Benchmarking the efficacy & economics of the Brassicaspot™ disease predictive models

against weekly sprays & fungicide alternatives for control of white blister on broccoli

Dr Liz Minchinton, Des Auer, Lindsay Trapnell, Dr Joanna Petkowski, Prof Roy Kennedy and Fiona Thomson

White blister• Ist report on broccoli 2001-02• Up to 100% crop losses• Complete change of cv• Albugo candida (Oomycete)• Infect young tissue

Broccoli• Grown year-round• Over-head irrigation

White blister model: Brassicaspot™

• Developed by Dr Roy Kennedy & Giles – UK• UK consultants• UK growers reduce 50% sprays• Model:

– Temperature– Rainfall– Relative humidity– Leaf wetness

White blister model: Brassicaspot™White Blister Crop Walking

27Apr05 11May05 25May05 8Jun05 22Jun05 6Jul05 20Jul050

100

200

300

Min / Max Temperatures

27Apr05 11May05 25May05 8Jun05 22Jun05 6Jul05 20Jul050

10

20

Hours of Leaf Wetness

27Apr05 11May05 25May05 8Jun05 22Jun05 6Jul05 20Jul050

10

20

BrassicaspotI™ (Old)• Red bars – high risk • Yellow bars – moderate risk• Green bars – low risk• Non bars – no risk of white

blister

Time to lesion Appearance

Dis

ease

Inde

x

22Dec08 29Dec08 5Jan090.0

0.5

1.0

1.5 5% Infection 50% Infection

White Blister Crop Walking

30Nov08 7Dec08 14Dec08 21Dec08 28Dec08 4Jan090

100200300400500600700

BrassicaspotII™ (New)Spray when blue line crosses the red threshold line = maximum spore release

Spray

• Brassicaspot I & II (Amistar), Weekly (Cu), Control (0)• Model reduced 90% (13) of sprays• Timing of model sprays varied• 25% increase in profit c/w weekly• Less H2O c/w commercial crop

Werribee:cv Ironman

Efficacy of treatments to control white blister Treatment contributions to profit/ha (‘000)

0

5

10

15

20

25

Control (0)

Brassicaspot II (2)

Brassicaspot I (2)

Weekly Cu (15)

Treatment

Con

tribu

tion

to p

rofit

('00

0)0

1

2

3

4

5

6

Control (0)

Brassicaspot II (2)

Brassicaspot I (2)

Weekly Cu (15)

Treatment (bars of different colour differ significantly)

Inci

denc

e of

whi

te b

liste

r on

head

s (%

)

Rosebud: Brassicaspot v/s weekly & alternatives

• Cv Grevillea

• Models reduced 10-11 sprays

• S.lyticus 58% efficacy

• Efficacy of weekly > models

• Economics weekly > models

Control of white blister on broccoli heads(Bars of different colour differ significantly)

Treatment contributions to profit/ha (‘000)

0

20

40

60

80

100

Control (0)

SLS (9)

BrassicaspotII (3)

S. lydicus (9)

BrassicaspotI (2)

Weekly (13)

Treatment

Inci

denc

e on

hea

ds (%

)

0

2

4

6

8

10

12

14

16

18

20

Weekly Cu(13)

Brassicspot I(2)

S. lydicus (9)

Brassicaspot II(3)

Control (0)

SLS (9)

Treatment

Con

trib

utio

n to

pro

fit ($

'000

)

Post harvest trial• Werribee South, cv Viper

• No significant difference in field

• Selected clean heads

• Post harvest: 5 ºC/12d 12 ºC/3d

• Post harvest less disease on Weekly

Post harvest treatment

Broccoli head with symptoms after post harvest storage

Incidence of white blister on Broccoli heads in the field

0

1

2

3

4

5

Brassicaspot I (2) Weekly (7) Control (0)

Treatment

Inci

denc

e of

whi

te b

liste

r on

broc

coli

head

s (%

)

0

5

10

15

20

25

30

Weekly (7) Brassicaspot I (2) Control (0)Treatment

Inci

denc

e of

whi

te b

liste

r on

broc

coli

head

s po

st h

arve

st s

tora

ge (%

)

White Blister Crop W

27Apr05 11May05 25May05 8Jun05 22Ju0

100

200

300

Min / Max Tempera

27Apr05 11May05 25May05 8Jun05 22Ju0

10

20

Hours of Leaf Wetn

27Apr05 11May05 25May05 8Jun05 22Ju0

10

20

Spore trapTest kit

Development of in-field spore detection kit

Brassicaspot disease predictive model

• In-field spore test kit = sporulation of A. candida

ConclusionEfficacy & economics• Weekly sprays > Models > Alternative• Models were effective in drier c/w wet conditions• Weekly Cu advantages/disadvantages• Incorporate post harvest treatments• Spore-test kit will improve efficacy of model

(sporulation & infection)

AcknowledgmentsProject team:Liz Minchinton - DPIVcRoy Kennedy – UKAlison Wakeham - UKVictor Galea - UQChrys Akem - QDPI&FHoong Pung - PeractoDes Auer - DPIVicJoanna Petkowski - DPIVicFiona Thomson - DPIVicRobert Faggian -DPIVic

Department of Primary Industries Victoria, Federal Government of Australia and Horticulture Australia Ltd

Enhance model - by adding sporulationSpore trapping Werribee South

Spore numbers over a 24-hr period, Bars indicate Brassicaspot model: red=high risk;yellow=medium risk; green=low risk.

0

50

100

150

200

250

300

350

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Infe

ctio

n In

dex

(Bra

ssic

aspot

)

0

100

200

300

400

500

600

700

Spore Count (24 hrs)

Edwards Lane, Werribee Sth Harrisons Road, Werribee Sth

Oct- Nov 2009 Nov – Dec 2009