update on managing citrus black spot, citrus canker, and
TRANSCRIPT
Update on Managing Citrus Black Spot, Citrus Canker, andPostbloom Fruit Drop
Megan M. DewdneyAssociate Professor of Plant Pathology and Extension Specialist University of Florida, IFASCitrus Research and Education Center
CITRUS CANKER
What is new in the Production guide?o Actigardo Not a traditional pesticide
– Plant activator that triggers natural defense mechanism called systemic acquired resistance (SAR)
– No direct effect against pathogenso Activates plant defense system prior to diseaseo Active ingredient: Acibenzolar‐S‐methyl
– Group 21 fungicide mode of action• Not a reference to efficacy against bacteria
Actigard trialso Conducted by Jim Grahamo Recently registered for use on
citrus in Floridao Intended to supplement copper
applications for fruit protection– Some foliar activity on non-
bearing trees
Chemical versus natural induction of SARo Can be naturally or chemically induced
– Natural induction is caused by a low level of plant pathogen attack
– Systemic throughout the planto Disease can develop before natural induction
becomes effectiveo High inoculum levels can overcome activationo Chemical induction has the advantage of being
able to occur before disease onset– Apply in anticipation of disease
Application dates for non-bearing trials (2 year-old ‘Vernia’)
Treatment Rate per tree
# of apps 2011
Untreated control ‐‐‐ ‐‐‐ ‐‐‐Actigard drench (0.007 oz) 4 4/1, 6/1, 7/29, 9/20Actigard micro‐sprinkler
(0.007 oz) 4 4/1, 6/1, 7/29, 9/20
PlatinumActigard drenchAdmire Pro
(0.035 fl oz)(0.007 oz)(0.046 fl oz)
232
4/1, 8/34/28, 6/1, 7/136/1, 7/29
Actigard drenchKocide 3000 spray
(0.007 oz)(0.0667 oz)
410
4/1, 6/1, 7/29, 9/20Every 21 days from 4/1 to 10/5
Kocide 3000 spray (0.0667 oz) 10 Every 21 days from 4/1 to 10/5
Graham and Myers, 2013 Crop Protection
Non-bearing trial 2011 ‘Vernia’
0
10
20
30
40
50
60
70
UTC Actigarddrench
Actigardsprinkler
Platinum,Actigard,Admire
Actigarddrench,
Kocide spray
Kocide spray
% le
aves
a
c
b
c cc
Graham and Myers, 2013 Crop Protection
Trees rated in October
Application dates for bearing trial on 7 year-old ‘Ruby red’ grapefruit Treatment # of
appsPer tree rate
Application dates (2015)
Untreated control ‐‐‐ ‐‐‐ ‐‐‐Actigard drench 4 0.031 3/16, 5/15, 7/15, 9/15Actigard drenchKocide 3000 spray
410
0.0310.459
3/16, 5/15, 7/15, 9/15Every 21 days from 3/16 to 9/21
Kocide 3000 spray 10 0.459 Every 21 days from 3/16 to 9/21
Bearing trial on 7 year-old ‘Ruby red’ grapefruit in 2015 (>8 ft. tall)
0
10
20
30
40
50
60
70
UTC Actigard Actigard, Kocide Kocide
% fr
uit w
ith le
sion
s
totaloldyoung
Fruit evaluated October 13a
a
ab
b
bc c
bc
b
b
b
Jim Graham
Actigard use recommendations
o New plantings (0‐3 year‐old trees)– Start as first growth beginning and continue non‐
