Evaluation of Fusarium spp. infected asparagus spears for fumonisin mycotoxins

Commercial asparagus spears harvested and packed from four geographical areas during different months of harvest were collected for evaluation of Fusarium infection and possible fumonisin production. Two asparagus producing areas of Mexico, one in Lower Baja California with November harvest, and the other in Caborca, Sonora, harvesting in February, were selected for evaluation. Spears were also collected from Imperial Valley in Southern California in March, and from the Stockton, California, area in April. Isolations from randomly selected spears established percent of infected spears and species of Fusarium present. Infected spears with an equal number of non-infected spears were retained at 5 degrees C and 26 degrees C for periods of five and ten days. Representative spears from each temperature regime were frozen and then prepared for HPLC fluorescent analysis. Ninety-eight percent of the spears from Baja California were infected with F. proliferatum, while the Caborca samples had a maximum F. proliferatum infection rate of 78%. F. oxysporum was also recovered, averaging five to twenty percent infected spears, in the Mexican samples. Fumonisins were not present in samples from either location. Imperial Valley, California, samples were found to be 63% infected with F. proliferatum and 27% infected with F. oxysporum while Stockton spears had but 10% maximum F. proliferatum infection and 70% F. oxysporum. The samples from the United States, like those of Mexico, were negative for fumonisins regardless of time between harvest and testing, the variety of asparagus involved, or the geographic area sampled.