Abstract
Blight is a major disease affecting citrus trees in Florida. The causal agent of this disease has not yet been determined or agreed upon. Symptoms are typified by shortened internodes on branches and severely cupped and yellowed leaves in spite of water availability, as well as flushing of leaves and blooms before tree death. A study was carried out on 'Valencia' oranges, at Indian River Research and Educational Center, Fort Pierce, Florida, during 1990-2004 to compare a frequent fertilization program (five split applications) to a conventional Florida fertilization program (three applications). Two liming rates were used, since previous work showed higher values of blight incidence on citrus at high soil pH. There was no difference in blight incidence with fertilization treatment. Liming rate, however, did have an effect on the number of blighted trees. The number of trees showing visual blight symptoms increased about 2.6% per year for trees receiving the low lime rate. Trees under the high lime rate had an increase in blight symptomatic trees of 5.6% per year. Average annual yields were nearly identical between the lime treatments for the first 7 years of production. Due to the rising number of blighted trees with reduced yields in the High lime treatment, yields were reduced in comparison to the low lime treatments during the last few years, resulting in a cumulative advantage of 254 box/ac for trees in the low lime plots.
