INTERNAL DECLINE OF LEMONS 
I. DISTRIBUTION AND CHARACTERISTICS 1 
E. T. Bartholomew, J. T. Barrett, and H. S. Fawcett 
(Received for publication April 12, 1922) 
Introduction 
The term “internal decline” has been applied to a physiological abnor¬ 
mality causing the destruction of internal tissues in the lemon fruit, usually 
in the stylar end. The term as here used includes “blossom-end decay,” 
“tip deterioration,” “yellow tip,” “dry tip,” and other terms all applied 
locally by growers, packers, and shippers to the same trouble. When the 
study of this malady was first begun, the term was applied also to a browning 
of the “core” (placenta) and of the membranes (inner carpellary walls) 
covering the pulp segments of the lemon. Now it is applied only to the 
abnormality having the characteristics described in this paper. 
Internal decline has been known by the lemon growers of California for 
at least 25 or 30 years, and the indications are that it is increasing in severity. 
Its seriousness fluctuates from year to year. For example, in 1920 in many 
of the groves as much as 10 to 60 percent of the fruit in an entire pick had 
to be culled out and discarded or sent to the by-products laboratory, while 
in the same groves in 1921 not more than 2 to 5 percent had to be discarded. 
Experimental studies on internal decline were begun by the junior 
authors in 1915, and have been carried on intensively by the senior author 
since the summer of 1920. His discussion concerning one phase of his work 
on this problem will appear in an early number of this journal as the second 
paper in this series. 
General Discussion 
Distribution. Internal decline may appear in the fruit of almost any 
lemon grove in southern California, except that it seldom, if ever, occurs in 
groves located within a few miles of the coast. Groves situated within the 
hot inland valleys are especially likely to show a large amount of the trouble. 
A great variation in distribution may occur not only in different groves 
but in different parts of a given grove. 
Varieties Affected. The two principal varieties of lemons grown in 
California are the Eureka and the Lisbon. Besides these there are a few 
other varieties which are grown in comparatively small numbers. Any of 
1 Paper no. 94, University of California, Graduate School of Tropical Agriculture and 
Citrus Experiment Station, Riverside, California. 
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