Field Survey of Tahiti Lime, Citrus latifolia, for Algal Disease, Melanose, and Greasy Spot in Southern Florida. R. B. Marlatt, Plant Pathologist, University of Florida, Agricultural Research and Education Center, Homestead 33031. Ken Pohronezny, Pest Management Specialist, and R. McSorley, Assistant Nematologist, University of Florida, Agricultural Research and Education Center, Homestead 33031. Plant Dis. 67:946-949. Accepted for publication 10 February 1983. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-946.

A mature lime grove in southern Florida was surveyed biweekly for algal disease, melanose, and greasy spot from April 1980 through November 1981. Algal disease symptoms began with sporulation on branches in April 1980 from long-established infections, then appeared on leaves in October 1980 and continued to spread until February 1981. It began again in July 1981 and continued to March 1982. Greasy spot appeared 3 wk after leaves reached maximum size in May 1980 and occurrence of new infections peaked in August. Greasy spot incidence reached 100% about 1 yr after the survey began. Except when disease incidence was low, use of the random selection of foliar growth flushes was an acceptable sampling method to assess the proportion of leaves with the three diseases, as evaluated by relative variation (standard error-to-mean ratio). Correlation coefficients between midseason greasy spot levels and late-season leaf loss were significant but no significant correlations were found between algal disease or melanose and leaf loss. Methodology is presented for developing statistical sampling plans for the three diseases.