TEAK-STAIN CF CITRUS FRUITS, 6 
The publications cited contain practically all the more important 
references to wither-tip tear-stain in Florida or near-by section where 
the round orange and grapefruit are grown in large quantities, and no 
presentation of actual experimental data is made therein on which the 
fungus theory regarding the cause of tear-stain is based. However, 
it can not be denied that this theory, first stated by Rolfs, is so plaus- 
ible that it has been accepted readily without the support of published 
experimental data. It was not until results very strikingly incon- 
sistent with this theory appeared in experimental spraying tests thai 
its validity was questioned, and this has led to a thorough investiga- 
tion of the causation of the type of injury commonly known in Florida 
as "wither-tip tear-stain. ;; The evidence presented in this bulletin 
indicates that Colletotrichum gloeosporioides is not responsible for 
tear staining in Florida. If this fungus ever produces such an 
effect, it must be extremely rare in that section. 
SPRAYING EXPERIMENTS. 
During the season of 1917, in connection with spraying experiments 
which were conducted in a bearing grapefruit grove for the control of 
citrus scab, it was observed that tear staining was almost entirely 
absent from those plats that received several applications of lime- 
sulphur solution, though it was quite prevalent where Bordeaux 
mixture had been applied during the scab-spraying season. Since 
this first observation, many similar manifestations of the lack of 
control of tear-stain by copper sprays have appeared in the experi- 
mental plats. Such a failure has been proportional to the severity 
of rust-mite attack. 
Ordinarily the scab-spraying season in Florida begins in February 
when the spring growth starts and extends over a period of two or 
three months. It is followed rather closely by the period of very 
severe attack by rust mites. The latter are usually most abundant 
during May and June and are readily controlled by two or three appli- 
cations of lime-sulphur solution diluted 1 to 66. With this explana- 
tion the data in Table I can be readily interpreted. 
In general, the results of this spraying experiment show (1) that 
tear-stain was controlled on plats 3 and 5, which received applications 
of lime-sulphur solution shortly before the period of maximum abun- 
dance of rust mites; (2) that tear-stain was materially reduced on 
plat 4, which received applications of lime-sulphur solution consid- 
erably in advance of the period of maximum numbers of ru t mites; 
(3) that tear-stain was not reduced on plats 1 and 2, which received 
spray applications of copper mixtures. Assuming that tear-stain is 
caused by a species of Colletotrichum or other fungus, it would be 
reasonable to expect that plats 1 and 2 would show at least as good 
control as plat 4. The fact that control of tear-stain was so closely 
