TEAR-STAIN OF CITRUS FRUITS. 1 I 
CONCLUSIONS. 
While the foregoing evidence is to the effect that tear staining of 
Florida citrus fruits is caused by rust mites rather than by the fungus 
Colleiotrichum gloeosporioides , as claimed by Rolfs, it must be admit ted 
that the writer may not have seen all types of this injury. However, 
if a special type of tear staining caused by this fungus occurs in Florida 
it must have been exceedingly rare during the past four years to have 
escaped detection by the writer. The experimental and observation a] 
data on the control of what has been regarded as wither-tip tear-stain 
by investigators and Florida growers seems to be definite enough to 
warrant the conclusion that practically all of the so-called wither-tip 
tear-stain in Florida is caused by rust mites and can be readily con- 
trolled by controlling these pests. 
SUMMARY. 
(1) Pure cultures from typically tear-stained fruit show that Cal- 
if iotriclium gloeosporoides is not confined characteristically to the tear 
streaks, but is even more prevalent on the larger russeted areas and is 
almost invariably found on normally colored areas. 
(2) Inoculations on grapefruit in various stages of development 
with cultures of the fungus CoUeiotriclium gloeosporioides failed to pro- 
duce tear streaks or other positive reaction. 
(3) Dead wood that might harbor Colletotrichum gloeosporioides was 
found associated with not more than 10 per cent-of the affected fruit. 
(4) It is impossible to distinguish by histological methods between 
the ordinary rust-mite russet and so-called wither-tip tear-stain. 
(5) Rust mites were found very abundant in recently developed 
tear-streak patterns on grapefruit. 
(6) Spring-bloom fruit on unsprayed trees usually becomes seriously 
tear stained; June-bloom fruit on such trees usually ripens free from 
these markings. 
(7) Copper sprays applied in the spring and not followed by rust- 
mite applications of sulphur sprays tend to increase tear staining, 
but when followed by rust-mite applications no appreciable amount 
of tear staining develops. 
(8) When sulphur sprays are applied during the early spring, 
which is usually too early for the best rust-mite control, and are not 
followed by the regular rust-mite application tear staining is greatly 
reduced. 
(9) When only the rust-mite applications are made, tear staining 
is practically eliminated. 
(10) The same local and seasonal conditions of moisture and light 
that favor rust-mite injury also favor tear-stain. 
(11) Practically all of the so-called wither-tip tear-stain in Florida 
is associated with rust mites and can be readily controlled by con- 
trolling these mites. 
