Uptake and metabolism of a systemic fungicide (triadimenol) by pre-veraison grapes

Triadimenol (1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4,-triazol-1-yl)butan-2-ol, formulated as Bayfidan® 250 EC), is one of the most frequently used systemic fungicides in viticulture. However, little is known about the behaviour of this compound once applied to Vitis vinifera sp. and hence strategies to use this fungicide are hard to optimise in an informed manner. Accordingly, uptake and metabolism of triadimenol applied to berries of Vitis vinifera cultivars Chardonnay, Cabernet Sauvignon and Riesling was investigated. Triadimenol rapidly became resistant to removal by washing with aqueous solutions in all cultivars studied, indicating that this fungicide is unlikely to succumb to rain wash erosion after spraying. Metabolism of triadimenol by grapevines was also investigated using 14C-triadimenol by thin layer chromatography/autoradiography. Direct conversion of a minor proportion of triadimenol into polar conjugates, and into conjugates of its oxidation product, was evident. Although similar patterns of triadimenol metabolism were observed with all three cultivars, the proportion of triadimenol metabolised differed, possibly due to minor differences in berry maturity. Metabolism of triadimenol in grapes does not involve breakdown of the fungicide into simpler and smaller compounds, but rather, does result in formation of bigger, conjugates with the original fungicide structure largely conserved

A framework for characterizing fluvial sediment fluxes from source to sink in cold environments

Fluvial processes dominate sediment flux from most cold environments and as such are particularly sensitive to environmental change. However, these systems demonstrate high variability in flow and sediment transfer rates in both the short and long-term which presents specific problems for establishing integrated sediment flux studies. The objective of this paper is to briefly review the nature of fluvial and floodplain sediment sources in cold environments and to make recommendations on the measurement of fluvial sediment fluxes from these sources to sinks. The paper outlines a framework for examining fluvial sediment fluxes in cold environments including: sources of sediment in glacial and periglacial environments; techniques for measuring fluvial sediment transfers; and methods for measuring contemporary deposition in lacustrine sediment sinks. Within this framework, we stress that it is particularly important to provide consistency in methods for monitoring sediment flux and to adopt appropriate sampling frequencies. We recommend that the most appropriate methods for establishing integrated sediment flux studies in these cold environments are: repeat surveys and terrestrial laser scanning of valley and slope sediment stores on a monthly – daily frequency; weekly-daily sediment budgeting of bedload transfer using rapid resurvey methods; hourly or better time series of suspended and solute transport using data logger acquisition systems; and monitoring of lacustrine sedimentation using sediment accumulation sensors and/or weekly-daily estimates from passive sediment traps. Application of the proposed integrated framework will improve our understanding of sediment flux in cold environments and allow us to better assess the sensitivity of cold environments to environmental change within the context of contemporary and past sediment flux