bearing cycle– Soil applied neonicotinoid insecticides can induce
SAR and can be alternated with Actigard– Use other canker management methods as well– Maintain SAR throughout season
o Objective to limit the establishment of canker during juvenile phase
Actigard use recommendationso Young and mature bearing plantings
– Initiate post‐bloom, prior to conditions favorable to canker
– Use other canker management methods as well– 4‐5 year‐old trees
• Continue throughout spring, summer, and fall on 30‐60 day intervals depending on tree size and planting density
– 6+ year‐old trees • Continue throughout summer on 30‐45 day intervals
depending on tree size and planting density
o Can limit foliar lesion development and reduces inoculum potential
POSTBLOOM FRUIT DROP
Buttons in 0.25m2/tree sideJanuary 12-17, 2017
Valencia Old Buttons Fort Meade 2017
Fungicide treatment
Rhyme + Ferbam + Cohere
Luna Experience + Activator 90Topsin M
Topguard + Ferbam + Cohere
Luna Sensation + Activator 90 UTCPristine
Priaxor 9 + Cohere
Topguard 5 + Cohere
Rhyme + Cohere
Luna Sensation + Ferbam + Activator 90
Priaxor 11 + Cohere
Topguard 8 + Cohere
Luna SensationEndura
Quadris Top
Num
ber o
f old
but
tons
per
tree
sid
e (0
.25
m2 )
0
5
10
15
20
25
30
35
40
45
AA A
AB
ABCABC ABCABCABC ABC ABC
BCD CDCD CD
D
Trial detailso Valencia oranges in Fort Meade area
– Infected with HLB but relatively healthy– Off‐season bloom on most trees– Trees in block were slow to bloom compared to
others in area– Trees selected for uniform disease pressure
• HLB and PFD
o Applications made on recommendation of PFD model
o Applications on March 24
PFD trials 2017 – ValenciaProduct Active Ingredient Rate/acreRhyme 2.08 SC Cohere
Flutriafol 5 oz.16 fl oz.
Rhyme 2.08 SCFerbam GranufloCohere
FlutriafolFerbam
7 oz.5 lb16 fl oz.
Topguard EQ 4.3SC Cohere
Flutriafol + azoxystrobin 5 oz.16 fl oz.
Topguard EQ 4.3SCCohere
Flutriafol + azoxystrobin 8 oz.16 fl oz.
Topguard EQ 4.3SCFerbamCohere
Flutriafol + azoxystrobinFerbam
5 oz.5 lb16 fl oz.
Pristine Pyraclostrobin + boscalid 18.5 oz.Endura boscalid 6.5 oz.PriaxorCohere
Pyraclostrobin + fluxapyroxad 9 fl oz.16 fl oz.
PFD trials 2017 – Valencia cont.Product Active Ingredient Rate/acrePriaxorCohere
Pyraclostrobin + fluxapyroxad 11 fl oz.16 fl oz.
Topsin M Thiophanate‐methyl 2.0 lbLuna Sensation Trifloxystrobin + fluopyram 6.5 fl oz.Luna SensationActivator 90
Trifloxystrobin + fluopyram 6.5 fl oz.0.25% v/v
Luna SensationFerbamActivator 90
Trifloxystrobin + fluopyramFerbam
6.5 fl oz.5 lb0.25% v/v
Luna ExperienceActivator 90
Tebuconazole + fluopyram 8 fl oz.0.25% v/v
Quadris Top Azoxystrobin + difenoconazole 15.4 fl oz.Untreated control ‐‐ ‐‐
Buttons in 0.25m2/tree sideJune 5-6, 2017
Valencia New Buttons Fort Meade 2017
Fungicide treatment
Topgd. + Ferb. + Coh.
