Imazamox dissipation in two rice management systems

Abstract

SUMMARYThe current study focuses on the dissipation pattern of imazamox in a soil-water environment under the two most adopted rice management systems in Europe, conventional water seeding and dry-seeding. Changes in imazamox concentrations were studied over time in topsoil, field water, irrigation water, outlet water and ground water. The study was performed from 2010 to 2011 in one of the most important rice growing areas of Europe (Vercelli, northwest Italy).Imazamox dissipated rapidly in both the water and soil environments. In soil, imazamox halflife ranged from 2.2 to 3.3 days in 2010 and from 2.2 to 3.1 days in 2011. In paddy water, imazamox dissipated rapidly and no important differences among the management systems were found. In addition, the study showed that despite the short half-life of imazamox, the herbicide might be transported from treated fields in outlet waters by means of floodgates.The highest concentrations in outlet waters were found in the conventional water-seeded system, at the sampling site close to herbicide spraying. Imazamox residues were even found in inlet waters, suggesting discharge of the herbicide from paddies located upstream or drift during spraying. Imazamox residues in ground waters were always below the quantification limit. Overall, the low imazamox persistence observed during the 2-year study did not allow 2 important differences between the two systems to be revealed. To reduce imazamox discharge from treated fields in the first days after spraying, a useful practice might be to keep water inside the fields for at least a week after spraying.

Relationship between weedy rice (Oryza sativa) infestation level and agronomic practices in Italian rice farms

“…The prevalent level of infestation on these farms was medium (about 47%), while a prevalence of low O. sativa infestations was observed on the farms where imazamox was not applied ( Figure 2I). This technique was specifically developed for O. sativa control, and it is therefore also conceivable that the farms with higher amounts of O. sativa infestations decided to cultivate Clearfield® rice varieties (Milan et al 2017;Singh et al 2017).…”

Changes in sorption and bioavailability of herbicides in soil amended with fresh and aged biochar

“…4). The experiments were performed in absence of light, so that, photodegradation can be discarded here and biodegradation can be considered the main degradation pathway (Milan et al, 2017). Finally, as will be discussed below, the high affinity of BC aged for imazamox observed in the standard batch experiment did not translate into greater soil persistence of the herbicide under incubation conditions.…”

Validation of an Analytical Workflow for the Analysis of Pesticide and Emerging Organic Contaminant Residues in Paddy Soil and Rice

“…These results could be reasonably explained by its high utilization rate in paddy cultivation. Apart from these examples, the rare occurrence of prothioconazole, trifloxystrobin, imazamox, and cypermethrin could be attributed to their high dissipation rates in soil samples. − Boscalid, which is another most frequently found fungicide in European soils, was monitored at levels of 25% in the soil samples and detected in three rice samples (<LOQ), in line with the soils in which they were grown. In addition, pendimethalin, diuron, imazamox, mepiquat chloride, hexaconazole, and pyraclostrobin were detected in at least half of the soil samples.…”