Scheduling copper applications and management of greasy spot and alternaria brown spot

M. Dewdney1, C. Fraisse2, T. Zortea2, J. Yates1 1University of Florida, IFAS, Citrus Research and Education Center, Lake Alfred

2University of Florida, IFAS, Agricultural and Biological Engineering, Gainesville

Purpose of the Scheduler

•To improve timing of copper sprays over the calendar-based spray schedule of applications every 21 days

•To warn when residue levels are lower than expected

•To avoid unnecessary copper sprays

•To reduce management costs

•To reduce the environmental

impact of copper applications

Diseases Effectively Managed with Copper

• Foliar fungal diseases

– Melanose

– Greasy Spot

– Alternaria brown spot

– Citrus scab

– Black spot

• Non-systemic bacterial diseases

– Citrus canker

Copper Facts

• Copper residue is significantly

reduced by rain washing

• Copper does not move once dried

• Copper residue is cracked by

fruit growth

As the fruit grows, copper must be reapplied to continually cover the fruit as it becomes larger

Proper Application of Copper

•Use label rate recommended for a disease

•Be cautious in hot weather (> 94°F; 34C) –Phytotoxicity can occur more easily in hot weather

•Potential for phytotoxicity can be reduced with greater water volume per acre

•Complex tank mixes, oil applications, and nutritional materials contribute to phytotoxicity

•Aerial applications not likely to get adequate penetration of canopy for control, best method is with an air blast sprayer

How the scheduler operates

•Incorporates rainfall data from FAWN (Florida Automated Weather Network-www.fawn.ifas.ufl.edu) or own weather data

•Incorporates data on copper residue degradation

•Incorporates fruit growth size

•This program may not be

suitable for other citrus production

regions due to varying climatic

conditions and fruit growth habits The blue specks are copper residue

What’s New?

• Lay out

• Select weather option and scion first

• Metric units

Select Bloom

Every 21- day Schedule

• Have insufficient coverage for 6 days

• About perfect timing for third spray

By Forecasts of Scheduler

• Moved first spray up 8 days

• Did not move third spray

What’s New?

• Mobile version www.Agroclimate.org/mobile

– Under tools

Location, Bloom, Spray Date

1

3

2

Cultivar and Results

Gives results in table format

Copper Residue Summer 2011

Valencia

Date

Jun Jul Aug Sep Oct Nov

To

tal d

aily

ra

infa

ll (m

m)

0

20

40

60

80

100

120A

vera

ge

co

pp

er/

surf

ace

are

a (

g/c

m2)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Copper Residue Summer 2011

Grapefruit

Date

Jun Jul Aug Sep Oct Nov

To

tal d

aily

ra

infa

ll (m

m)

0

20

40

60

80

100

120A

vera

ge

co

pp

er/

surf

ace

are

a (

g/c

m2)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Future Plans

• Incorporate additional fruit growth data

– Two seasons collected

– Data collection resumed this year

• Potential Features

– Allow data to be stored on a server to avoid inputting the information every time

– Send alerts, as requested

– Login service

GREASY SPOT

Greasy Spot Disease Cycle Mycosphaerella citri

• Control products

– Copper - All formulations

– Strobilurin fungicides (Abound, Gem, Headline, Quadris Top and Pristine)

• Only once a year for greasy spot

Mar Apr May Jun Jul Aug Sept Oct

Oranges

Valencia

Grapefruit

Greasy Spot Control

• Fungicides effective for greasy spot – Enable – good substitute for copper if concerned

with stippling

• Petroleum oil – Less consistent control on fruit than copper

– Can be mixed with all other fungicides

Further Products

Treatment Metallic Cu (%)

Rate (lbs/acre)

Metallic Cu/acre

Kocide 3000 30 2.0 0.66

Kocide 3000 30 2.5 0.75

Nu-Cop 50 HB 50 2.0 1.00

Nu-Cop 20 HB 20 1.25 0.25

Nu-Cop 20 HB 20 1.875 0.375

Nu-Cop 20 HB 20 2.5 0.50

Basic HB 53 4 2.12

Basic HB 53 8 4.24

Formulations and Products Rates Tested on Grapefruit

Treatment Metallic Cu (%)

Rate (lbs/acre)

Metallic Cu/acre

IQV 40 DF 40 1.5 0.60

IQV 40 DF 40 2.0 0.80

IQV 40 DF 40 2.5 1.00

Untreated Control (UTC) -- -- --

Formulations and Products Rates Cont.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8 a

b bc bcd bcd cde de de e e e e

Greasy Spot Control on Leaves (lb/acre)

0

0.1

0.2

0.3

0.4

0.5

0.6

a ab ab abc bc bcd bcd bcd cde de

ef f

Rind Blotch Control on Fruit (lb/acre)

70

75

80

85

90

95

a ab

abc abc abc bc bc

bc bc c c c

% Marketable Fruit (lb/acre)

ALTERNARIA BROWN SPOT

Alternaria Brown Spot Disease Cycle Caused by Alternaria alternata

• Common control products

– Copper - All formulations

– Strobilurin fungicides (Abound, Gem, Headline, Quadris Top and Pristine)

