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Lahnau, Germany

Bockmann E.,Julius Kuhn Institute | Bockmann E.,Leibniz University of Hanover | Koppler K.,Julius Kuhn Institute | Hummel E.,Trifolio M GmbH | Vogt H.,Julius Kuhn Institute
Pest Management Science | Year: 2014

BACKGROUND: The European cherry fruit fly, Rhagoletiscerasi, is the major insect pest of sweet and tart cherries. Its management is becoming increasingly difficult in many countries as formerly effective but broad-spectrum insecticides are removed from the market. With the objective of identifying suitable and environmentally safe alternatives, we investigated bait sprays containing two families of plant-derived insecticides: azadirachtins (NeemAzal-T® and NeemAzal-T/S®) and pyrethrins (Spruzit Neu®). RESULTS: In 12 semi-field trials conducted within cages, weekly applications of 0.0001 or 0.0005% neem in a bait formulation effectively reduced fruit infestation. However, addition of 0.000125-0.001% pyrethrins did not improve the efficacy of the neem formulations, and when used alone pyrethrins were less effective than neem alone. Two years of field trials were also conducted within orchards wherein an insecticidal barrier of treated trees excluded immigration of fertile R.cerasi from elsewhere. In blocks treated with 0.0005% neem in a bait formulation, we observed 94% (2011) or 86% (2012) reduction of fruit infestation over control blocks. CONCLUSION: Bait sprays containing neem are a promising alternative for the management of R.cerasi, especially where the risk of immigration of fertilized females is low, as in isolated orchards or as part of area-wide treatments. © 2013 Society of Chemical Industry.

Plant extracts (botanicals) are of special significance for plant protection, especially in organic farming. This is due to their origin, specific modes of action, toxicological and ecotoxicological properties as well as to ever changing legal, patent, economic and social/political issues. This paper surveys this complex background and presents data on two selected botanicals which pertain to the use of extract fractions from Glycyrrhiza glabra (sweet wood) for control of Bremia lactucae (downy mildew) in lettuce and azadirachtin for control of leafhoppers in Melissa officinalis L. Both compounds exhibited good effects in the greenhouse which were less pronounced or absent in the field. The effects of sweet wood were strongest when applied twice preventively at 5 % concentration. In the greenhouse, this resulted in a lower number of infected plants and smaller leaf areas attacked by the downy mildew pathogen at high disease pressure. Azadirachtin (plant protection chemical NeemAzal®-T/S in combination with the additive Trifolio S-forte; 1.5 l/ha + 3 l/ha in 600 l water per hektar, 3 applications, interval 7 days) was better in controlling leaf hoppers than natural pyrethrins in combination with rapeseed oil (Spruzit Schädlingsfrei; 6 l/ha in 1,000 l water per hektar, 1 application) in the greenhouse and exhibited very high insecticidal efficacy almost equivalent to that of thiacloprid (Calypso 480 SC; 0.12 l/ha in 400 l water per hektar, 1 application) at moderate disease pressure. Thiacloprid, however, is not applicable in organic farming. In order to introduce these promising results in practical plant protection further fundamental studies are needed. These can only be realized by a joint effort of private companies, research and plant protection institutions, as well as public funding bodies. This article is not meant as a presentation of "perfect" results, it is rather an example of the problems and pitfalls that need to be overcome during development of a botanical and its applications. They are the reason why the market for botanicals will remain small. © 2013 Springer-Verlag Berlin Heidelberg.

Using the insecticidal compounds Azadirachtin and Quassin and plant extracts for control of fungal diseases as examples, the problems and potential of the development of biological plant protection products based on plant extracts are described. Over thousands of years plants had the time and were able to develop mechanisms which protect them against pests and diseases. This natural potential can be used for a safe and environmentally friendly plant protection. Many recent publications are dealing with the topic of biological plant protection. Whether a new product idea will come into practice is also a political question, as well as one concerning registration requirements; until today there is hardly a legal difference between the registration requirements for synthetic and biological plant protection products. However, society appreciates biological plant protection, as is documented by the increasing turnover of biological products.

Scherf A.,Julius Kuhn Institute | Treutwein J.,Trifolio M GmbH | Kleeberg H.,Trifolio M GmbH | Schmitt A.,Julius Kuhn Institute
European Journal of Plant Pathology | Year: 2012

An ethanolic leaf extract of Glycyrrhiza glabra L. (licorice) was highly effective in former bioassays and semi-commercial trials in controlling cucumber downy mildew (efficacy up to 99. 0 % in bioassays and 83. 0 % in semi-commercial trials). In order to elucidate the active ingredients and the mode of action, licorice leaf extract was fractionated into six fractions of defined substance classes, of which the fraction containing acidic substances (F6) showed highest efficacy (97. 6 %). The calculated EC 50 values after a probit analysis of concentration series of crude extract and fraction F6 were concentrations of 1. 0 % (crude extract) and 0. 6 % (fraction F6). Interestingly, the slopes of the resulting graphs were significantly different, pointing to different modes of action for the two treatments. Three flavonoid compounds could be detected. The substances were glabranin, licoflavanon and pinocembrin. All three are known for their antimicrobial and antifungal capacity against plant and human pathogens. Besides these flavonoids, results, such as the different EC 50 values, indicated that other compounds may be involved in the activity of fraction F6 against P. cubensis on cucumber. © 2012 KNPV.

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