i.e. temperature more important.
Free water has negative effect on conidial sporulation, infection, and lesion
expansion.
2 mm or more of rainfall required for ascospore release at temperatures of 70-85 F
Free water has positive effect on ascospore germination
Bud Perennation
Occurs on same vines each year
Flag and monitor
Remove flag shoot(s) and treat that vine and the 4 around the infected vine with Rally+JMS Stylet Oil, Inspire Super or Luna Experience
Protect next year’s buds during 3-6 leaf stage.
Infection next year should be expressed at the same time as infection occurred this year i. e. if infection started during the formation of the 3rd leaf then that leaf will show disease next year. This allows the prediction of when the spray application should be made.
Cleistothecia (Chasmothecia)
Form in late summer and fall.
Wash from leaves with fall and winter rains onto cordons, canes, and spurs.
Monitor for disease 7-10 days after ascospore release—lower surface of basal leaves.
Control
Postharvest application of JMS Stylet Oil at 1.5-2.0% (for prevention of chasmothecia)
Dormant, directed spray application of Lime sulfur at 10 gal/A in 100 gal water
Budbreak application of df Sulfur at 5#/A
Budbreak application of JMS Stylet Oil at 1.5%
Effect of High Temperature
Negative effect spore production
Negative effect on lesion expansion
Negative effect on spore germination
Negative effect on infection process
Cessation of Spore Production
R2 = 0.84
R2 = 0.68
R2 = 0.59
R2 = 0.88
R2 = 0.94
R2 = 0.70
R2 = 0.92
R2 = 0.88
0
25
50
75
100
0 5 10 15 20 25
Duration of Temperature, hr
% C
olon
ies
Pro
duci
ng S
pore
s
30
32
34
36
38
40
42
44
Figure 8. The effects of temperature and duration on cessation of E. necator spore
production. Primary data were obtained as described for Figure 7. Colony survival was
calculated for each leaf, each isolate, averaged for each duration, and plotted with linear
regression trend lines. In order to obtain reasonable x-axis intercepts, only 1 zero value
was used if consecutive zero values occurred; consecutive values of 100% were similarly
truncated. Room temperature controls (22.5º C) were all 100% (data not shown).
Two Potential Outcomes with multiple exposure to
high temp
TimeTime
Gro
wth
“Loss of biological function”
“Acclimation”
Figure 10. Predicted loss of biological response as a function of temperature and duration of treatment for spore germination, colony size on day 10 and spore production. The predicted duration (h) at which the biological response is zero (x-intercept) was obtained from linear regression analysis of primary data in SAS.
Predicted Loss of Biological Function
0
25
50
75
100
30 32 34 36 38 40 42 44
Temperature, C
Du
rati
on
at
wh
ich
Bio
log
ica
l R
es
po
ns
e
Ex
tin
gu
ish
ed
, h
r
germination
colony size
spore production
Fungicide Resistance
Resistance to DMI’s!
Resistance to Strobilurins?
Combating Overwintering Resistance
Make sure the first application each year is NOT A DMI (Rally,
Elite, Metal, Procure, etc.) OR Strobilurin ( Abound, Sovran,
Flint, Pristine
Use multisite products first (Oil, df Sulfur, Dormant Lime
Sulfur)
Resistance Management
Aim- Reduce Selection pressure to prevent further buildup of
resistant strains.
Should not use within class of chemistry for mixes or
alternations i.e. NEVER DMI-DMI or Strob-Strob
Do not stretch intervals unless you know what the level of
disease pressure is. (UCDRI)
Spray coverage is as important as the product you use.
Coverage! Coverage! Coverage!
Powdery Mildew
Model Use
Stretch spray intervals under low to intermediate disease pressure.
Shorten spray intervals under high disease pressure
Organic products should be used on 5-7 day interval under high disease pressure
with the exception of JMS Stylet Oil which can be used on 14 day interval under high
pressure.
Sulfur dust use stretched to 30 day intervals using the RI model in California and
Germany.
