RESUMEN
Banana fruit of the Cavendish subgroup, Musa acuminata, are significant international commodities. Recently, a transnational company attempted to develop single fruit (fingers) as a product in the United States. In the summer of 2007, an unknown problem developed (hereafter, "fuzzy pedicel"), wherein mats of fluffy gray to white mycelial mats covered large portions of the pedicel surface of fruit when they were packed in gas-permeable containers. Fungi from two genera sporulated on examined pedicels: Sporothrix, which occurred on 72% of the affected pedicels, and Fusarium (6%); other fungi were sterile. From pedicel tissue, four genera of fungi were isolated on potato dextrose agar: Sporothrix and Fusarium and, less frequently, Pestalotiopsis and Nigrospora. Based on alignment with internal transcribed spacer and ß-tubulin sequence data, the Sporothrix isolates were closely related to those in an environmental Ophiostoma/Sporothrix clade that contains Sporothrix stylites, S. humicola, and S. pallida but not the human pathogen S. schenkii. Based on EF1α gene sequences, four species in the Gibberella fujikuroi species complex (Fusarium proliferatum, F. pseudocircinatum, F. sacchari, and F. verticillioides) and two unnamed taxa in the F. incarnatum-equiseti species complex were identified. After artificial inoculation, representative Sporothrix and Fusarium isolates caused fuzzy pedicel symptoms on fruit of 'Grand Nain,' a commercial Cavendish cultivar. Fuzzy pedicel development was inhibited at 14°C (temperature at which fruit are shipped) but developed at 25°C (temperature at which fruit are marketed). Sporothrix isolates were insensitive to thiophanate-methyl fungicide in vitro and when used to treat pedicel surfaces prior to inoculation. Thus, it appears that benzimidazole fungicides would be ineffective as postharvest treatments for this problem. In summary, a new postharvest disease of banana, fuzzy pedicel, affects single fingers. It is caused by Sporothrix sp. and several species of Fusarium. Sporothrix spp. and F. pseudocircinatum have not been reported previously on banana.
RESUMEN
Syzygium paniculatum (Myrtaceae) is an important plant in the South Florida ornamental industry. Known as eugenia in the trade, the plant was relatively free of diseases before Hurricane Wilma (2005). Since then, a serious dieback disease has become prevalent in local nurseries, especially during late summer. Symptoms included wilting and death of terminal and lateral branches, and vascular discoloration in dead and dying branches and the main stem. Several fungi were isolated from diseased plants, but Neofusicoccum parvum was usually the only fungus isolated from symptomatic tissue. Most isolates were sterile, but all that were tested produced significant (P < 0.05) dieback on, and reduced growth of, the cultivar Monterrey Bay. Glomerella spp. and a Pestalotiopsis sp. that were recovered from asymptomatic portions of diseased plants and Mycoleptodiscus terrestris recovered from healthy liners of Monterrey Bay did not cause dieback symptoms in pathogenicity studies or affect host growth. In incubator studies, N. parvum caused significant external symptoms, vascular discoloration, and mortality at 25 and 30°C; in general, only vascular symptoms developed at 20°C and no symptoms developed at 15°C. Thus, temperature may be associated with the seasonal development of this disease. Significant differences in disease development were not observed under a wide range of light intensities (2,000 to 300 µmol s-1 m-2). S. paniculatum is a new host record for N. parvum.