Pollen beetle: when and how to protect oilseed rape
Rape pollen beetle is controlled before flowering, while the flower buds are still closed, once numbers pass the damage threshold: about one beetle per raceme, with sources giving 0.8 to 1.5 depending on the stage. The beetles are counted on the plants; yellow water traps show that they have arrived. Once more than half the plants are in flower, a treatment usually no longer pays.
By Nikola Mojsa, MSc in Agricultural Engineering
What pollen beetle does to oilseed rape
Most of the damage is done by the adult beetles, which appear once the soil temperature passes 8 °C and the air temperature 12 °C (PSS Sombor, Mirjana Zorić, 2025). They chew into the flower buds, and seed yield can fall by 50% or more (same source), which is why ADAMA lists it as the most economically important pest of oilseed rape (ADAMA Serbia).
Cold weather increases the damage: the buds develop more slowly, so they are exposed to the beetles for longer (PSS Sombor). The larvae feed on pollen and parts of the flower and do less damage than the adults.
How to monitor pollen beetle: yellow traps and plant checks
Pollen beetle is monitored in two ways: with yellow water traps and by checking the plants (PSS Sombor). A trap shows that the beetles have arrived, but the threshold is expressed per raceme, so the plant check decides the treatment. Based on the recommendation of the Vojvodina Plant Protection Forecasting and Warning Service (PIS), Poljosfera advises checking at least 50 terminal racemes: diagonally across the field, at 10 points with 5 plants each, in the warmest part of the day, when the beetles are most active (Poljosfera, 2026).
The damage threshold depends on the crop stage:
| Crop stage | Treatment threshold | Source |
|---|---|---|
| Early buds, just formed | 0.8 beetles per raceme | Poljosfera (PIS) |
| Buds tightly packed, not yet separated | 1 to 1.5 per raceme | Poljosfera (PIS); PSS Sombor gives 1 per raceme; ADAMA: a single adult beetle is enough |
| Individual flower buds separated | 2 to 3 beetles | ADAMA |
| Start of flowering | a higher number of beetles, because the beetle feeds on pollen from open flowers | ADAMA |
| More than 50 to 60% of flowers open | treatment is usually not needed | ADAMA; PSS Sombor |
The threshold for your field is set by the PIS warning and your agronomist, according to the current crop stage; the table only shows how the threshold changes from stage to stage.
When to spray oilseed rape against pollen beetle, and when not to
The critical period runs from closed buds to buds turning yellow, that is, BBCH 50 to 59 (PSS Sombor). During this period the beetles chew into the raceme before it opens, so that is when to treat, not at flowering.
Once more than 50% of the plants are in flower, PSS Sombor considers control unjustified, because the beetle then eats pollen from open flowers and does less damage (ADAMA). At flowering, think of the bees: whether a product may go on flowers is stated on the label, and oilseed rape in flower is an important bee forage. Poljosfera warns that there may be hives near the field, so beekeepers should be informed before an insecticide is applied.
That is how we work too: before every insecticide flight we inform nearby beekeepers so they can close their hives.
Spraying oilseed rape by drone
Pollen beetle is small, but the drone covers it well: it flies about 3 metres above the crop, and the strong downdraught from the rotors drives fine droplets down to the lower leaves, so the product reaches every part of the plant. Field crops take 15 to 20 litres of water per hectare. Your agronomist chooses the product and rate from the label, and our agronomist Nikola mixes it at the field, in the tank on our trailer.
A tractor can enter oilseed rape without damage only while the crop is low. Once the rape is taller than 1 to 1.5 m, a tractor tramples and destroys 5 to 6% of the crop. After rain, the drone needs only the road to the field to dry, not the whole field.
The working conditions are the same as for a tractor sprayer: we don't work in the worst of the heat, because the treatment has no effect then. If the wind goes above 3 to 5 m/s, we pause. More on drift in drift in drone spraying.
More on our work in oilseed rape: protecting oilseed rape by drone.
Price of spraying oilseed rape by drone
Spraying oilseed rape costs €25 per hectare up to 20 ha, €22 from 20 to 100 ha and €20 above 100 ha. You supply the product and the water. Travel within 50 km of Opovo is free, and new clients ordering at least 10 ha get the first hectare free on their first order.
Pollen beetle control, a fungicide at flowering and desiccation of the oilseed rape on the same field make three treatments, which earn 5% off. Check the price for your location in the calculator.
Frequently asked questions
Before flowering, while the buds are closed, once numbers pass the threshold. Until the individual buds have separated, the threshold is one to 1.5 beetles per raceme; after that it is 2 to 3 beetles (Poljosfera, ADAMA). Once more than 50% of the plants are in flower, a treatment is usually not done.
Whether a product may go on flowers is stated on the label. Against pollen beetle, treatment at flowering is usually not needed, and before applying an insecticide we always inform nearby beekeepers, because there may be hives close by. A fungicide at flowering is a separate treatment, with its own timing and label.
Yes. The drone flies about 3 metres above the crop and its rotor downdraught carries fine droplets down to the lower leaves, so it covers small pests well. It does not trample the crop, and after rain only the road to the field needs to dry.
- First hectare free
- Free travel up to 50 km
Book your treatment before the buds open
Tell us the location, the number of hectares and what your crop check has shown. We agree the date in advance; the exact day is set by the damage threshold and the wind forecast.