Influence of agricultural practices on the contamination of maize by fumonisin mycotoxins.

The objective of the present work was to investigate the effect of different agricultural practices on the contamination of maize by fumonisin mycotoxins. Corn samples were collected from 16 maize fields located in Aragón (northeastern Spain) during the 2007 crop year. Corn samples were collected from each field five times at different maturation stages: F1, day 0 (milky corn); F2, day 15; F3, day 30 (yellow corn); F4, day 45; and F5, ripe corn at harvest. The agricultural practices evaluated were type of seed (conventional and transgenic), planting method (dry and wet planting), tillage system (plowing and minimum tillage), type of irrigation (flood and sprinkler), residue management of preceding crop (removal and burial), nitrogen fertilization level (kg N per ha), and harvest date. Mycotoxin analysis was carried out with the ROSA Fumonisin test, which measures both fumonisin B1 and B2 by lateral flow immunoassay. No fumonisins were detected in milky corn (F1 and F2 stages). Only one field had fumonisins in F3 yellow corn (1,037 microg/kg); this field was part of the only farm affected by borer insects. One-third of fields had fumonisins at the F4 stage (363 microg/kg), and 62.5% of the fields were positive for fumonisins at the F5 harvest stage (520 microg/kg). Wet planting and the removal of debris from the previous crop significantly lowered the risk of fumonisin in corn. The use of insect-resistant maize seeds tended to reduce fumonisin levels. However, higher levels of nitrogen fertilizer had a tendency to increase fumonisin levels in corn. Tillage system, type of irrigation, and harvest date had no clear effect on fumonisin levels.