The cabbage seedpod weevil
Adult : 2.5 to 3 mm long, grey-black beetle with dorsal striations.
Larva : Worm 4.5 to 5.3 mm long, pale beige head, translucent white to yellow body depending on stage.
Symptoms in oilseed rape
The larvae develop in the siliques and consume the seeds.
The adults cause wounds on the siliques, which encourage midge egg-laying and fungal diseases.
Flower buds and young siliques may be destroyed during the sexual maturation period (early arrival on crops).
Period of presence
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Observation method
Attention : The presence of this pest should only be monitored from the G2 stage (the length of the first 10 siliques is between 2 and 4 cm) to the G4 stage (the first ten siliques are bumpy).
Visual observation in the field :
3 observation plots on 10 plants.
The number of individuals on the 10 plants is counted and an average is taken per plant.
Pressure level
Low : Presence of a few silique weevils but the plant has not reached the G2 stage (length of the first 10 siliques between 2 and 4 cm).
Medium : Silique weevils are present but the plant has not reached the G2 stage (length of the first 10 siliques between 2 and 4 cm).
Strong : From the E stage to the G2 stage : presence of siliques weevils in the edge of the plot.
From the G2 stage to the G4 stage : presence of a siliques weevil for 2 plants on average within the plot (beyond the 10 m border).
Pressure levels are given for information only and should not be taken as an exact indication of the severity of infestation at a given time or of subsequent damage. Other factors specific to the crop and the dynamics of the development of symptoms or infestations are involved.
Sources
Cultures and produces
This article was written in partnership with <a href="https://www.agrifind.fr/alertes/colza/colza-charancon-des-siliques">Agrifind</a> and <a href="https://www.terresinovia.fr/">Terres Inovia</a>.
