Yellow bowl
The yellow bowl (also Moerickeschale or Moerickefalle) is an instrument for the detection of insects. She will u. a. Used in integrated pest management to control the amount of pest insects that have flown into the plant population ( monitoring ). Information obtained in this way can serve as a basis for decision-making as to whether chemical plant protection measures are necessary.
Appearance
The yellow bowl is mostly made of yellow plastic (in a similar shade to the rapeseed blossom). The color can fade over the course of a growing year. Faded colors have little attraction for the rapeseed pests, so the yellow skin should be replaced or freshly painted. The shape and size can vary, mostly it is rectangular (210 mm long and 90 mm wide) with a volume of up to 1.5 liters. Significantly larger or round shapes are also available. In general, it is given as a free item by crop protection companies. However, it can also be obtained from agricultural or specialist retailers.
Application and use
In order to record the influx of pests in winter rape , four yellow bowls should be set up per field (one bowl per corner of the field). More bowls may be necessary for larger fields. The distance to the edge of the field should be between 15 and 20 m. The trays should be set up so that they can be adjusted in height, i. H. the yellow bowl must grow with the plant population. If the bowl is too high or too deep, the insects will not perceive it properly. The bowls are half filled with water to which a few drops of washing-up liquid are added. The detergent breaks the surface tension of the water and the insects sink into the bowl. The yellow bowls should be checked continuously (every 3 days). Heavily polluted water should be changed. The bowls should have a few holes on the upper edge so that excess water can run off in the event of heavy rainfall without flushing out the previously trapped insects. In order to record the rape pests in autumn, it is advisable to position the yellow pods immediately after sowing (end of August). The yellow bowls should be installed from the end of February or beginning of March (depending on the weather) to control the pests in spring. When the yellow bowls are checked (every 3 days), the pest insects caught are identified and counted. A mean value is determined from the results of the four yellow cups per field. This mean value is compared with the control guide value for the respective pest species. If the control guideline value is reached, then a chemical plant protection measure makes economic sense, i. H. the costs of the plant protection measure are lower than the expected loss of yield.
In Germany, the yellow bowl is used to record the following harmful insects in winter rape:
| Surname | Control benchmark |
|---|---|
| Great rapeseed flea ( Psylliodes chrysocephala ) | 50 beetles / yellow shell in a period of 10 days |
| Great rapeseed weevil ( Ceutorhynchus napi ) | 10 beetles / yellow shell in a period of 3 days |
| Spotted cabbage weevil ( Ceutorhynchus pallidactylus ) | 10 beetles / yellow shell in a period of 3 days |
In addition, the yellow shell also records the influx of the rapeseed beetle ( Meligethes aeneus ) and the cabbage pod weevil ( Ceutorhynchus assimilis ). It is difficult to record the cabbage mosquito ( Dasineura brassicae ) in May and the small cabbage fly ( Delia brassicae ) in September / October, as these species are difficult to distinguish from other species. There are a number of other pests in winter oilseed rape, but these can only be poorly detected with the yellow peel, e.g. B. the cabbage moth ( Plutella xylostella ) or the rapeseed wasp ( Athalia rosae ). Statements about control are not possible in these cases, but the farmer only receives a general indication that these species occur in his rape field.
Current discussion
In recent years, the use of lattice supports (close-meshed 8 mm × 8 mm) on the yellow dishes has been discussed in order to prevent the influx of larger beneficial insects, e.g. B. Bumblebees and bees . Unfortunately, the overlay of the grid has meant that the control guidelines have been partially changed, as a grid also reduces the capture of harmful insects. Uniform control values throughout Germany are therefore de facto no longer available, or a number of special cases are constructed that tend to confuse the farmer. Orientation based on the specifications in the established specialist literature therefore seems to make sense.
In the literature there are instructions to equip the yellow skin with an additional attractant ( isothiocyanate and salicylic acid methyl ester , or rapeseed meal ) in order to improve the attractiveness and thus the catch results. However, since this also artificially influences the influx of insect pests, this method is of no practical relevance for the farmer, as it would simulate a strong influx of pests that actually does not exist.
In principle, the control values are based on results from the 1970s, where relationships between pest incidence and loss of yield were established in field trials. It must be emphasized that the winter oilseed rape varieties have changed significantly since then in terms of breeding (introduction of the double-zero varieties, emergence of the hybrid varieties , etc.). To what extent the control guidelines are still up to date is questionable.
Individual evidence
- ↑ M. Schaefer: Dictionary of Ecology. Heidelberg 2012.
- ↑ JB Free, IH Williams (1979): The infestation of crops of oil-seed rape (Brassica napus L.) by insect pests. Journal of Agricultural Science 92, 203-2018.
- ↑ E Erichsen, F Daebler (1987): To monitor the cabbage pod mosquito (Dasyneura brassicae Winn.) In winter rape. News sheet for the plant protection service of the GDR 41, 33–34.
literature
- David V. Alford: Biocontrol of Oilseed Rape Pests. Blackwell Publishing, Oxford 2003, ISBN 0-632-05427-1
- Olaf Christen, Wolfgang Friedt: Winter rapeseed - The manual for professionals. DLG Verlag, Frankfurt am Main 2007, ISBN 3769006801
- Ingrid H. Williams (ed.): Biocontrol-Based Integrated Management of Oilseed Rape Pests. Springer Netherlands, 2010, ISBN 9048139821