Powdery Mildew Spore Trapping
Gubler-Thomas Risk Index, Courtland CA. 2007
0
10
20
30
40
50
60
70
80
90
100
20
-Ap
r
27
-Ap
r
4-M
ay
11
-May
18
-May
25
-May
1-J
un
8-J
un
15
-Ju
n
22
-Ju
n
29
-Ju
n
Date in 2007
Gu
ble
r-T
ho
mas
PM
Ris
k I
nd
ex
.
Gubler-Thomas PM Risk Index 2010
000
20
30
20
40
30
20
10
20
30
20
40
60
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40
60
50
30
20
10
30
50
90
80
60
50
70
60
80
60
50
40
30
20
10
0
20
40
60
50
70
100100100100100
90
100100100100
90
80
100100
90
100100100100100100100100100100
90
80
100100100100100100100100100100100
90
100100100100
90
80
70
60
50
0
20
40
60
80
100
120
RIS
K A
SS
ES
SM
EN
T I
ND
EX
Gubler-Thomas PM Risk Index 2011
000000000000
20
30
40
50
60
70
80
60
40
20
30
10
20
30
10
0000
20
30
40
20
000000000000000
20
30
40
50
60
70
80
90
100100100100100100
80
60
70
80
90
100100
80
90
100100
80
60
40
20
0
20
0
20
30
40
50
60
70
80
90
100100100
80
60
70
80
90
100100
80
0
20
40
60
80
100
120
RIS
K A
SS
ES
SM
EN
T I
ND
EX
Gubler-Thomas PM Risk Index 2012
00000
20
40
60
80
70
90
80
70
60
80
100100
90
80
70
60
80
100
90
80
70
90
80
70
60
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100
90
80
100100
90
100100100100
90
80
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50
70
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100100100100
90
80
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100100
90
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100100100100100100
90
100100
90
80
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60
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30
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60
50
40
60
80
70
60
50
70
90
0
20
40
60
80
100
120
RIS
K A
SS
ES
SM
EN
T I
ND
EX
Gubler-Thomas PM Risk Index 2013
00
20
000000
20
40
60
50
40
30
20
10
30
50
70
90
100100100
80
90
100100100100100100100100
80
60
40
20
30
40
20
30
40
50
60
40
20
30
40
50
70
60
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100100100
80
60
40
20
30
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60
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80
90
100100100100100
80
60
40
50
60
40
20
00000
20
40
60
80
100
120
RIS
K A
SS
ES
SM
EN
T I
ND
EX
Gubler-Thomas PM Risk Index 2014
80
100100
90
100100100100
90
100100100100
90
80
70
60
50
40
60
80
70
60
50
70
90
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100100100
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30
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90
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60
50
40
30
20
10
0000
20
40
30
20
10
30
50
70
Ris
k A
SS
ES
SM
EN
T I
nd
ex
Effect of Dormant or Delayed Dormant Treatment on viability of
Ascospores—Vineyard Trial
Treatment Rate % Germ % w/Appressoria
Micronized S 5# 2 0
JMS Stylet Oil 2% 1 0
Lime Sulfur 10 g 1 0
Rally/Topsin 5oz+1.5# 0 0**
LS+JMS Oil 2+10 0 0
Citricide 2% 33 4
Untreated ---- 30 6
**Also effective for canker disease
Fungicide Application: Rally + Topsin MPowdery Mildew & Canker Disease Control
Early Season Powdery Mildew Control
Budbreak applications = 95% control at disease onset.
Micronized S 5#/A in 100 gal water/A (above temperature of 22-23 C)
JMS Stylet Oil 1-2 % in 100 gal water/A
Other oils ?
