Florida Agricultural Experiment Station


or some staining or bark excrescence associated among the
buds.
 SECONDARY SYMPTOMS
 While the foregoing symptoms are the ones that characterize
the disease, they do not constitute all of its manifestations. There
are other symptoms that are largely secondary and are not char-
acterized by any production of gum. They are chiefly growth
disturbances that arise incident to the development of the disease..
These may occur in trees entirely unaffected by dieback.
 Deep Green Color of Foliage.-Trees that are chronically af-
fected with and trees that are on the verge of dieback and are
growing under favorable food and moisture conditions, may
show an exceptionally deep green color of the foliage. Where
such occurs, the leaves are usually large and the trees may have
a very promising appearance.
 Frenching.-Frenching is a lack of green color in tissues
 between veins of the leaves, and often shows in parts of the af-
 fected trees (fig. 14). This is not a constant symptom, and oc-
 curs in trees entirely unaffected by dieback.
 Abnormal Leaves.-In the more severe cases of dieback,
 where the disease stimulus has affected the growth of the whole
 tree, the foliage sometimes shows a condition that is typical of
 the disease. The leaves will be thick and coarse to the touch.
 The length of some of them will be so increased, and the breadth
 so decreased, that they resemble large peach or mango leaves.
 S-shaped Growth of Branches.-Trees making a rapid, rank
 growth often develop long, immature, angular branches of a
 distorted shape. In some cases they appear to have been bent
 over by their own weight, and the tips to have grown upward
 again, resulting in an S-shaped appearance of the branches (fig.
 15). In other cases they appear to have grown downward and
 then upward again, giving the S-shaped appearance. This type
 of growth is frequently seen in dieback trees, and often precedes
 the development of the disease.
 Rosette-like Growth.-In a number of instances some of the
 multiple buds will develop into branches, giving a bushy, rosette-
 like growth. Branch growth will also be made from an excep-
 tionally large number of the nodes. These growths give the
 tree a thick, bushy head.
 DEVELOPMENT OF DIEBACK
 Dieback may be said to exist in two forms-chronic and
 acute. The only difference between the two is the persistence of