Bulletin 140, Dieback of Citrus Trees


and dropping varies with conditions. It sometimes happens
that a crop of fruit is. badly scarred by the disease, yet
very little of it splits and falls.
 The stained areas are often
coincident with thrips marks,
when they occur on dieback
fruits. Melanose markings on
such fruits are usually more
pronounced than those on nor-
mal fruits, and may stimulate
dieback staining in the adjacent
tissues.
 Collections of a clear to am-
ber colored gum sometimes show Wb I
in the angles of the segments
and surrounding the seed of die-
back fruits. It may be so plen-
tiful that the seeds are floating in
it. This is not known to occur
in other than dieback fruits.
When found, it furnishes evi-
dence that the fruit is affected
with dieback.
 Dieback fruits are often coarse
and may have a thick rind (fig.
9), particularly if the disease f
has been brought on by the use
of excessive amounts of organic
fertilizers. On the other hand,
very prominent staining may oc-
cur on fruits that are normal in
all other respects. Dieback-af-
fected fruits are usually insipid
in flavor. They are lacking in FIG. 4.-Stained terminal branch.
acid and bouquet. The marked Note the gum pockets (blister-
fruits are mostly culls and are olie risi no the bark) near
worthless for shipment.
 Multiple Buds.-Multiple buds are clusters of several to
thirty or more buds in a leaf axil where normally two would
occur (figs. 12, 13). Strictly speaking, this symptom is not a
gum symptom. But a multiple bud is rarely found that does
not have either some gum formation in the cambium region,