The side effects of 9 insecticides, 8 fungicides and 4 herbicides on 19 different beneficial arthropods and 1 entomopathogenic fungus were tested by the IOBC/WPRS Working Group “Pesticides and Beneficial Organisms”. Twenty research workers from 13 countries participated. A combination of 5 different types of test methods was used: a. laboratory, exposed life stage of the organism, b. laboratory, less exposed life stage, c. semi‐field, initial toxicity, d. semi‐field, persistence (duration of harmful activity), e. field. Although nearly all the insecticides tested were harmful to most of the beneficial insects tested, especially in the first test, few of them were shown to be less harmful or less persistent in further testing. The fungicides Milgo‐E (ethirimol) and Trimidal EC (nuarimol) which are used on cereal crops as well as Rubigan Vloeibaar (fenarimol) and Ortho‐Phaltan 50 (folpet) which are used in fruit orchards were found to be harmless to all beneficial organisms relevant for these crops tested in the experiments and can be recommended for use in integrated control programmes. With different predatory mites, there was clear agreement between the results of laboratory, semi‐field and field experiments. The insecticides Asepta Nexion (bromophos), Birlane EC 40 (chlorfenvinphos), Dursban Spritzpulver (chlorpyrifos), Ambush C (cypermethrin), Basudine Vloeibaar (diazinon), Perfekthion (dimethoate), Phosdrine W 10 (mevinphos), Dimecron 20 (phosphamidon), Hostathion (triazophos) as well as the fungicide Polyram‐Combi (metiram) were found to be harmful to predatory mites in all types of tests. The fungicides Milgo‐E (ethirimol), Corbel (fenpropimorph) and Trimidal EC (nuarimol) were harmless. The agreement of results between the laboratory, semi‐field and field tests indicated that, at least with predatory mites, reliable results can also be expected on the harmfulness of pesticides from laboratory experiments. The results also showed that 6 insecticides, 1 fungicide and 2 herbicides were harmless to the entomopathogenic fungus Verticillium lecanii. Zusammenfassung Ergebnisse des vierten gemeinsamen Prüfprogrammes von Pflanzenschutzmitteln durch die IOBC/WPRS‐Arbeitsgruppe “Pflanzenschutzmittel und Nutzorganismen” Neun Insektizide, 8 Fungizide und 4 Herbizide wurden auf Nebenwirkungen gegenüber 19 verschiedenen Nutzarthropoden und einem entomopathogenen Pilz von Mitgliedern der internationalen IOBC/WPRS‐Arbeitsgruppe “Pflanzenschutzmittel und Nutzorganismen” geprüft. An diesen Versuchen nahmen 20 Wissenschaftler aus 13 Ländern teil. Eine Kombination folgender 5 Arten von Prüfmethoden fand hierbei Verwendung: a. Labor, stark gefährdete Nützlingsstadien, b. Labor, weniger gefährdete Nützlingsstadien, c. Halbfreiland, Initialwirkung, d. Halbfreiland, Persistenz (Schadwirkungsdauer), e. Freiland. Während fast alle geprüften Insektizide gegenüber den meisten Nutzinsekten stark schädigend waren, besonders im Test a., konnte in weiteren Prüfungen bei einigen Präparaten ein geringerer Schädigungsgrad bzw. eine ...

Plant water status indicators have been increasingly used for scheduling irrigation. Different variables may be used to do this, depending on personal preferences and the resources available. Many studies have suggested that selection of an indicator should take into account plant behavior in relation to isohydricity. In two Iberian studies, deficit irrigation (DI) was applied in a vineyard and in a plum orchard while plant water status and fluxes were monitored. These case-studies are discussed with special focus on the use of predawn leaf water potential (Ψ pd ) versus stem water potential (Ψ st ) to determine whether Ψ st performed better and would therefore be the preferred stress indicator for plants exhibiting anisohydric behavior. In contrast, in plants with isohydric behavior, Ψ pd would be generally preferred. This hypothesis seems to be supported by the present results obtained and by prior studies. The cultivars used and the intensity of stress applied have an important influence on the results. This suggests that, if no specific information is available from the existing literature, daily preliminary studies would be recommended prior to application in order to select the most appropriate plant water stress indicators.

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