Florida Agricultural Experiment Station


the former drastic quarantine measures adopted by the State
Inspector of Nursery Stock in 1911 and the State Plant Board
in 1915, which prohibited the shipment of citrus stock grown
in areas declared to be scaly bark territory, to points outside
of such areas. Accordingly, these were greatly modified in 1925.

 SYMPTOMS OF SCALY BARK
 Scaly bark is primarily a disease of the bark and of the rind
 of the fruit. The greatest injury is done to the twigs and young-
 er branches up to about one-half inch in diameter, and to the
 fruit. The symptoms of the disease are very distinctive and
 characteristic, especially in the early stages.
 On the Twigs and Branches.-In their initial stages, the young
 spots appear on the surface of the green bark as inconspicuous
 greenish-yellow spots which have a somewhat translucent ap-
 pearance (Fig. 33). According to Fawcett, twig infections may
 occur at any time of the year but the greatest number appear
 to occur between about June 1 and December 1. He found that
 the spots rarely occur on twigs which are less than six months
 old and that they are more commonly observed in the bark of
 growth from nine months to a year old. On twigs of this age
 the spots, in the course of eight or ten months, become from one-
 sixth to one-half inch in diameter, raised above the surface of
 the surrounding bark, rusty in color, and with well defined mar-
 gins. As the spots grow older the bark becomes glazed, then
 brittle, develops longitudinal cracks, and finally breaks into
 small flakes and scales (Fig. 33). A zonate effect is often seen
 in the more advanced stages. The spots may be isolated and
 distinct or, in severe cases, they may increase in number until
 several join together, forming large patches of rusty or red-
 dish-brown, scaly bark (Fig. 34) ; hence the name of this disease.
 The branch is rarely killed the first year. During the second
 year additional spots may form between the old ones and this
 may continue for several years until the bark becomes decidedly
 rough and scaly and the branch is finally killed as a result of
 girdling. The watersprouts, which develop abundantly when
 badly attacked trees are cut back, are especially susceptible to
 infection.
 On the larger branches and trunks, where the disease is of
long standing, the original spots are no longer distinct and the
surface of the affected bark becomes broken into thin flakes or