• If severity high, useful for early sprays but also when hot

Mar Apr May Jun Jul Aug Sept Oct

Tangerines

Alternaria Brown Spot Control

• Ferbam

• Start with clean trees

• Increase air drainage in grove when planting

• Avoid excessive growth promotion

– Too much nitrogen

– Overwatering

– Severe hedging

– High vigour rootstocks

Cultural Controls

Fungicide Resistance

• Where the target population is no longer sensitive enough to a fungicide for sufficient control

• Occurs in response to the repeated use of a fungicide or related fungicides

– Field resistance

• Often becomes apparent with sudden total failure of control

Alternaria alternata isolates recovered in field survey (2010-2011)

Resistant

Sensitive

64% 36%

N = 318

Strobilurin Resistance In Florida

Number of isolates according to cultivar

Cultivar

Dancy Lee Minneola Murcott Orlando Sunburst

No

. Is

ola

tes

0

20

40

60

80

100

120

140

160

Resistant

Sensitive

Alternate Modes of Action?

• Currently registered – Copper

– Ferbam

• Newer products released 2010 – Quadris Top and Pristine

• Mixtures of strobilurins and novel modes of action

– Shown to be efficacious in two years of trials on Alternaria Brown Spot

– Two years of data on Melanose and Greasy Spot Rind blotch also effective

Programs with Pristine in 2010 Program April 20 May 21 June 16 July 7

Program 1 Boscalid (6.5 oz/acre) + Kocide 3000 (2.5 lb/acre)

Kocide 3000 (3.5 lb/acre)

Boscalid (6.5 oz/acre) + Kocide 3000 (2.5 lb/acre)

Kocide 3000 (3.5 lb/acre)

Program 2 Boscalid (6.5 oz/acre)

Kocide 3000 (3.5 lb/acre)

Boscalid (6.5 oz/acre)

Kocide 3000 (3.5 lb/acre)

Program 3

BAS703 (5.48 oz/acre) + Non-ionic surfactant (1 pint/acre)

Kocide 3000 (3.5 lb/acre)

Bas 703 (5.48 oz/acre) + Non-ionic surfactant (1 pint/acre)

Kocide 3000 (3.5 lb/acre)

Program 4 Pristine (18.5 oz/acre)

Kocide 3000 (3.5 lb/acre)

Pristine (18.5 oz/acre)

Kocide 3000 (3.5 lb/acre)

Program 5 Untreated control Untreated control

Untreated control Untreated control

Efficacy on Minneola

TreatmentsUntre

ated control

Program 1

Program 2

Program 3

Program 4

Dis

ea

se

Ra

tin

g

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

a

b b

c c

Treatments

Program 4

Program 3

Program 2

Program 1

Untreated Contro

l

% M

ark

eta

bilit

y

0

10

20

30

40

50

60

70

80

90

100a ab

b b

c

Programs with Quadris Top, 2010

Date April 1 May 4 June 2 June 14 July 9 Aug. 9

Program 1 Untreated control

Untreated control

Untreated control

Untreated control

Untreated control

Untreated control

Program 2 Headline (12 fl oz)

Kocide 3000 (3.5 lb)

Headline (12 fl oz)

Kocide 3000 (3.5 lb)

Kocide 3000 (3.5 lb)

Headline (12 fl oz) + 2% 435 Oil

Program 3 Quadris Top (12 fl oz)

Kocide 3000 (3.5 lb)

Quadris Top (12 fl oz)

Kocide 3000 (3.5 lb)

Kocide 3000 (3.5 lb)

Quadris Top (12 fl oz) + 2% 435 Oil

Program 4 Quadris Top (15.4 fl oz)

Kocide 3000 (3.5 lb)

Quadris Top (15.4 fl oz)

Kocide 3000 (3.5 lb)

Kocide 3000 (3.5 lb)

Quadris Top (15.4 fl oz) + 2% 435 Oil

Program 5 Quadris Top (15.4 fl oz)

SA 123 (6 pints)

Quadris Top (15.4 fl oz)

SA 123 (6 pints)

SA 123 (6 pints)

Quadris Top (15.4 fl oz) + 2% 435 Oil

Program 6 SA 123 (6 pints)

Kocide 3000 (3.5 lb)

SA 123 (6 pints)

Kocide 3000 (3.5 lb)

Kocide 3000 (3.5 lb)

SA 123 (6 pints)

Efficacy on Murcott with Strobilurin Resistance

TreatmentsUntre

ated Control

Program 2

Program 6

Program 3

Program 4

Program 5

Dis

ea

se

Ra

tin

g

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0 a

b bc c

d

Treatments

Program 5

Program 3

Program 4

Program 6

Program 2

Untreated Contro

l

% M

ark

eta

bilit

y

0

10

20

30

40

50

60

70

a

b bccd

d

e

Looking for Tangerine Groves

• Sampling for strobilurin resistance

• Want to sample all groves with or without problems

• Contact Megan Dewdney

– CREC ph. 863-956-1151

Questions?