Effects of pendimethalin at lower trophic levels—a review

Pendimethalinʹs herbicidal action lies in its inhibition of the steps in plant cell division responsible for chromosome separation and cell wall formation. Terrestrial studies show that 10–20% of the herbicide evaporates during the first weeks after application. The remainder may dissipate biologically or chemically. Half-maximal dissipation time, or half-life (DT50) values vary from a few days to>200 days. Field and laboratory studies showed that reduced temperatures and drought prolong dissipation time to as long as 72–2094 days. In freshwater, pendimethalin concentrations reach 6 μg/L after runoff. In water the 10% lethal concentration (LC10) for Daphnia was 6 μg/L when exposed via suspended food. The LC50 was 78 μg/L. An invertebrate field study showed that soil nematodes were reduced by 35–60% at pendimethalin application rates of 0.75 and 1.0 kg/ha, respectively. After application, soil microbiota is affected by pendimethalin for not, vert, similar4 weeks. Plant–Rhizobium symbiosis is affected at application rates of 0.5–1.0 kg/ha.