Is your pest control regime up to scratch?04-Apr-2017
Pollen beetles are the number 1 enemy of oilseed rape in the run up to flowering time. They appear from mid March, favouring warm dry weather. These pests bite into the flower buds and lay eggs, from which larvae develop. Buds that are not already open will die as a result of this activity.
However, once the flowers are open on the crop the risk of damage has passed and this pest goes from being a pest to being a pollinator. The adults and the larvae feed on pollen and nectar. In recent seasons pollen beetle levels have often been below thresholds for treatments and thus for most crops treatment has not been justified.
Observation of crop rotation, collection and destruction of plant debris, ploughing and observation of the sowing period are the most important preventive measures against this pest. It’s also important to note that pollen beetles have natural predators such as the Clivina Fossor species of ground beetle.
Assessment – before flowering - of pest pressure should be made before any insecticides are used to target the pest. Larger plants can in any case withstand higher pest pressure since they can compensate more.
Treatment should only take place if thresholds are exceeded, as shown below:
Standard industry thresholds for treatment: less than 30 plants m2 - 25 beetles per plant, 30-50 plants m2 - 18 beetles per plant, 50-70 plants per m2 - 11 beetles per plant, 70+ plants - 7 beetles per plant.
The pest can be worth control but this should be against proper stewardship of insecticides and protection of beneficial insects so routine spraying must be avoided and applications should relate only to properly determined need.
Chemical treatments may be carried out with the products and at the dosages recommended in CODEX.
ALWAYS READ AND FOLLOW DIRECTIONS FOR USE ON PESTICIDE LABELING.