Rally + Topsin M as a delayed dormant
Powdery mildew and canker control
Cultural Practices
Increase direct sunlight
Leaf removal at cluster set- reduces pm by 50%
Shoot thinning
Crown suckering
Decrease RH
BOTRYTIS BUNCH ROTBotrytis cinerea
Leaf removal at cluster setAlso reduces blossom debris
Effect of Leaf Removal and fungicide sprays on Botrytis bunch rot in Zinfandel,Lake County
Unsprayed
ControlBloom
Bloom+
Post-
bloom
Pre-bloom+
Bloom+
Post-bloom
Mean
No Leaf
Removal28.2 31.1 22.7 18.7 25.2a
Leaf
Removal5.7 5.9 3.4 6.4 5.4b
Mean 16.9 18.5 13 12.6
INCIDENCE: PERCENT CLUSTERS WITH ROTRovral at 1.5 lb/acre applied at following timings:
Effect of Leaf Removal and fungicide sprays on Botrytis bunch rot in Zinfandel,Lake County
Unsprayed
ControlBloom
Bloom+
Post-
bloom
Pre-bloom+
Bloom+
Post-bloom
Mean
No Leaf
Removal 10.7 14.2 11.2 8.2 11.1a
Leaf
Removal 1.2 1.0 1.1 2.9 1.6b
Mean 5.9 7.6 6.1 5.6
SEVERITY: PERCENT ROT PER CLUSTERRovral at 1.5 lb/acre applied at following timings:
Blossom debris removal
Leaf blower study
Reduced bunch rot by 30%
Canker Diseases
Eutypa dieback
Bot Canker
Esca (Black measles, Spanish measles)
Eutypa Dieback
Canker Disease Control
- Dieback of grapevines in CA caused by a complex of fungi
- At least 25 different fungi in the Diatrypaceae, Botryosphaeriaceae and Valsaceae family
-The Family Botryosphaeriaceaeconstitutes the main fungi isolated from grapevine cankers in California
- Lasiodiplodia theobromae, Neofusicoccum parvum, Neofusicoccum luteum, and Neofusicoccum australe
- much more virulent than the well-known pathogen E. lata.
Dormant Liquid Lime Sulfur(ca polysulfide)
10 gal/a = 75% kill of overwinteringfruiting structures.
Coverage is an issue
Togninia minima
Botryosphaeria obtusa
Phaeomoniella
0
5
10
15
20
25
30
35
40
45
50
55
60
7/9
/07
12/9
/07
19/9
/07
25/9
/07
1/1
0/0
7
8/1
0/0
7
15/1
0/0
7
23/1
0/0
7
30/1
0/0
7
7/1
1/0
7
20/1
1/0
7
27/1
1/0
7
5/1
2/0
7
13/1
2/0
7
20/1
2/0
7
28/1
2/0
7
7/1
/08
14/1
/08
22/1
/08
29/1
/08
4/2
/08
11/2
/08
18/2
/08
25/2
/08
3/3
/08
11/3
/08
17/3
/08
24/3
/08
31/3
/08
7/4
/08
15/4
/08
21/4
/08
28/4
/08
5/5
/08
13/5
/08
20/5
/08
27/5
/08
2/6
/08
9/6
/08
16/6
/08
23/6
/08
30/6
/08
7/7
/08
15/7
/08
22/7
/08
29/7
/08
4/8
/08
11/8
/08
18/8
/08
26/8
/08
1/9
/08
9/9
/08
15/9
/08
23/9
/08
30/9
/08
7/1
0/0
8
14/1
0/0
8
21/1
0/0
8
28/1
0/0
8
3/1
1/0
7
10/1
1/0
8
17/1
1/0
8
25/1
1/0
8
1/1
2/0
8
9/1
2/0
8
16/1
2/0
8
23/1
2/0
8
30/1
2/0
8
6/1
/09
13/1
/09
20/1
/09
27/1
/09
3/2
/09
10/2
/09
18/2
/09
24/2
/09
28/2
/09
4/3
/09
10/3
/09
17/3
/09
25/3
/09
1/4
/09
7/4
/09
15/4
/09
22/4
/09
1/5
/09
7/5
/09
15/5
/09
22/5
/09
Bot spores Precipitation (mm) Temperature (C)
Epidemiology of Botryosphaeriaceae spp. in California
Vaseline slides spore trapping results in Monterey County
Bot spores values = Total spores / 2 ml of H2O
Úrbez-Torres et al. Plant Dis. (In revision)
Chardonnay 2008-2009 Time Course Inoc
November December
January February
0
10
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40
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60
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80
90
100
