Fungi associated to the seeds of ipê-amarelo (Tabebuia serratifolia) and ipê-roxo (Tabebuia impetiginosa): incidence, germination effect and seedlings transmission.
A study was conducted to identify the fungi present in 8 samples of ipê-amarelo seeds (Tabebuia serratifola) and ipê-roxo (T. impetiginosa) collected from the region of Piracicaba, Mogi-Guaçu (Sao Paulo) and south of Minas Gerais (Lavras, Ijaci and Itumirim) in Brazil, and to determine the possible damages in the seedling production of those species. The method used for the health test was the blotter test and, for the germination, gerbox had been used with paper substratum at temperature of 30°C under constant light regime. The seeds, as much in the health test as in the germination test, were subsampled in one part that was submitted to superficial disinfestation with sodium hypochlorite, and one part that was not. The fungi transmission had been evaluated through lesions found in the seedlings during the germination test. Sixteen fungi had been identified and quantified: Cladosporium sp., Alternaria alternata, Epicoccum sp., Phoma sp., Geotrichum sp., Penicillium sp., Trichothecium sp., Phomopsis sp., Drechslera sp., Aspergillus spp., Curvularia sp., Fusarium spp., Macrophomina phaseolina, Nigrospora sp., Lasiodiplodia theobromae [Botryodiplodia theobromae] and Septoria sp. In general, the asepsis provided a drastic reduction in the incidence of all the fungi, in both species, with an average rate of 90%. It can be inferred that most of the fungi were contaminating the seeds. The percentage of normal seedlings had not been interfered directly by the fungi. The asepsis decreased the germination by 64%, indicating phytotoxicity. In the transmission, on average, 17% and 10% of the seedlings were observed with symptoms in the samples without asepsis and with asepsis, respectively. The most frequent fungi transmitted by the ipê-amarelo and ipê-roxo seeds were: A. alternata, Fusarium spp., Aspergillus spp., Phoma sp. and Phomopsis sp.