Época e intensidade de ocorrência da necrose floral em gemas de pereira japonesa cultivar Housui durante o inverno

The commercial exploration of the pear culture in Brazil has little expression, being the internal consumption supplied by imports. The lack of edafoclimatic adaptation of the commercial cultivars of interest andthe flower bud abortion are the main problems for the development of this crop. The aim of this study was to evaluate the occurrence time and the intensity of the flower bud necrosis in pear trees cv. Housui (Pyrus pyrifolia) during the winter period. The experiment was conducted in 2007, using plants belonging to the orchard of Embrapa Clima Temperado, in Pelotas, RS, Brazil. The buds were collected at five different moments (May 24th, June 20th, July 19th, August 21st, and September 18th), fixed in a solution of formalin, acetic acid and alcohol and dissected under a stereoscopic microscope. The parameters evaluated were the percentages of healthy buds and buds withmoderate and severe necrosis. At the beginning of the winter the symptoms were not present in practically any buds. The buds were seriously affected in the final period of dormancy, when the symptoms began rising from a negligible level to a sharp peak toward the end of the winter.