Fleas are waiting to feed
Winter rapeseed sowing in Poland has already been completed or will be completed in the coming days, depending on the region. Where rapeseed had good conditions for emergence, the plants quickly emerged to the surface. Unfortunately, pests, which are favored by high temperatures, are already "waiting" for emergence. Flea beetles are already visible locally, which can damage young plants from the earliest stages of development.
Rapeseeds that emerge from seeds additionally dressed with insecticides are protected against flea beetles. Unfortunately, this will not provide plants with protection until the end of autumn. Seed insecticide dressings work until the 3-4 leaf phase. In the case of rapeseed sown from seeds dressed only with fungicides, flea beetles may start feeding on the cotyledons.
Rapeseed flea beetles and ground flea beetles are quite characteristic pests, associated primarily with rapeseed damage in autumn. At that time, on young plants we are able to see small beetles with a dark body color and a metallic sheen. Feeding on cotyledons and leaves, they bite small, round holes in them. In large numbers, the pests can actually perforate leaves like a sieve, depriving them of their assimilation surface and destroying them completely. The larvae, in turn, can bite into leaf petioles and shoots, which worsens the winter hardiness of plants.
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How long do seed dressings protect rapeseed?
When and how to combat fleas?
Initial indication of the presence of pests on the plantation is possible thanks to the control using yellow vessels. First we observe the occurrence of ground flea beetles, a little later the rapeseed flea beetle appears on the plantations.
Chemical control of flea beetles in foliar treatment with insecticide is carried out after exceeding the economic damage thresholds. For ground flea beetles after rape emergence, this is 1 beetle per 1 running meter of plant row; in the case of rape flea beetles, 3 beetles per 1 running meter of plant row.
For the control of flea beetles on rapeseed plantations, currently registered (apart from seed dressings) are insecticides with active substances: acetamiprid, cypermethrin, deltamethrin, lambda-cyhalothrin. It is worth noting that the last three substances belong to the pyrethroid group, which show optimal action at temperatures below 20°C, and in our country there is a period of heat, which according to preliminary forecasts will last until September. Acetamiprid shows good action in a wider temperature range. Most of the registered insecticides are intended for post-emergence foliar application from sprayers, but there are also preparations in the form of microgranulates for soil application.
Table – sample insecticides for controlling ground flea beetles and rapeseed flea beetles. Source: Plant protection product search engine of the Ministry of Agriculture and Rural Development, as of 29.08.2024*
Active substance Dose Application date Control of flea beetles/rapeseed flea beetles Examples of pesticides Acetamiprid 0.25 l/ha BBCH 10-17 Rapeseed flea beetles Apis 200 SE, Los Ovados 200 SE Cypermethrin – in microgranulates 12 kg/ha in soil during sowing Rapeseed flea beetles Belem 0.8 MG, Columbo 0.8 MG Deltamethrin 0.05 l/ha- 0.25 l/ha depending on the pesticide from BBCH 10/12, depending on the pesticide Flea beetles, rapeseed flea beetles Decis Mega 50 EW, Delmetros 100 SC
Lambda-cyhalothrin 0.12-0.15 l/ha. BBCH 10-14 Flea beetles, rapeseed flea beetles Karate Zeon 050 CS, Topgun 050 CS
Acetamiprid + lambda-cyhalothrin 0.25-0.30 kg/ha BBCH
13-19 Rapeseed flea beetle Inazuma 130 WG, Nepal 130 WG
* – illustrative information. Before using a plant protection product, read the label and follow its recommendations.
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