The fate of five herbicides (glyphosate, glufosinate-ammonium, phenmedipham, ethofumesate and metamitron) was studied in two Finnish sugar beet fields for 26 months. Soil types were sandy loam and clay. Two different herbicide-tolerant sugar beet cultivars and three different herbicide application schedules were used. Meteorological data were collected throughout the study and soil properties were thoroughly analysed. An extensive data set of herbicide residue concentrations in soil was collected. Five different soil depths were sampled. The study was carried out using common Finnish agricultural practices and represents typical sugar beet cultivation conditions in Finland. The overall observed order of persistence was ethofumesate > glyphosate > phenmedipham > metamitron > glufosinate-ammonium. Only ethofumesate and glyphosate persisted until the subsequent spring. Seasonal variation in herbicide dissipation was very high and dissipation ceased almost completely during winter. During the 2 year experiment no indication of potential groundwater pollution risk was obtained, but herbicides may cause surface water pollution.
The aim of the project was to produce updated information during 2005-14 on the Fusarium species found in Finnish cereal grains, and the toxins produced by them, as the last comprehensive survey study of Fusarium species and their toxins in Finland was carried out at the turn of the 1960s and the 1970s. Another aim was to use the latest molecular and chemical methods to investigate the occurrence and correlation of Fusarium species and their mycotoxins in Finland. The most common Fusarium species found in Finland in the FinMyco project 2005 and 2006 were F. avenaceum, F. culmorum, F. graminearum, F. poae, F. sporotrichioides and F. langsethiae. F. avenaceum was the most dominant species in barley, spring wheat and oat samples. The occurrence of F. culmorum and F. graminearum was high in oats and barley. Infection by Fusarium fungi was the lowest in winter cereal grains. The incidence of Fusarium species in 2005 was much higher than in 2006 due to weather conditions. F. langsethiae has become much more common in Finland since 2001. F. graminearum has also risen in the order of importance. A highly significant correlation was found between Fusarium graminearum DNA and deoxynivalenol (DON) levels in Finnish oats, barley and wheat. When comparing the FinMyco data in 2005-06 with the results of the Finnish safety monitoring programme for 2005-14, spring cereals were noted as being more susceptible to infection by Fusarium fungi and the formation of toxins. The contents of T-2 and HT-2 toxins and the frequency of exceptionally high DON concentrations all increased in Finland during 2005-14. Beauvericin (BEA), enniatins (ENNs) and moniliformin (MON) were also very common contaminants of Finnish grains in 2005-06. Climate change is leading to warmer weather, and this may indicate more changes in Finnish Fusarium mycobiota and toxin contents and profiles in the near future.
Translocation of glyphosate (N-(phosphonomethyl)glycine) to plant roots and its impact on detected herbicide residues in sandy loam soil were studied in a glasshouse pot experiment in Finland. Quinoa (Chenopodium quinoa, Willd) plants in two different growing phases (6-8 and 12-14 leaf stages, groups A and B, respectively) were sprayed with nonlabelled glyphosate. Bare soil pots were included as controls (group C). Soil surface contamination with glyphosate was prevented in groups A and B but not in group C. Soil samples were collected 1 h, 8 days and 44 or 53 days after the glyphosate applications. Root samples were taken 8 days after the application from group B. After 8 days from the treatment, 4% of the applied glyphosate was detected in soil and about 12% in roots (group B). One and a half months later 12% and 8% of the applied glyphosate (groups A and B, respectively) was detected in soil samples incubated with roots. The main metabolite of glyphosate, aminomethyl phosphonic acid (AMPA), was not found in root samples. Glyphosate fate was simulated with the PEARL 3.0 model. Simulated concentrations in bare soil pots were very close to the observed ones. However, the model lacks a process description for herbicide transport within a plant and, therefore, the observed and simulated glyphosate residues in soil after canopy applications did not correlate. Simulations highlight the importance of the translocation process in glyphosate fate. We conclude that also in field studies part of the detected glyphosate soil residues must originate from plant roots, and translocation process should be included both in leaching assessments and pesticide fate models.
Glyphosate [(N-(phosphonomethyl)glycine)] is a widely used herbicide and it is known to compete for the same sorption sites in soil as phosphorus. Persistence and losses of glyphosate were monitored in a field with low phosphorus status and possible correlation between glyphosate and phosphorus leaching losses was studied. Glyphosate and its metabolite AMPA (aminomethyl phosphonic acid) residues in soil samples were analysed after a single application in autumn. Twenty months after the application the residues of glyphosate and AMPA in the topsoil (0-25 cm) corresponded to 19% and 48%, respectively, of the applied amount of glyphosate, and traces of glyphosate and AMPA residues were detected in deeper soil layers (below 35 cm). These results indicate rather long persistence for glyphosate in boreal soils. Surface runoff and subsurface drainflow were collected continuously all year round for 20 months and analysed for glyphosate, AMPA, dissolved phosphate, total phosphorus and total suspended solids.The glyphosate concentrations in the surface runoff water were highest, with 99% of the total leaching losses obtained, during the periods of snow melting and soil thawing in the first winter following the autumn application. The total leaching of glyphosate was 5.12 g ha −1 and that of AMPA 0.48 g ha −1 , corresponding to about 0.51% and 0.07%, respectively, of the applied amount of glyphosate. No residues of glyphosate and AMPA were detected in the subsurface drainflow. The correlations between concentrations of glyphosate and dissolved orthophosphate as well as glyphosate and total phosphorus in surface runoff were significant (p<0.01).
Analysis of survey data from 804 spring-oat fields divided into five climatic regions suggested that low inoculum level of Fusarium langsethiae was a major limiter of T-2 + HT-2. A 30-year climate with a cool and rainy 10-day period preceding estimated mid-anthesis and a warm 3-week period following anthesis were positively associated with T-2 + HT-2 contamination. In 12 survey years, warm weather from 4 weeks before GS65 until harvesting increased T-2 + HT-2, except in the 1-2 weeks preceding mid-anthesis, when the requirement for high humidity dominated. F. langsethiae and F. sporotrichioides were consistently promoted by high temperature from mid-anthesis onwards. A positive response of T-2 + HT-2 to high humidity peaked 5-10 days earlier and was shorter and weaker than the responses of DON and F. graminearum. The probability of high concentration and regional mean concentration of T-2 + HT-2 tended to be lower under ploughing than under nonploughing, and they tended to increase with increasing cereal intensity. T-2 + HT-2 was positively associated with zero tillage when compared with minimum tillage. The responses of F. langsethiae and F. sporotrichioides to ploughing and cereal intensity varied by region. In contrast to T-2 + HT-2, DON was the same or higher under ploughing than under non-ploughing, not consistently affected by cereal intensity and not associated with zero tillage. F. graminearum was consistently more common under ploughing than under non-ploughing, and decreased with increasing cereal intensity in four regions. Also, F. culmorum and F. poae tended to be more common under ploughing. F. culmorum increased with cereal intensity in three regions.
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