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EVALUATION OF AERIAL PHOTOGRAPHY
AS A TECHNIQUE FOR ESTIMATING
CITRUS FRUIT YIELD
By
Richard D. Allen
STATISTICAL REPORTING SERVICE
U. S. DEPARTMENT OF AGRICULTURE
Published September 1977
TABLE OF CONTENTS
INTRODUCTION .••..•.................................•.
1
DATA AVA I LAB LE •...•..........•.•.
'•..•.•........•.....
2
FRUIT COUNTS FROM PHOTOGRAPHS .•........••............
3
Analys is of Fruit Counts ...........•..........•.
3
OPTICAL DENSITY READINGS
6
November Photography Results -
20 Yea r Old Tr e e 5 .........•.........•...•.......
7
November Photography Results -
6 Year Old Trees
13
December Photography Results -
20 Year Old Trees
13
December Photography Results -
6 Year Old Trees
16
February Photography Results -
20 Year Old Trees ......................•........ 20
February Photography Results -
6 Year Old Trees
22
Summary of Optical Density -
Yield
Correlations
25
ACKNO\\tLEDGEMENTS
Publication of this report was delayed following reassignment
of the author.
The report is being issued at this time to
document this one-of-a-kind research study.
I wish to thank Harold F. Huddleston and Wendell W. Wilson
for their assistance in reviewing the final draft and in
arranging .for publication.
INTRODUCTION
Considerable research has been conducted in recent years
in efforts to determine improved procedures or techniques
for estimating and forecasting yields of citrus and other
fruit trees.
Various procedures involving counts of fruit
on sample limbs or on ground level photographs have been
tried.
Aerial photography has been suggested as a possible
technique for estimating fruit yield.
Since fruit counts
from ground level photographs are significantly correlated
with fruit counts, perhaps counts from aerial photographs
would be also.
Another possibility might be the correlation ..
of optical density measures of photography with fruit counts.
That is, varying fruit sets may cause a shift in photo-
graphic response which can be detected by appropriate
instruments.
At present, aerial photography is utili