Florida Agricultural Experiment Station


of the leaves and to the fruit. By keeping it from the large
branches and the under surface of the leaves some of the fungi
will be preserved and serve as a source of inoculation for the
scale that may develop on the sprayed parts.
 After spraying, close watch should be kept for any consider-
able increase in numbers of the scale. If they become numerous
spray the trees with some of the oil-emulsion sprays to control
them. Do not wait until the trees are severely infested before
applying the spray.




 SUMMARY

 1. Dieback is a disease of citrus trees, that is characterized
by the production of gum in different tissues of the develop-
ing parts.
 2. It is a disease of the growing tissues of the citrus tree.
 3. Its five primary symptoms are the gum pockets, the
stained terminal branches, the marked or ammoniated fruits,
the bark excrescences, and the multiple buds.
 4. The mere dying of the limbs backward is not dieback.
The disease can be identified only in the presence of one or more
of its primary symptoms.
 5. The secondary symptoms of dieback are an exceptionally
deep green color of the foliage, a distorted S-shaped growth of
the immature angular terminal branches, frenching of the foli-
age, and thick, coarse and somewhat peach-leaf shaped leaves.
 6. The absolute cause of dieback is not known. It is thought
to be in some way connected with organic matter which has been
added to the soil, or which is residual therein.
 7. The soil conditions known to be favorable for the de-
velopment of dieback in citrus trees are the presence of excessive
quantities of organic ammoniates, a lack of drainage, hardpans
too near the soil surface, excessive cultivation, and irregular
moisture conditions.
 8. The disease is more prevalent in trees planted in certain
locations, such as near stables, outhouses and cess-pools; on