management strategies for brassica production Aaron Heinrich and Alex Stone Dept of Horticulture Its called clubroot for a reason Hosts And more Susceptibility varies by species and cultivar ID: 332148
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Slide1
Clubroot management strategies for brassica production
Aaron Heinrich and Alex StoneDept. of HorticultureSlide2
It’s called clubroot for a reason…Slide3
Hosts
And more…
Susceptibility varies by species and cultivarSlide4
Clubroot’s impact
“In the past 3 years [2009-12] we have had a 25% loss in our brassica crops due to clubroot, costing us between $60-80K/year. We are running out of clubroot
free ground on which to rotate brassica crops.” “In 2013 we experienced a 30 to 50% loss in 5 of our highest yielding brassica crops this year totaling $20K. Three
years ago we played out this scenario knowing that our future looked quite bleak... We need to figure out a way to grow brassicas in fields that have a high clubroot population.”Slide5
Is incidence increasing?
Increase in radish and turnip cover crop seedMore farms with 15+ year history of short rotations (<4 yrs
)Increased brassica production to meet demandMore overwintering brassica cropsSlide6
Disease cycle
Disease severity affected by:MoistureTemperature
Low soil pHSpore densitySlide7
Management strategies
Rotation5 to 7 years out of brassicasSanitationpH manipulationlime to pH ≥7.0
Boron?Biologic controls?Resistant cultivars?Water management
Control not eradication is the goalSlide8
Management strategies
Rotation5 to 7 years out of brassicasSanitation
pH manipulationlime to pH ≥7.0Boron?Biologic controls?
Resistant cultivars?Water managementControl not eradication is the goalSlide9
Liming success in California1978 clubroot
first identifiedStarted aggressive liming programStill present but controlledSlide10
2012 clubroot survey
Response from 19 of 37 farmers83% had used lime as a control21% aimed for pH ≥6.8
52% verified if target pH reached26% said liming helpedIs liming effective in western Oregon?
Are farmers liming “correctly”?Slide11
2014 Greenhouse study: Cauliflower
Control
pH= 5.7Infection rate: 100%Avg plant wt:
0.3 gLimedpH ≥ 7.1Infection rate: <4%Avg
plant
wt
:
0.8 gSlide12
2014 Greenhouse studies: cauliflower
Dead/
dying
Minor clubs on lateralsSerenade not effective Boron reduced severity but not infection rate
Increasing pH from 5.7 to 6.3 slightly effective
pH >7.0 highly effective
pHSlide13
2014 Field studies: broccoli & kaleSlide14
2014 Field studies
pH 6.7
pH 7.3Slide15
2014 Field studies: Lacinato Kale
In
3
field trials:44-77% reduction in infection rate74-90% reduction in disease severitySerenade and B (4 and 8
lb
/A) not effective in these studies
>50% clubbed
<50% clubbed
clubs on laterals
pHSlide16
Why is there a difference between greenhouse and field studies?
Treatment
pH
Infected plants (%)Control
6.0
91
Limed (
field mixed
)
7.0
34
Limed (
sieved/mixed
)
7.0
6
(Adapted from
Dobson et al., 1983)
Clubroot
field trial: western WA
Same pH, different infection rateSlide17
Importance of uniform soil mixing
Treatment
pH
Infected plants (%)Microscale pH variability (pH unit)
Control
5.9
100
0.7
Limed (
field mixed
)
6.4
86
1.1
Limed (
sieved/mixed
)
6.5
25
0.3
(Adapted from
Dobson et al, 1983
)
Clubroot
greenhouse trial
Under field conditions, 100%
clubroot
control highly unlikely with liming.Slide18
Implementing a successful clubroot liming programSteps:
Estimate lime requirementChoose lime materialApply at correct time
Incorporate thoroughly Measure soil pHTarget pH ≥ 7.0Slide19
Step 1: Estimate lime requirement
Use SMP buffer test and OSU pub. EM 9057 to raise pH to ~6.7 (6” incorporation depth)Multiply SMP buffer rate by 1.5-2.0 to increase pH >6.7
SMP Buffer
1.5-2.0 x SMP BufferSlide20
Step 2: Choose lime material
ProductFormCost material only ($/ton)
Microna Ag-H2O
Powder210Microna Access
Powder
105
Ash Grove Ag lime
Powder
60
CalPril
Prilled
260
Microna
Garden Pearls
Prilled
392
Most reactive
Least reactive
Most economical, similar performanceSlide21
Using pelleted limeAdvantagesEasy to handle
DisadvantagesExpensive Less reactive (i.e. requires higher rates)Requires additional stepsSlide22
Using pelleted lime efficiently If incorporated too soon, the pellets will not disperse!
Option 1:Broadcast Apply irrigation (or wait for rain)TillOption 2:Broadcast 1
st tillage If sufficient moisture, no irrigation needed2nd tillage
1.5 minutesSlide23
Step 3: Apply at correct timeApply 1
wk minimum before plantingSlide24
Step 4: Incorporate thoroughly
Treatment
pH
Infected plants (%)Microscale pH variability (pH unit)
Control
5.9
100
0.7
Limed (
field mixed
)
6.4
86
1.1
Limed (
sieved/mixed
)
6.5
25
0.3
Clubroot
greenhouse trial
(Adapted from Dobson et al., 1983) Slide25
Step 5: Measure soil pHSoil sample!
Verify if target pH reachedCaution: if you can see unreacted lime, the soil test pH may be higher than what the plants are experiencing!Slide26
Integrated Club
root Management
ScoutingRotation (4-5+ yrs)Maintain soil pH
≥6.8Plant resistant varietiesIrrigation managementNo one strategy is enough!Slide27
AcknowledgementsWe thank our farmer partners for their collaboration as well as the following organizations for funding this project: The Agriculture Research Foundation
Oregon Processed Vegetable Commission