T1 T2 T3 T4 T5 T6 T7 T8
% o
f in
fec
ted
wo
un
ds
Lasiodiplodia theobromae
0
10
20
30
40
50
60
70
80
90
100
T1 T2 T3 T4 T5 T6 T7 T8
% o
f in
fecte
d w
ou
nd
s
Lasiodiplodia theobromae Neofusicoccum parvum
0
10
20
30
40
50
60
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80
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100
T1 T2 T3 T4 T5 T6 T7
% o
f in
fecte
d w
ou
nd
s
Lasiodiplodia theobromae Neofusicoccum parvum
0
10
20
30
40
50
60
70
80
90
100
T1 T2 T3 T4 T5%
of
infe
cte
d w
ou
nd
s
Lasiodiplodia theobromae Neofusicoccum parvum
11-04-08 11-16-08 11-28-08 12-10-08 12-22-08
12 d 24 d 36 d 48 d 60 d 72 d 84 d
12 d 24 d 36 d 48 d 60 d 72 d 84 d
1-02-09 1-14-09 1-26-0912-10-08 12-22-08 1-02-09 1-14-09 1-26-09 2-07-09 2-19-09 3-03-09
12 d 24 d 36 d 48 d 60 d 72 d
1-02-09 1-14-09 1-26-09 2-07-09 2-19-09 3-03-09 3-15-09
12 d 24 d 36 d
2-07-09 2-19-09 3-03-09 3-15-09
0
10
20
30
40
50
60
70
80
90
100
T1 T2 T3
Lasiodiplodia theobromae Neofusicoccum parvum
12 d
3-03-09 3-15-09
March
Canes are mechanically pruned (10-15 buds) late fall - early winter
Double Pruning-First pruning in Nov-Jan
Final pruning (2 buds) late February - early March
Eutypa dieback Canker
Botryodiplodia theobroma=Botryosphaeria rhodina=Lasiodiplodia theobromae
● Botryosphaeria canker “Bot Canker” in California 1990
Botryosphaeria Canker Department of Plant Pathology, UC Davis
“Bot Canker”
Disease Cycle
Old pruning woundsPruned debris on the ground
Late fall - winter
Fruiting bodies (Pycnidia) Spores (conidia)
Blockage of vascular system
Yield losses / Death of the plant
Spore release:RainfallSprinkler irrigationFog
Canes are mechanically pruned (10-15 buds) late fall - early winter
Double Pruning Final pruning (2 buds) late February -early March
Effective Products Against Canker Pathogens
DMI’s- some have activity against Eutypa (Rally, 2X) Benzimidazole- Excellent activity against all pathogens (Topsin M,
2X) B- excellent activity against Eutypa (B-LOCK, 1X) Vitiseal with or w/o Rally + Topsin M
Paint or daub 1X Spray (1: 9 dilution)1X
Biological’s- good activity if applied 2 weeks before infection (Trichoderma, Cladosporium)
New products being tested BSP tractor application Nanofiber hand application
Fungicide Application: Rally + Topsin MPowdery Mildew & Canker Disease Control
Thank You!
Resistance Management
Aim- Reduce Selection pressure to prevent further buildup
of resistant strains.
Use mixes or alternate use of fungicides with different
modes of action i.e. DMI’s and Strobilurin’s, Quinoxyfen,
Boscalid etc.
Should not use within class chemistry for mixes or
alternations.
Make sure spray coverage is not an issue
What does Mildew Index mean???
Index = 0 to 30 Spray interval lengthened
Stop applications
No reproduction
Index = 40 to 50 Spray interval normal
Reproduction 15 days
Index = 60-100 Spray interval shortened
Reproduction 5 days
![P. Gubler, K. Morita, and M. Oka, Phys. Rev. Lett. 107, 092003 (2011) K. Suzuki, P. Gubler, K. Morita, and M. Oka, arxiv:1204.1173 [hep-th]](https://img.pdfslide.net/doc/110x75/56649f0e5503460f94c22a75/p-gubler-k-morita-and-m-oka-phys-rev-lett-107-092003-2011-k-suzuki.jpg)
