Chemistry and biology of novel amine fungicides: Attempts to improve the antifungal activity of fenpropimorph

In spite of considerable efforts by many workers, there has been a lack of progress in the area of amine fungicides since fenpropimorph. Random synthesis of a large variety of different amine compounds, as well as intelligent structural modification of the lead structure fenpropimorph (well over 15 000 amines have been screened at BASF alone) have not led to a new market product so far. Further work has been focused on the reported mode of action of fenpropimorph, notably on the inhibition of the sterol Δ¹⁴-reductase. Although some doubt has to be cast on the hypothesis that fenpropimorph behaves as a sterol mimic, the concept of ‘high energy intermediate’ inhibitors has been employed successfully. Rational drug design of azasterol mimics has led to a number of very potent inhibitors of the sterol Δ¹⁴-reductase which also displayed high fungicidal activity in the greenhouse. Although many of these compounds are more powerful reductase inhibitors than fenpropimorph, under field conditions none showed significant advantages over this established fungicide. Most likely, fenpropimorph already exhibits the maximum fungicidal activity which can be attained by blocking the sterol Δ¹⁴-reductase. This would mean that, with the development of the ‘second generation’ amine fungicide fenpropimorph, this class of compounds has already virtually been optimized.     

Herbicidal activity of derivatives of 9-aminofluoren-9-ylphosphonic acid

A series of derivatives of 9-aminofluoren-9-ylphosphonic acid (phosphonic analogues of morphactins) were synthesized and screened for herbicidal activity against Lepidium sativum, Cucumis sativus and Lycopersicon esculentum. Ethyl 9-(N-alkylamino)fluoren-9-yl(phenyl)phosphinates appeared to be equipotent with glyphosate and thus may be recognized as new lead compounds for further structural modifications.     

Simulation of the water and nitrogen balances of forests within a catchment in the northeastern German lowlands

The simulation model FOREST-BGC was used to calculate the regional water and nitrogen balances of coniferous and deciduous forests within the Stöbber catchment area over a period of 4 years. This catchment area is located in the northeastern German lowlands. The forest inventory database of the Landesforstanstalt Eberswalde served as a basis for the estimation of initial values of the forest stands and the soil conditions. The mean annual precipitation rate of the calculation period was 560 mm a^–1, the overall mean annual rate of the calculated interception loss was 178 mm a^–1. Furthermore, a mean annual transpiration rate of 329 mm a^–1 and a mean annual soil water discharge of 77 mm a^–1 were calculated by the model. The simulation of nitrogen leaching resulted in a mean annual rate of 7 kg N ha^–1 a^–1. Some simulation results are compared with measurements, and the database used for the estimation of the model initial values as well as for the model calibration is discussed. Additionally, an evaluation of the model performance was carried out for the purposes of our study. Due to the results of this evaluation, the model algorithms of the nitrogen turnover processes, especially in the soil, seem to be too simple and inappropriate for a realistic calculation of the nitrogen budget of forest ecosystems.