Can Doppler Radar Precipitation EstimatesAccurately Estimate Rainfall? |
Not always. Doppler precipitation estimates do not always compare well with rain gauges measuring precipitation on the ground. However, to use the AUPecan and AUPnut advisories, the radar must distinguish above 0.10 inches or below 0.10 inches. Doppler radar can be used to make this determination efficiently and with reasonable accuracy. For more information, see the abstract below. |
Assessment of Doppler Radar-based AU-pnut Leaf Spot Advisory for Use in Georgia. R. C. KEMERAIT*, G. HOOGENBOOM, R. G. McDANIEL, AND W. A. MILLS, III. Departments of Plant Pathology, University of Georgia, Tifton, GA, 31794; Department of Biological and Agricultural Engineering, University of Georgia, Griffin, GA 30223; University of Georgia Cooperative Extension Service, Waynesboro, GA 30830; and Southwest Georgia Research and Education Center, Attapulgus, GA 31715. Field trials were
conducted to verify the effectiveness of the Doppler radar-based AU-pnut
advisory in Georgia and compare rainfall data from ten weather stations
(Georgia Automated Environmental Monitoring Network) with Doppler radar
estimates. Data was collected from 1 May until 31 Oct 01 and field trials
were established at Tifton and Attapulgus with the cv . Georgia Green.
A factorial design was used at both sites where main effects were spray
schedule (14-d calendar vs. AU-pnut) and fungicide program. Fungicide
programs included 1) chlorothalonil, 1.5 pt/A, full season, 2) propiconazole,
2 fl oz/A, +chlorothalonil, 1 pt/A, sprays 1 and 2, azoxystrobin, 18.5
fl oz/, sprays 3 and 5, and chlorothalonil, 1.5 pt/A, sprays 4, 6, and
7; and 3) chlorothalonil, 1.5 pt/A, sprays 1, 2, and 7, and tebuconazole,
7.2 fl oz/A, sprays 3-6. All fungicide applications at Tifton were initiated
35 days after planting (DAP) while the AU-pnut and calendar treatments
in Attapulgus were initiated 24 and 34 DAP, respectively. Data from
all weather stations and the Doppler radar provided by the Agricultural
Weather Information Service, Inc., were in agreement 90.5% of the
time as to whether or not a rain event (accumulation >=0.10 in 24 h)
had occurred. Doppler radar provided false positive results (rain event
predicted but did not occur) 8.8% of the time and false negative results
(failed to predict a rain event) 0.7% of the time. At Tifton, all
plots received 7 fungicide applications; however, fungicide applications
for AU-pnut treatments were generally 3 or 4 days earlier than for the
calendar schedule. There was no interaction between spray schedule and
fungicide program. There were no differences in leaf spot control, severity
of southern stem rot, or yield between the calendar-based and the AU-pnut
programs, nor were there differences in leaf spot control or yield across
fungicide treatments. There was significantly more southern stem rot in
plots that received only chlorothalonil. At Attapulgus, 8 fungicide applications
were required for the AU-pnut schedule versus 7 for the calendar program.
There was a significant interaction between spray schedule and fungicide
program. For fungicide programs that included azoxystrobin or tebuconazole,
there were no differences in yield, leaf spot severity, or severity of
soilborne disease (Rhizoctonia limb rot + southern stem rot) based upon
spray schedule. Where chlorothalonil was used alone, leaf spot control
was better when fungicides were applied on the AU-pnut schedule rather
than the calendar program. Control of soilborne disease and yields were
significantly greater in plots that received azoxystrobin or tebuconazole.
Use of a Doppler radar-based AU-pnut leaf spot advisory was an effective
tool to manage diseases of peanut without loss of yield in this study.
Doppler radar data is not as precise as weather stations in determining
rain events; however it appears to be accurate enough to use with AU-pnut. |