Bulletin 229, Diseases of Citrus in Florida


sity from sparse to numerous and often are so crowded that they
become fused together so that extensive areas of twigs may de-
velop a continuous eruptive appearance. In severe cases, more
or less extensive ridges of corky tissue may be extruded from the
bark and split longitudinally (Fig. 64). This characteristic
symptom of the disease is commonly termed "red rust" by grow-
ers. These bark eruptions usually
persist for a number of years be-
fore they are sloughed off by the
continued growth of the bark.
 Multiple buds frequently de-
velop in the axils of the leaves.
From several to thirty or more
buds may occur where but from
one to three would occur normally
(Fig. 65). This multiple bud
formation is commonly associated
with more or less gum formation
in the cambium region, staining
or bark eruption.
 Twigs developing bark excres-
cences and other symptoms of ex-
anthema commonly drop their
leaves and then die. As the af-
fected terminal portions die, new
growth is developed from the
nodes farther back. A number of
shoots may commence to grow
from the multiple buds but the
growth is usually weak, with the
result that a bunch of short, slen-
der twigs occurs in place of the
one or two, or sometimes three,
normally produced. The inter-
nodes of affected twigs usually
are shortened and the result is a
bushy, rosette or "stag-horn" Fig. 63.-Stained terminal branch
type of growth. This new growth resulting from exanthema.
may die back in turn; hence, the misleading term diebackk"
that has been used for this disease. Long continued cases of
the disease result in a tree with a more or less rounded, com-