Luna Sen.+ Ferb. + Act.Topsin M
Rhyme + Ferbam + Cohere UTC
Luna SensationPristine
Topguard 5 + Cohere
Priaxor 11 + Cohere
Luna Experience + Activator 90
Rhyme + Cohere
Priaxor 9 + Cohere
Topguard 8 + CohereEndura
Luna Sensation + Activator 90
Quadris Top
Num
ber o
f new
but
tons
per
tree
sid
e (0
.25
m2 )
0
2
4
6
8
10
12
14
16
18
20
22
No Signficant Differences
Number of fruit/tree sideJuly 20-27, 2017
Valencia Fruit Fort Meade 2017
Fungicide treatment
Endura
Topguard 5 + Cohere
Luna Sensation
Rhyme + Ferbam + Cohere
Rhyme + Cohere
Quadris Top
Luna Experience + Activator 90Topsin M
Topguard + Ferbam + Cohere UTCPristine
Priaxor 9 + Cohere
Priaxor 11 + Cohere
Topguard 8 + Cohere
Luna Sensation + Ferbam + Activator 90
Luna Sensation + Activator 90
Num
ber o
f fru
it pe
r tre
e si
de
0102030405060708090
100110120130140150160170180190200210
A
AB ABC ABC ABCA-DBCD
B-ECDE
E E
DE
ABCA-D
BCD B-E
Conclusionso Weather was very dry for major bloomo Significant differences in the number of
buttons prior to trial initiation despite random selection
o The number of buttons for 2017 did not have significant differences
o Most treatments did not have significantly more fruit than UTC– Likely because of low disease pressure
Buttons in 0.25m2/tree sideJanuary 26-27, 2017
Navel Old Buttons Polk City 2017
Fungicide treatment
Headline + Ferbam 6Abound
Headline + Ferbam 4 UTC
Quadris Top + Abound + activator 90
Abound + activator 90Headline
Quadris Top + Abound
Headline + Ferbam 5Ferbam 5
Ferbam 6
Num
ber o
f old
but
tons
per
tree
sid
e (0
.25
m2 )
0
5
10
15
20
25
A ABABC ABC ABC A-D A-D
BCDCD CD
D
Trial detailso Navel oranges in Polk City area
– Heavily infected with HLB– Off‐season bloom on most trees– Trees hedged on one side in January
• Consequence bloom not consistent on trees but majority at end of March
• Bloom very long on trees– Trees selected for uniform disease pressure
• HLB and PFD but more trees collapsed this year
o Applications made on recommendation of PFD model
o Applications on March 14 and 26
PFD trials 2017 – Navels Product Active Ingredient Rate/acreAbound Azoxystrobin 15.5 fl oz.
AboundActivator 90
Azoxystrobin 15.5 fl oz.0.25% v/v
Quadris TopAbound
Azoxystrobin + difenoconazoleAzoxystrobin
15.4 fl oz.3.2 fl oz.
Quadris TopAboundActivator 90
Azoxystrobin + difenoconazoleAzoxystrobin
15.4 fl oz.3.2 fl oz.0.25% v/v
Headline Pyraclostrobin 15 fl oz.
HeadlineFerbam
PyraclostrobinFerbam
15 fl oz.4 lb
HeadlineFerbam
PyraclostrobinFerbam
15 fl oz.5 lb
HeadlineFerbam
PyraclostrobinFerbam
15 fl oz.6 lb
Ferbam Granuflo Ferbam 5 lb
Ferbam Granuflo Ferbam 6 lb
Untreated control ‐‐ ‐‐
Buttons in 0.25m2/tree sideMay 19-22, 2017
Navel New Buttons Polk City 2017
Fungicide treatment
Headline + Ferbam 4Abound
HeadlineFerbam 5 UTC
Abound + activator 90
Headline + Ferbam 5
Headline + Ferbam 6Ferbam 6
Quadris Top + Abound
Quadris Top + Abound + activator 90
Num
ber o
f new
but
tons
per
tree
sid
e (0
.25
m2 )
0
2
4
6
8
10
12
14
16
18
20
22
24
26
No Signficant Differences
Number of fruit/tree sideJuly 19-20, 2017
Navel Fruit Polk City 2017
Fungicide treatment
Headline + Ferbam 6
Headline + Ferbam 4Headline
Headline + Ferbam 5 UTC
Quadris Top + Abound + activator 90
Abound + activator 90
Quadris Top + AboundFerbam 5
AboundFerbam 6
Num
ber o
f fru
it pe
r tre
e si
de
0
10
20
30
40
50
60
70
AA
BCCD
CDEEF
F
DE
B
F
G
Conclusionso Significant differences in the number of
buttons prior to trial initiation despite random selection
o The number of buttons from 2017 infectionhad no significant differences
o Some treatments significantly better than UTC
o Ferbam is still best when mixed with other fungicides– See poster to for details on economic benefit
Any Questions?