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Tevell, Daniel (2004) Resistenta rapsbaggar. Other thesis, SLU.

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Oilseed rape crops are an important in southern Sweden because of the high intensity of wheat growing. Pollen beetles are the most important pest in oilseed rape and causes often economic losses. Therefore it's of great importance that we can control the population density, e g by using insecticides if necessary, to avoid mayor yield losses. In year 2000 pollen beetles were numerous in the province of Östergötland. The farmers sprayed with insecticides several times, but with low effects on the beetles. Field trials and laboratory experiments showed that pollen beetles had developed resistance against pyrethroids. Between 2001 and 2003 several field trials were laid out in Östergötland to investigate pollen beetle mortality from different groups of insecticides. The results shows that only the highest recommended dose (72 g/ha) of tau-fluvalinat and OP-compounds had acceptable effects on pollen beetles, giving more than 80 % mortality. It might seem strange that tau-fluvalinat had good effects, because it's also a pyrethroide. There is no explanation for this. Inventories among 32 farmers in Östergötland indicate that 78 % of the treatments were made with tau-fluvalinat and 22 % with OP-compounds. The widespread use of tau-fluvalinate has resulted in the first indications of resistance also against this insecticide. Interviews with farm advisers in mayor agricultural districts were held to find out what kind of treatments against pollen beetles they recommended next year to their farmers and how to minimize the risk of more problems with resistance. Recommendations are not to grow spring- and winter oilseed rape crops in the same area, to use winter oilseed rape crops instead of spring varieties and only to use the highest recommended dose. These recommendations will lead to fewer treatments and therefore less risk of resistance development against insecticides.

Item Type: Thesis (Other)
Keywords: rapsbaggar, oljeväxter, växtskydd
Subject (faculty): Faculty of Landscape Planning, Horticulture and Agricultural Science
Divisions: SLU > Faculty of Landscape Planning, Horticulture and Agricultural Science
Depositing User: Users 96 not found.
Date Deposited: 15 Dec 2004
Last Modified: 18 Aug 2015 09:31
URI: http://ex-epsilon.slu.se/id/eprint/270

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