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Recent studies have confirmed the widespread of Yellow Leaf Syndrome (YLS) throughout Cuba, being the central and western regions the most affected areas. Sugarcane yellow leaf phytoplasma (SCYLP) was found in 99.3% of symptom plants; however, isolates have not been characterized yet. Polymerase chain reaction (PCR) products from 381 leaf samples with and without YLS symptoms, collected in previous surveys in 2002, and containing SCYLP phytoplasma, were digested with RsaI and AluI restriction enzymes. Polymorfic samples were selected and total DNA used as template to amplify the intergenic 16/23S region by a nested PCR (nPCR) assay with specific primers P1, P4, P7. P4/P7 PCR products were purified and used for direct sequencing. Intergenic sequences obtained were compared with those from 22 GenBank reference phytoplasmas, including those associated with Aster Yellows (16SrI) group previously reported in 1999. Phylogeny revealed a wide biodiversity related to YLS phytoplasmas present in the country since phytoplasmas from 16SrI, 16SrIII (X-disease) groups and a possible new 16SrI subgroup were identified. Results indicate that the main phytoplasma circulating in Cuba belongs to a new 16SrI subgroup called Cuban Sugarcane Yellow Leaf Phytoplasma, CScYLP (Cuba). [ABSTRACT FROM AUTHOR]

A sampling plan was designed, starting from the results about the distribution in plant and field of T. palmi potato crop. For this, two sampling proceedings were considered in productive areas of Havana province during three years. They consisted on evaluating larvae density in parcels or in the diagonal of the sector. Mean density was valued by means of variance analysis and means were compared by Duncan (p< 0.05). Relative variation , net relative precision and the most adequate sample size were also calculated. The results showed that, starting from means superior to 3.01 larvae/ folioles, the best procedure is in diagonal, while at lower values, the best estimation was achieved in parcels. In this case the sample required approached at 100 folioles. In a way that population increases 50 and 64 folioles, a reliable sample size can be obtained. [ABSTRACT FROM AUTHOR]