Diagnostic agronomy,
Dubbo, 18th October 2010
Allan Mayfield,
Clare, SA
Nutrition
P - P audits, plant tests, P rate test strips
N - Soil N, plant NIR & sap N,
NDVI (GreenSeeker), look at it!,
Baldock model, Yield Prophet, experience
Other nutrients – visual symptoms, plant tests
(diagnosis & monitoring)
‘Berkshires’
Nutrition management in zones
EM38 Vertical
Soil water
Yield Prophet
Sensors – eg Sentek
Metal push probes
Using zones to improve soil water
assessments
Weeds
Acceptable weed control is typically well below
the economic thresholds for yield loss
For herbicide resistance – Quick-Test (green
plants), seed tests, herbicide test strips
Weed control according to zones
Ryegrass % cover
/canola % cover
Diseases
Diseases
Pre-emptive for root diseases – Predicta B test,
observations in previous crop(s)
For foliar diseases – when symptoms or pre-emptive.
Fungicide use now very common.
Varietal resistance can be a major factor in crop
selection (eg CCN, stem rust, canola blackleg)
Insects
Some pre-emptive treatments used, especially for
canola & virus control, otherwise, treat as needed.
Close monitoring of crops can be critical
Need to identify beneficials as well as pests
Gaps include thresholds - the understanding of effect
of beneficials, and the impact of pesticides
Grower’s situation & attitude to risk
is important
Retrospective monitoring Improvements in water use efficiency
Water use efficiency (kg/mmGSR),
5 year average, wheat, Redhill, SA.
2008
2006
2004
2002
2000
1998
1996
1994
1992
1990
1988
1986
1984
1982
1980
1978
1976
22
20
18
16
14
12
10
8
6
4
2
0
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Alan Mayfield – diagnostic agronomy